Bangladesh has achieved a sharp reduction in the number of new cases of visceral leishmaniasis (VL) thanks to strong community engagement, a motivated workforce, the availability of medicine, easy-to-use diagnostics and an integrated vector control programme.
Cases of VL (also known as kala azar or black fever) have plummeted from more than 9 300 in 2006 to just 159 in 2016 amid sustained progress. Mortality has remained at around 1% or below, indicating that the country is close to eliminating the disease as a public health problem.1
“Our ultimate aim is to eliminate kala azar as a public health problem by 2020 and the results we have today show that we are on track,” said Dr Sanya Tahmina, Director, Disease Control and Line Director, Communicable Disease Control, Directorate General of Health Services “From January till the end of September this year, we recorded only 151 new kala azar and 78 post-kala azar dermal leishmaniasis (PKDL) cases.”
This spectacular achievement is the result of a combination of factors. These include willingness of the population to support heightened surveillance activities and monitoring – crucial to the success of the National Kala-azar Elimination Program (NKEP) since its launch in 2005.
“Our biggest challenge, as we continue to make progress, is to modify and test new approaches to mapping and surveillance in low prevalence settings,” said Dr Tahmina. “Our community-based approach provided us with opportunities to do things differently, more rapidly and more efficiently”.
Kala azar is fatal if left untreated in over 95% of cases and is highly endemic in the Indian subcontinent and in East Africa.
A breakthrough in defeating VL in Bangladesh was the implementation of a novel rapid diagnostic test – a reliable alternative to conventional methods – which in the past was limited to laboratories.
Now, the rK39 immunochromatographic test gives correct, positive results.
Furthermore, community-based interventions like indoor residual spraying kill the sand fly (the primary vector that transmits the disease). These interventions are supported by case management by Upazila Health Complexes (community clinics) which target the treatment of all VL cases with the WHO-recommended treatment regimen.2
The National Kala-azar Elimination Programme (NKEP)
When Bangladesh launched the NKEP in 2008,3 liposomal amphotericin B (AmBisome) – a safe and effective alternative medicine sold by the American pharmaceutical company Gilead Sciences – was too expensive for use in national control programmes.
The feasibility of a single intravenous infusion of liposomal amphotericin B administered at the primary health-care level in a remote, rural part of the country revolutionized the treatment of VL.
Following the recommendations of the Expert Committee for the Indian subcontinent, WHO modified its treatment policy and advised that the medicine be used as first-line treatment in Bangladesh.
In 2011, an agreement was signed between WHO and Gilead Sciences for the donation of 445 000 vials of AmBisome to accelerate treatment in Bangladesh. In 2016, the agreement was extended to 2021 to guarantee the donation of 380 400 vials of AmBisome and to allow populations to benefit from enhanced access to diagnosis and treatment. The financial contribution is enabling WHO to expand and reinforce surveillance and control in many endemic countries – some well beyond South-East Asia.
In ensuring a stable supply of AmBisome, WHO continues to support the NKEP’s efforts in areas such as training, surveillance and active case detection activities from funds provided by the United Kingdom’s Department for International Development.
First joint NKEP monitoring mission
To evaluate progress, including an analysis of the programme’s overall impact on disease burden, programme coverage and outcomes, Bangladesh hosted its first joint NKEP monitoring mission on 20–30 October 2017. WHO staff from regions, country offices and headquarters participated in the mission.
“Bangladesh was the first country in the South-East Asia Region to implement liposomal amphotericin B as the first-line treatment regimen for kala-azar,” said Dr Daniel Argaw Dagne, Coordinator, Innovative and Intensified Disease Management unit, WHO Department of Control of Neglected Tropical Diseases. “WHO is committed to supporting the country’s efforts in achieving elimination and to sustaining the gains made against this dreaded disease.”
The 10-day mission was led by Dr Shyam Sunder, Professor of Internal Medicine at Benares Hindu University, India along with Professor Dr M. A. Faiz, a former Director-General of Health Services in Bangladesh. It was attended by 38 national and international experts in epidemiology, medicine, entomology, research, public health and programme management.
The teams visited 12 upazilas (sub-districts) and health complexes across six districts of Dhaka, Mymensingh and Rajshahi divisions. Field activities included visits to the offices of Chief Medical and Health officers, district and referral hospitals, medical colleges, community health clinics, endemic villages and communities in these areas.
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.
Leishmaniasis owes its name to Sir William Leishman, a British army medical officer, who discovered the disease in 1901 and published his findings in 1903.
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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.
2 WHO recommends treatment of anthroponotic visceral leishmaniasis caused by L. donovani in Bangladesh, Bhutan, India and Nepal by liposomal amphotericin B, ranked by preference.
3 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 problem.