Iranian scientists have shown that a rapid and non-invasive diagnostic test for visceral leishmaniasis, or kala-azar, can distinguish between active, subclinical and latent cases of the disease.
Diagnosis of kala-azar — the most severe form of leishmaniasis — is complex because its symptoms, such as fever, are similar to those seen in other diseases such as malaria and tuberculosis.
The most common diagnostic procedure is microscopic examination of bone marrow samples — an invasive test — and time-consuming isolation of the parasite by culture. Other molecular tests have recently been developed, but they are expensive and not commonly used.
Lead researcher AbdolSamad Mazloumi Gavgani and co-workers from Tabriz University of Medical Sciences, Iran, examined urine samples from 313 children in districts of the East Azerbaijan province in Northwest Iran, where leishmaniasis is endemic.
Using a test called KAtex, which detects proteins from Leishmania infantum in the urine, the researchers found ten positive cases. Clinical follow up of these children revealed that three of them went on to develop the disease and showed high parasite load.
The team also found that the test did not produce false positive results when tested on individuals suffering from tuberculosis, toxoplasmosis or brucellosis were examined.
The KAtex is more specific than antibody-based tests that continue to give a positive result long after the disease has been cured, say the researchers.
"The test could be considered an ideal tool for wide-scale diagnosis of kala-azar diseases in the difficult field conditions of remote endemic areas, as there is no need for any specific expertise or electrical appliances," Gavgani told SciDev.Net
Morad Ahmed Morad, a professor of medicine at Tanta University, Egypt, welcomed the new development saying, "It will be a vital tool for fighting endemic visceral leishmaniasis which is spreading in Iran and the Mediterranean region."
The study was published in the African Journal of Biotechnology.
African Journal of Biotechnology 7, 852 (2008)