CHAPTER 1: PUBLIC AND

ENVIRONMENTAL HEALTH

FOR ECH4102

BY N. ABDULLAH

LEARNING OBJECTIVE

1. To explain environmental engineering aspect in public health.

2. To identify and describe dissemination of infectious disease

related to water and other route of transmission.

PUBLIC HEALTH CONCEPT

Important major areas of public health:

1. Health Services

2. Epidemiology

3. Social/Behavioral Science

4. Environmental Health

Deals with all environmental aspects (physical, chemical & biological) that impact human

health.

Involve assessment & control of these environmental factors to prevent disease &

improve health

5. Biostatistics

Health Services

Deals with diagnose & treatment of diseases

Epidemiology

Study the causes of illness and distribution of disease in populations.

The science behind public health study disease control & prevention.

Social/Behavioral Science

Deals with human psychology, economics, history, and anthropology. Focus to describe, understand, predict,

and change the public's health

Biostatistics

Application of statistic in area of biology via data collection, analysis and interpretation.

applied in public health including epidemiology, health services research, nutrition, and environmental health

PUBLIC HEALTH POLICE POWERS

1. Inspections & closures

2. Licensing & discipline of health professionals & facilities

3. Quarantine & isolation

4. Vaccination, testing and treatment requirement

5. Seizure, embargo and impounding of unsafe substances

Public Health vs. medical care:

1. Skills are very often different

2. Public Health deals with populations, prevention and policy, and

includes research on all of these.

3. Treatment of individual patients is NOT its focus, but rather

populations at risk

MAJOR TYPES OF PUBLIC

HEALTH ACTIVITIES

1. Surveillance

2. Outbreak investigation

3. Reference diagnosis and consultation

4. Research (bench-to-field-to-prevention)

5. Technical assistance & training (lab &

epidemiology)

6. Initiate & support implementation

projects

7. Health policy and Health

communication

[Philosophically founded on Epidemiology]

1. SURVEILLANCE

Definition:

Ongoing systematic collection,

analysis, interpretation and

dissemination of health data =

information for action.

Types of Surveillance:

1. Active

2. Passive

3. Enhances passive

4. Sentinel

6 core activities of public health

surveillance:

1. detection,

2. registration,

3. confirmation,

4. reporting,

5. analysis and

6. feedback

1. Active surveillance: health department

visit or call a location to collect data

2. Passive surveillance: report is sent to

health department based on known rules

and regulations

3. Enhanced passive : Health Department

distribute information on a particular

disease and ask for data/report

4. Sentinel surveillance: a pre-selected

sample of potential data sources submit

information.

1. SURVEILLANCE SYSTEM

Hospital syndromic

surveillance

Syndromes

Diagnostic tests

Bed and ventilator availability

Prescription pharmaceutical stocks/usage

School surveillance

Absenteeism

Syndromes

Reportable disease surveillance

Environmental surveillance

24/7 phone duty

Death surveillance

Pneumonia and influenza

Unusual deaths

Death certificates

OTC pharmaceutical surveillance

EMS surveillance

ELCIDS food-borne disease surveillance

EMS = Environmental Management System/

emergency medical service

OTC = over the counter

ELCIDS = epidemiological and Laboratory

Capacity for Infectious Disease Surveillance

GL

OB

AL

PU

BL

IC S

UR

VE

ILL

AN

CE

:

CO

MP

ON

EN

T &

PR

OC

ES

S

Ref: WHO

GL

OB

AL

PU

BL

IC S

UR

VE

ILL

AN

CE

:

DE

CIS

ION

INS

TR

UM

EN

T

2. OUTBREAK INVESTIGATION

Definition of Outbreak:

The occurrence of more cases than is expected in a given area

over a period of time.

Types of Outbreak:

1. Common source: everyone is exposed to same thing

2. Propagated: spread gradually from a person to another

3. Mixed: common source+propagation

4. Others: zoonotic or vector-borne

2. OUTBREAK INVESTIGATION

Work flow:

1. Prepare for field work

2. Establish the existence of an outbreak

3. Verify the diagnosis

4. Define and identify cases

1. Establish a case definition

2. Identify and count cases

5. Perform descriptive epidemiology

6. Develop hypotheses

7. Evaluate hypotheses

8. Reconsider/refine hypotheses and conduct additional studies

9. Implement control and prevention measures

10. Communicate findings

Objectives:

1. Describe the outbreak: person, place, & time

2. Determine disease characteristics

Specific agent Pathogenicity Incubation period Communicability

3. Identify modes of transmission

Person-to-person/ Airborne/ Common source (food or water)/Zoonotic/Vector-borne

4. Identify additional cases and

contacts

5. Identify the source of infection

6. Interrupt disease transmissionpresent and future.

2. HOW TO CONTROL EPIDEMIC?

1. Insect or animal reservoir- effective control by eliminate

them.

2. Control transmission of pathogen

Food or water: water purification, pasteurised milk, food protection law

Air-borne: difficult to control, wear mask 3. Vaccination-tetanus, small pox, diphtheria, whooping

cough, polio myelitis

1. MMR vaccine (mump, measles and rubella)

2. HPV vaccine-given to young girl (prevent cervical cancer)

4. Quarantine- limit freedom of movement of infected individual

6 quarantinable diseases (international agreement) are: 1) smallpox, 2) cholera, 3) typhoid fever, 4) plague, 5) yellow fever, 6) relapsing fever.

Signal flag called

YELLOW JACK or LIMA

show ship is under

Quarantine.

Vaccination-tetanus, small pox, diphtheria, whooping cough, polio myelitis have been eliminated.

Adult inadequately immunised against childhood disease- low titre of Antibodies as immunity gradually disappear with age., so tetanus vaccine to be given every 10yr

Two vaccines (dead polivirus & oral live-attenuated virus) have eradicated polio from most countries in the world,[3][4] and reduced the worldwide incidence from an estimated 350,000 cases in 1988 to just 223 cases in 2012

Quarantine- involve limitation of freedom of movement of individual with active infection to prevent spread of disease, yellow

HOW VACCINE WORKS?

WHAT IS DISEASE?

Disease (due to an infectious agent) is what may happen while your immune response tries to control

an infection;

Disease may be the final outcome if your immune system either fails, or over reacts.

Infection does not necessarily equal disease

Infectious disease: disease caused by replicating agent transmissible to human from other person,

animal or environment

STAGES OF DISEASE

In term of clinical symptom, typical course of disease can be divided into 6

stages:

1. Infection organism lodged in host

2. Incubation period- time of infection & appearance of symptoms. Length can

be short/long depends on inoculum size, virulence of pathogen, resistance of

host and distance from entrance site to the focus infection site

3. Prodromal period-a short period where 1st symptoms such as headache and

feeling of illness appear

4. Acute period- disease at its height, with overt (done or shown openly; plainly

apparent) symptoms such as fever and chills

5. Decline period- symptom is subsiding, temperature falls, followed by intense

sweating and feeling of well-being

6. Convalescent period- patient regains strength and return to normal.

During later stage of infection cycle, immune mechanism of the host becomes

increasingly important. Recovery is normally due to these immune mechanism.

Endemic low incidence of disease constantly present in population

Outbreak cases number sudden increase in short time

Epidemic larger cases number spread to wider area

Pandemic disease spread cross the globe

Mortality death incidence

Morbidity fatal + nonfatal cases.

Statistically more precise to tell the health of a population compare to mortality- as major cause of illness is quite

different than a major cause of death.

