Pesquisa de anticorpos contra arbovírus e o vírus vacinal da febre amarela em uma amostra da população de Rio Branco, antes e três meses após a vacina 17D

Abstract

During a yellow fever vaccination campaign among residents of Rio Branco (Acre State), the frequency of HI antibodies to the most prevalent arboviruses in the Amazon region and to yellow fever virus was determined before and three months after immunization with YF 17D vaccine. From 390 inhabitants included in the first phase of serologic survey (August 1999), only 190 provided a second serum sample, after the use of 17D vaccine (January 2000). Among first phase samples, the frequency of HI antibodies was: 17D (27.2%); Ilheus (5.9%); Mayaro (5.4%); Caraparu (4.9%); Dengue-2 (4.1%); Oropouche (2.3%); and Dengue-1 (0.3%). In the second study phase, the serologic conversion to YF reached 89.7% among previously negative persons. Serologic conversions were also observed to Ilheus (6.2%); Dengue-3 (3.2%); Mayaro (1.1%); and Oropouche (1.1%) viruses. In conclusion, considering the high YF antibody rate after vaccination, the risk of urban yellow fever seems insignificant, although the lower prevalence of HI antibodies to dengue viruses, is of concern and inhabitants are under high risk of dengue outbreaks, especially to DEN-3 recently introduced in Brazil, as was observed in 2000 and 2001 with DEN-1 and DEN-2.

The Acre Project: the epidemiology of malaria and arthropod-borne virus infections in a rural Amazonian population

“…Epidemiological data on dengue transmission in Brazil come mostly from large cities in the Southeast, Northeast, and more recently the North of the country 20,21,22,23 . The disease has received little epidemiological, clinical, and laboratory research in small cities 24 25 , indicating intense circulation of the dengue virus in rural areas.…”

“…Acre was the last Amazonian State to report autochthonous dengue cases (DEN-1 and DEN-2), with a major increase (40%) in incidence from 2002 and 2003 (FUNASA, unpublished data). The only available data on prevalence of antibodies to the dengue virus and other arboviruses in populations in Acre refer to a sample in the city of Rio Branco 21 .…”

“…In Ramal do Granada, as well as in Rio Branco 21 , the prevalence of antibodies to the vaccinal yellow fever virus (17D) was surprisingly low given the frequency of reported previous immunization. For example, in Rio Branco only 30% of individuals reporting prior yellow fever vaccination showed antibodies to the 17D virus 21 .…”

“…For example, in Rio Branco only 30% of individuals reporting prior yellow fever vaccination showed antibodies to the 17D virus 21 . However, we feel that the proportion of the sample population effectively vaccinated against yellow fever is higher than indicated by the serological data.…”

Virus Mayaro: un arbovirus reemergente en Venezuela y Latinoamérica

“…La gran mayoría de los brotes epidémicos, luego del primero acaecido en 1955 en Brasil y Bolivia, se han registrado de manera esporádica y aislada en localidades rurales y semirurales de la Panamazonia (10)(11)(12)(13)33,69,77,71). Históricamente, las zonas más afectadas por brotes esporádicos de virus Mayaro son las localidades que colindan con la selva amazónica, en especial, la parte norte de Brasil (10,11,33,69 En localidades rurales cercanas a bosques húmedos y a la selva amazónica, de Perú, Bolivia, Surinam, Guayana Francesa, Guyana, Colombia, Brasil y Venezuela, el virus Mayaro ha ocasionado brotes de manera esporádica y los estudios serológicos revelan frecuente contacto de los pobladores con el virus (11,12,22,33,52,69,71,72,75,78,79,84,85). En Guyana, se ha reportado alta seroprevalencia en habitantes de la sabana Rupununi y en la región del río Mazaruni, mientras que en la zona de la costa del país la infección con el virus es prácticamente inexistente (33).…”