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Could lessons in controlling Kala-Azar guide our response to other diseases?

Read time: 4 mins

A sandfly taking a blood meal through human skin. [Image credits: WHO]

The current COVID-19 pandemic has shown how unprepared we are in handling a global crisis. In many parts of the world, it has relentlessly exposed the inefficiencies and misplaced priorities of policy-makers. But the current pandemic may not be the exception as experts predict increased outbreaks of diseases in the future. In this light, how do we prepare ourselves? In a recent study, researchers from the Rajendra Memorial Research Institute of Medical Sciences (ICMR-RMRI) present a success story of controlling the spread of Kala-azar in Bihar.

Kala-azar or visceral leishmaniasis is an infectious disease transmitted by the bite of a species of sandflies. Typical symptoms of the disease include fever, weight-loss and the swelling of internal organs like the spleen and liver. Although treatable, it can lead to death if left untreated. It is a significant health concern in some parts of India, like Bihar, which alone contributes to a third of the total 2,00,000-4,00,000 cases that are reported each year worldwide.

In 2005 the World Health Organisation, along with the Government of India, set a goal to eliminate this public health crisis in India by 2015, which was later postponed to 2020. The current study details how successful the state of Bihar has been in achieving this. It was published in the journal PLOS Neglected Tropical Diseases.

The study was conducted in the Vaishali district, which is the second worst-hit district in Bihar, where a fifth of the villages is affected by Kala-azar. In 2015, the district administration introduced a comprehensive program to eliminate the disease which contained effective containment strategies. The researchers studied the effectiveness of this program using an exhaustive database containing patient details, including their address and the date of disease diagnosis, to track the disease.

The study found out that spraying insecticides, training people, awareness programs, disease surveillance and treatment, and having the necessary equipment, were successful in containing the spread of the disease. In villages, households with Kala-azar cases in recent years, or those at high risk of contracting the infection, were disinfected twice in a year. If a new case was reported, all houses within a 500m range were immediately disinfected if not done earlier. DDT (Dichlorodiphenyltrichloroethane), which was traditionally used for disinfection, was replaced by better insecticides and the spraying equipment was upgraded.

The district administration put up a three-tier monitoring system that was responsible for implementing the activities under the disease control program. They also trained a generation of frontline workers, such as doctors. Several mass-awareness campaigns, where people were informed about the disease, how to contain it, and why they should get their house disinfected, were conducted to engage with the community. The study found that almost all households were successfully disinfected and received relevant information before the process. More than half of the villagers took precautionary measures as a result of this mass-media campaign.

Everyone in an infected village was checked for the disease by frontline workers using diagnostic tests to keep a tab on the spread of the disease. Those who tested positive were sent to health centres, after which they were followed up for up to six months. The researchers noticed that within a day of diagnosis, those who tested positive were treated and did not have symptoms later on. Multiple health centres in the district ensured efficient treatment without the need for patients to burden a few centres.

With these measures, the study found that Vaishali district had achieved the target of eliminating the disease by 2020. Now, it has less than one case for every 10,000 people. The population of sandflies in disinfected villages dropped by around 40% in three months, and the number of villages with two or more cases reduced drastically during the period of the study.

The results of the study show how an integrated control strategy could eliminate Kala-Azar at a district level.

“This strategy could be the stepping stone for achieving the VL (visceral leishmaniasis) elimination target at the block level in other highly affected districts of Bihar,” say the authors. It could also be used to reduce new cases of the disease and its spread in new geographical areas. “This step could be a game-changer for achieving the VL elimination target in Bihar as well as in the country by 2020,” they conclude.