TERMINOLOGY

RELATED TO DISEASE

Endemic

Disease that is constantly present in a population, usually at low incidence

Pathogen may no be highly virulent

Majority of people is immune

Though, few individual may suffer and remain reservoir for the infection

CAUSE OF WORLDWIDE DEATH

TOP10 CAUSE OF DEATH WORLDWIDE

Low Income

1. Lower respiratory infections

2. Diarrhoeal diseases

3. HIV/AIDS

4. Heart disease

5. Malaria

6. Stroke

7. TB

8. Premature birth

9. Birth asphyxia

10. Neonatal infection

Middle income

1. Heart attack

2. Stroke

3. Pulmonary disease

4. Lower respiratory infection

5. Diarrhoeal diseases

6. HIV/AIDS

7. Road accidents

8. TB

9. Diabetes

10. High blood

High Income

1. Heart attack

2. Stroke

3. Lung Cancer

4. Alzheimer

5. Lower Respiratory infection

6. Pneumonia

7. Colon cancer

8. Diabetes

9. High blood

10. Breast cancer

TOP10 CAUSE OF DEATH IN

MALAYSIA (2008)-MEDICALLY CERTIFIED

1. Heart attack

2. Pneumonia

3. Cerebrovascular disease

4. Septicaemia

5. Road accident

6. Chronic respiratory disease

7. Lung cancer

8. Diabetes

9. Condition originating in the perinatal

10. Liver diseases

NATION HEALTH BURDEN-DALY

The WHO global burden of disease (GBD) measures burden of disease using the disability-adjusted life year

(DALY).

This time-based measure combines years of life lost due to premature mortality and years of life lost due to

time lived in states of less than full health.

DALY include assessment on the burden of disease consistently across diseases, risk factors and regions.

EMERGING INFECTIOUS DISEASES

Newly identified & previously unknown infectious agents that cause public health problems either locally or internationally

Re-emerging infectious disease Infectious agents that have been known for some time, had fallen to such low levels that they were no longer considered public health problems & are now showing upward trends in incidence or prevalence worldwide

EMERGING INFECTIOUS DISEASE 1.SARS

2. West Nile disease

3. Variant CJD disease

4. Monkey pox

5. Ebola and Marburg viruses

6. Dengue

7. Influenza H5/N1 (?)

8. Hanta virus

9. E. Coli O157:H7

10. Antibiotic-resistant

Pneumococci

S.aureus (MRSA)

Gonococci

Salmonella

11. Cryptosporidium

12. Anthrax

13.Spanish flu

14. Dengue & DHF

Factor contribute the emergence of EID: AGENT

1) Evolution of pathogenic infectious agents (microbial adaptation & change)

2) Development of resistance to drugs 3) Resistance of vectors to pesticides

EMERGING INFECTIOUS DISEASE

(AIDS-RELATED)

1. Pneumocystis carinii

pneumonia

2. Tuberculosis

3. Mycobacterium-avium

complex

4. Kaposis sarcoma (HHV-8)

5. HSV-2

6. Cryptosporidium

7. Microsporidium

8. Cryptococcus neoformans

9. Penicillium marneffei

10. Disseminated salmonella

11. Bacillary angiomatosis

(Bartonella henselae)

12. HPV

ANIMAL-HUMAN EID

>2/3rd emerging infections originate from animals- wild & domestic

Emerging Influenza infections in Humans associated with Geese, Chickens & Pigs

Animal displacement in search of food after deforestation/ climate change (Lassa fever)

Humans themselves penetrate/ modify unpopulated regions- come closer to animal reservoirs/ vectors (Yellow fever,

Malaria)

FACTORS CONTRIBUTING TO EMERGENCE

AGENT

Evolution of pathogenic infectious agents

(microbial adaptation & change)

Development of resistance to drugs

Resistance of vectors to pesticides

Note : Increasing virulence of microbes like Influenza A virus, which exhibits frequent changes in its antigenic structure giving rise to new strains with endemic and pandemic propensities.

FACTORS CONTRIBUTING TO EMERGENCE

HOST

Human demographic change (inhabiting new areas)

Human behaviour (sexual & drug use)

Human susceptibility to infection (Immunosuppression)

Poverty & social inequality

Aging of population

HOST FACTORS CONTRIBUTING TO EMERGENCE ARE:

1.Mass migration of people provoked by natural and man made disaster with concomitant rehabilitation of displaced people in temporary human settlements under unhygienic conditions.

2.Uninhibited and reckless industrialization leading to migration of labor population from rural to urban areas in unhygienic squatter settlements

3.International travel as a result of trade and tourism contributing to global dispersion of disease agents, disease reservoirs and vectors

4.Changes in lifestyle that promote unhealthy and risk prone behavior patterns affecting food habits and sexual practices.

5.Declining immunity of as a result of HIV infection, which make him vulnerable to a host of infections.

FACTORS CONTRIBUTING TO EMERGENCE

ENVIRONMENT

Climate & changing ecosystems

Economic development & Land use (urbanization, deforestation)

Technology & industry (food processing & handling)

International travel & commerce

Breakdown of public health measure (war, unrest, overcrowding)

Deterioration in surveillance systems (lack of political will)

Environmental sanitation characterized by unsafe water supply , improper disposal of solid and liquid waste, poor hygienic practices and congested living conditions all contribute to emergence of infection.

Climatic changes resulting from global warming inducing increased surface water evaporation , greater rainfall changes in the direction of bird migration and changes in the habitat of disease vectors are also contributory factors.

Deforestation forces animals into closer human contact- increased possibility for agents to breach species barrier between animals & humans

El Nino- Triggers natural disasters & related outbreaks of infectious diseases (Malaria, Cholera)

Global warming- spread of Malaria, Dengue, Leishmaniasis, Filariasis

EXAMPLES OF RECENT EMERGING DISEASES

Source: NATURE; Vol 430; July 2004; www.nature.com/nature

Dr. KANUPRIYA CHATURVEDI

EXAMPLES OF EMERGING INFECTIOUS DISEASES

Hepatitis C- First identified in 1989

In mid 1990s estimated global prevalence 3%

Hepatitis B- Identified several decades earlier

Upward trend in all countries Prevalence >90% in high-risk population

Zoonoses- 1,415 microbes are infectious for human

Of these, 868 (61%) considered zoonotic 70% of newly recognized pathogens are zoonoses Notes : Zoonoses process whereby an infectious disease is transmitted between different species of animals

EMERGING ZOONOSES: HUMAN-ANIMAL INTERFACE

Marburg virus Ebola virus

Bats: Nipah virus Avian influenza virus

EMERGING ZOONOSES: HUMAN-ANIMAL INTERFACE

Hantavirus Pulmonary Syndrome

Borrelia burgdorferi: Lyme

Deer tick (Ixodes scapularis)

Mostomys rodent: Lassa fever

DISEASE

CLINICAN VIEW

classified according to signs and symptoms

1. Diarrheal diseases

2. Respiratory diseases

3. Cutaneous/soft tissue infection

4. CNS diseases

5. Septicemic diseases

6. Fever of undetermined origin

EPIDEMIOLOGIST VIEW

Mean of spread of infectious diseases

1. Contact

Direct

Indirect formites, body secretions

2. Vector

3. Air-borne

4. Food-borne

CAUSATIVE AGENTS OF DISEASE

1. biological- bacteria , virus, protozoa, helminth (virus) and fungi, prion

2. chemical- pesticide, petroleum product, cleansing agent

3. physical- sun UV, X-ray equipment,

4. too little of something- lack of Vit. D cause rickets, lack of niacin cause kwashiorkor

5. too much of something- excessive food or water can be fatal, excess CO2 in respiratory can cause fatal

6. hereditary- haemophilia, baldness, poor eyesight

7. stress-emotional disorder, stroke, heart attack

8. disease of unknown cause- many die due to environmental pollutant working synergistically with other factors. Eg. cancer

CAUSATIVE AGENTS OF DISEASE

Biological, Chemical and Physical cause of disease

are spread through air, water, food, insect, fomites

(fork, doorknob etc) and animal.

