Introduction: Yellow fever is a zoonotic infection maintained in nature by non-human primates. Appropriate surveillance with sensitive laboratory techniques is necessary to evidence viral activity in the tropical forest habitats of these primates.
Objective: Yellow fever virus was detected in hepatic tissue samples from non-human primates by reverse transcriptase polymerase chain reaction (RT-PCR) technique using specific primers for diagnosis.
Materials and methods: Hepatic tissue samples were processed from five monkeys belonging genus Alouatta spp found dead in sylvatic areas of Cesar and Magdalena Provinces, Colombia, between December 2003 and June 2004. Samples were treated with lysis buffer prior to the isolation of viral RNA, which was then subjected to reverse transcriptase polymerase chain reaction (RT-PCR) using yellow fever-specific primers. Simultaneously, viral proteins were identified by immunohistochemistry on parafin-embedded hepatic tissue.
Results: The PCR method amplified fragments of the expected size (424 bp) in four of the tested samples. In addition, these samples showed a positive reaction by immunohistochemistry, supporting the evidence that the virus was present.
Conclusion: The detection of yellow fever virus in wild monkeys was clear evidence of enzootic activity in northern Colombia. Increased probability of yellow fever transmission among human populations is indicated due to urbanization processes as a consequence of forced migration and displacement of the human populations. Molecular tests for rapid and specific detection of yellow fever in tissue samples of non-human primates is an important tool for epidemiologic surveillance. Rapid virus identification will permit the timely activation of control systems for prevention of further cases and epidemic situations.