Fighting visceral leishmaniasis

mosquito bite

Leishmaniasis is one of the neglected tropical diseases (NTDs), a group of dangerous conditions endemic mostly in developing countries. Historically, these have been disregarded by the scientific community and, although it is changing and much has been done in the recent past to increase infectious tropical medicine research, they still remain a major problem in the world. Leishmaniasis, Chagas Disease, Sleeping Sickness, Elephantiasis and Leprosy are just a handful of examples of terrible diseases which tend to receive much less attention from the scientific world than Malaria, HIV-AIDS and Tuberculosis, despite causing a huge number of human deaths.

Leishmaniases are vector-borne diseases, transmitted by the female sandfly. They come in three forms, the most dangerous of which is Visceral Leishmaniasis, also known as Black Fever. This is the second largest parasitic killer in the world behind malaria, and will almost certainly result in the death of the host if left untreated. This is a particular problem in Southern Asia, East Africa and Brazil, mainly because the diagnostic tools available to healthcare professionals are limited at best and inadequate at worst. Without further research this won’t change, so is it time someone took notice?

TrypanosomatidsLuckily, scientists at the London School of Hygiene & Tropical Medicine have done just that. They are working to identify antigenic markers on the organisms responsible for these diseases: the trypanosomatids. These are protozoa with a distinct kinetoplast and a single flagellum, and if they succeed in determining the antigenic markers of the organism (also known as epitopes), this may allow us to spot the organism and prescribe treatment. Such techniques are already employed in areas where the disease is prevalent, where two antigens (labelled rK39 and rK28) are screened for. However, the sensitivity of the screening process is not good enough as yet, hence the pursuit of new antigenic markers. By analysing the genetic sequences of the rK39 and rK28 antigens, scientists are hopeful they will be able to find new antigens by matching them to similar sequences elsewhere in the trypanosomatid genome.

Additionally, because peptide excretion is a specific symptom of Visceral Leishmaniasis, urine samples are also being analysed in the hope that there may be useful diagnostic antigens to be found there. Should this be the case, it will help the diagnosis of the disease in developing countries enormously, and perhaps save thousands of lives in the coming years.