In Environmental health, many programmes

address the need to control the causative agent

while it is in the environment before it get into the

public and cause disease

SOME IMPORTANT DISEASES

1. Spread by Contact

STD

Staphylococcus infections

Streptococcal infections

Nosocomial

Rhinovirus colds

Brucellosis (slaughter house contact)

Hepatitis B

2. Vector-borne

Malaria, dengue, yellow fever

Viral encephalitis

Schistosomiasis

Leishmaniasis

Trypanosomiasis

Tularemia

SOME IMPORTANT DISEASES

3. Air-borne

Tuberculosis

Influenza

Childhood infections (measles, mumps, rubella, pertussis)

Legionella

4. Food- & Waterborne

Cholera

Giardiasis

Listeriosis

Staphylococcal enterotoxin food poisoing

Shigellosis

Campylobacter

Salmonellosis

Clostridium perfringens food poisoning

1. TYPES OF TRANSMISSIONS BY

CONTACT 1) Direct Host-to-host

infected host transmit disease to a

susceptible host

route can be respiratory (cold, flu),

direct contact

(syphilis, gonorrhea),

skin direct contact

(staphyloccus causes

boil, pimples) or fungi

(ringworm)

2) Indirect host-to-host

occur by living/ inanimate means

living agent transmit disease is called vector- usually anthropods (insect, mites or fleas) or

vertebrates (dog, cats)

Anthropods only carrier of agent from 1 host to another , not a host for the disease- via biting

Some pathogen replicate inside anthropods (this consider an alternate host) and build up

inoculum

Inanimate agent (fomites)- bedding, toys, books, surgical equipment- which come in contact with

people can also transmit disease.

Food and water are referred to as disease vehicles.

ASSESSING INFECTIOUS DISEASE

TRANSMISSION

Epidemiologist follows the incidence of disease by correlate geographical, seasonal and age-group distribution of a disease with possible modes of transmission.

If disease is limited to a restricted geographical location- it may suggest vector, eg. Tropical region, malaria via mosquito vector

If disease is limited by seasonal- often indicate mode of transmission eg. Measles, chickenpox for school children and close contact

Age distribution- important for statistic to eliminate particular routes of transmission

Different pathogen, have different mode of transmission- usually related to the habitat of the organism in the body

Eg. Respiratory pathogen is usually airborne, intestinal pathogen usually, waterborne/ food borne

PARASITOLOGY VOCABULARY

Host: The animal the parasite lives on/in

There can be more than one host during a life cycle

Often life cycle include larval stages and adult stages in different hosts

Vector: an animal that carries a parasite to the host

Reservoir: Non-human host where the parasite can live

This term is only applied when the parasite can infect humans

DISEASE RESERVOIR

1) Human

AIDS

Syphilis

Gonorrhea

Shigellosis

Typhoid fever

Hepatitis B

Herpes Simplex virus

2) Animal (zoonoses)

Anthrax

Listeriosis

Viral encephalitis

Rabies

Plaque

Brucellosis

Non-typhoidal salmonellosis

DISEASE RESERVOIR

3) Soil

Botulism

Tetanus

Blastomycosis

Coccidioidomycosis

Histoplasmosis

4) Water

Legionnaires disease

Meliodosis

Pseudomonas infections- sepsis, UTI, hot tub folliculitis

CARRIERS

infected individual not showing obvious sign of clinical disease.

Potential cause of infection to others

Acute carrier- individual in the incubation period of disease, then follow by development of the infection

Chronic carrier-individual who had a clinical disease and recovered, or may have subclinical infection that remained in apparent throughout.

Identify carrier by X-ray, immune test, cultural

2 diseases with significant carrier- typhoid fever and TB (usually food handler) eg. Typhoid Mary in early 1990s

EPIDEMIOLOGICAL PROPERTIES

OF INFECTIOUS AGENTS

1. Infectivity

The propensity for transmission

Measured by 2o attack rate in household, school, etc

2. Pathogenicity

The propensity for an agent to cause disease or clinical symptoms

Measured by the ratio of apparent: inapparent

3. Virulence

The propensity for an agent to cause severe disease

Measured by the case:fatality ratio

EPIDEMIOLOGICAL TERMINOLOGY

OF INFECTIONS

Incubation Period

Secondary attack rate

Persistent infection

Latent infection

Inapparent (subclinical infection)

Immunity

Herd immunity

Incubation period - The period between exposure to the agent and onset of infection (with symptoms or signs of infection)

Secondary attack rates - The rates of infection among exposed susceptibles after exposure to an index case, such as in a

household or school

Persistent infection - A chronic infection with continued low-grade survival and multiplication of the agent

Latent infection - An infection with no active multiplication of the agent, as when viral nucleic acid is integrated into the nucleus of a

cell as a provirus. In contrast to a persistent infection, only the

genetic message is present in the host, not viable organisms.

Inapparent (or subclinical infection) An infection with no clinical symptoms, usually diagnosed by serological

(antibody) response or culture

Immunity The capacity of a person when exposed to an infectious agent to remain free of infection or clinical illness

Herd immunity

The immunity of a group or community. The resistance of

a group to invasion and spread of an infectious agent, based

upon the resistance to infection of a high proportion of

individual members of the group.

The resistance is a product of the number of susceptible

and the probability that those who are susceptible will come

into contact with an infected person.

PORTAL OF ENTRY

1. Skin- epidermis provide defence vs. pathogen

entry, if cut occur, pathogen may allow in

2. reproductive organ- penis, uterus and ovaries

require body contact, STD- prevention by prophylactics or abstention from sex

3. respiratory tract (nose, bronchi, aveoli)- TB,

pneumonia, strep, human nose has hair to

filter pathogen, cilia, mucus to prevent it

4. Digestive tract- mouth, aesophagus,

stomach, small intestine and large intestine-

HCL secreted in stomach kill some germ, bile

has an antiseptic power because eof its high

pH

HUMAN DEFENCE AGAINST DISEASE

1st line of defence (ENVIRONMENTAL MANAGEMENT)- prevention. Apply technology and art of science to control causative agent of disease in environment before it gets to human. This use the environmental health element

2nd line of defence (PUBLIC HEALTH & PREVENTIVE MEDICINE)-based on human body adaptation to prevent agent of disease. This include skin, mucous membrane, cilia, tears- so, proper nutrition, good personal health practise, routine check up

3rd line of defence (PUBLIC HEALTH &PREVENTION MEDICINE)-if the 2nd defence are not sufficient to prevent the entrance of pathogens, then use immunity (active and passive) and phagocytosis (natural- leukocytes destroy pathogen in blood).

4th line of defence (CURATIVE MEDICINE)- when sick, need surgery-medication.

THE 1ST LINE OF DEFENCE VS.

