Arbovirus Flashcards
What is arbovirus?
Virus that spread by arthropod vectors
Humans can serve as…
dead-end host, accidental host, or they can be maintenance reservoir
What are the three types of arboviruses?
Flavivirus, Togavirus, and Bunyavirus
What are the tests used to diagnose arbovirus infections?
Serology: ELISA, Complement Fixation Test (CFT)
Culture
Animal Inoculation
Direct detection test: detection of antigen and nucleic acids (PCR)
What is the treatment for arbovirus infection?
Treatment for most infections is supportive only.
In haemorrhagic fevers, bleeding may require phytonadione (vitamin K1)
Transfusion of packed RBCs or fresh frozen plasma
Why are aspirin and other NSAIDs contraindicated (avoided)?
Because of antiplatelet activity
What are the preventions?
Surveillance
Vector control: proper clothing, using insect repellents
Vaccine: only available for JE and YF
Flavivirus. Humans are dead-end hosts, as they do not develop high concentrations of the virus in their bloodstream to infect feeding. Transmission: The virus is maintained in a cycle between mosquitoes and vertebrate hosts, primarily pigs and wading birds.
Japanese Encephalitis (JE)
Initial symptoms: fever, headache, vomiting, encephalitis
Mental status changes, neurologic symptoms, seizures are common, especially among children, neck stiffness, and paralysis or muscle weakness.
JE
What is the diagnosis and treatment for JE?
Detection of IgM antibodies in serum or cerebrospinal fluid. Positive IgM antibodies indicate past infection or vaccination.
No treatment is available, and hospitalization for supportive care and close observation is generally required.
Inactivated Vero cell culture-derived JE vaccine is mainly used. It is recommended for travellers who plan to spend 1 month or more in endemic. Two dose series will be given 28 days apart. The last dose should be given at least 1 week before travel.
Belongs to Flavivirus, mainly found in West Africa and South America. Is transmitted by mosquitoes.
Yellow Fever
What are the two cycle forms in YF?
The jungle cycle: Transmission between non-human primates (monkey) and mosquito species found in the jungle. The virus is transmitted by mosquitoes from monkeys to humans in the jungle.
The urban cycle: Transmission is between humans and urban mosquitoes, primarily Aedes. The virus is usually brought to the urban setting by a viremic human who was infected in the jungle.
Viremic means infected people are infectious to mosquitoes.
Initial symptoms: Sudden onset of fever chills, severe headache, back pain, body aches, nausea, vomiting, fatigue, and weakness.
Severe: high fever, jaundice, bleeding, and eventually shock and failure of multiple organs.
YF
What is the diagnosis of YF?
Serology test
What is the treatment for YF?
There are no specific treatments. Hospitalization for supportive care and close observation.
Plenty of rest, fluids, and use of pain relievers.
Avoid aspirin or other nonsteroidal anti-inflammatory drugs as they may increase the risk of bleeding
Protection from further mosquito exposure
What are the preventions for YF?
Protection from mosquito bites. This way, the YF virus in their bloodstream will not be available to uninfected mosquitoes, thus breaking the transmission cycle and reducing risk to the persons around them.
Vaccines for YF, Dakar and 17D vaccine.
Biggest arbovirus problem in the world. Belongs to Flavivirus, 4 serotypes (DEN 1-4) transmitted by Aedes mosquitoes which reside in water-filled containers. Human infections arise from a human-mosquito-human cycle.
Dengue virus
High fever - Breakbone fever (painful bone), lymphadenopathy, myalgia, bone and joint pains, headache, and a maculopapular rash.
Severe cases: Haemorrhagic fever (DHF) and shock
Dengue virus
What is the diagnosis of Dengue virus?
Production of IgM and IgG antibodies primarily directed against the virus envelope proteins.
The tests that can be performed are PCR, MAC-ELISA (IgM antibody capture enzyme-linked immunosorbent assay), IgG, NS1 ELISA, and PRNT.
Treatment and prevention for Dengue virus
No specific therapy but supportive care
Prevention: Mosquito Eradication. The population should be removed from all containers which serve as vessels for egg deposition.
The vaccine is only given to those who were previously infected only.
Flavivirus, transmitted by Aedes mosquitoes. It can also be sexually transmitted and possibly via blood transfusions.
Zika virus
Symptoms: fever, rash, headache, joint pain, red eyes, and muscle pain.
This virus infection during pregnancy can cause microcephaly, a condition in which the fetus has a smaller head than normal. Other problems before birth, such as eye and hearing defects and impaired growth.
Guillain-Barre syndrome, a serious condition of the nervous system.
Zika virus
Treatment and prevention for Zika virus
No medicine or vaccine for Zika virus at present. Mainly prevention from mosquito bites is important.
Belongs to Flavivirus, human infection is often the result of bites from infected mosquitoes. Birds are natural hosts. Mosquitoes become infected when they feed on infected birds, which circulate in their blood for a few days.
West Nile Fever
Can cause fatal neurological disease
Encephalitis, meningitis, poliomyelitis, headache, high fever, neck stiffness, stupor, disorientation, coma, tremors, convulsions, muscle weakness, and paralysis.
WNF
Diagnosis for WNF
ELISA for IgM antibodies and PCR
Treatment for WNF
Supportive care, fluids, respiratory support, and prevention of secondary infections. No vaccine is available for humans
Belongs to Togavirus. Transmitted by infected mosquitoes of Aedes species. The name of the virus means to become contorted, which describes the stooped appearance of sufferers with joint pain (arthralgia).
Chikungunya virus
Symptoms: fever, severe joint pain, stooped appearance, headache, muscle pain, joint swelling, rash.
Chikungunya virus
Diagnosis for Chikungunya
Serology test, mainly rapid card test, ELISA and molecular test PCR
Treatment for Chikungunya
No specific antiviral drug treatment. Only supportive, no vaccine. Travellers can protect themselves by preventing mosquito bites by using appropriate measures.
