What is kala-azar, and how is it tested in Kenya?

Kala-azar, known medically as visceral leishmaniasis (VL), is a disease caused by Leishmania parasites that sandflies pass on through their bites. The World Health Organization (WHO) says it is fatal in over 95% of cases if left untreated, and that diagnosis combines a patient's clinical signs with parasitological or serological tests, rapid tests included. The Kenya Medical Research Institute (KEMRI) is taking part in a multicountry study of five rapid test kits.

Leishmaniasis is caused by protozoan parasites transmitted by the bite of infected female phlebotomine sandflies, and some 70 animal species, humans included, can be a source of the parasites. VL is the most serious form of leishmaniasis; the most common form, cutaneous leishmaniasis, causes skin lesions, and the mucocutaneous form can destroy the mucous membranes of the nose, mouth and throat.

WHO describes VL as characterised by "irregular bouts of fever, weight loss, enlargement of the spleen and liver, and anaemia". KEMRI's bulletin says VL's often-overlapping symptoms can make clinical diagnosis challenging.

WHO estimates 50,000 to 90,000 new VL cases a year worldwide, of which only 25% to 45% are reported to WHO. Most cases occur in Brazil, East Africa and India, and outbreaks of VL are frequent in East Africa. A 2013 Kenyan study lists Kenya among the East African countries where the disease is found.

How is it confirmed? WHO says diagnosis combines clinical signs with parasitological tests (finding the parasite) or serological tests (finding the body's antibodies to it), including rapid diagnostic tests. The 2013 study says confirming the diagnosis requires examining under a microscope a smear taken by needle from the spleen. The authors call this invasive and say it should be done by experienced clinicians in reference hospitals or research centres.

The rapid tests detect antibodies against a parasite protein called rK39, and in clinical practice they are likely to be used on whole blood from a finger prick, the study says.

That 2013 paper, now 13 years old, tested two rapid kits in Kenya. It was published in PLOS Neglected Tropical Diseases on 26 September 2013 by Jane Mbui of KEMRI's Centre for Clinical Research in Nairobi and colleagues. It was a prospective diagnostic study (patients were recruited and tested as they came) run from May 2010 to July 2011 at Kimalel Health Centre in Baringo and Kacheliba Kala-azar Treatment Centre in Pokot North, both in the Rift Valley.

Spleen microscopy served as the reference. Of 219 patients analysed, 131 had VL and 88 did not. The DiaMed IT LEISH test had a sensitivity (the share of true patients it catches) of 89.3% and a specificity (the share of people without the disease it correctly clears) of 89.8%. The Signal KA test scored 77.1% and 95.5%. Combining the two did not improve results, because every patient positive on Signal KA was also positive on DiaMed IT LEISH.

The authors concluded that DiaMed IT LEISH can be used to diagnose VL in peripheral health facilities in Kenya where spleen microscopy or advanced serological tests are not feasible. They also wrote that "a more sensitive RDT for primary VL diagnosis in East Africa remains deeply needed". The tests were run on serum rather than finger-prick blood, and the authors say they cannot exclude some spectrum bias (a patient mix that differs from real clinic patients) or an under-estimate of sensitivity. None of the VL patients tested for HIV had the virus.

The RDT ViLEA project, in which KEMRI is taking part, tests five rapid kits in Kenya, Ethiopia and Sudan, first in the laboratory and then in the field under real-world conditions. KEMRI says the project seeks evidence to inform the selection and use of reliable diagnostic tools, as part of regional efforts to eliminate the disease. The Special Programme for Research and Training in Tropical Diseases (TDR) and the WHO Department of Malaria and Neglected Tropical Diseases support the research.

KEMRI held a three-day hands-on laboratory training from 3 to 5 November 2026 at the Immunology Laboratory of its Centre for Clinical Research in Nairobi. It covered the project's standard operating procedures, use of the kits, reading results and the REDCap data platform. Prof Matilu Mwau is KEMRI's principal investigator on the project. Co-investigator Dr Margaret Mbuchi said: "KEMRI is strengthening its contribution to regional efforts to improve the diagnosis of visceral leishmaniasis."

WHO's advice, in its fact sheet of 12 January 2023, is that people suspected of having VL should seek medical care immediately. It says leishmaniasis is treatable and curable, and that "all patients diagnosed with visceral leishmaniasis require prompt and complete treatment". To cut sandfly numbers it lists insecticide spraying, insecticide-treated nets, environmental management and personal protection, and it says poor housing and domestic sanitary conditions may increase sandfly breeding.