epidemiology of smallpox,chickenpox,rubella and measles
Post on 17-Jan-2017
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TOPICS:1. SMALL POX
2. CHICKEN POX3.RUBELLA
Caused by Variola virus
Double stranded DNA Orthopox virus
Variola major or minor
Stable outside host(retains infectivity)
SMALLPOX (चेचक ,शीतला, बड़ी माता)
RESERVOIR Before global eradication, the only reservoir - humans. No natural reservoir for the virus currently exists. AGENT variola major or minor
TRANSMISSION Inhalation of droplet or aerosols originating from
the mouth of smallpox-infected humans Direct contact with skin lesions or infected body
fluids of smallpox-infected humans Direct contact with contaminated clothing or bed
In the 18th century, British troops in North America gave smallpox infected blankets to their enemies, who went on to suffer severe outbreaks of smallpox.
Russian scientists describe covert Russian operations during the 1970s and 1980s that focused on bioweapons research and development including creation of more virulent smallpox strains and development of missiles and bombs that could release smallpox
SMALLPOX AS A BIOLOGICAL WEAPON
LAST CASE IN INDIA- 24TH MAY,1975 ( SAIBAN BIBI, ASSAM) INDIA DECLARED FREE OF SMALLPOX- 5TH JULY 1975LAST CASE OF SMALLPOX in WORLD- OCT 26, 1977MAY 8, 1980, OFFICIAL DECLARATION BY WHO - SMALLPOX
The End of Smallpox
Last case of Variola minor, Somalia 1977
Last case of Variola major, Bangladesh 1975
EPIDEMIOLOGY OCCURRENCE – both as endemic and epidemic RESERVOIR – human AGENT – varicella zoster
TRANSMISSION person to person respiratory tract secretions direct contact with lesions
TEMPORAL PATTERN In temperate areas-distinct seasonal fluctuation with the highest incidence occurring in winter and early spring. In the United States, incidence is highest between March and May lowest between September and November. Herpes zoster has no seasonal variation and occurs throughout the
GLOBAL STATUSChickenpox led to about 105 deaths a year during
the pre-vaccine years of 1990 to 1994. Between 2002 and 2007, the annual average
number of chickenpox deaths was the lowest ever reported, with 14 deaths recorded in 2007 and just 13 the year before.
In 2006, a second dose was added to the vaccination roster which really eliminates casualties
Chickenpox related deaths are now extremely rare.
The CDC's new report from THE NATIONAL
CENTER FOR IMMUNIZATION AND RESPIRATORY DISEASES, which updates an earlier analysis from 1995 to 2001, shows deaths have dropped by as much as 88 percent over the first 12 years in all age groups and by 97 percent in young people( 20 and under), since the varicella vaccine was introduced.
INDIAN STATUS OF CHCKEN POXIn 2013- 28090 cases of chicken pox with 61
deathsCase fatality rate = 0.21%Kerala – highest (121168 cases)West bengal – max deaths
•From Latin meaning “little red”•GERMAN MEASLES•Discovered in 18th century•thought to be variant Of measles•Togavirus •RNA virus
EPIDEMIOLOGYOCCURRENCE -Rubella occurs worldwideRESERVOIR -human There is no known animal reservoir Transmission - spread from person to person
via droplets shed from the respiratory secretions of infected persons. There is no evidence of insect transmission
Temporal pattern - peak in late winter and spring
MEASLES (खसरा)morbilli, rubeola or red measlesParamyxovirus (RNA) Rapidly inactivated by - heat, sunlight, acidic
pH, ether and trypsin Highly contagious viral illness First described in 7th century Near universal infection of childhood in
prevaccination era Common and often fatal in developing countries
OCCURRENCE -Measles occurs throughout the world RESERVOIR -human There is no known animal reservoir, and an asymptomatic
carrier state has not been documented.
TRANSMISSION - respiratory Airborne via aerosolized droplet nuclei has been documented in
closed areas (e.g., office, examination room) for up to 2 hours after a person with measles occupied the area.
Temporal pattern -peak in late winter–spring
Communicability -4 days before to 4 days after rash onset
In 2012, the World Health Assembly endorsed the Global
Vaccine Action Plan* with the objective to eliminate measles in 4 World Health Organization (WHO) regions by 2015 & 2 regions by 2020.
WHO Region Target Date for Measles Elimination
Target Date for Rubella Elimination or Control
African Region 2020 -
Region of the Americas
South-East Asia Region
European Region 2015 2015
Eastern Mediterranean Region
Western Pacific Region
Endemic transmission interrupted Record low annual total in 2004 (37 total
cases) Many cases among adults Most persons with measles were unvaccinated
or unknown vaccination status In 2011, CDC reported 16 outbreaks of
measles and 220 measles cases, most of which were imported cases in unvaccinated persons
GLOBAL STATUS OF MEASLES Estimates of measles-related deaths have
been considered a crucial indicator to evaluate the progress of any nation towards measles elimination
The global estimates for the year 2013 suggest that close to 0.14 million deaths were attributed to measles, accounting for nearly 16 deaths each hour
(Infection Ecology and Epidemiology 2015)
MEASLES STATUS IN INDIA More than one third of all measles deaths
worldwide (around 56 000 in 2011) are among children in India.
With support from WHO, in November 2010, India launched a massive polio-style measles vaccination project in 14 high-burden states, in a three-phase campaign.
Health workers were trained to detect and report measles outbreaks, and they found an unexpectedly high number of infections.
INCREASING CHILD VACCINATION
The government responded by establishing a system to ensure that every child who receives a first dose of the vaccine routinely gets a second. They also initiated ‘catch-up’ campaigns in areas where first-dose coverage was less than 80%.
With two phases of the measles vaccination campaign completed, and the third phase ongoing, more than 102 million children in 344 districts have been vaccinated, achieving between 87% and 90% coverage.
While it is not yet possible to assess
national impact, as the campaign is in different phases in different states, in some states the impact has been dramatic.
Gujarat, for example, has gone from nearly 1000 cases in 2010 to none in 2012.
In Bihar, once the state with the lowest immunization coverage levels in the country, the proportion of children immunized against common childhood diseases tripled as polio eradication activities intensified (from 18.6% in 2005 to 66.8% in 2010), underscoring the synergistic links between polio and measles efforts.