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Isolation of yellow fever virus from nulliparous Haemagogus (Haemagogus) janthinomys in eastern Amazonia
B Mondet1, P F C Vasconcelos, A P A Travassos da Rosa
1Institut de Recherche pour le Développement, Paris, France. mondet@ird.sn
Abstract:
In 1998, an epizootic of yellow fever (YF) killed many howler monkeys (Alouatta spp.) in eastern Amazonia near the city of Altamira. An infection level with YF virus of approximately 3.6% was determined from analysis of 456 females of Haemagogus janthinomys Dyar, the main enzootic YF vector in South America. One month later, a second study of 164 females captured in the same place led to infection levels of 0.8% for parous and 2.9% for nulliparous females. These results lead to the conclusion that vertical transmission, one of the key elements in the epidemiology of YF, occurs in South America as it does in Africa.
Insights
Yellow fever virus (YFV) epizootics in Amazonia killed howler monkeys. Studies found YFV in the main mosquito vector, Haemagogus janthinomys, indicating vertical transmission occurs in South America.
Area of Science:
- Veterinary Medicine
- Epidemiology
- Arbovirology
Background:
- An epizootic of yellow fever (YF) caused significant mortality in howler monkeys (Alouatta spp.) in eastern Amazonia in 1998.
- The primary enzootic vector for YF in South America, Haemagogus janthinomys, plays a crucial role in disease transmission dynamics.
Purpose of the Study:
- To investigate the infection levels of yellow fever virus in the primary mosquito vector, Haemagogus janthinomys.
- To assess the potential for vertical transmission of YF virus in South America.
Main Methods:
- Field collection of Haemagogus janthinomys females in eastern Amazonia near Altamira.
- Laboratory analysis to determine the infection rate of YF virus in captured mosquito populations.
- Comparison of infection rates between nulliparous and parous female mosquitoes.
Main Results:
- An initial analysis of 456 female Haemagogus janthinomys revealed a YF virus infection level of approximately 3.6%.
- A subsequent study of 164 females, one month later in the same location, showed infection levels of 0.8% in parous and 2.9% in nulliparous females.
- The higher infection rate in nulliparous females suggests a potential role for vertical transmission.
Conclusions:
- The findings provide evidence for vertical transmission of yellow fever virus in South America.
- Vertical transmission in Haemagogus janthinomys is a significant factor in the epidemiology of YF, similar to observations in Africa.
- This supports the understanding of YF virus maintenance and spread in Neotropical ecosystems.
