Entomological and Rodent Surveillance in Plague-Suspected Areas During September 1994 and Thereafter

Abstract

SUMMARY: Studies carried out in the states of Maharashtra, Gujarat, Uttar Pradesh and Union Territory of Delhi after the bubonic plague outbreak during 1994 revealed the presence of seven species of rodents, viz. Rattus rattus, R. norvegicus, Mus. musculus, Tat era indica, Suncus murinus, Bandicoota bengalensis and B. indica. The flea species encountered were Xenopsylla cheopis and X. astia. The X. cheopis and X. astia index recorded in different areas of Beed district of Maharashtra; Surat, Vadodra and Baruch districts in Gujarat and Varanasi district in Uttar Pradesh and their implications have been discussed. Insecticide suspectibility tests carried out against DDT, dieldrin, malathion and deltamethrin with X. cheopis collected from Maharashtra, Delhi and Varanasi revealed that this vector species is resistant to DDT and dieldrin but susceptible to malathion and deltamethrin. The prevalence and distribution of rodents species, high cheopis index and prevalence of Tatera indica just at the door steps of houses in village Mamla of Beed district provides highly congenital conditions for the intermingling of wild and domestic rodents and transfer of flea population from wild to domestic rodents and vice-versa. These conditions were found to be highly supportive for bubonic plague transmission in the district. The presence of Yersinia pestis antibodies in Rattus rattus collected from Beed, Surat and Varanasi areas are also indicative of bubonic plague in Beed and Varanasi and pneumonic plague in Surat during 1994.97

Molecular Detection of Bartonella Quintana, B. Elizabethae, B. Koehlerae, B. Doshiae, B. Taylorii, and Rickettsia Felis in Rodent Fleas Collected in Kabul, Afghanistan

“…To our knowledge, no description of flea species infesting rodents has been conducted in Afghanistan for more than 30 years. In Asia, Xenopsylla cheopis, the oriental rat flea, is often prevalent, 9,10 but as many as 53 different flea species have been described among rodent populations in the same geographic area. 11 Fleas were transported to Marseille, France and washed in phosphate-buffered saline for 72 hours at 4°C.…”

Social vulnerability and pneumonic plague: revisiting the 1994 outbreak in Surat, India

“…Sylvatic rodents were ruled out as plague sources by Saxen and Verghese (1996b) who noted both the lack of necessary ecological linkages between wild and domestic habitats and of human bubonic plague cases. Rodent and flea surveys conducted after the outbreak found that 16% of trapped black rats tested positive for plague antibodies; however, flea densities were low making transmission to humans unlikely (Kumar et al, 1997).…”

“…Residents returning to these makeshift granaries to replenish supplies encountered swarms of rats and fleas. By August 1994 rat-flea densities were sufficiently high for plague to become epizootic in the rat population (Saxena & Verghese, 1996a) and reports of severe flea nuisances and 'rat falls' increased (Garrett, 2000;Kumar et al, 1997). The first human case of bubonic plague was reported on 26 August 1994, with 90 additional cases appearing in the following weeks; none proved fatal (Richardson, 1995).…”