Observations on the endemicity of plague in Karatu and Ngorongoro, northern Tanzania

Abstract

Commensal and field rodents and wild small carnivores were live-trapped in five villages of Karatu district and one settlement in the Ngorongoro Conservation Area in Ngorongoro district in Tanzania. Blood samples were taken and serologically tested for plague, using the Blocking ELISA technique. Some domestic dogs and cats in the Karatu villages were aseptically bled and similarly tested for plague. Fleas were collected from the examined animals and from randomly selected residential houses. A total of 241 rodents, 1 Crocidura spp, 43 dogs, 12 cats and 4 slender mongooses were involved in the survey. Of the rodents, 14.5% were infested with fleas, which comprised of Xenopsylla brasiliensis (45.8%) and Dinopsyllus lypusus (54.2%), with an overall population density of 0.2 fleas/animal. Thirty one (72.1%) of the dogs were infested with fleas, all of which were Ctenocephalides spp. Thirty five (63.3%) houses were infested with fleas whose population was composed of Ctenocephalides spp, Pulex irritans, Tunga penetrans and Echinophaga gallinacea. Infected rodents were found in all the villages while the infected dog was found at Rhotia-Kati. Nineteen (11%) of the rodents and one (2%) dog harboured specific plague antibodies. It was broadly concluded that sylvatic plague was endemic in Karatu district and Ngorongoro Conservation Area and that outbreaks of the disease can occur in the area any time if and when relevant conditions become favourable. Prompt application of appropriate preventive and control measures and survey for substantiating the status in the Lake Manyara National Park, which is adjacent to some of the infected villages, are recommended.

Effects of Land Use on Plague (Yersinia pestis) Activity in Rodents in Tanzania

“…This increase appears to be largely driven by the high numbers of M. natalensis found in agricultural habitats, with the abundance of this species being very strongly correlated to plague seroprevalence. Mastomys natalensis is one of the most frequently seropositive species for Y. pestis in Africa and is a widespread commensal species 38,59 (and an important host of various other human pathogens, including Lassa virus 60,61 ). Analogous changes in community composition, with a common commensal species serving as a major reservoir and "key host" for a pathogen, have been reported elsewhere, Figure 4.…”

“…Nevertheless, our host community model should accommodate incomplete sampling, and the species-specific seroprevalence patterns observed in the rodents sampled in this study are compatible with other surveys of rodent seroprevalence in the same region. 38 Also, although seroprevalence studies are widely adopted for plague surveillance, we note that plague seroprevalence studies offer insights into rates of Y. pestis resistance rather than infection or infectiousness, that is, animals that die of Y. pestis infection are not available to sample. Can M. natalensis act as infectious plague hosts, or do they simply exhibit resistance to infection and not play a part in infecting fleas?…”

“…Sampling was carried out in a region of northern Tanzania where plague is endemic and is a source of public health concern. 38 We compare metrics of rodent community assembly (i.e., abundance, richness, and diversity) and plague ecological risk (i.e., the presence/absence of plague activity and calculated abundance of seropositive rodents) in these two landscape types. Results from this work should contribute to our understanding of how landscape change influences wildlife communities and zoonotic disease risk on the local scale and can inform relevant intervention actions.…”

Tungiasis infestation in Tanzania

“…A historical report from Tanzania described severe tungiasis in pigs [14]. Recently, Kilonzo et al (2006) identified Tunga penetrans fleas inside dwellings in northern Tanzania [15].…”

Current perspectives on the spread of plague in Africa

“…96 Since 1983, outbreaks of human plague have occurred almost nonstop, which had not been the case for the previous 30-year period. 18,23,24,32,[50][51][52]66,67,78,85,[97][98][99][100][101][102] In Uganda, the earliest documented cases of plague were recorded by missionaries in 1877. 103 During the first half of the 20th century, the main plague foci in Uganda were localized in the Ituri forest, around Lake Albert, Burungu Island in Lake Victoria, Rubaga hill near Kampala and the Kyaggwe areas in the districts of Mukono, Masaka, Rakai, Pallisa, Tororo, and Busia.…”