Human African trypanosomiasis: the current situation in endemic regions and the risks for non-endemic regions from imported cases

Abstract

Human African trypanosomiasis (HAT) is caused by Trypanosoma brucei gambiense and Trypanosoma brucei rhodesiense and caused devastating epidemics during the 20th century. Due to effective control programs implemented in the last two decades, the number of reported cases has fallen to a historically low level. Although fewer than 977 cases were reported in 2018 in endemic countries, HAT is still a public health problem in endemic regions until it is completely eliminated. In addition, almost 150 confirmed HAT cases were reported in non-endemic countries in the last three decades. The majority of non-endemic HAT cases were reported in Europe, USA and South Africa, due to historical alliances, economic links or geographic proximity to disease-endemic countries. Furthermore, with the implementation of the 'Belt and Road' project, sporadic imported HAT cases have been reported in China as a warning sign of tropical diseases prevention. In this paper, we explore and interpret the data on HAT incidence and find no positive correlation between the number of HAT cases from endemic and non-endemic countries. This data will provide useful information for better understanding the imported cases of HAT globally in the post-elimination phase.

Keywords: Human African trypanosomiasis; T. b. rhodesiense; Trypanosoma brucei gambiense; non-endemic disease countries; sub-Saharan Africa.

Fig. 1.

Total number of reported cases of HAT in endemic countries from 1990 to 2018.

Fig. 2.

(A) Number of reported cases of gambiense-HAT per year from 1990 to 2018 in endemic countries with a breakdown for each country. (B) Number of reported cases of rhodesiense-HAT per year from 1990 to 2018 in endemic countries with a breakdown for each country. Data taken from the World Health Organization (WHO).

Fig. 3.

Distribution of human African trypanosomiasis in endemic countries, 2017 and 2018. Data are taken from the World Health Organization (WHO).

Fig. 4.

HAT cases that were diagnosed and confirmed in non-endemic countries from 2011 to 2018. (A) (B) Dots represent the place of diagnosis; (C) Triangles indicate the probable place of infection. Numbers refer to the designations in Table 1.

Fig. 5.

Number of HAT cases diagnosed in non-endemic countries in different periods.

Fig. 6.

HAT cases reported in non-endemic countries in different time periods.

Fig. 7.

The dynamic trend changes in HAT cases diagnosed in non-DECs and DECs. Bar graphs indicate the annual figures. The line graphs indicate the distribution of 3-year averages.