Rocio viral encephalitis

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Rocio viral encephalitis is an epidemic flaviviral disease of man first observed in São Paulo State, Brazil, in 1975.[1] Rocio virus was responsible for several epidemics of meningoencephalitis in coastal communities in southern São Paulo, Brazil, during 1975 and 1976.[2] The outbreak affected over 1,000 people and killed about 10% of those infected, but apparently responded well to treatment for viral encephalitides.[3] The disease progresses rapidly after onset, with patients dying within 5 days of symptoms first appearing. The disease first presents with fever, headache, vomiting, and conjunctivitis, then progresses to neurological symptoms (confusion, disorientation, etc.) and muscle weakness; about one-third of cases enter a coma, and a third of them die,[4] though supportive care such as intensive nursing and symptomatic treatment might reduce the case fatality rate to 4%.[5] Survivors show neurological and psychological after-effects (sequelae) in about 20% of cases.[6] It is hypothesized that Rocio virus is a mosquito-borne arbovirus with the potential for transmission by two prevalent Culex species mosquitoes, should it be introduced into North America.[7]


  1. ^ Carl J. Mitchell, Thomas P. Monath and C. Bruce Cropp: Experimental Transmission of Rocio Virus by Mosquitoes, Am. J. Trop. Med. Hyg., 30(2), 1981, pp. 465-472, abstract at
  2. ^ Carl J. Mitchell, Oswaldo Paulo Forattini, and Barry R. Miller: Ensaios sobre a capacidade vetora para o vírus Rocio, de três espécies de culicídeos da zona epidêmica no Brasil [Vector competence experiments with Rocio virus and three mosquito species from the epidemic zone in Brazil], Rev. Saúde Pública vol.20, no.3, São Paulo, June 1986,
  3. ^ CBWInfo: Secondary Biological Agents: Rocio virus encephalitis, undated,
  4. ^ CBWInfo.
  5. ^ O. Souza Lopes, Francisco P. Pinheiro, and L. B. Iversson: "Rocio Viral Encephalitis", in: Handbook of Zoonoses, Second Edition, Section B: Viral Zoonoses, George W. Beran (ed.-in-ch.), CRC Press, 1994, pp. 205-209.
  6. ^ CBWInfo.
  7. ^ Mitchell et al, 1981.