Pattern and spatial distribution of plague in Lushoto, north-eastern Tanzania

Abstract

A review of plague records from 1986 to 2002 and household interviews were carried out in the plague endemic
villages to establish a pattern and spatial distribution of the disease in Lushoto district, Tanzania. Spatial data of households
and village centres were collected and mapped using a hand held Global Positioning System and Geographical Information
System. During the 16-year period, there were 6249 cases of plague of which 5302 (84.8%) were bubonic, 391 (6.3%)
septicaemic, and 438 (7.0%) pneumonic forms. A total of 118 (1.9%) cases were not categorized. Females and individuals
aged 7-18 years old were the most affected groups accounting for 54.4% (95% CI: 52.4–56.0) and 47.0% (95% CI: 45–49)
of all reported cases, respectively. Most cases were found in villages at high altitudes (1700-1900m); and there was a
decline in case fatality rate (CFR) in areas that experienced frequent outbreaks. Overall, there was a reduction in mean
reporting time (from symptoms onset to admission) to an average of 1.35 days (95% CI: 1.30–1.40) over the years,
although this remained high among adult patients (>18 years). Despite the decrease in the number of cases and CFR over
the years, our findings indicate that Lushoto district experiences human plague epidemic every year; with areas at high
altitudes being more prone to outbreaks. The continued presence of plague in this focus warrants further studies. Nonetheless,
our findings provide a platform for development of an epidemic preparedness plan to contain future outbreaks..

Keywords: plague, epidemics, pattern, spatial distribution, Tanzania

Tanzania Health Research Bulletin Vol. 9 (1) 2007: pp. 12-18