India is redoubling efforts to resolve remaining challenges in the elimination of visceral leishmaniasis, also known as kala-azar, as a public health problem.1 After years of steady progress, several measures and cross-sectoral interventions are being envisaged, with 4 centres of excellence to become operational in disease endemic areas, in order to provide improved access to specialized care for complicated cases of kala-azar.
“Coordinated intersectoral work by health and non-health sectors as well as sharing of responsibilities for community actions will be crucial to sustaining gains in a post elimination phase” said Dr Neeraj Dhingra, Director of the National Vector Borne Disease Control Programme (NVBDCP). “We also want to further improve capacity to make treatment and primary health care services more accessible to people in rural areas endemic for kala-azar.”
If left untreated, visceral leishmaniasis can be fatal in over 95% of cases. It is caused by the protozoan parasite of the genus Leishmania. Its clinical manifestations include irregular bouts of fever, weight loss and anemia.
“India has a comprehensive elimination strategy and has made great strides to eliminate kala azar as a public health problem among the estimated 130 million at risk population in 54 districts of four states2 where the disease is endemic,” said Dr Roderico H. Ofrin, the World Health Organization (WHO) Representative to India. “Well trained health workers and volunteers provide promotive, preventive, curative and rehabilitative services which is backed by an effective case referral system.”
© Dr D. Pandey/WHO India. Indoor residual spraying for vector control in a high kala-azar endemic village.
India has also expanded vector control interventions. In endemic villages that have reported cases of kala-azar over the past 3 years, 2 rounds of indoor residual spraying are being applied. Due to the development of resistance in sandfly vectors to dichlorodiphenyltrichloroethane (DDT), the NVBDCP introduced a synthetic pyrethroid3 for indoor residual spraying in 2015. Every year, 35–38 million people at risk of kala-azar are covered by the spray campaign. This intervention has contributed to a major reduction in disease incidence.
“We encourage every country in the world to adopt and implement vector control as stipulated in the Global Vector Control Response which repositions the control of vectors as a key approach to prevent and eliminate vector-borne diseases” said Dr Nipur Roy, Additional Director and Head of Kala-azar and Lymphatic Filariasis Elimination Programme, NVBDCP . “This global strategy, built on the basic concept of integrated vector management, provides a framework for coordinated multi-sectoral actions including enhanced advocacy, to support effective interruption of transmission.”
There are 3 major forms of leishmaniasis found in India: cutaneous, visceral and post-kala azar dermal leishmaniasis or PKDL. All 4 kala-azar endemic states are required to report cases to the NVBDCP every month, even if there are zero cases.
© Dr D. Pandey/WHO India. A treated kala-azar man, posing with grandchildren.
To achieve universal health coverage, India has prioritized actions in its national health policy to strengthen a well-dispersed network of comprehensive primary health care services, supported by health education and social mobilization. For example, a community health volunteer, known as an accredited social health activist (ASHA), is available for every 1000 people at village level.
After entrusting the NVBDCP with the task of coordinating control of all vector-borne diseases, India created the National Health Mission in 2013 to target the elimination of kala-azar as a public health problem.
Evidence-based practices to drive kala-azar elimination
The prevention, control and elimination of kala-azar in India are founded on evidence-based practices. The programme is aligned with WHO’s global and regional strategies, which include:
- early diagnosis and complete treatment;
- integrated vector management, including indoor residual spraying;
- advocacy, communication for behavioural impact and inter-sectoral convergence;
- surveillance, supervision, monitoring and evaluation, and
- capacity-building and programme management.
Since 1992, after years of accelerated programme implementation, the number of kala-azar cases in India has dropped by 97%. Fatalities have fallen from 1419 in 1992 to 58 in 2018. In 2020, only 37 deaths4 were reported.
A series of public health measures have sustained the Indian kala-azar elimination drive. These include:
- financial commitment and trained human resources;
- microstratification in high-risk areas and case-based surveillance;
- electronic health record to facilitate monitoring and initiate prompt action;
- introduction of new, single-dose treatment with liposomal amphotericin B;
- construction of concrete houses in kala azar-endemic areas;
- regular review of programmes by technical advisory groups, and
- collaboration with effective network of partners.
Despite tremendous progress, last-mile challenges to eliminate kala-azar remain. These are mainly attributed to factors such as difficult geographical terrain, indigenous populations, poor health-seeking behaviour, poor socio-economic conditions, inadequate housing, and difficulties facing the implementation of the kala-azar programme.
With a progressive reduction of cases, it is important to maintain a robust surveillance – this is now being integrated with those of other health programmes. Focused governmental efforts and sustained political commitment have kept kala-azar elimination high on the public health agenda.
Overcoming the last mile challenges is bound to eliminate the disease as a public health problem soon.
Kala-azar is characterized by irregular bouts of fever, weight loss, enlargement of the spleen and liver, and anaemia. Most cases occur in Brazil, East Africa and India. An estimated 50 000 to 90 000 new cases occur worldwide annually, with only 25% to 45% reported to WHO.
Kala-azar remains one of the top parasitic diseases for outbreak and mortality potential. In 2019, more than 90% of new cases reported to WHO occurred in 10 countries: Brazil, Eritrea, Ethiopia, India, Iraq, Kenya, Nepal, Somalia, South Sudan and Sudan.
Poverty is an increased risk factor as is poor housing and domestic sanitary conditions (such as a lack of waste management or open sewerage).
© Dr D. Pandey/WHO India. A family with treated three kala-azar cases, including one for PKDL.
These increase sandfly breeding and resting sites, as well as their access to humans. Sandflies are attracted to crowded housing which provides a good source of blood-meals. Human behaviour, such as sleeping outside or on the ground, may also increase the risk. Other factors include malnutrition, population mobility and environmental and climate changes.
1Elimination of visceral leishmaniasis as a public health problem in WHO’s South-East Asia Region is defined as achieving an annual incidence of less than 1 case per 10 000 population at the district level in Nepal and at the subdistrict level in Bangladesh and India.
2The four states endemic for kala-azar are: Bihar (33 districts, 458 blocks), Jharkhand (4 districts, 33 blocks), West Bengal (11 districts, 120 blocks) and Uttar Pradesh (6 districts, 22 blocks).
3Alpha-cypermethrin 5% wettable powder formulation is currently applied for indoor residual spraying in India. It kills the sandflies that land on sprayed wall surfaces. Leishmania parasites are transmitted through the bites of infected female sandflies, which feed on human blood to produce eggs.