An analysis of Human African Trypanosomiasis (HAT) in Nigeria

Abstract

The purpose of this paper is to evaluate the trends of Human African Trypanosomiasis (HAT) in Nigeria 1931-1990, identify the relationship between the infection rates and the control measures applied and estimate the annual percent change of the disease over the period. The data for this paper were obtained from the unpublished records of epidemiological section of the Nigerian Institute for Trypanosomiasis Research (NITR). Death from sleeping sickness was modeled using natural logarithm to identify the disparity between the predicted rates based on log-linear models which increases or decreases as the time periods being forecasted move further from the time of observation and also to identify the fluctuation across time and variability at each time point. The first peak of the epidemic was between 1931-1940 when more than 370,000 persons were diagnosed. By the end of 1950, the number had dropped to about 40,000, which further declined to about 30,000 by the beginning of 1951. There was a slight increase in the number of cases which was sustained up to late 1970’s. The period 1981-1990 witnessed a sudden upsurge in infection rates which suggest that the disease may be on the increase unnoticed. Analysis of the mortality rate for the available data for 1970-1979 showed a total mortality of 0.003 % out of approximately 28,000 infected persons. The peak rate was in 1974 with 18.1 % deaths followed by 1972 with 17.7 % deaths. The overall mortality rate was 0.11 per 10,000 persons. It appears the overwhelming success achieved in the control of the disease in the past has affected the way governments perceive the disease. What followed was dwindling funding over several decades, resulting in the breakdown of surveillance and vector control activities. The ecological conditions that could result to epidemic outbreak of HAT are still present. The reason why there has been no outbreak so far, as in other endemic countries is not known. Urgent attention needs to be taken to avoid catastrophe.