What is the role of arboviruses in the etiology of viral meningitis?

Updated: Jul 17, 2018
  • Author: Cordia Wan, MD; Chief Editor: Niranjan N Singh, MBBS, MD, DM, FAHS, FAANEM  more...
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Answer

Arboviruses account for about 5% of cases in North America.

Arboviruses consist of more than 500 viruses from different viral families, all given the common name "ar-bo," for arthropod-borne disease. Blood-sucking arthropods, usually mosquitoes, serve as vectors for transmission.

Because exposure to mosquitoes or ticks is the risk factor for transmission, the number of infections is highest in summer and early fall, in concordance with high mosquito populations.

Some of the important arboviruses include the eastern and western equine encephalitis viruses, from the Togavirus family; St. Louis encephalitis’ West Nile, Japanese B, and Murray Valley viruses, from the Flavivirus family; and California group and Jamestown Canyon viruses, from the Bunyaviridae family. Colorado tick fever is caused by a coltivirus in the western regions of the United States.

The most common clinical manifestation is meningoencephalitis rather than pure meningitis.

Seizures are more common with arboviral meningitis than with any other group of viruses.

Some agents preferentially infect certain age groups, such as St. Louis encephalitis, which affects the extremes of age, and California virus, which infects young children. Children with St. Louis or California group encephalitis viruses may not exhibit any neurologic signs or altered mental status.

St. Louis encephalitis (SLE) virus is the most common cause of arboviral meningitis, and is also the most common mosquito-transmitted disease in the United States. Internationally, Japanese B virus is the biggest offender in this group.

Of the arboviruses, West Nile virus caused much attention, as it was first recognized in the United States only in 1999 and quickly became an epidemic in 2002, with more than 4,000 reported cases. In 2008, 1,356 cases were reported. [2]

Infection with the West Nile virus is usually asymptomatic or manifests as mild symptoms of nonspecific fever, myalgia, and fatigue. However, 1 in 150 cases develop into severe disease involving the nervous system, with encephalitis reported more than meningitis. In 2008, 687 cases of West Nile neuroinvasive disease were reported to the US Centers for Disease Control and Prevention (CDC) from all across the United States. [2]

Neuroinvasive West Nile disease occurs more often in elderly persons.


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