I read yesterday about an outbreak of visceral leishmaniasis (VL) — also known as kala-azar — in Southern Sudan on the Doctors Without Borders/Médecins Sans Frontières (MSF) news pages. MSF are setting up additional treatment centres to cope with the influx of VL patients. VL, which is the second-largest parsitic killer in the world and can be fatal if left untreated, afflicts half a million people annually, and is endemic in much of south-east Asia (including India, Nepal, Pakistan, Bangladesh) and Sudan. Seems odd then that such a big killer is a neglected disease. I suppose its important to remember that neglected disease doesn’t mean one that affects few people, but is usually a disease that disproportionately affects the poor. Treatment can be effective and usually comprises multiple daily intramuscular injections of sodium stibogluconate or paromomycin and sodium stibogluconate. Immunity usually developes, but relapses can occur and the risk factors for relapse were analysed in the Southern Sudanese population, by researchers from MSF and academic colleagues, as reported earlier this year in PLoS Neglected Tropical Diseases. They found that ‘patients treated for 17 days with a combination of two drugs (sodium stibogluconate and paromomycin) were more likely to relapse (but less likely to die) than patients treated for 30 days with a single drug (sodium stibogluconate)’.
But treatment works best in the context of better health, and before drug therapy those who are severly ill are treated for pneumonia, diarrhoea, and anaemia. Malnutrition predisposes to infection, as do environmental conditions favouring multiplication of the vector for VL, which is a sandfly. It seems that a perfect storm of food insecurity, failed crops, altered weather and reduced immunity owing to time elapsed since the last outbreak, has led to the current outbreak.