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* This is the Professional Version. *

Other Arbovirus Infections

By Matthew E. Levison, MD

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Patient Education

Chikungunya disease

This disease is an acute febrile illness followed by more chronic polyarthritis. It is transmitted by Aedes mosquitoes and is common in Africa, India, Guam, Southeast Asia, New Guinea, China, Mexico, Central America, islands in the Caribbean, Indian Ocean and Pacific, and limited areas of Europe. Local transmission has been identified in Florida, Puerto Rico, and the US Virgin Islands.

Prevention of chikungunya disease involves avoiding mosquito bites.

Mayaro disease

This dengue-like disease is transmitted by mosquitoes. It is common in Brazil, Bolivia, and Trinidad.

Prevention of Mayaro disease involves avoiding mosquito bites.

Tick-borne encephalitis

In northern Asia, Russia, and Europe, this infection is caused by 3 subtypes of flaviviruses: a far-eastern subtype, a Siberian subtype, and a European subtype. In the US, tick-borne encephalitis is caused by Powassan virus, a flavivirus.

Initially, a mild flu-like illness occurs, accompanied by leukocytopenia and thrombocytopenia, which clears up within a few days. About 30% of patients develop more severe symptoms (eg, meningitis, meningoencephalitis).

A vaccine is available in Europe and Russia.

California encephalitis

The California encephalitis virus belongs to the Bunyaviridae family. This encephalitis and related infections are transmitted by mosquitoes and occur in the US Midwest and probably worldwide.

California encephalitis causes symptoms (eg, fever, somnolence, obtundation, focal neurologic findings, seizures) primarily in children. Temporal lobe involvement may mimic herpes encephalitis; 20% of patients develop behavioral problems or recurrent seizures. Mortality rate is < 1%.

No treatment is available.

Omsk hemorrhagic fever and Kyasanur Forest disease

These infections are transmitted by ticks or by direct contact with an infected animal (eg, rodent, monkey). Omsk hemorrhagic fever is caused by a flavivirus; it occurs in Russia, including Siberia; Kyasanur Forest disease, also caused by a flavivirus, occurs in India.

Omsk hemorrhagic fever and Kyasanur Forest disease are acute febrile illnesses accompanied by bleeding diathesis, low BP, leukopenia, and thrombocytopenia; some patients develop encephalitis in the 3rd wk. Mortality rate is < 3% for Omsk hemorrhagic fever and 3 to 5% for Kyasanur Forest disease.

Prevention involves avoiding tick bites and infected animals.

Rift Valley fever

This infection, caused by a phlebovirus, is spread by mosquitoes and can be transmitted by the following:

  • Direct or indirect contact with the blood or organs of infected animals (eg, during slaughtering, butchering, or veterinary procedures)

  • Inhalation of infected aerosols

  • Ingestion of raw milk from infected animals

Rift Valley fever occurs in South Africa, East and West Africa, Arabia, and Egypt.

Rarely, Rift Valley fever progresses to ocular disorders, meningoencephalitis, or a hemorrhagic form (which has a 50% mortality rate).

A vaccine for livestock is available, and a human vaccine is under investigation.

* This is the Professional Version. *