Encephalitis Flashcards
mode of transmission of arbovirus
arthopods- ticks and mosquitoes*
Ar-thropod Bo-rne
arbovirus causes this disease
encephalitis
virus families that include arboviruses
flaviviruses, togaviruses, bunyaviruses
TFB- transmitted from bites
viruses of the flavivirus family
west nile, Japanese encephalitis, yellow fever, dengue virus
arbovirus characteristics
- what genome, what does it trigger?
- labile or lytic?
- location of replication?
all have RNA genome*, which triggers interferon
*enveloped viruses, so labile
all replicate in cytoplasm of infected host cells
mechanism of action of togavirus family of arboviruses
temporarily regulate expression of non-structural and structural proteins through the use of SUBGENOMIC RNA*
genome of flavivirus family, and how it is processed
linear, pos sense, single stranded RNA
entire genome is translated as a polyprotein, processed to structural and non-structural proteins*
describe the bunyavirus family virion
*helical capsid, single-sranded, segmented, negative sense RNA genome
bunyavirus family is capable of this type of transmission
*transovarial transmission: by eggs to offspring
the critical determinants for disease invidence or arbovirus
*presence of the natural host AND the vector
humans can serve as reservoirs for spread of Arbovirus disease in these specific viruses
dengue and yellow fever
modes of transmission of arboviruses
*person to person: blood transfusion, organ transplantation,, transplacental transmission, possibly via breast milk
since arboviruses replicate in the CNS, they can cause..
encephalitis
pathogenesis of general arbovirus
*virus introduced to blood by arthropod, viremia, initial sxs (rapid onset fever, chills, myalgia), depending on virus it can cause encephalitis, fever, rash fever
majority of WNV are…/ this generates…
asymptomatic
life-long immunity
age groups most at risk for arbovirus causing encephalitis
children and elderly; need immunocompetence for limiting the disease
how reliable is detection of viral genome/antigen in blood for WNV?
its transient. only detected in early stages.
current guidelines mandate this drug as soon as encephalitis is suspected
acyclovir
what’s the primary obj in diagnosing viral encephalitis?
is it caused by herpes (treatable) or arbovirus (untreatable)
vaccines available for preventing arboviral encephalitis?
NOT in the US
the most important arboviral concern for human health is this disease
dengue
the most significant human arboviral infection in the world
dengue
diagnosis tips for dengue virus
anyone with a fever who has visited the tropics
pos tourniquet test: vascular permeability and clotting disorders
dengue: treatment? prevention?
treatment is aggressive supportive care
no vaccine available; eliminate mosquitoes, wear protective clothing
pathogenesis of dengue virus
enhanced disease may occur by ANTIBODY-DEPENDENT ENHANCEMENT- non-neutralizing antibodies may enhance viral uptake into phagocytic cells
what’s another name for tourniquet test? what marks the test as positive?
capillary fragility test.
positive if 10-20 petechial hemorrhages per square inch on tourniquet arm
Colorado rick fever- what virus? is it an arbovirus?
reovirus
NO
seasonal trend of US arbovirus infections
summer to early fall
a robovirus transmitted by rodents that causes neurologic disease
lymphocytic choriomeningitis
characteristics of arenaviridae
- area = sandy (host ribosomes in virion)
- 2 circular ss RNA genome segments
s segment is ambisense*-
diagnosis of lymphocytic choriomeningitis is done by
RT-PCR
supportive treatment only; no vaccine