DISEASE Water quality management

Human waste disposal

Solid and hazardous waste management

Rodent control

Insect control

Milk sanitation

Food quality management

Occupational health practice assure healthy and safety of worker

International travel sanitation

Air pollution control

Water pollution control

Environment safety & accident prevention

Noise control

Housing hygiene

Radiological health control

Recreational sanitation

Institutional environmental management- prevent nosocomial

infection

Land use management

Product safety & consumer protection

Environmental planning

2nd LINE of DEFENCE vs.

DISEASE: Host defenses: physical, chemical, anatomical barriers:

3rd LINE OF DEFENCE:

nonspecific defenses (passive defenses; innate immunity) respond to any invader natural barriers, antimicrobial compounds phagocytes (neutrophils or polymorphonuclear leukocytes, PMNs) complement natural killer cells (NK cells)

specific defenses (adaptive immunity) respond to a specific invader cell-mediated cytotoxic T cells, activated macrophages humoral - antibodies

cytokines, chemokines small proteins; coordinate, modulate

Host immunity: the ability of higher organisms to resist infection

blood and lymph systems

extravascation:

extravascation:

bacteria

phagocytosis:

PMN

nucleus

lysosome

bacteria are engulfed

in phagosome of PMN

phagosome fusion of

phagosome

and lysosome

degradation of

bacteria within

phagolysosome release of bacterial

fragments to external

environment

several pattern recognition molecules (PRMs) on PMN membrane (aka Toll-like receptors (TLRs))

recognize a pathogen-associated molecular pattern (PAMP)

e.g., TLR-4 recognizes bacterial LPS

Innate host defenses:

natural host resistance some organisms more sensitive to infection by given pathogen than others

age very young, very old individuals are most susceptible

stress fatigue, exercise, dehydration, large climate changes, stress-related hormone release, suppression of inflammation; predispose to infection

diet alteration may influence normal microbiota, decrease resistance, alter susceptibility

physical, chemical, anatomical barriers may prevent successful infection when integrity is intact

tissue specificity pathogen must contact environment suited to its needs, for successful infection

compromised host: one or more resistance mechanisms inactive;

susceptibility increased

suppressed e.g., drug therapy-induced versus compromised e.g., AIDS

3rd LINE OF DEFENCE (continue)

ZOONOSES

disease that occur primarily in animal, but occasionally transmitted to human.

Since public health for animal is less, infection rate for these disease in animal is very high.

to control zoonosis in human is not good approach to eradicate it from animal reservoir.

Success case for zoonosis control are bovine TB and brucellosis via pasteurization of milk.

Some have more complex life cycle. Eg. Protozoa (malaria) and metazoans(tapeworms). So, control in human or in the alternative

animal host.

NOSOCOMIAL INFECTION

Hospital acquired infections Cross infection from patient or hospital personnel and vice versa

present a constant hazard

Hospital are hazardous because

1. many patients are weakened resistance to disease

2. reservoir for highly virulent pathogen

3. Crowding of wards

4. much movement of hospital personnel from patient to patient

5. hospital procedure such as catheterisation, hypodermic injection, spinal puncture, removal of tissue/fluid/biopsy carry risk of introducing pathogen to patient

6. In maternity ward, infant immune system usually susceptible to infection

7. surgical procedure is major hazard, body exposed to source of contamination

8. drug for immunosuppressant (organ transplant patient) increase susceptibility to infection

9. use antibiotic to control infection carry risk of resistant strain (MRSA)

HOSPITAL PATHOGEN

E.coli as most causes for Urinary tract infection, others are yeast Candida albican, Psedomonas aeruginosa,

enterococcus

Staphylococcus aureus - associated with skin, surgical, and lower respiratory tract- problem for newborn baby

S.aureus habitat is in nasal passage as normal flora. So, in healthy personnel show no disease, but once infected the

susceptible patients may cause serious infection

Pseudomonas aeruginosa- causing infection of lower respiratory and urinary tract. Also cause infection in burn

patients (where patient loss barrier to skin infection) It is drug

resistant, so difficult to treat.

WHAT ARE THE

SCARIEST INFECTIOUS THREATS? Bioterrorism (anthrax; smpox; etc.

Pandemics (influenza; plague;..)

Can you say: BIRD FLU ???

Nosocomial

Infections

Ebola; SARS;

Lyme; Hanta;

Cryptosp;

Cyclospora;

E. coli 0157/H7

Mass Casualty =

Bioterrorism; Pandemics

New Infectious Agents =

Nipah virus; Pulmonary Hantavirus

Syndrome; Cyclospora;

Antimicrobial Resistance =

Bacterial, Fungal, Viral, Parasitic

POSSIBLE AGENTS OF BIOTERRORISM

Category A: (anthrax, botulism, plague, smallpox, tularemia,

VHFs)

can be easily disseminated or transmitted from person to person;

result in high mortality rates and have the potential for major public health impact;

might cause public panic and social disruption; and

require special action for public health preparedness

POSSIBLE AGENTS OF BIOTERRORISM

POTENTIAL BIOTERRORISM AGENTS

Category B: (ricin, food/water threats, brucellosis, Q fever, etc.)

are moderately easy to disseminate;

result in moderate morbidity rates and low mortality rates; and

require specific enhancements of CDC's diagnostic capacity and enhanced disease surveillance.

POTENTIAL BIOTERRORISM AGENTS

Category C: (emerging infections like Nipah virus and hantavirus)

availability;

ease of production and dissemination; and

potential for high morbidity and mortality rates and major health impact.

CHARACTERISTICS OF

BIOTERRORISM

Presentation of a rare and serious disease

Presentation of rare and serious symptoms

Large number of people seeking care for nonspecific symptoms

Unexpected rapidly increasing disease incidence

Disease clusters w/a common source of infection

Endemic disease rapidly emerging at an uncharacteristic time or in an unusual pattern

Low attack rates for people who stay indoors

Sudden increase in mortality

BIOLOGICAL AND CHEMICAL

WARFARE

threat to human population,

An emerging challenge for public health

Silent, invisible and deadly

Use to injure, kill and incapicitate

Chemical warfare: gas or liquid form

Biological warfare: living bacteria (B.anthracis-anthrax) or viruses (variolae- small pox)

Use in terrorism act

Chemical warfare: will be discussed in Chapter 7 (sub-section).

CHALLENGE ON DECISION MAKING

Infectious diseases: Some are global, Some are geographically focal, Some are economically important & Some are socially important

Whether to Eradicate or Eliminate or control? Depends on:

Ability of available tools (vaccines, drugs, etc.)

Epidemiologic vulnerability: ability to implement available tools in a cost-effective manner. Based on the LIFE CYCLE

Availability of sustained funding.

Political will:

Burden of disease Perception and promotion of outcome Impact on over all health services sector Impact on over all development Luck

CHALLENGES TO UNDERSTAND &

CONTROL PARASITIC DISEASE

BROAD SCIENTIFIC CHALLENGES

Vaccine development Vector manipulation Drug development Drug resistance Host genetic contribution Rapid surveillance/diagnostic tools Few new scientists entering the field

BROADER SOCIETAL CHALLENGES

Universal Sanitation/Public Health Adequate Housing Adequate Food - nutrition Available Health Care Sustainability (Public/Private/Political Commitment) Few new public health officials entering the field

SOME OF THE REAL CHALLENGES OF

PARASITIC HELMINTH E/E/C CAMPAIGNS

Implementation i.e, Just Doing It

Donor fatigue it takes a long, sustained effort

Drug resistance the threat of any drug- based anti-infectious disease program - especially with a single drug

Monitoring ??

