Experts warn resurgence of ‘Kala-Azar’ in endemic states as spraying postponed due to COVID-19

The postponement of Indoor Residual Spraying (IRS), a critical component in the prevention of build up of ‘sandfiles’ (the vector that spreads Kala-Azar, a dreaded disease in which a parasite causes sickness after migrating to internal organs, including liver, spleen and bone marrow) in the endemic states owing to COVID-19 pandemic could result in a resurgence of cases of the disease, warn experts.

With a commitment to eliminate Visceral Leishmaniasis (VL) or Kala-Azar as a public health problem by 2020, the government’s targeted interventions have resulted in a significant reduction in a number of VL cases over the years with only 3128 cases reported from four endemic states -- Bihar, Jharkhand, Uttar Pradesh and West Bengal -- in 2019. The number of Post Kala-Azar Dermal Leishmaniasis (PKDL) cases has also significantly reduced with only 817 cases recorded in 2019.

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Prof Shyam Sunder, head of medicine department at the Institute of Medical Sciences at Varanasi-based Banaras Hindu University (BHU), who had developed the first orally effective drug ‘miltefosine’ for the treatment of VL, said that the current strategy for Kala-Azar elimination was based on two pillars, that included early diagnosis and treatment and Indoor Residual Spraying (IRS).

‘’IRS is the application of a long-lasting, residual insecticide on surfaces such as internal walls, eaves and ceilings of all houses or structures (including domestic animal shelters) to prevent build-up of sandflies,’’ he said while speaking to DH over the phone.

"The timing of IRS rounds is a critical factor for a successful programme…the best practice is to schedule the completion of spray application to coincide with the build-up of vector populations just before the onset of the peak transmission season…the IRS was scheduled to be undertaken in all endemic states in the last week of March…however, due to COVID-19 pandemic, IRS has been postponed in Jharkhand, UP and West Bengal, which might lead to a resurgence of cases,’’ Prof Shyam Sunder warned.

He said that IRS rounds were started in Bihar from April 24 this year. ''UP, Jharkhand and West Bengal should also start IRS following the example of Bihar,'' he added.

He stressed the need for ‘Integrated Vector Management’ stating that it was key to controlling diseases, vector-borne diseases, including Kala-Azar, filariasis, malaria, dengue and chikungunya.

With India up for the elimination of VL (by 2020), LF (by 2021), and malaria (by 2027), improved disease prevention through IVM based approaches should be initiated as per usual timelines.

In recent directives, in view of the COVID-19 pandemic and subsequent lockdown, the health ministry and WHO have recommended continuing with preventive activities to protect people from vector-borne diseases.