Arboviruses (1) Flashcards
What are arboviruses?
A group of viruses that are transmitted by arthropod vectors.
They are all RNA viruses
What are the 4 types of clinical syndromes of the mosquito- borne viruses?
1- Systemic febrile illness
2- Fever with arthritis
3- Encephalitis
4- Hemorrhagic fever
What are the 4 viruses that cause systemic febrile illness?
Chicungunya, O’nyong-nyong, Ross River, and Dengue
What are the 3 viruses that cause fever with arthritis?
Chicungunya, O’nyong-nyong, and Ross River
What are the 6 viruses that cause encephalitis?
JE, VEE, EEE, WEE, MVE, West nile virus
What 4 viruses cause hemorrhagic fever?
Yellow fever, Dengue, Rift Vally Fever, Chikungunya
What is the family and genera of the EEE virus?
Family= Togaviridae
Genera= alphavirus
What are the 4 members of the alpha virus family?
EEE (eastern USA), WEE (western USA), VEE (south america and north america), and everglades
Which alpha virus has the highest probability of developing encephalitis? The lowest probability?
EEE- highest
VEE- lowest
What are the mortality rate associated with EEE, WEE and VEE?
WEE: 5%
VEE: 35%
EEE: 50%
Describe the transmission cycle of EEE?
The host is birds, and the vector is mosquitos. Humans are horses are incidental hosts.
What are the symptoms of EEE?
Usually present in AUGUST. Fever, headache, mental status changes, stiff neck.
Family and genome of Japanese Encephalitis virus?
Family: Flavaviridiae
Genome: ssRNA (+)
T/F: There is more than 1 serotype for JE virus?
False…it circulates as 1 serotype but has 5 different genotypes.
What is the vector for JE? Also describe some characteristics of the vector.
Culex mosquitos.
Night feeders that live in rice fields, marshes and small collections of water. They are prevalent in the rainy season. They pass on their virus to other mosquitos vertically and sexually.
Natural hosts of the JE virus?
Pig and migrating birds and domestic fowl
What is special about the pig host of JE?
Prolonged and high titer viremia which is asymptomatic.
Accidental hosts of JE?
Humans and horses
What are the two transmission patterns of JE?
Seasonal transmission (april- july): prevalent in japan, china, taiwan, korea, n. vietnam, and thailand
Year round transmission: S. vietnam, thailand, india, indonesia, malaysia, philippines, sri lanka
Incidence and deaths per year of JE?
50,000 cases per year
10, 000 deaths per year.
These numbers are underreported though.
Incubation period of JE virus?
6-16 days
How long does the JE prodrome last and what are the symptoms?
2-3 days
Headache, fever, chills, anorexia, N/V, dizziness
How long does acute JE last and what are the symptoms?
3-4 days
High fevers, seizures, dull flat mask like faces, unblinking eyes, tremor, hypertonia, abnormal behavior, acute flaccid paralysis
How long does subacute JE and convalescence last? What are the symptoms?
Subacute: 7-10 days
Convalescence: 4- 7 weeks
Symptoms: tremors, paresis, incoordination, pathogenic reflexes, lip smacking, rapidly changing CNS
What indicates a poor prognosis with JE?
Respiratory dysfunction, prolonged seizures and fevers, albuminuria
Infectious virus in CSF
Low IgM in CSF
What are the vaccines for JE?
JE- Vax: no longer available because SAEs
IXIARO: Purified inactivated vaccine, 2 doses (28 days apart)
Family, genus, and genome of yellow fever virus?
Family: Flaviviridiae
Genus: Flavavirus
Genome: single open reading frame
Where did yellow fever virus originate? Where is it found now?
Originated in Africa.
Geographic localization to tropical regions of Africa and South America in the amazon region
Host and vector for yellow fever virus?
Host: nonhuman primate and humans
Vector: mosquito
Yellow fever virus incubation period?
Incubation period: 3-6 days
Clinical features of the acute phase of yellow fever virus?
mild nonspecific, febrile illness
symptoms last for 3 days and there is a period of viremia
Clinical features of hemorrhagic period of yellow fever virus?
“coffee ground” hematemesis, melena, metorrhagia, petechiae, eccymoses
volume depletion, renal failure, liver failure
death usually occurs on 7th -10th day
How long does the convalescent phase of yellow fever virus infection last and what are the symptoms?
Lasts 1-2 weeks
increased serum transaminase levels can persist of 2 months after illness
Late death can occur because cardiac and renal complications
What are the 3 adverse reactions to the YF vaccine?
Immediate hypersensitivity or anaphlactic reaction
YF Vaccine associated neurologic disease (YF-AND)
YF vacine associated viscerotropic disease (YF-AVD)
When does the YF-AVD reaction typically occur?
3-5 days after vaccination
Family and genus of dengue fever virus?
Family: Flaviviridiae
Genus: Flavivirus
How many serotypes of dengue fever virus are there?
4 serotypes, all are antigenically distinct.
Of you are infected and recover from one serotype are yoy safe from future infection from other serotypes?
No, actually at much greater increased risk for developing hemorrhagic dengue fever
What is the vector of Dengue fever? What are some characteristics of
Aedes aegypti mosquito.
It is an urban mosquito that is a daytime feeder and prefers humans for its bloodmeal
What is the incubation period of dengue fever?
2-7 days
Symtoms of dengue fever virus?
High fever (that lasts 6-7 days and has associated flu like symptoms)
retrobulbar pain, lumbosacral aching pain, conjunctival congestion, facial flushing, generalized macular rash (on first or second day) and a secondary rash (on day 3-5), leukopenia and thrombocytopenia
Symptoms of dengue hemorrhagic fever?
petechia, epistaxis, intestinal bleeding, menorrhagia, positive tourniquet sign
Symtoms of the shock syndrome associated with dengue hemorrhagic fever?
Intravascular volume depletion from plasma leakage into 3rd space or blood loss
Cardiovascular collapse is possible
What is the most common arbovirus causing human infection in subtropical and tropical regions?
Dengue fever virus
