You might expect a disease that can kill 95 percent of its victims would be on everyones radar. But in the case of visceral leishmaniasis, thats not the case.
Known as Black Fever, the adversity remains on the World Health Organizations list of neglected tropical diseases. Why? Well, because it affects the most severe of the poor, said David Poch, director of field research at Genesis Laboratories. Transmitted by adult sand flies that bite cattle and whose larvae feed on their feces, it affects 400,000 people every year and kills as many as 30,000.( Malaria, by comparison, was contracted by 214 million people last year, killing 438,000.)
More than 90 percentage of new VL cases occur in India, Brazil, Bangladesh, Ethiopia, South Sudan, and Sudan, but Poch said the disease is spreading. VL and other forms of leishmaniasis are subtle diseases that kill untreated individuals slowlysometimes over the course of multiple yearsmeaning theres still not a perception of urgency among infected individuals and the medical community, said Mark Wiser, a professor in Tulane Universitys department of tropical medicine.
Estimating the growth of VL and other forms of leishmaniasis is challenging because of its slow-burn progression as a disease, as well as its rapid appearance in specific locations, Wiser said. Although mortality has decreased in some areas, recent conflicts in the Middle Eastand an increase in Syrian refugees caused spikes elsewhere.
Poch worked with colleagues from Texas A& Ms department of wildlife and fisheries sciences to examine how the insecticide fipronil can be used to kill the sand flies that spread VL. Their findings, published on Thursday in the publication PLOS Neglected Tropical Diseases , showed that when used on cattle, single annual fipronil treatments could reduce sand fly populations by more than 90 percent. Employing a model, the researchers showed that monthly treatments could eradicate the flies within two years. Their work was funded by the Bill and Melinda Gates Foundation.
Because of the lack of information about the proportion of sand flies that feed on cattle, and the proportion of eggs laid in cattle feces, they had to use a probabilistic model to analyse the potential impact of the insecticide. In their simulations, they found that the timing of insecticide application as it relating to such sand fly life cycle was also important. Sufficient planning would be needed to apply the insecticide at the right time to avoid the compliance issues that prevent medications from being effective. The researchers hope to start a field trial to meet more data about how fipronil could restriction sand fly populations.
Unfortunately for those affected by the disease, which causes fever, weight loss, and anemia, frequent insecticide treatment of cattle that live in close proximity might be too costly.
A drug to treat VL, miltefosine, was approvedby the U.S. Food and Drug Administration in 2014 and is available at little or no expense in Indiaspecifically Bihar, which has a vast majority of that countrys VL cases, Wiser said.( The insecticide analyze model was based on Bihar .) But Poch noted that in Bihar, one of the poorest areas in India, testing is costly. Transportation is an additional roadblock, as is the fact that medications like miltefosine have to be taken for 45 to 60 days, said Rajesh Garlapati, senior vector ecologist at Genesis Labs.
Once fever goes down, people neglect to take the whole course of therapy. They act as reservoirs and spread illnes, Garlapati said. Other leishmaniasis narcotics come with toxic side effect, and the prospect of developing a more practical treatment is unlikely, Wiser said. He argues there is little incentive for pharmaceutical companies to invest in the necessary research.
Rich people get cancer, so developing an anti-cancer medication, you know people can afford to buy it. If its a disease that merely poor people get, its a little bit different narrative, he said. Drug companies arent particularly interested because the people with the disease dont have a lot of fund, so they cant make a profit on these things.
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