India on the verge of eliminating kala-azar, second deadliest parasitic disease

Kala-azar, also called visceral leishmaniasis, is the second deadliest parasitic disease after malaria.

It affects 200 million people in dozens of countries. When Sishu Kumari started working as a rural health worker in 2008, there were 33,000 cases of kala-azar, or black fever, in India. Two years later, India would miss its first target deadline to eliminate the deadly infection. The future seemed bleak. But the South Asian country has since made rapid progress in tackling the tropical disease, with the number of cases dropping to 520 last year, according to government data.

Now on January 30, the World Health Organization’s (WHO) Neglected Tropical Disease Day, India is on the verge of eliminating kala-azar. Dr. Nirmal Kumar Ganguly, former director general of the Indian Council of Medical Research (ICMR), called this a “significant gain” for the world’s most populous country.

Dr. Kavita Singh, director for South Asia at the Drugs for Neglected Diseases initiative (DNDi), said, “The achievement could strengthen the commitment to future public health initiatives and potentially attract more support and resources for similar endeavors towards other vector-borne diseases.”

What is kala-azar?
Kala-azar — also known as visceral leishmaniasis — is a severe form of the vector-borne disease leishmaniasis caused by protozoan parasites that are transmitted by the bite of infected female sandflies. According to the Medicines Sans Frontiers (MSF), kala-azar is the second deadliest parasitic disease after malaria, affecting 200 million people in 76 countries.

The disease is characterized by symptoms like anemia, fever, weight loss, and enlargement of the liver and spleen. There is a treatment, but kala-azar is invariably fatal if the treatment is not administered in time. India, Bangladesh and Nepal were considered hot spots of the disease in the South Asian region. In India, the cases of kala-azar are predominantly found in four states: Bihar, Uttar Pradesh, Jharkhand and West Bengal. In 2023, Bangladesh announced the elimination of kala-azar.

Why is it so hard to diagnose kala-azar?
One main reason for the prevalence of kala-azar is the delay in detection. The disease starts as a mild, slowly progressing condition. “Patients often dismiss it as a regular fever and refuse to seek medical care, at times, up to a month or more,” said Kumari, the rural health worker. Kumari is an Accredited Social Health Activist (ASHA) health care facilitator. While in the field, she and her fellow ASHA workers are often approached by people who have had fever lasting more than 15 days, Kumari said.

ASHA workers have played a big role in getting to the hard-to-reach rural pockets of India and educating the masses about the disease and its treatment. Their work, however, is not without challenges. Oftentimes, when they reach a village set for insecticidal spraying — a technique used to eradicate the sandfly vector — residents refuse, thinking their homes would be harmed.

“We then have to educate the people that from one case of kala-azar in the village, it can spread to more people,” Kumari noted.

Roadblocks India had to overcome
According to Ganguly, the battle against kala-azar dragged on for so long because of various factors. “Initially, all the drugs were toxic,” he said.

Another reason for its prevalence was that the disease primarily impacted some of the poorest in the country, the doctor added. Even though treatment was available, “infected people (due to lack of education) did not know where to go.”

“Moreover, vectors (sandflies) are difficult to eliminate,” the former ICMR chief pointed out.

Singh also believes that the patients’ poverty was one of the reasons for the delay in eliminating the disease. Their socioeconomic status put them on the blind spot of profit-driven Big Pharma, she said. “That’s why the process of finding safe and effective treatments for these diseases has been slow,” according to the DNDi doctor.

In 2014, DNDi was one of the organizations that helped introduce the single-dose drug Liposomal amphotericin B (LAMB) to be a part of the Indian Ministry of Health’s kala-azar elimination program. LAMB played a big part in the gradual reduction of the number of cases.

What steps India needs to take to keep up the fight?
According to WHO guidelines, for India to sustain this elimination, less than one case should be recorded in a population of 10,000 people. Health officials should maintain this status for the next three years. India had previously missed kala-azar elimination deadlines in 2010, 2015, 2017 and 2023.

Next, experts say, India now needs to focus on post-kala-azar dermal leishmaniasis (PKDL). This is a skin rash that appears in some people who have recovered from kala-azar, who, in turn, act as carriers of the infection. Right now, there are not very effective and safe drugs for this disease. Moreover, the treatment process is long, so adherence is low.

While the number of kala-azar cases has reduced in the past 10 years, the number of PKDL cases hasn’t fallen to the same extent. “The number of PKDL cases has reduced but they still exist because the treatment of PKDL isn’t ideal at the moment,” Ganguly said. Unless all PKDL cases are treated, there will always be the threat of a kala-azar resurgence. Due to the stigma associated with PKDL, patients are reluctant to come forward and seek treatment.

Currently, various NGOs, as well as DNDi, are working with ASHA workers to identify cases of PKDL. According to DNDi, having successfully battled kala-azar, the next tropical diseases on India’s radar are lymphatic filariasis, dengue, and chikungunya.