Fleas (Siphonaptera) as vectors in natural plague foci worldwide: host-parasite relationships, faunistic and geographical analysis, epizootic significance

The fauna of fleas in the world is currently known by 2162 species, of which 262 species (12.1%) from 6 families are found infected with plague in nature. Fleas of the families Hystrichopsyllidae (74 species), Ceratophillidae (69 species) and Leptopsyllidae (40 species) are most involved in the epizootic. Among all flea species found infected with the plague pathogen, only 64 (24%) are considered as the main plague vectors. The species distribution by families is as follows: Ceratophillidae – 24 species, Pulicidae – 18 species, Hystrichopsyllidae – 10, Leptopsyllidae – 8, Rhopalopsyllidae – 4. The flea Oropsylla silantiewi takes the leading position among all main plague vectors. The approximate number of plague natural foci in the world is at least 316. O. silantiewi acts as the main vector and keeper of infection in 59 natural foci of plague. In 41 natural foci, this species is the only main vector, ensuring the circulation of the pathogen without significant assistance of other flea species. No other flea species is so powerfully involved in the plague pathogen circulation in any region of the world. O. silantiewi is a specific parasite of marmots, whose origin is associated with the mountain steppes of Central Asia, where the center of origin of the plague microbe is probably located. From this territory, the plague microbe began its further worldwide spread with penetration and development of new ecological niches in flea’s populations of ground squirrels, mice, rats, voles and other small mammals.