Research ??

See example: Dracunculiasis

TASK TO DEAL WITH EMERGING

DISEASES

Surveillance at national, regional, global level

epidemiological, laboratory ecological anthropological

Investigation and early control measures

Implement prevention measures

behavioural, political, environmental

Monitoring, evaluation

CURRENT SCENARIO OF

SURVEILLANCE SYSTEM

Independent vertical control programmes

Surveillance gaps for important diseases

Limited capacity in field epidemiology, laboratory diagnostic testing, rapid field investigations

Inappropriate case definitions

Delays in reporting, poor analysis of data and information at all levels

No feedback to periphery

Insufficient preparedness to control epidemics

No evaluation

Dr. KANUPRIYA CHATURVEDI

SOLUTIONS

Public health surveillance & response systems

Rapidly detect unusual, unexpected, unexplained disease patterns

Track & exchange information in real time

Response effort that can quickly become global

Contain transmission swiftly & decisively

Dr. KANUPRIYA CHATURVEDI

SOLUTION: GOARN PROGRAMME

Global Outbreak Alert & Response Network

Coordinated by WHO

Mechanism for combating international disease outbreaks

Ensure rapid deployment of technical assistance, contribute to long-term epidemic preparedness & capacity building

Dr. KANUPRIYA CHATURVEDI

SOLUTION: GOARN PROGRAMME The Global Outbreak Alert and Response Network (GOARN) is a technical collaboration of existing institutions and networks who pool human and technical resources for the rapid identification, confirmation and response to outbreaks of international importance. The Network provides an operational framework to link this expertise and skill to keep the international community constantly alert to the threat of outbreaks and ready to respond.

The Global Outbreak Alert and Response Network contributes towards global health security by:

combating the international spread of outbreaks

ensuring that appropriate technical assistance reaches affected states rapidly

contributing to long-term epidemic preparedness and capacity building.

SOLUTIONS Internet-based information technologies

Improve disease reporting

Facilitate emergency communications &

Dissemination of information

Human Genome Project

Role of human genetics in disease susceptibility, progression & host response

Microbial genetics

Methods for disease detection, control & prevention

Improved diagnostic techniques & new vaccines

Geographic Imaging Systems

Monitor environmental changes that influence disease emergence & transmission

KEY TASKS - CARRIED OUT BY WHOM?

National

Regional

Global

Synergy

WHAT SKILLS ARE NEEDED?

Multiple expertise needed !

Infectious

diseases

Epidemio-

logy

Public Health

International

field experience Information

management

Laboratory

Telecom. &

Informatics

GLOBAL DISEASE INTELLIGENCE:

A WORLD ON THE ALERT

Collection

Verification Distribution

Response

THE BEST DEFENSE (MULTI-FACTORIAL)

Coordinated, well-prepared, well-equipped PH systems

Partnerships- clinicians, laboratories & PH agencies

Improved methods for detection & surveillance

Effective preventive & therapeutic technologies

Strengthened response capacity

Political commitment & adequate resources to address underlying socio-economic factors

International collaboration & communication

END PART 1

PARASITIC DISEASES

PATHOGENS CATEGORY CAUSING

DISEASE

1. Virus

2. Bacteria

3. Fungi

4. Parasites

PATHOGENS CATEGORY CAUSING DISEASE Dissemination of fungi in the body indicates a breach or deficiency of host defenses.

Superficial fungal infection: on cutaneous skin, hair, no discomfort to patient, eg tinea vigra, tinea visicolor

Cutaneous fungal infection: dermatophyte, ringworms-most fungal infection in human

Subcutaneous mycoses: deeper layer of epidermis

Systemic mycoses: eg in lung, can be life threatening

Biphasic or dimorphic: can exist as mold/hyphal/filamentous form[1] or as yeast.

Prion: is PrP is an infectious agent composed of protein in a misfolded form

Some fungi, eg yeast Candida spp. can be found on skin rich in subaceous gland (eg: mouth, vagina). Found in healthy tissue, but sometimes under certain condition can cause disease

MAJOR GROUPS OF PARASITES

1. Protozoans Single-cell eukaryotes Eg: Malaria, Giardia, Trichomonas vaginalis Can invade:

Tissues- Trypanosomes, Toxoplasma, Plasmodium Intestinal lumen- Entamoeba histolytica, cryptosporidium

2. Helminths (The Worms)

Multicellular animals Flukes, Tapeworms, Roundworms

3. Ectoparasites

Multicellular animals Live outside the host Ticks, Lice, Flea

PROTOZOA: TRYPANOSOMA CRUZI

Causing Chagas disease

Epidemiology:

Mexico to S. America 16-18 million people infected (45,000 die/yr)

Vector: Reduviid bug (aka. kissing bug)

Reservoir: rodents, dogs, cats, armadillos,

Pathologies:

Inflammation at bite Swelling of the eyes Fever, malaise Enlarged Heart Heart Failure

PROTOZOA: MALARIA See example for challenge to control and eradicate section.

PROTOZOA: ENTAMOEBA HISTOLYTICA

Epidemiology:

Worldwide distribution- Mexico, India, West and South Africa, South America

10% of the worlds population is infected (50 million)

Most are asymptomatic (carriers)

50-100,000 deaths per year

Vector: Flies carry cysts from human feces to human food or water or humans self-infect after touching fecally contaminated items, can be sexually transmitted

PROTOZOA: ENTAMOEBA HISTOLYTICA

Reservoir: Humans are the only hosts

Pathologies:

Mild to severe intestinal discomfort

Dysentary (bloody diarrhea)

Can invade and destroy the liver (abscess)

Treated with Metronidazole (flagyl)

HELMINTHS (THE WORMS) Three main groups:

1. Flukes- Liver flukes, Lung flukes, Intestinal flukes, Schistosoma

species (blood flukes)

2. Roundworms-

Intestinal (Pinworm, Whipworm, Ascarids, hookworms)

Tissue (Trichinella, Anisakis, Baylisascaris)

3. Tapeworms-

Intestinal (Teania solium-beef tapeworm)

Tissue (Echinichoccus granulosus)

HELMINTHS : PIN WORM

Enterobius vermicularis (Pin Worm)

Epidemiology:

Worldwide

Most common helminth in North America

No vector

No reservoir

Treatment: Mebendazole

HELMINTHS : ASCARIS LUMBRICOIDES

Giant Roundworm of Humans

Epidemiology:

Temperate/tropical regions with poor hygiene

2 billion (~1/3 of world pop.)

Fecal-oral transmission (eggs)

No vector, No reservoir

Night-soil

Pathologies:

Adults (12-20cm) in intestine can cause mechanical obstruction

Abdominal pain

Bowel perforation

Cough & wheezing from juveniles in lungs

Treated with Mebendazole

HELMINTHS : ASCARIS LUMBRICOIDES

HELMINTHS : FASCIOLOPSIS BUSKI

(INTESTINAL FLUKE)

Epidemiology: Southeast Asia

Females (2-7cm) produce about 25,000 eggs/day.

no vector, but has 3 hosts

Abdominal pain, diarrhea, malabsorption, toxemia

Attaches to mucosa

Reservoir: Pigs

Treatment: Praziquantel

HELMINTHS : FASCIOLOPSIS BUSKI (INTESTINAL FLUKE)

HELMINTHS: ECHINOCHOCCUS

GRANULOSUS

(Hydatid Cyst Disease)

Epidemiology: S. America, Australia, Kenya, Europe,

Russia- (where dogs are used for herding sheep)

Canine tapeworm (dogs, wolves, coyotes)

No vector

Reservoirs: Sheep, elk, caribou

Pathologies: cysts can infect liver, lungs or spleen.

