A molecular epidemiological study of rabies in Puerto Rico.

The mongoose is the principal reservoir for rabies on the island of Puerto Rico. This report describes a molecular epidemiological study of representative rabies viruses recovered from the island in 1997. Two closely related but distinct variants circulating in regionally localised parts of the island were identified. The lack of a monophyletic relationship of these viruses suggests that two independent incursions of rabies onto the island have occurred. Both of these Puerto Rican variants were closely related to a variant, known as the north central skunk strain, currently circulating in North American skunk populations and all are members of the cosmopolitan rabies lineage spread during the colonial period. However, the Puerto Rican viruses are clearly distinct from those presently circulating in mongooses in Cuba and which are epidemiologically closely linked to the Mexican dog rabies virus. This study clearly establishes the distinct origins of the rabies viruses now circulating on these two Caribbean islands.

The molecular epidemiology of rabies associated with chiropteran hosts in Mexico.

While large-scale dog vaccination campaigns have significantly reduced urban rabies throughout Mexico, reports of sylvatic rabies, including cases of spill-over of bat strains into livestock and humans, are increasing. To improve knowledge of these epidemiological trends, 64 Mexican rabies virus isolates from various host species, have been characterized. Phylogenetic analysis at the viral P locus identified distinct viral strains associated with terrestrial reservoirs (dog, skunk and fox/bobcat) and a variant associated with the insectivorous bat, T. brasiliensis, consistent with prior reports. Of the two distinct clades of viruses associated with the vampire bat reservoir, one comprised just four specimens and formed an outlying group to all other vampire bat rabies isolates including those from South America and the Caribbean, a finding consistent with the early emergence of the vampire bat reservoir in Mexico. Antigenic variation of the vampire bat specimens did not correlate with the main genetic groupings; moreover complete N gene sequence analysis of selected specimens indicated limited variation within the encoded nucleoprotein that could form the basis of antigenic variation. A single isolate recovered from a cat represents a new viral variant not previously identified in North America that probably circulates in a species of insectivorous bat.