Kenya Trypanosomiasis Research Institute Cryobank for Human and Animal Trypanosome Isolates to Support Research: Opportunities and Challenges

Human African trypanosomiasis (HAT) is classified in the category of the most neglected tropical diseases. In man, the disease is caused by two tsetse (Glossina spp.)-transmitted trypanosome subspecies: Trypanosoma brucei gambiense, which is responsible for the chronic form of HAT in West and Central Africa, and T. b. rhodesiense, which causes acute disease in eastern and southern Africa. African animal trypanosomiasis (AAT) is caused by various trypanosome species, the major ones being T. vivax, T. congolense, and T. evansi [1]. Current diagnostic tools are inadequate and diagnosis is complicated, whereas the drugs for treatment are highly toxic and not very effective; patients die if untreated [2]. In 2005, an annual prevalence of 50,000–70,000 cases per year and incidence rates of 15,000–17,000 cases per year were reported [3]. Although recent data from the World Health Organization (WHO) shows that the number of reported cases of HAT declined to less than 10,000 in 2009, leading to speculation that the disease could be eliminated [4,5], there is great need to maintain vigilance. The East African Trypanosomiasis Research Organization (EATRO) was established to carry out research and develop technologies for effective control of trypanosomiasis. In view of this, a trypanosome cryobank was established in Tororo, Uganda, in the mid-1950s to provide materials for research. At that time, dry ice was used as a refrigerant, but in 1977 it was replaced with liquid nitrogen. Following the collapse of the East African Community in 1977, the Kenya Trypanosomiasis Research Institute (KETRI) was established to take over the functions of tsetse and trypanosomiasis research in Kenya. The cryobank was therefore transferred to KETRI during this period. In 2003, following a reorganization of research institutions by the Government of Kenya, KETRI was merged with the Kenya Agricultural Research Institute (KARI) and renamed the Trypanosomiasis Research Centre (KARI-TRC). KARITRC continued with all the research programmes and activities that were being carried out under KETRI, including collection and preservation of trypanosome stabilates. The institution developed a policy on stabilate collection by scientists and clinicians for cryopreservation. We describe the establishment of the cryobank and procedures used in cryopreservation of stabilates and summarize the data (numbers and types) on trypanosome species stored in the cryobank, which are available for use in research by the scientific community. The cryobank contains 2,347 stabilates, including 1,747 primary isolates, out of which there are 42 mixed infections and one miscellaneous Herpetomonas muscorum, and 600 derivatives, including six mixed infections. Primary isolates were collected mainly from countries in the eastern Africa region, including Kenya, Uganda, Tanzania, Sudan, and Ethiopia. However, collections or donations from countries outside the region, including Nigeria, Mozambique, Botswana, Germany, and South America, have been added as part of collaborations between KARI-TRC and other institutions around the world. The stabilates were isolated between 1934 and 2010. The majority of the stabilates were recovered between 1960 and 1970 (Figure 1), the same period when some of the worst epidemics occurred, after which the numbers added have been on the decline. The period from 1940 to 1949 coincided with World War II, when the work on trypanosomiasis research and control stalled: the laboratories in eastern Africa that were the source of isolates were closed, only to resume after 1945 when the war came to an end.