Pathologies depend on location of the cyst Jaundice, coughing etc

If ruptured, the cyst fluid will typically kill the host

HELMINTHS: ECHINOCHOCCUS GRANULOSUS

3) ECTOPARASITES

Insect, mites (scabies), lice, pubic louse

(crab), head louse.

Epidemiology: Worldwide

Usually no vector

Usually temporary

Reservoirs: variable

Pathologies: Itching, scabs at the site of the bite, rashes, redness etc.

Often carriers of bacterial infections

PUBLIC HEALTH CONCERN:

EXAMPLES OF PARASITIC CASES

1) Drancunculiasis

2) Malaria

Guinea worm being removed in Zabzugu-Tatale, Ghana; 2000

1) Dracunculiasis

Dracunculus medinensis (Guinea worm)

PROGRESS IN THE ERADICATION OF DRACUNCULIASIS

1981 -- > 4,000,000 cases

1986 -- 3,500,000 cases

1989 -- 890,000 cases

1992 -- 374,000 cases

1995 -- 129,000 cases

1998 -- 79,000 cases (61%, Sudan)

1999 80,000 cases (70%, Sudan)

2000 -- 70,000 cases (73%, Sudan)

2001 -- 60,000 cases (78%, Sudan)

2002 -- 50,000 cases (74%, Sudan)

2003 -- 31,000 cases (62%, Sudan; 27%, Ghana)

2004 -- 16,026 cases (45%, Sudan; 45%, Ghana)

2005 -- 10,715 cases vs. 14,418 in 2004 (Jan-Oct)(61%, Sudan; 29%, Ghana)

[Down from 20 to 4 countries; Chad, Ethopia, Mali & South Sudan, 2012 only 542 cases]

DRACUNCULIASIS ERADICATION

Coordinating Programs:

WHO; UNICEF; Peace Corps; World Bank; NGOs;NHDI

Global 2000/Carter Center; B&M Gates Fdn ($28.5M)

WHO Collaborating Center (CDC)

Industrial partners

Critical Elements:

Safe water: Borehole or scoop wells; Rx source water (temephos); Filter water (nylon nets; PVC pipe filters)

Community-level health education

Case Containment, plus rewards

Regional/Country/Local (village level) commitment

Monthly reporting and feedback

Coordination and financing

WHAT ARE THE MAJOR CHALLENGES

TO GUINEA WORM ERADICATION?

It requires behaviour change !!!

People need to stay out of the water when they have lesions

People need to filter their water through nylon nets

In part this depends on knowledge and alternatives, but not

entirely

Other aspects are organizational, financial, technical and political

CHALLENGE OF ANTIMICROBIAL

RESISTANCE

Example: Malaria

~2.5 Billion (40% Worlds Population) At Risk

400-900 million febrile infections/year

0.7-2.7 million deaths/year, >75% African children

~4 die per minute ~5000 die per day ~35,000 die per week

< 20% come to attention of the health system

Pregnant women at high risk of dying, low birth weight children

Children suffer cognitive damage and anemia

Families spend up to 25% of income on treatment

Major Impediment to Economic Growth and Development, as well as health

2) MALARIA

Is malaria an emerging disease? YES !!! [At least drug-resistant malaria is an emerging disaster]

1940

Chloroquine

16 years

Fansidar

6 years

Mefloquine

4 years

Atovaquone

6 months

1950 1960 1970 1980 1990

DEVELOPMENT OF RESISTANCE TO

ANTIMALARIAL DRUGS

CHALLENGE OF ANTIMICROBIAL

RESISTANCE

SOLUTIONS..

Reduce infections (hand washing, vaccines, etc.)

Judicious (done with good judgement or sense) use of antibiotics (not every ear ache)

Limit human antibiotic use in animals

Combination therapy

Target virulence factors

Competitive exclusion

Malaria Prevention

Mosquito Avoidance - Evening and night behaviour - Mosquito Nets - Air conditioning - Screens - Repellant - Pyrethrin coils Mosquito Killing - Destroy breeding sites - Fog spraying - Residual spraying Plasmodium killing - Chemoprophylaxis

WATER-RELATED INFECTIONS

WATER RELATED

INFECTIONS

Related to water or impurities in water

Transmission by 4 mechanism :

1) Water- borne

2) Water-washed

3) Water-based

4) Insect vector

1. WATER-BORNED MECHANISM Pathogen in water taken by human/animal

Disease eg. Cholera, typhoid, diarrhoeas and dysenteries

These disease also can be transmitted by any route which allow faecal-

mouth contact

Preventive strategy- improve drink water quality, prevent casual used of

unimproved sources

cholera patient showing evidence of extensive fluid loss (hand, cheeks)

(CDC Public Health Image Library)

2.WATER-WASHED

MECHANISM

Infections of intestinal tract and skin

Poor hygiene and limited availability of water

3 types:

Infection of intestinal tract diarrhoeal, cholera, dysentery

Infection of skin and eyes-skin sepsis, scabies and fungal infection due to poor hygiene

Infection due to lice and mites

Prevention-increase water quality, improve

accessibility and reliability of domestic water supply,

improve hygiene

3.WATER BASED

MECHANISM

Pathogen spends a part of its life cycle in a water snail or other aquatic animal

Infection of parasitic worms (helmiths)

Eg: Guinea worm, larvae escape man through blister and into small aquatic animal, then man drink

water containing these larvae

Acquire by eating insufficiently cooked fish

Prevention: reduce contact with infected water, control snail population

4. INSECT VECTOR MECHANISM

Spread by insect which either

breed in water or bite near water

Eg. Malaria, yellow fever,

dengue, river blindness and

sleeping sickness

Prevention-improve surface

water management, destroy

breeding sites, decrease visit to

breeding sites, use mosquito

netting

EXCRETA-RELATED

INFECTIONS

All disease in the faecal-oral route, most water-based diseases are caused by pathogen transmitted in human excreta (normally in

faeces)

This can be controlled by improvement of water supply and hygiene, excreta disposal, toilet, final disposal or re-use

A). FAECAL-ORAL DISEASE (NON-

BACTERIAL)

Cause by virus, protozoa and helmiths

Spread easily from person due to bad hygiene

Improve excreta disposal unlikely to reduce their incidence. Health

education

b). Faecal-oral disease (Bacterial)

Person-to-person transmitted,

Also contaminated food crops, water source with faecal material

Eg. Salmonella passed in the faces of bird

C). SOIL-TRANSMITTED

HELMITHS Parasitic worms whose eggs are

passed in faeces

This route require period of development in favourable of their growth- usually moist soil

Reach to human via ingestion

Latrine help to avoid faecal contamination of the floor hep to limit transmission

Eggs survive for months between host

Eliminate eggs by sedimentation in stabilisation ponds, heat or prolonged storage

D). BEEF AND PORK TAPEWORMS

(TAENIA)

Require period in body of host before infecting human

When meat eaten without sufficient cooking

Prevent untreated excreta eaten by pig/cattle help

prevent transmission of

parasite

E). WATER-BASED HELMINTHS

Passed in excreta and then to snail (aquatic host)

Re-infect man through skin or eating uncooked fish

One egg can multiply in snail to produce thousand larvae

F). EXCRETA-RELATED

INSECT VECTORS

2 kinds:

1.Culex pipens group of mosquitoes, breed in highly polluted water and

transmits filariasis

2. Flies and cockroaches, breed where faeces exposed, they carry

pathogen on their bodies and intestinal tract.

