arboviruses (2)
TRANSCRIPT
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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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