Title: Plague in tanzania: from a host and vector perspective
Authors: Laudisoit, Anne
Makundi, Rhodes
Neerinckx, Simon
Krasnov, Boris
Leirs, Herwig #
Issue Date: Feb-2010
Publisher: Mary ann liebert inc
Host Document: Vector-borne and zoonotic diseases vol:10 issue:1 pages:101-101
Conference: Symposium on the Ecology of Plague and Its Effects on Wildlife location:Fort Collins date:4-6 November 2009
Abstract: Today, in Tanzania Yersinia pestis apparently persists in sylvatic enzootic cycles,
sometimes lasting for decades. Plague circulation remains undetected until an epizootic
or an epidemic is observed. In 1982, Akiev wrote ‘‘The evidence available concerning
plague in Africa indicates that the infection is enzootic throughout the
continent and that under certain conditions cases of human plague might occur in any
African country’’. This single sentence summarizes what we don’t know about plague.
In fact, we still know very little about the ‘‘certain conditions’’ that favour long-term
maintenance of plague in African foci. In Mbulu district for example, in northern
Tanzania, a sudden plague outbreak in February 2007 reminded the Tanzanians that
plague was still present, despite the fact that no plague cases had been reported since
1977. In the Lushoto district, the first recorded plague outbreak occurred in 1980. The
outbreak began in a single village and rapidly spread to more than 50 villages. By
2004, 7,603 cases had been reported from this region. There was great variation in the
number of cases of plague among the villages. Although evidence of infection with Y.
pestis has been observed in several wild rodent and flea species during epidemics,
the actual reservoir in which the infection survives has not yet been identified. The
ecology of plague and the source from which humans acquire infection are poorly
understood. We compared the domestic and sylvatic ecology in villages having frequent
plague outbreaks with those in villages where plague is relatively rare. In particular,
we studied the prevalence of the infection in small mammals including their
species composition and distribution, and the seasonal and spatial pattern of host-flea
association. During this 4 years study we found no seropositive animals and no difference
in sylvatic rodent and flea diversity between the two sets of villages. The
reason for the differences in plague incidence between villages may not be the difference
in species composition of either rodents or fleas, but rather difference in
relative abundances of those rodent and flea species that possess ecological characteristics
that facilitate transmission of the plague pathogen. Within affected villages,
socio-cultural factors might be responsible for the observed differential plague incidence
in females and different age groups recorded in the Lushoto hospital dataset.
Interviews suggest that the risk of exposure to domestic fleas during daily activities
is higher in children and women. Moreover, we found that Pulex irritans, the
human flea, was the predominant flea species in houses and that P. irritans index was
strongly positively correlated with plague frequency and with the logarithmically
transformed plague incidence. These observations suggest that in Lushoto District, at
the domestic level, human fleas may play a role in plague epidemiology in the domestic
environment. However, this doesn’t explain how plague reaches the village, nor does it
answer where and how do plague persists between outbreaks, especially on the long
ISSN: 1530-3667
Publication status: published
KU Leuven publication type: IMa
Appears in Collections:Division Soil and Water Management
# (joint) last author

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