REFUSE-RELATED

INFECTION

Poor refuse disposal encourage fly breeding

Promote disease associated with rats, such as plague, salmonellosis, endemic typhus

Uncollected refuse can obstruct streets and drainage channel

Refuse is potential source for composting, food source of animal

HOUSE-RELATED

INFECTION

Interaction between housing and human health are numerous

Location affect the health of inhabitant

In manner promote airborne disease- overcrowding, ventilation, air, temp, humidity

In manner promote population of rats, fleas, mites, lice- share with animals, poultry, pets.

WATER RELATED

DISEASES-EXAMPLES

transmitted almost exclusively via contaminated water (fecal-oral route); also raw shellfish, vegetables (Americas)

7 or 8 world-wide pandemics since 1817 endemic in Africa, parts of Asia, Indian subcontinent, Central & South America controlled by applying appropriate water treatment, sanitation measures

V. cholerae: gram negative, curved rod; free-living in coastal waters, adhering to

normal microbiota

disease: initiated when ingested bacteria attach to epithelial cells of small

intestine, begin to grow and release enterotoxin (toxin affecting GI tract)

characterized by copious watery diarrhea rice water stools fluid losses may exceed 20 L per day untreated, mortality rate can reach 60%

treatment: intravenous or oral liquid and electrolyte replacement therapy

(20 g glucose, 4.2 g NaCl, 4.0 g NaHCO3, 1.8 g KCl in 1 L H2O)

EXAMPLE 1 : CHOLERA

EXAMPLE 2: Typhoid (Salmonella typhi)

most common route of transmission is via water; may also be foodborne, by direct contact with infected individuals

virtually eliminated in developed countries as a result of water treatment practices

carrier state can be important (carrier: individual that harbours organism but shows no disease symptoms)

story of Typhoid Mary see p. 823 (11th ed) or p. 853 (10th ed) of Madigan

S. typhi: gram negative rod, one of the Enterobacteriaceae

disease: systemic infection with sustained bacteremia (bacteria in blood),

characterized by high fever (several weeks)

also initial headache, often constipation, then diarrhea complications may include perforation of intestinal wall mortality may approach 15% in untreated typhoid; reduced to less than 1% with antibiotic therapy (e.g., chloramphenicol, ampicillin, cephalosporins)

Example 3: Legionellosis (Legionella pneumophila)

severity of infection varies:

may be asymptomatic Pontiac fever: mild cough, mild sore throat, mild headache, self-limiting Legionellosis: a type of pneumonia, more likely to affect elderly, immune-

impaired, associated with certain L. pneumophila serotypes

intestinal disorder. then high fever, chills, muscle aches, followed by dry cough, chest and abdominal pain

Legionella: discovered in late 1970s, probably a recent human pathogen

present in small numbers in natural waters and soil, may live inside free-living protozoa, heat- and chlorine-resistant

lives happily in cooling towers, air conditioning systems, hot water tanks, whirlpool spas, etc.

bacteria disseminated in humidified aerosols, human infection is via airborne droplets (showering, water-dependent heating/cooling systems)

no person-person transmission

entirely different than other pathogens involved in respiratory infections a newly emergent disease resulting from changing human behaviour

Example 4: Cryptosporidiosis and Giardiasis

common waterborne diseases in areas with regulated water supplies cysts or oocysts of these parasitic protozoa found in most surface waters

chlorine-resistant; dose rates can be low cryptosporidiosis in Milwaukee, WI affected over 400,000 people (spring 1993)

outbreak attributed to overburdened water supply system + spring rains and runoff from surrounding farmland into L. Michigan (source for supply system)

Giardia lamblia: flagellate; infects animals (e.g., beaver), humans

environmentally resistant cyst (~10 m dia) is infective agent ingested cysts germinate in intestine, resultant trophozoites grow on intestinal wall explosive, foul-smelling, watery diarrhea, cramps, flatulence, nausea, weight loss

Cryptosporidium parvum: infects variety of warm-blooded animals

resistant oocysts transmitted to new host via feces-contaminated water oocysts (~2-5 m) smaller than Giardia, more chlorine-resistant ingested oocysts germinate, trophozoites growth within epithelial cells of stomach,

intestine

mild, self-limiting diarrhea in healthy individuals chronic diarrhea in individuals with impaired immunity (+ possible

complications)

trophozoites

cyst stained

with iodine

Giardia lamblia life cycle (US CDC)

Giardia lamblia life cycle (US CDC)

E.COLI 0157:H7

Illness through food & water, undercooked, contaminated food

Enterohemorraghic, diarrhea, kidney failure

Highly virulence. 10-100 cfu can cause illness

Outbreak: 1982 in USA due to consumption of hamburger

SHIGELLOSIS

infectious disease caused by bacteria Shigella

Symptoms: diarrhea, fever, stomach cramps, bloody stool after 1-2days expose to bacteria. Last 5-7days.

WATERBORNE VIRAL

DISEASES

Waterborne viral diseases: many cause gastroenteritis (e.g., rotaviruses, Norwalk-like) may cause eye throat infections (e.g., adenoviruses) hepatitis (liver disease): hepatitis A, hepatitis E viruses polio: wild poliovirus been eliminated from western hemisphere

most are neutralized by chlorination

ENTEROTOXIGENICITY OF E.COLI INFECTION

ROTAVIRUS INFECTION

SHIGELLA INFECTION

AIR-BORNE INFECTIOUS

DISEASES

PART OF CHAPTER 8 OF THIS COURSE

WHATS THE PROBLEM TO HUMAN?

RESPIRATORY SYSTEM

Respiratory

System

OBJECTIVES

To describe transmission, prevention and control of respiratory

diseases caused by microbial agent (air pollutant) due to poor

environmental health.

Other types of air pollutants (PM, chemicals, Sox, Nox, Pb, VOC,

O3, DPM, smog, etc will discuss in separate chapter; Air pollution)

RESPIRATORY

DISEASES Air inside building contains 500-1000 microbes/cubic meter of air,

humans breathe 6 liters/min at rest. So up to 10,000 microbes per day enter lungs.

Air contains fungal spores, some bacteria.

But most infections occur by coming in contact with fluids from sneezes, coughs, hands of other infected people.

Respiratory infection l-develop colds just from inhaling droplets via sneezing or coughing. Hand contact is much more frequent, and rubbing eyes after contact is an especially effective way of getting virus into body.

Best defenses: Frequent hand washing and avoidance of close contact with infected people

SUMMARY OF EPIDEMIOLOGY FOR

TYPICAL RESPIRATORY DISEASE

EXAMPLES OF RESPIRATORY TRACT

PATHOGENS: COMMON COLD

The most common of all infectious diseases. Average American gets 2/year.

Over 200 different viruses may cause cold. Most are RNA viruses in rhinovirus or adenovirus family

Reproduce best at temperatures cooler than body temp. (33C rather than 37C), which is nasal pathway temp., so most infections occur in epithelial lining of nasal passageway.

Infection usually last a week or so, until antibodies to virus are made.

