Isolation of viral and rickettsial agents from Panamanian Acarina.

Abstract

Over a 21-month period, large and diverse collections of Acarina parasitic on Panamanian vertebrates were tested for infection with arboviruses and rickettsiae by inoculating suckling mice or guinea pigs with pooled specimens. Most specimens tested were rodent parasites of the families Trombiculidae, Laelapidae, Ixodidae, and Macronyssidae. No viruses were recovered from 468 pools of mites, but 2 strains of unidentified, filterable agents were isolated in mice from 2 of 173 tick pools. One isolate was from a pool of 75 immature Amblyomma sp. and 9 larval Haemaphysalis juxtakochi taken off the Coati Coatimundi), Nasua nasua narica , in Gamboa, Canal Zone C.Z.). The other was from 1 male Amblyomma parvum and immature Amblyomma sp. pooled from mixed hosts and localities of C.Z. Both strains were of low and variable pathogenicity for mice and failed to survive frozen storage. Evidence of rickettsial infections of mites was seen in 3 instances: Coxiella burneti was recovered in a guinea pig from a pool of 13 chiggers, Intercutestrix mondolfii , taken off the Spiny Rat, Proechimys semispinosus , in Pina, C.Z. Two additional pools of mites were infected with C. burneti as shown by serological conversion of inoculated guinea pigs. One of these pools consisted of 27 chiggers ( Tecomatlana sandovali ) off bats ( Saccopteryx bilineata ) in Panama Province. The other contained 226 mixed Laelapidae off C.Z. rodents. Rickettsia rickettsi was isolated in a guinea pig from 20 immature Amblyomma sp. pooled from mixed hosts in the C.Z. These results indicate that parasitic mites play a minimal role, if any, in circulating arboviruses in this area of the Neotropical Region. In addition, further evidence is provided for the possible participation of mites, including chiggers, in the natural cycle of Coxiella burneti .