Bunyavirus - Epidemiology, Clinical Manifestation, Lab diagnosis, Treatment, Control
Epidemiology of Bunyavirus
Bunyaviruses are found throughout the world, but each serotype has a limited geographic distribution because it relies on one or at best, a few arthropod species to maintain its natural cycle.
Hantaviruses are maintained in rodent reservoirs and are not arthropod-borne. Transmission to humans is believed to occur by inhalation of the virus excreted in rodent urine and other body fluids
Clinical Manifestation of Bunyavirus
The major clinical manifestation of bunyavirus includes:
La Crosse Virus
Phlebotomus Fever Viruses
Crimean- Congo Hemorrhagic Fever- virus
Rift Valley Fever virus
La Crosse Virus
The most serious disease of bunyavirus origin in the US is La Crosse encephalitis. It was first recognized when there was a fatal case in La Crosse, Wisconsin, in 1960. It is now diagnosed not only in the north-central US but also in much of the eastern portion of the country in Canada.
Phlebotomus Fever Viruses
Naples and Sicilian phlebotomus fevers are endemic in North Africa and Southern Europe and from the Middle East to Pakistan. During World War II, a severe epidemic of these diseases was recognized as febrile illness in troops in the Mediterranean theater
Human and sand flies are believed to be reservoirs. The sand flies Phlebotomus papatasi proved to be the vector.
Crimean- Congo Hemorrhagic Fever- virus
It is a tick-transmitted viral disease found in Bulgaria, Yugoslavia, the former Soviet Union, China, Iraq, United Arab Emirates, Pakistan, and Sub-Saharan Africa.
The vector tick is usually of the Hyalomma genus and domestic mammals may be amplifying reservoir hosts. Human infection also occurs directly from contaminated blood so the patient must be isolated.
Rift Valley Fever virus
Rift valley fever appears as epizootics in sheep, cattle, camels, and goats in Africa. Massive outbreaks have been recognized in South Africa, Kenya, Uganda, Sudan, Egypt, and Mauritania.
Transmission of the virus is via aerosolized infected blood and mosquitoes. There is evidence that the virus is maintained in nature in the dried eggs of the Aedes mosquito that hatch only in very moist years.
Human cases are usually restricted to veterans, butchers, and others in close contact with the blood of domestic livestock.
Lab diagnosis of Bunyavirus
Laboratory diagnosis of Bunyavirus begins with the collection of specimens.
Specimen
Blood
Biopsy/autopsy tissues
Isolation
The bunyavirus can be isolated from blood (or from the brain, liver, and other organs postmortem) during the virulence phase, but not usually after the third day of fever.
It is propagated in baby mice or mosquitoes or in vertebrates or invertebrate tissue cultures.
Serological test
Several serological tests have been developed for laboratory diagnosis of bunyavirus such as:
ELISA
CFT
fluorescent Ab neutralization
hemagglutination inhibition test
* CFT, Fluorescent Ab, and ELISA are group reactive Hemagglutination inhibition tests that are type specific.
Molecular test
One of the molecular tests for laboratory diagnosis of bunyavirus is RT- PCR.
Treatment of Bunyavirus
The drug of choice for the treatment of bunyavirus is Ribavirin.
Control of Bunyavirus
The control of bunyavirus infection can be done by:
vaccines are available
restriction of arthropod vector or vertebrate reservoir