EXAMPLES OF RESPIRATORY

TRACT PATHOGENS: PNEUMONIA

One disease (inflammation in alveoli of lungs) -- many possible causes.

Normally occurs as secondary infection following viral infection or other ilness.

One of top 10 cause of death

Most frequent pathogen in many cases = Streptococcus pneumoniae.

Bacterium grows rapidly in alveoli, protected from phagocytosis by capsule. Lung spaces fill with blood, bacteria, phagocytes fluid buildup lung inflammation.

EXAMPLE OF RESPIRATORY TRACT

PATHOGENS: PNEUMOCYSTIS PNEUMONIA

a fungal disease, caused by Pneumocystis carinii, a yeast.

Used to be rare, but since AIDS, disease has exploded into prominence. In early days of AIDS, 80% of patients developed this

type of pneumonia.

In lung, Pneumocystis carinii elicits intense inflammatory response, produces foamy exudate of fluid. As infected cells die, leaves

honeycomb appearance.

Can be treated with certain antifungal antibiotics.

OTHER CAUSES OF

PNEUMONIA

Staph. aureus, often after influenza infection.

Legionella pneumoniae, first isolated in 1976 at a Legionnaire's convention. Bacteria can grow in water-cooling towers used for

air conditioners, was spread as fine aerosol in closed

buildings.

Mycoplasma pneumoniae, often spread by people living in close quarters (schools, military barracks)

Diphtheria

Caused by bacterium Corynebacterium diphtheriae.

Infection can lead to a "pseudomembrane" covering the posterior pharynx (back of the throat to you non-clinical types).

Diphtheria toxin: Toxins released by the organism create an inflammation on the pharyngeal mucosal surfaces. The pseudomembrane may obstruct breathing to the point of asphyxation and death. The toxin may travel to the heart and lead to heart failure

STREPTOCOCCAL

DISEASES

Streptococcus pyogenes-microbiota of 5-15% of humans,

usually in respiratory tract, usually not producing obvious

disease.

Streptococcal infections can produce a family of diseases -

examples:

suppurative (pus-forming) infections

pharyngitis (sore throat)

scarlet fever (extensive skin rash)

impetigo (infection of superficial skin layers

cellulitis (infection of deep skin layers)

necrotizing fasciitis (bacteria attack and destroy muscle tissue)

streptococcal toxic shock syndrome

TUBERCULOSIS

M. tuberculosis is a strictly aerobic bacterium, with a very slow doubling time (12-18 hours)

long latent period; antibody response are 8-12 weeks after infection.

TB is usually asymptomatic; only 10-20% of infected persons become diseased.

How does M. tuberculosis cause disease? any, but lung is common focus of infection, so consider sequence of infectious TB in lung:

Bacterium is taken up inside phagosome by macrophage (first stage of phagocytosis), grows and replicates & form tubercule which may spread through respiratory system and other tissues

Patients with pulmonary TB have respiratory problems, cough up mucus secretions frequently. TB can attack many other sites in body as well as lungs.

TB is one of the most common diseases world-wide.

Worldwide annual deaths from TB: 3 million (98% in developing countries)

Worldwide annual reported disease cases: 8 million Worldwide incidence of infection: somewhere between 1 in 10 to 1 in 3

people

LEPROSY

Mycobacterium leprae

Bacterium cannot be grown in culture, only in footpads of

armadillos (lower body temperatures).

One of the most dreaded (and joked about) of diseases.

Still a major problem, 14 million people worldwide,

Transmission is still a mystery. Most people who come in

contact with lepers do not get infected. Lepers have high

bacterial counts in nasal discharges, but disease does

not spread in epidemic fashion.

Disease manifestation: 2 types

Lepromatous leprosy. The worst form of the disease,

bacteria spread to every organ and part of body. Can

lead to loss of fingers, toes, nasal deformation,

eventually death.

Tuberculoid leprosy. Mild disease, symptoms due to

delayed hypersensitivity to proteins. Full recovery often

occurs.

INFLUENZA

infectious disease of birds and mammals

fever, sore throat, muscle pains, severe headache, coughing, and weakness and fatigue

Pneumonia

Can be confused with common cold. Flu is much more severe!!!

INFLUENZA VIRUS

RNA, enveloped

Viral familyorthomyxoviridae

Size80-200nm in diameter

Three types

A, B, C

Surface antigens

H (haemaglutinin)

N (neuraminidase)

Highly contagious

Incubation 2days (1-4days)

Mode of transmission

Droplet (conjunctiva, nasal and nasal mucosa)

Airborne Contact

Viral Survival

Humidity (35-40%), 28oC 1-2days on nonporous

surface

Can undergo antigenic shift and drift

NATURAL HOST OF INFLUENZA VIRUS

PANDEMIC FLU

Bird Flu

Human Flu

Swine Flu

Horse Flu

Dog Flu

ANTIGENIC SHIFT: RE-ASSORTMENT

In human

ANTIGENIC SHIFT: RE-ASSORTMENT in pigs

ANTIGENIC DRIFT: MUTATION

In human

EXAMPLE 1: SARS- BIRDS TO HUMAN

Hong Kong, SAR

China, 1999, H9N2

The Netherlands,

2003, H7N7

Hong Kong, SAR

China, 2003, H5N1

Hong Kong, SAR China, 1997, H5N1-Hundreds of infections

with H5N1 bird flu (over a short timeframe)

18 hospitalizations

6 deaths

BIRD FLU -WORLD-WIDE THREATS

Wash. Post, Dec. 16, 1997

EXAMPLE 2: H1N1 INFLUENZA

Spanish flu-1918

Global death total: 50 million to 100 million

In 6 months 20 million deaths

The greatest medical holocaust in history" and may have killed as many people as the Black Death

was misdiagnosed as dengue, cholera, or typhoid

category 5 influenza CDC pandemic severity index (ie: projected death in USA 2 Million)

H1N1 PANDEMIC- 2009

Refer to swine flu

Over 182166 reported cases, 1799 death, in 177

countries

rates of influenza illness continue to decline in the

temperate regions

Tropical Asia -increasing rates of illness as they

enter their monsoon season

India, Thailand, Malaysia, and Hong Kong-have

active surveillance programs

H1N1PANDEMIC- 2009

MALAYSIA

Nipah virus outbreak in 1999,

Severe Acute Respiratory Syndrome (SARS) not affected

(H5N1 (bird flu) outbreak in 2004.- not affected

National Influenza Pandemic Preparedness Plan

(NIPPP) which serves as a time bound guide for

preparedness and response plan for influenza

pandemic.

HINI in 2009

STRATEGY TO SLOWDOWN

H1N1 ANTIVIRAL DRUG &

VACCINE Oseltamivir (trade name Tamiflu)

Zanamivir (trade name Relenza)

PUBLIC RESPONSE

Social distance

Respiratory hygiene

Mask (N95 mask for health-care worker)

Hygiene

Risk communication

PANDEMIC PROBLEMS

Not enough vaccine

Not enough antivirals (oseltamvir)

Classical epidemic control

Physical restriction of people

Isolation of the sick

Quarantine of the exposed

Ban all public gatherings: work, school, shopping malls, theaters, churches, and yes, bars and clubs

BENEFIT OF PANDEMIC

INFLUENZA PLANNING AND

FEARS

Silver lining factor

Improved surveillance

Planning for vaccine strategies, vaccine supply

Attention of media, governments, markets

May break the vicious cycle of neglect, followed by no effort or investment

END OF CHAPTER