Yellow fever outbreak affecting Alouatta populations in southern Brazil (Rio Grande do Sul State), 2008–2009

Abstract

The natural transmission cycle of Yellow Fever (YF) involves tree hole breeding mosquitoes and a wide array of nonhuman primates (NHP), including monkeys and apes. Some Neotropical monkeys (howler monkeys, genus Alouatta) develop fatal YF virus (YFV) infections similar to those reported in humans, even with minimum exposure to the infection. Epizootics in wild primates may be indicating YFV circulation, and the surveillance of such outbreaks in wildlife is an important tool to help prevent human infection. In 2001, surveillance activities successfully identified YF-related death in a black-and-gold howler monkey (Alouatta caraya), Rio Grande do Sul State (RGS) in southern Brazil, and the YFV was isolated from a species of forest-dwelling mosquito (Haemagogus leucocelaenus). These findings led the State Secretariat of Health to initiate a monitoring program for YF and other 18 arboviral infections in Alouatta monkeys. The monitoring program included monkey captures, reporting of monkey casualties by municipalities, and subsequent investigations. If monkey carcasses were found in forests, samples were collected in a standardized manner and this practice resulted in increased reporting of outbreaks. In October 2008, a single howler monkey in a northwestern RGS municipality was confirmed to have died from YF. From October 2008 to June 2009, 2,013 monkey deaths were reported (830 A. caraya and 1,183 A. guariba clamitans). Viruses isolation in blood, viscera, and/or immunohistochemistry led to the detection of YF in 204 of 297 (69%) (154 A. g. clamitans and 50 A. caraya) dead Alouatta monkeys tested. The number of municipalities with confirmed YFV circulation in howlers increased from 2 to 67 and 21 confirmed human cases occurred. This surveillance system was successful in identifying the largest YF outbreak affecting wild NHP ever recorded.

What Does the Future Hold for Yellow Fever Virus? (I)

“…First, the susceptibility to YFV of South American NHPs. In contrast, YFV is known to be far less pathogenic for African NHPs [2,103,104,148]. Taken together with the historical evidence described earlier this is wholly consistent with the concept that the virus was relatively recently introduced into the New World and evolution towards decreased disease severity has not yet reached the levels seen in Africa.…”

“…), squirrel monkeys (Saïmiri genus) and howler monkeys from the genus Alouatta [65][66][67][68][69][70]102]. Importantly, in these species, lethality was reported, reaching degrees of severity that were never observed in monkeys from the African continent [103,104]. Such susceptibility to severe YFV infection may reflect the relatively recent introduction of the virus into the Americas [2].…”

Avaliação do impacto da epizootia de Febre Amarela sobre as populações de primatas não humanos nas unidades de conservação do Rio Grande do Sul, Brasil

“…No mais recente surto, a partir dos primeiros registros em Misiones, Argentina (HOLZMANN et al, 2010) a propagação do VFA no Rio Grande do Sul tomou sentido oeste-leste, com a detecção de FA em primatas avançando pelo Estado ao ritmo de 100km/ mês (ALMEIDA et al, 2012). Logo, a mortandade atingiu, num primeiro momento, o bugio-preto e, subsequentemente, as populações do bugio-ruivo.…”

“…Posteriormente, no ano de 2002, nova ocorrência do vírus afetou populações de Alouatta guariba no centro do Estado, nos municípios de Jaguari e Mata . No verão de 2008No verão de /2009 (ALMEIDA et al, 2012) e o vírus foi isolado em mosquitos de dois municípios do Estado (CARDOSO et al, 2010). O número real de animais mortos pode ter sido muito maior FREITAS, 2010;ALMEIDA et al, 2012).…”

“…No verão de 2008No verão de /2009 (ALMEIDA et al, 2012) e o vírus foi isolado em mosquitos de dois municípios do Estado (CARDOSO et al, 2010). O número real de animais mortos pode ter sido muito maior FREITAS, 2010;ALMEIDA et al, 2012). Em julho de 2009, 154 cidades deste Estado estavam em alerta para a FA e quase sete milhões de pessoas necessitavam vacinação contra FA.…”