arboviruses (2)

8/14/2019 ARBOVIRUSES (2)

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ARBOVIRUSES: viruses

spread by ANTHROPODVECTORS

JAMES FELIX GALES


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Arbovirus

is a shortened name given to viruses that

are transmitted by arthropods, or

arthropod-borne viruses

Some Arboviruses are able to cause

emergent disease. Arthropods are able to

transmit the virus upon biting allowing the

virus to enter the bloodstream which cancause viraemia.


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Arthropod

is an invertebrate that has an exoskeleton

(external skeleton), a segmented body,

and jointed attachments called

appendages. Arthropods are animals

belonging to the Phylum Arthropoda (from

Greek arthron, "joint", andpodos "foot",

which together mean "jointed feet"), andinclude the insects, arachnids,

crustaceans, and others.


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Viremia

is a medical condition where

viruses enter the bloodstream

and hence have access to therest of the body. It is similar to

bacteremia, a condition wherebacteria enter the bloodstream


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Major ARBOVIRUSES

Togavirus (Alphavirus)

Flaviviruses (Flavivirus) Bunyaviruses (Bunyavirus and Phlebovirus)

Reonivius (orbivirus)


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Chief VECTORS

MOSQUITOS

TICKS

FLIES

GNATS


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Epidemiologyof Arbovirus

Disease

Anthropods are found WORLDWIDE so as

the ARBOVIRUSES they carry.

The vectors and viruses tend to be cluster

in trpics abd subtropics but manytemperate zones report periodic edemics.


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The influence of vectors

The carriers of arbovirus are the

anthropds themselves

FACTORS THAT WEIGHS HEAVILY FOR

RAMPANT SPREAD OF ARBOVIRUS:

1. Anthropds lifespan

2. Availablity of food and breeding sites3. Climatic influences


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Most anthropod vectors feed on blood host

Humans can serve s the dead end andaccidental hosts or they can be amaintenace reservior

Risk for arboviral infections are great inwilderness areas where encounters with

anthropod vectors are frequent


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General Charcteristics of

ARBOVIRUS infections

FEBRILE ILLNESS

One ytpe of disease elicited by arbovirusesis an acute, undifferentail fever, often

accompanied by rush.

Example:DENGUE FEVER

COLORADO TICK FEVER


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Prominent symptoms:

Fever Prostration

Headache

Myalgia

Orbital pain

Muscle aches

Joint stiffness

And later through the illness, a maculopapular r petechial

rash can erupt over the trunk and limbs.


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ENCEPHALITIS

Encephalitis is an acute inflammation of thebrain.

Encephalitis with meningitis is known as

meningoencephalitis.

General Charcteristics of

ARBOVIRUS infections


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Symptoms

Patients with encephalitis suffer from fever,headache and photophobia with weakness andseizures also common.

Less commonly, stiffness of the neck can occurwith rare cases of patients also suffering from

stiffness of the limbs, slowness in movementand clumsiness depending on which specificpart of the brain is involved.

The symptoms of encephalitis are caused by thebrain's defense mechanisms activating to get ridof the infection. Other symptoms can includedrowsiness and coughing.


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Most common type American types are:

eastern equine

St. Louis

California encephalities

The viruses cycle between wild animals andmosqiutoes or ticks, but humans are noot usually

reservior hosts.

The disease begins with a bite, which releases a virus

into the tissues and nearby lymphatics.


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Prolonged viremia establishes virus in the brain,where inflammation can cause swelling anddamage t the brain, nerves, and meninges.

Symptoms may also include:

Coma loss of coordination

Convulsions memory deficits

Paralysis changes in speech andpersonality

Tremor heart disorders


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COLORADO TICK FEVER

also called Mountain tick fever,Mountain fever, andAmericanmountain fever)

is an acute viral infectiontransmitted from the bite of aninfected wood tick(Dermacentor andersoni).

It should not be confused with

the bacterial tick-borneinfection, Rocky MountainSpotted Fever.


