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Febre do Nilo Ocidental, Efeito das Alterações Climáticas na Dispersão dos Culicídeos e Estratégias de Prevenção
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Authors
Abstract(s)
A Febre do Nilo Ocidental (FNO) é uma zoonose de transmissão vetorial emergente, causada por um
Flaviviridae do género Orthoflavivirus, com impacto cada vez mais relevante em saúde pública global
desde a sua identificação em 1937, no Uganda. Atualmente, o vírus encontra-se distribuído em todos
os continentes, exceto a Antártida, com registos de circulação ativa e surtos em África, Europa, Ásia,
Médio Oriente, Austrália, Américas e Caraíbas.
A transmissão do vírus ocorre principalmente através da picada de mosquitos infetados, sobretudo do
género Culex, que atuam como vetores. As aves silvestres são os principais reservatórios naturais e
amplificadores do vírus, sendo essenciais para a manutenção e dispersão do ciclo enzoótico. Humanos
e equídeos são considerados hospedeiros acidentais e terminais, pois, apesar de poderem desenvolver
doença, não apresentam níveis de virémia suficientes para perpetuar o ciclo de transmissão.
As alterações climáticas, com o aumento das temperaturas e mudanças nos padrões de precipitação,
têm favorecido a expansão das áreas de reprodução dos mosquitos vetores, aumentando as suas
populações e ampliando as zonas geográficas de risco. Este fenómeno contribui diretamente para a
expansão da circulação do vírus e para o aumento da probabilidade de infeção de aves e,
consequentemente, de hospedeiros acidentais como equídeos e humanos.
Embora cerca de 80% das infeções em humanos e outros mamíferos sejam assintomáticas, as formas
sintomáticas podem ser graves, sobretudo em idosos e imunodeprimidos, com manifestações
neurológicas como encefalite e meningite, frequentemente com prognóstico reservado. A FNO é
atualmente uma das principais causas de encefalite viral em humanos em várias regiões do mundo,
sendo responsável por surtos com impacto significativo em saúde pública.
A crescente globalização, com o movimento intenso de pessoas, animais e mercadorias, aliada às
alterações ambientais, reforça a necessidade de vigilância epidemiológica, conhecimento aprofundado
do ciclo do vírus e das características dos vetores, bem como da implementação de estratégias
integradas de prevenção e controlo. A abordagem One Health, que integra saúde humana, animal e
ambiental, é fundamental para enfrentar os desafios emergentes associados à propagação da Febre
do Nilo Ocidental.
West Nile Fever (WNF) is an emerging vector-borne zoonosis caused by a Flaviviridae of the Flavivirus genus, with increasingly significant global public health impact since its identification in 1937 in Uganda. Currently, the virus is distributed across all continents except Antarctica, with records of active circulation and outbreaks in Africa, Europe, Asia, the Middle East, Australia, the Americas, and the Caribbean. The virus is primarily transmitted through the bite of infected mosquitoes, particularly those of the Culex genus, which act as vectors. Wild birds are the main natural reservoirs and amplifiers of the virus, playing a crucial role in maintaining and spreading the enzootic cycle. Humans and equids are considered accidental and terminal hosts, as although they can develop the disease, they do not exhibit sufficient levels of viraemia to sustain the transmission cycle. Climate change, with rising temperatures and altered precipitation patterns, has favoured the expansion of vector mosquito breeding grounds, increasing their populations and widening geographical risk areas. This phenomenon directly contributes to the spread of viral circulation and raises the likelihood of infection in birds—and consequently in accidental hosts such as equids and humans. Although approximately 80% of infections in humans and other mammals are asymptomatic, symptomatic cases can be severe, particularly in the elderly and immunocompromised individuals, with neurological manifestations such as encephalitis and meningitis, often resulting in a guarded prognosis. WNF is currently one of the leading causes of viral encephalitis in humans in various regions of the world and has been responsible for outbreaks with significant public health impact. Increasing globalisation, with intense movement of people, animals, and goods, coupled with environmental changes, underscores the need for epidemiological surveillance, in-depth knowledge of the virus’s cycle and vector characteristics, as well as the implementation of integrated prevention and control strategies. The One Health approach, which integrates human, animal, and environmental health, is essential to address the emerging challenges associated with the spread of West Nile Fever.
West Nile Fever (WNF) is an emerging vector-borne zoonosis caused by a Flaviviridae of the Flavivirus genus, with increasingly significant global public health impact since its identification in 1937 in Uganda. Currently, the virus is distributed across all continents except Antarctica, with records of active circulation and outbreaks in Africa, Europe, Asia, the Middle East, Australia, the Americas, and the Caribbean. The virus is primarily transmitted through the bite of infected mosquitoes, particularly those of the Culex genus, which act as vectors. Wild birds are the main natural reservoirs and amplifiers of the virus, playing a crucial role in maintaining and spreading the enzootic cycle. Humans and equids are considered accidental and terminal hosts, as although they can develop the disease, they do not exhibit sufficient levels of viraemia to sustain the transmission cycle. Climate change, with rising temperatures and altered precipitation patterns, has favoured the expansion of vector mosquito breeding grounds, increasing their populations and widening geographical risk areas. This phenomenon directly contributes to the spread of viral circulation and raises the likelihood of infection in birds—and consequently in accidental hosts such as equids and humans. Although approximately 80% of infections in humans and other mammals are asymptomatic, symptomatic cases can be severe, particularly in the elderly and immunocompromised individuals, with neurological manifestations such as encephalitis and meningitis, often resulting in a guarded prognosis. WNF is currently one of the leading causes of viral encephalitis in humans in various regions of the world and has been responsible for outbreaks with significant public health impact. Increasing globalisation, with intense movement of people, animals, and goods, coupled with environmental changes, underscores the need for epidemiological surveillance, in-depth knowledge of the virus’s cycle and vector characteristics, as well as the implementation of integrated prevention and control strategies. The One Health approach, which integrates human, animal, and environmental health, is essential to address the emerging challenges associated with the spread of West Nile Fever.
Description
Keywords
Alterações climáticas Culicídeos Febre do Nilo Ocidental Influência climática Mosquitos Vetores Climatic changes Climatic influence Culicidae Vectors West Nile Fever