Salivary excretion of rabies virus was evaluated in 14 adult vampire bats (Desmodus rotundus) intramuscularly injected with a large dose (10(6) MICLD50) of vampire rabies virus variant CASS88. Saliva samples were obtained from surviving bats every other day for 30 days, then weekly for 2 months, and finally 1 and 2 years later. Rabies virus was isolated in murine neuroblastoma cells and in randomly selected cases by PCR. Rabies virus was not detected in the saliva of any of the 11 animals that succumbed (somewhat early) to rabies challenge, nor in the control bats. In contrast, virus was detected early, and only once (days 6, 6 and 21) in each of the three animals that survived rabies challenge and remained healthy for at least 2 years after challenge. At that time even vigorous dexamethasone and cyclosporine administration failed to provoke further viral excretion.

Abstract. Twenty-eight samples from humans and domestic and wild animals collected in Mexico between 1990 and 1995 were characterized by using anti-nucleoprotein monoclonal antibodies and limited sequence analysis of the nucleoprotein gene. The variants of rabies viruses identified in these samples were compared with other isolates from Mexico and the rest of the Americas to establish epidemiologic links between cases and outbreaks and to increase the understanding of rabies epidemiology in the Western Hemisphere. Antigenic and genetic diversity was found in all samples from dogs and dog-related cases, suggesting a long-term endemic situation with multiple, independent cycles of virus transmission. Two isolates from bobcats were antigenically and genetically homologous to the rabies variant circulating in the Arizona gray fox population, indicating a wider distribution of this variant than previously reported. Rabies isolates from skunks were unrelated to any variant analyzed in this study and represent a previously unrecognized cycle of rabies transmission in skunks in Baja California Sur. Two antigenic and genetic variants cocirculating in southern and eastern Mexico were found in viruses obtained from cases epidemiologically related to vampire bats. These results serve as a baseline for the better understanding of the molecular epidemiology of rabies in Mexico.Urban and sylvatic rabies is an important public health and economic problem in Latin America. During the period 1990-1996, there were 1,372 human rabies cases in this region, but the animal responsible for the exposure was known for only 1,117 cases. The domestic dog and various Chiroptera species, mainly the vampire bat (Desmodus rotundus), were represented in 80.6% and 11.3% of these cases, respectively. 1 Urban rabies constitutes a dog-to-dog transmission cycle that is maintained in cities. Dogs are the primary source of infection for humans and other domestic animals. Rabies epidemiology is highly influenced by both human and dog population density and the cultural and socioeconomic factors that govern the interaction between those 2 populations. 2,3 These factors are particularly relevant in the case of Mexico. This country has one-fifth of the human population (approximately 93 million people) and one-fourth of the canine population (approximately 13.5 million dogs) of Latin America. 1,4 As a consequence of the implementation of an aggressive public health policy in Mexico for rabies control in the urban centers, there has been a substantial decrease in the number of canine rabies cases from 2,077 in 1992 to 521 in 1997. 5 Although the annual canine vaccine coverage in Mexico is approximate 78%, ultimate rabies control has been difficult to achieve. 4 Strategies for the application of control programs should involve careful planning based on the knowledge of the local epidemiologic situation. 6 The availability of detailed surveillance data, the identification of different transmission cycles, and the geographic distribution in urban settings are...

Individuals belonging to five families, 12 genera, and 19 different species of bats from dengue endemic areas in the Gulf and Pacific coasts of Mexico were examined by ELISA, RT-PCR, and for the presence of dengue virus (DV) NS1 protein. Nine individuals from four species were seropositive by ELISA: three insectivorous, Myotis nigricans (four positives/12 examined), Pteronotus parnellii (3/19), and Natalus stramineus (1/4), and one frugivorous Artibeus jamaicensis (1/35) (12.86% seroprevalence in positive species). DV serotype 2 was detected by RT-PCR in four samples from three species (all from the Gulf coast - rainy season): two frugivorous, A. jamaicensis (2/9), and Carollia brevicauda (1/2), and one insectivorous, M. nigricans (1/11). The latter was simultaneously positive for NS1 protein. DV RT-PCR positive animals were all antibody seronegative. M. nigricans showed positive individuals for all three tests. This is the first evidence suggesting the presence of DV in bats from Mexico.