Invasive Rats and Bubonic Plague in Northwest Uganda

Major introductions of roof rats (Rattus rattus) likely occurred in the ports of East Africa during the Third Plague Pandemic in the late 1800’s. Transport via trains, boats, and trucking likely introduced this species to inland areas of East Africa, ultimately including Northwest Uganda. Historic plague outbreaks occurred during the early part of the 20th century and continue to cause a human disease burden in the West Nile region of NW Uganda via the bubonic, septicemic, and pneumonic forms. Four field sites in this area were trapped to determine the rodent species composition in commensal and peridomestic areas of villages and associated flea burdens of the rodents. Rattus rattus were the most prevalent rodent trapped in commensal areas followed by the Nile rat (Arvicanthis niloticus). The most common peridomestic species of rodent was the Nile rat. Other peridomestic rodent species captured included, Mastomys natalensis, Lophuromys flavopunctatus, L. sikapusi, Gerbil (Tatera spp.), Lemniscomys spp., and 4 unknown species. Flea burdens on commensal R. rattus averaged 1.7±1.2 fleas per animal and on all peridomestic rodents, average 2.0±0.7 per animal. Additionally, commensal areas were sampled to determine free-living flea populations. Burrow swabbing indicated an average 0.19±0.12 fleas/burrow. Lighted flea traps averaged 1.3±0.6 fleas per household and dark flea traps averaged 0.5±0.4 fleas per household.