Three countries in the World Health Organization’s (WHO) South-East Asia Region that were once highly endemic for visceral leishmaniasis are poised to eliminate the disease as a public health problem by 2020.
Control efforts in Bangladesh, India and Nepal have resulted in significant decreases in the numbers of new cases of visceral leishmaniasis – also known as kala-azar – reported between 2012 and 2015. As the three countries sustain their drive to achieve elimination, WHO has published a document that outlines the steps for validating the elimination of this form of leishmaniasis.
“This is the first document of its kind and comes amid tremendous progress achieved in tackling this serious form of the disease” said Dr Jamsheed Mohammed, Regional Advisor for Neglected Tropical Diseases in WHO’s South-East Asia Region. “It clearly explains the process for documentation and defines the specific criteria for elimination as a public health problem.”
In 2005, the governments of Bangladesh, India and Nepal – supported by WHO – launched a regional kala-azar elimination initiative to reduce the number of cases to a level where the infection no longer represents a public health problem1. The strategy focuses on early diagnosis and complete treatment as well as integrated vector management.
“All three countries implemented effective disease and vector control measures” added Dr Mohammed. “Social mobilization, partnerships and clinical and operational research played a crucial role in rallying overall support.”
In 2012, the WHO Roadmap on neglected tropical diseases targeted regional elimination of visceral leishmaniasis by 2020. Substantial progress has been made since 2012: the incidence of reported new cases decreased by around 67% (Bangladesh), 61% (India) and 46% (Nepal) in 2015.
Validation process
WHO’s validation process involves a standardized, objective approach based on agreed criteria. The elimination initiative thus needs to be an international, trans-border effort in which countries voluntarily adopt a common approach.
The document details the steps that a country must follow before a national report can be prepared to request validation of elimination. Validation by an independent validation team can take place if requested by a country.
Reaching the Roadmap target in South-East Asia
A major factor in progress towards eliminating visceral leishmaniasis in India has been the country’s adoption in 2014 of liposomal amphotericin B as first-line treatment.
“India treated around 66% of the total number of kala-azar cases with this medicine, which is donated through WHO by Gilead Sciences” said Dr José Antonio Ruiz Postigo, head of the leishmaniasis control and elimination programme in WHO headquarters. “Bangladesh and Nepal have also adopted liposomal amphotericin B as their first-line treatment.”
In order to maintain the progress made in the elimination of visceral leishmaniasis in the Indian subcontinent, WHO has signed a new five-year agreement with Gilead Sciences that extends the donation up to 2021.
The disease
Leishmaniasis is caused by protozoan parasites from more than 20 Leishmania species and is transmitted to humans by the bite of infected female sandflies. There are three main forms of the disease: visceral, cutaneous and mucocutaneous.
Visceral leishmaniasis, the most serious form of the disease, is endemic in more than 80 countries. It is characterized by irregular bouts of fever, weight loss, enlargement of the spleen and liver, and anaemia. The disease is highly endemic in the Indian subcontinent and in East Africa, where an estimated 200 000 – 400 000 new cases occur each year.
Some 90% of all new cases are reported from six countries: Brazil, Ethiopia, India, Somalia, South Sudan and Sudan.
Left untreated, visceral leishmaniasis is fatal in more than 95% of cases within 2 years after the onset of the disease.
1 Defined as less than 1 case per 10 000 population at district level in Nepal and at sub-district level in Bangladesh and in India