Human African Trypanosomiasis in the Kafue National Park, Zambia.

Abstract

Human African Trypanosomiasis (HAT) is a neglected tropical disease [1] caused by Trypanosoma brucei rhodesiense (eastern and southern Africa) or Trypanosoma brucei gambiense (western and central Africa) and is transmitted through the bite of an infected tsetse fly (Glossina species) [2,3]. The tsetse flies acquire their infections from humans or animals harbouring the human pathogenic parasites [2]. The disease is endemic in tropical and subtropical Africa [4], where it affects low-income populations [3]. Whereas T. b. rhodesiense causes acute HAT [5,6], T. b. gambiense causes a more chronic form of the disease [5]. Although HAT has been re-emerging in most of the old foci within sub-Saharan Africa since the 1970s, with T. b. gambiense accounting for more than 98% of the reported cases [7], the latest World Health Organization (WHO) reports suggest that the number of new cases have been reduced [1]. In the year 2009, after continued control efforts, the number of cases of HAT reported dropped below 10,000 (9,878) for the first time in 50 years. This decline in number of cases has continued with 6,314 new cases reported in 2012 [1]. However, the estimated number of actual cases is about 20,000 and the estimated population at risk is 65 million people. Despite such progress, only a fraction of the population at risk for contracting HAT in sub-Saharan Africa is under surveillance and relatively few cases are diagnosed annually [8,9]. In particular, there is considerable underdiagnosis of rhodesiense HAT in sub-Saharan Africa, including Zambia, mainly due to lack of HAT surveillance and control programmes [10,11]. Historically, epidemics of rhodesiense HAT were reported from the northern and southern regions of the Luangwa Valley and the Kafue River Valley in the 1960s and early 1970s [12]. According to WHO [1], Zambia currently reports <100 new HAT cases annually, mainly from the old foci in the tsetse-infested Luangwa River Valley, including the Chama, Mpika, Chipata, Mambwe, and, recently, Rufunsa districts, where the disease is re-emerging [13–15]. The Kafue National Park (KNP) and its surrounding Game Management Areas (GMA) form the Kafue ecosystem, which is a vast and continuous wildlife conservation area located in the central part of Zambia [16] and rich in biodiversity of high biomass [17]. It is a pristine ecosystem that supports a wide variety of undisturbed flora and fauna of important conservation status [17]. The area also supports the communities that live there by harnessing the benefits from ecotourism and ecosystem services [18]. Importantly, it has abundant wildlife and tsetse flies [16]. The Kafue ecosystem has in the past reported cases and epidemics of HAT [16,19]. The Primitive Methodist Church of England established Nkala Mission in 1893, which was later abandoned in 1930 because of tsetse flies and sleeping sickness [16]. Today Nkala lies in the heart of the Kafue ecosystem. Another focus, Itumbi Safari Camp, which was opened in 1958 in the KNP, was closed down in 1959 due to severe cases of sleeping sickness [19]. This demonstrates the historical presence of HAT in the Kafue ecosystem. However, for over 50 years now no reports or notable incidences of HAT have been recorded in the area. Based on this fact, it has been assumed that the area was devoid of HAT despite the obvious presence of tsetse flies. The present report describes a case of HAT in an adult male from KNP, 16 km away from Itumbi Safari Camp, its diagnosis, and management.