The phleboviruses

The sandfly-transmitted viruses are all within the Bunyavirus group, the phleboviruses; globally, some 45 viruses are associated with sandflies. Sandfly fever, which is widespread in southern Europe and the Middle East, has not been found in the USA or Canada. In fact the only phlebovirus which is known to occur in the USA is Rio Grande virus which was isolated in Texas from pack rats (Neotoma micropus) (Calisher et al., 1977). The infectious agent has not been reported from humans.

Most phleboviruses are associated with sandflies. A notable exception is Rift Valley fever which is found in Africa, Egypt and, most recently, in Saudi Arabia and Yemen. The infection, transmitted by culicine mosquitoes, causes severe illness and mortality in man and animals and, as has been noted earlier, the movement of the infectious agent should be kept under close surveillance to prevent its entry to the Americas.

Leishmaniasis

Leishmaniasis occurs focally in the Americas from Yucatan, Mexico, through Central and South America to the Peruvian Andes. The pathogenic New World species include the Leishmania braziliensis complex (L. braziliensis, L. panamensis and L. guyanensis), L. mexicana complex (L. mexicana, L. amazonensis, L. venezuelensis), L. peruviana and L. chagasi.

Several foci of endemic leishmaniasis have been reported in the USA. Autochthonous human cutaneous leishmaniasis (CL) caused by Leishmania mexicana appears to be limited to south central Texas and perhaps Oklahoma in the USA; the infection is not found in Canada other than as an imported infection or, in a single instance, in a dog.