NAIROBI, 15 October 2010 (IRIN) - A failed harvest and the effects of prolonged flooding may be fuelling an outbreak of Visceral leishmaniasis, also known as Kala-azar, in parts of Southern Sudan, say health officials.

Some 6,363 Kala-azar cases and 303 deaths have been reported since the outbreaks began in September 2009, according to a UN World Health Organization (WHO) update  from 8 October. The caseload is six times higher than the number reported over a similar period in 2007 (758) and 2008 (582), with a spike in cases being recorded during the May-September rainy season when normally fewer cases are experienced.

"Kala-azar outbreaks occur in a cyclical pattern, and to understand factors contributing to the upsurge of cases one needs to undertake a thorough epidemic investigation and assessment," Abdinasir Abubakar, a medical officer with WHO's communicable disease surveillance and response team in Southern Sudan, told IRIN.

"Nonetheless, some of the possible factors that may contribute to the rise in cases [include] a high level of malnutrition, which may negatively impact on the body's immunity, a predisposition to infection and subsequent progression to disease development, and severity of the disease." Most of those affected are malnourished children.

"The affected areas have experienced food insecurity due to failed crops and prolonged flooding," Abubakar noted.

"Hundreds of people who would have been taking in a harvest of sorghum and groundnuts - now ruined, along with their homes - are instead camping by the roadside," commented the International Rescue Committee recently on the flooding situation.

As well as several locations in Jonglei state, the most affected areas include Malakal and Baliet in Upper Nile State, while sporadic cases have been reported in Unity and Eastern Equatoria states.

Kala-azar is caused by parasitic protozoa transmitted by the bite of an infected female sand fly. Sand flies thrive in the cracks and crevices of mud-plastered houses, cow dung heaps, rat burrows and in vegetation around the houses. Infection leads to lowered immunity, persistent fever, anaemia, liver and spleen enlargement and loss of weight. It kills if left untreated.

Ongoing interventions include case management and laboratory diagnostics for Kala-azar, capacity building among health workers and community awareness. Nutritional support is also being provided to Kala-azar patients and their families and monitoring and evaluation of the outbreak situation is continuing. The distribution of mosquito nets to affected communities is also being carried out for prevention.

According to WHO, increased funding is required to sustain such interventions.

The Ministry of Health warned that the outbreak could deteriorate until April 2011, with insecurity, flooding and the lack of health facilities limiting access to treatment. Kala-azar treatment involves daily injections of sodium stibogluconate for a month so patients have to be near medical centres.

"Increased population movement to and from endemic areas, particularly [the] low-immune population, or environmental conditions favouring the multiplication and biting behaviour of the sand fly, could exacerbate the outbreak," said WHO's Abubakar.