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WESTERN EQUINE

ENCEPHALITIES

The Western equine encephalitis virus is thecausative agent of relatively uncommon viraldisease Western equine encephalitis (WEE).An Alphavirus of the family Togaviridae, theWEE virus is an arbovirus (arthropod-bornevirus) transmitted by mosquitoes of thegenera Culexand Culiseta. There have beenunder 700 confirmed cases in the U.S. since1964.


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EASTERN EQUINE

ENCEPHALITIES

Eastern equine encephalomyelitis virus (EEE),commonly called sleeping sickness or "Triple E",is a zoonotic alphavirus and arbovirus present inNorth, Central and South America and theCaribbean. EEE was first recognized inMassachusetts, USA in 1831 when 75 horsesdied of encephalitic illness. Epizootics in horseshave continued to occur regularly in the United

States. EEE is found today in the eastern part ofthe country and is often associated with coastalplains.


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http://upload.wikimedia.org/wikipedia/commons/0/00/Eastern_equine_encephalitis.jpg


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California encephalitis

California encephalitis virus causesencephalitis in humans. Mosquitos serve as itsvectors. For this reason this virus is known as anarbovirus (arthropod-borne virus).

California encephalitis virus belongs to theBunyaviridae family of viruses, and the genusBunyavirus. La Crosse Virus is the most

important California encephalitis virus in theUnited States. Other related viruses includeCalifornia encephalitis virus and JamestownCanyon virus.


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La Crosse encephalitis

Symptoms

nausea

headache

vomiting in milder cases and

seizures

coma

paralysis

permanent brain damage in severe cases


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St. Louis encephalitis

St. Louis Encephalitis is a disease

caused by the Culex mosquito borne St.

Louis Encephalitis virus. St. Louis

encephalitis virus is related to Japaneseencephalitis virus and is a member of the

Flaviviridae subgroup. This disease mainly

affects the United States. Occasionalcases have been reported from Canada

and Mexico.


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Viral hemorrhagic feverThe viral hemorrhagic fevers (VHFs) are a diverse

group of animal and human illnesses that are causedby five distinct families of RNA viruses: theArenaviridae, Filoviridae, Bunyaviridae, Togaviridae,and Flaviviridae.

All types of VHF are characterized by fever andbleeding disorders and all can progress to high fever,shock and death in extreme cases. Some of the VHF

agents cause relatively mild illnesses, such as theScandinavian nephropathia epidemica, while others,such as the African Ebola virus, can cause severe,life-threatening disease.


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Signs and symptoms of VHFs

fever and bleeding diathesis flushing of the face and chest petechiae

frank bleeding edema Hypotension shock

Malaise headache vomiting diarrhea


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Yellow fever

is an acute viral disease. The virus, a 40 to

50 nm enveloped RNA virus of the family of

Flaviviridae is transmitted by the bite of

mosquitoes (the yellow fever mosquito,Aedesaegypti, and other species). Yellow fever is an

important cause of hemorrhagic illness in

tropical and subtropical areas of African and

South American despite existence of an effectivevaccine. The yellowrefers to the jaundice

symptoms that affect some patients.


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Dengue fever

dengue hemorrhagic fever(DHF) are

acute febrile diseases, found in the

tropics, and caused by four closely related

virus serotypes of the genus Flavivirus,family Flaviviridae.

It is also known as breakbone fever.


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diagnosis of dengue

The diagnosis of dengue is usually made

clinically. The classic picture is high fever with

no localising source of infection, a petechial rash

with thrombocytopenia and relative leukopenia -low platelet and white blood cell count. Care has

to be taken as diagnosis of DHF can mask end

stage liver disease and vice versa.

Fever, bladder problem, constant headaches,eye pain, severe dizziness and loss of appetite.


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Hemorrhagic tendency (positive tourniquet test,spontaneous bruising, bleeding from mucosa,

gingiva, injection sites, etc.; vomiting blood, orbloody diarrhea)

Thrombocytopenia (


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arboviruses (2)

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