Determination, innovation and adaptation can keep lymphatic filariasis elimination on track

COVID-19 has severely disrupted the implementation of large-scale treatment programmes for neglected tropical diseases (NTDs), including lymphatic filariasis (LF).

According to the latest published data, the number of people who received treatment in 2020 declined by 34% compared to 2019, with fewer countries implementing the mass treatment recommended by the World Health Organization (WHO). This resulted in a 19.7% decline in the total number of endemic districts reached.

“Delays in mass drug administration will slow efforts to stop transmission of the infection among people living in endemic areas” said Dr Daniel Argaw Dagne, Head of the Prevention, Treatment and Care unit, Department of Control of Neglected Tropical Diseases. “National programmes need to innovate and adapt strategies wherever feasible to mitigate any potential resurgence of transmission.”

The pandemic interrupted plans for transmission assessment surveys (TAS), which are recommended by WHO to decide whether to stop large-scale treatment programmes or mass drug administration (MDA).

In WHO’s South East-Asia Region, where many countries are highly endemic for LF, 167 surveys were postponed to 2021. Countries also reported disruptions in treatment and care, surgical procedures, support for self-care, rehabilitation, and psychosocial services for people with NTDs.

Innovative methods and solutions

Since 2017, WHO has recommended the triple-drug therapy IDA – a combination of albendazole, diethylcarbamazine and ivermectin – because clinical studies show that this regimen is more efficient at clearing parasites from the blood than the conventional 2-drug therapy.

Implementing IDA in all areas, where warranted, has the potential to not only mitigate the risk of recrudescence caused by delayed MDA, but also accelerate the reduction of transmission below target thresholds.

During TAS, young school children are tested for infection to determine whether LF transmission has been reduced. As schools have remained closed in most countries, there is a need to switch to community-based sampling methods. This is recommended by WHO when school enrolment is lower than 75%.

To ensure ongoing care for people affected by LF, some countries have developed innovative solutions such as virtual training and mailing selfcare kits to people with lymphedema through the national postal service.

Potential for progress, despite COVID-19

While the timeline for many countries to achieve elimination of LF as a public health problem is expected to shift, it is too soon to see any major divergence from achieving the NTD road map targets for 2030.

In fact, to mitigate the projected increase in transmission and morbidity due to the delayed or skipped rounds of large-scale treatment programmes, WHO is now encouraging:

  • safe resumption of MDA and TAS as soon as conditions allow;
  • evaluation and improvement of MDA delivery strategies to raise coverage;
  • adoption of IDA/MDA in all areas where warranted;
  • implementation of community-based sampling methods for TAS where schools are closed; and
  • continued provision and expansion of the essential package of care for people affected by lymphedema and hydrocele.

Mandate

In 2002, WHO launched its Global Programme to Eliminate Lymphatic Filariasis, following World Health Assembly resolution WHA50.29, which called on Member States to eliminate LF as a public health problem. WHO’s global strategy is based on:

  • stopping the spread of infection through large-scale annual treatment for all eligible people in an area or region where infection is present; and
  • alleviating the suffering caused by LF through provision of the recommended essential package of care.

Currently, 17 countries have been validated as having eliminated LF as a public health problem.

The disease

LF is a mosquito-borne NTD. It is caused by 3 parasites: Wuchereria bancrofti, Brugia malayi and Brugia timori – all of which are transmitted between humans by mosquitoes.

The parasites damage the lymphatic vessels in infected people and can lead to lymphedema and severe hydrocele. Without care, the disease can progress to elephantiasis.

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