Rabies virus in naturally infected bats in the state of Sao Paulo, southeastern Brazil

OBJECTIVE: To identify the species of bats involved in maintaining the rabies cycle; to investigate the distribution of the rabies virus in the tissues and organs of bats and the time taken for mortality among inoculated mice. METHODS: From April 2002 to November 2003, bats from municipalities in the State of Sao Paulo were screened for the presence of the rabies virus, by means of direct immunofluorescence. The virus distribution in the bats was evaluated by inoculating mice and N2A cells with 20% suspensions prepared from fragments of different organs and tissues, plus the brain and salivary glands. The time taken for mortality among the mice was monitored daily, following intracerebral inoculation. RESULTS: Out of the 4,395 bats received, 1.9% were found positive for the rabies virus. They belonged to ten genera, with predominance of insectivores. The maximum mean times taken for mortality among the mice following inoculation with brain and salivary gland material were 15.33 +/- 2.08 days and 11.33 +/- 2.30 days for vampire bats, 16.45 +/- 4.48 days and 18.91 +/- 6.12 days for insectivorous bats, and 12.60 +/- 2.13 days and 15.67 +/- 4.82 days for frugivorous bats, respectively. CONCLUSIONS: The species infected with the rabies virus were: Artibeus lituratus, Artibeus sp., Myotis nigricans, Myotis sp., Eptesicus sp., Lasiurus ega, Lasiurus cinereus, Nyctinomops laticaudatus, Tadarida brasiliensis, Histiotus velatus, Molossus rufus, Eumops sp. and Desmodus rotundus. Virus investigation in the different tissues and organs showed that the brain and salivary glands were the most suitable sites for virus isolation.