OUTBREAK OF OROPOUCHE VIRUS-DISEASE IN VICINITY OF SANTAREM, PARA, BRAZIL

  • 1 January 1976
    • journal article
    • research article
    • Vol. 27  (2) , 213-223
Abstract
An epidemic of human febrile illness caused by Oropouche virus was studied in the village of Mojui dos Campos, Para State, Brazil, in Feb. 1975. The major clinical symptoms, fever, chills, headache, myalgia, arthralgia and dizziness persisted for 2-7 days. Leukopenia was commonly observed. Some patients were severely ill, but no deaths were attributed to the disease. Recurrence of symptoms was reported in several people. Cases of recent infection (55) were diagnosed in Mojui dos Campos between Feb.-April. In the same period 26 cases were recorded from the Palhal area, near Mojui. Two additional cases were observed, 1 in the small settlement of Terra Preta and the other in the town of Santarem, 12 and 20 km from Mojui, respectively. Of the 83 infections, 65 were proven by virus isolation from the blood of patients and 18 by the demonstration of an increasing antibody level to the agent. Both sexes of the population were infected in equal proportions. Most patients were < 20 yr of age. In the village of Mojui dos Campos with a population of about 2900, 45 (40.1%) of 112 students aged 4-18 yr had HI hemagglutination-inhibiting antibodies to the virus when examined late in Feb. The epidemic only declined after the middle of March. Two isolations of Oropouche virus were obtained from 15,000 Culicoides inoculated into mice. About 4000 Culicoides and all the 9420 mosquitoes captured during the outbreak remain to be inoculated. Over 95% of the Culicoides were C. paraensis. Only 1 rodent of the genus Proechimys had HI antibodies to Oropouche virus out of the 602 wild and domestic mammals captured in the area. All 5 reptiles examined were negative. Of 681 wild birds 34(4.9%) and 12 (5.8%) of 206 domestic birds examined were positive for the presence of HI antibodies to the agent.

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