Diagnostic techniques for visceral leishmaniasis: An overview of methods used in East Africa

Leishmanias is a parasitic infection caused by a protozoan belonging to the genus Leishmania and transmitted by sand fly, Phlebotomus fly in the old world and Lutzomyia in the New world. The disease is prevalent in the tropics, subtropics, and Southern Europe, where it affects about 1.5 million to 2 million people annually. India, Bangladesh, Sudan, South Sudan, Brazil and Ethiopia account for up to 90% of all the VL cases. While Leishmania cases in Asia are declining, cases in East Africa especially in Somalia, Sudan, South Sudan, Ethiopia and Kenya have been increasing. The rise in East African cases is partially attributed to ongoing armed conflicts especially in Somalia, Sudan and Southern Sudan, which has displaced people and increased their exposure to sand fly bites. Migration from endemic to non-endemic regions, misdiagnosis, famine, malnutrition, climate change and an increase in HIV cases are other contributing factors. The clinical diagnosis of Leishmania in East Africa combines the patient's clinical signs with either serological or parasitological test, with rK39 strip and microscopy being the major methods used. Diagnosis of the condition remains challenging, as current techniques have limitations, including the inability to detect parasites in tissue, the need for specialized expertise, prohibitive costs of testing equipment, low antibody titers, and the risk of misdiagnosis due to co-infections with diseases such as HIV, tuberculosis, malaria and typhoid. Various techniques, including serological and molecular parasitological methods, have been employed in attempts to address these challenges, but with limited success. This article therefore, reviews some of the techniques that have been used in Leishmania diagnosis in East Africa and discusses other available new techniques with aim of overcoming the current challenges.