Bangladesh focuses on surveillance to sustain Kala-azar elimination success

Following the successful eradication of visceral leishmaniasis also known as Kala-azar, Bangladesh is shifting its focus on implementing robust surveillance measures to maintain the achieved milestone, said Prof Dr Nazmul Islam, director of Disease Control at the Directorate General of Health Services (DGHS). 

He also emphasised this strategic focus as a crucial component of the country's post-validation efforts. Bangladesh recently achieved a historic milestone by becoming the first country in the world to eliminate kala-azar.

Professor Dr Nazmul highlighted the need to enhance surveillance and expand diagnostic facilities to effectively address the substantial reduction in the disease's prevalence. Strengthening the training of doctors and community health workers is deemed crucial, given the remarkable decrease in patient numbers from an initial count of over 10,000. Therefore, the training should be conducted so that not a single patient is missed."

"Vector management should be monitored, and after three years, the World Health Organization (WHO) will reassess our programme. We hope we will do well then," he told The Business Standard. 

According to the WHO, Kala-azar, a life-threatening disease caused by Leishmania spp. Parasites are transmitted by infected female phlebotomine sandflies, posing a significant risk to impoverished rural communities. Factors like poverty, substandard housing, malnutrition, genetics, and other infectious diseases amplify the threat. Symptoms include fever, weight loss, and organ enlargement. Left untreated, Kala-azar proves fatal in over 95% of cases. Bangladesh received WHO validation as reported cases of visceral leishmaniasis remained below 1 per 10,000 population in each upazila for three consecutive years.

Prof Dr Be-Nazir Ahmed, line director of CDC at DGHS, closely involved in the process of eradicating black fever in Bangladesh, also emphasised strengthening surveillance.

He said the eradication of black fever transmission must be unequivocally ensured. There will be no old patient and no new patient will be identified. "We want a black fever-free Bangladesh although the public health elimination of black fever has been achieved. That's why we need to strengthen our surveillance for another 7-8 years."

Dr Be-Nazir also said "The surveillance programme must not be scaled back merely by acknowledging the success achieved in eradicating Kala-azar. History has shown that leprosy resurged 25 years after its eradication, indicating a resurgence due to inadequate implementation of surveillance programmes. Therefore, sustained and effective surveillance measures are imperative to prevent a recurrence."

Dr Nazmul affirmed that despite the successful elimination of black fever, there will be no reduction in the allocation to combat the disease. To ensure enduring success, the budget for Kala-azar in the next sector program will be maintained at its current level.

How did Bangladesh eliminate Kala-azar?

In 2005, Bangladesh, India, and Nepal launched the Regional Kala-azar Elimination Initiative, targeting 70% of the global disease burden (2004-2008). The initiative prioritised early diagnosis, comprehensive case management, integrated vector control, robust disease surveillance, social mobilisation, and operational research.

Professor Dr Be-Nazir ‍said that until 2006, the Institute of Epidemiology Disease Control and Research (IEDCR) exclusively diagnosed black fever. Subsequently, rapid diagnostic tests for visceral leishmaniasis were deployed in 100 Kala-azar-prone upazilas, enhancing patient identification. Historically, sodium stibogluconate was the primary treatment, causing significant pain and a 15% mortality rate.

 "In 2006, under the direct supervision of the WHO, our team, in collaboration with IEDCR and the National Institute of Preventive and Social Medicine (Nipsom), launched a thorough study on miltefosine, an oral kala-azar therapeutic. Medication administration began in 2008, a pivotal milestone in eliminating visceral leishmaniasis, or black fever," he added. 

Dr Be-Nazir said since 2012, pesticide use for vector control began in 8 hyper-endemic and 15 moderately endemic upazilas, resulting in a notable decline in black fever cases. Initially, 8,000 to 10,000 cases annually have decreased to 100. Another pivotal development was the introduction of single-dose liposomal amphotericin B. 

In 2022, Bangladesh reported only 47 cases, marking a historic low of 1069 cases in the Southeast Asia Region. Collaborative efforts of Tropical Diseases (TDR), WHO, and partners in research led to innovative tools like the rK39 rapid immunochromatographic test and improved treatments such as miltefosine and liposomal amphotericin B, playing a pivotal role in early detection and treatment in remote communities.