Development of a safer laboratory vervet monkey model for the study of human African trypanosomiasis.

BACKGROUND

There are three subspecies of : and . The first two are infectious to humans, whilst is not. Identifying an animal model of that mimics human African trypanosomiasis (HAT) would enable researchers to study HAT without subjecting themselves to undue risks such as accidental infection.

OBJECTIVES

This study assessed the sequential clinical, parasitological and haematological changes in vervet monkeys infected with .

METHODS

Three vervet monkeys were infected with a 10 inoculum of (isolate GUTat 1). Late-stage disease was induced by subcurative treatment with diminazene aceturate 28 days post-infection. The animals were treated curatively with melarsoprol upon relapse. Parasitaemia and clinical signs were monitored daily and, at weekly intervals, the monkeys' blood and cerebrospinal fluid (CSF) were sampled for haematology and parasitosis assessments, respectively.

RESULTS

The first-peak parasitaemia was observed between seven and nine days post-infection. Clinical signs associated with the disease included fever, dullness, pallor of mucous membranes, lymphadenopathy, splenomegaly and oedema. Late-stage signs included stiffness of joints and lethargy. The monkeys developed a disease associated with microcytic hypochromic anaemia. There was an initial decline, followed by an increase, in total white blood cell counts from early- to late-stage disease. Trypanosomes were detected in the CSF and there was a significant increase in white cell counts in the CSF during late-stage disease. Infected vervet monkeys displayed classical clinical symptoms, parasitological and haematological trends that were similar to monkeys infected with .

CONCLUSION

The vervet monkey model can be used for studying HAT without putting laboratory technicians and researchers at high risk of accidental infection.