Elimination of lymphatic filariasis as a public health problem in Malawi

Abstract

Background Lymphatic filariasis (LF) is a parasitic disease transmitted by mosquitoes, causing severe pain, disfiguring, and disabling clinical conditions such as lymphoedema and hydrocoele. LF is a global public health problem affecting 72 countries, primarily in Africa and Asia. Since 2000, the World Health Organization (WHO) has led the Global Programme to Eliminate Lymphatic Filariasis (GPELF) to support all endemic regions. This paper focuses on the achievements of the Malawi LF Elimination Programme between 2000 and 2020 to eliminate LF as a public health problem, making it the second sub-Saharan country to receive validation from the WHO. Methodology/principal findings The Malawi LF Programme addressed the widespread prevalence of LF infection and disease across the country, using the recommended WHO GPELF strategies and operational research initiatives in collaboration with key national and international partners. First, to stop the spread of infection (i.e., interrupt transmission) and reduce the circulating filarial antigen prevalence from as high as 74.4% to below the critical threshold of 1–2% prevalence, mass drug administration (MDA) using a two-drug regime was implemented at high coverage rates (>65%) of the total population, with supplementary interventions from other programmes (e.g., malaria vector control). The decline in prevalence was monitored and confirmed over time using several impact assessment and post-treatment surveillance tools including the standard sentinel site, spot check, and transmission assessment surveys and alternative integrated, hotspot, and easy-access group surveys. Second, to alleviate suffering of the affected populations (i.e., control morbidity) the morbidity management and disability prevention (MMDP) package of care was implemented. Specifically, clinical case estimates were obtained via house-to-house patient searching activities; health personnel and patients were trained in self-care protocols for lymphoedema and/or referrals to hospitals for hydrocoele surgery; and the readiness and quality of treatment and services were assessed with new survey tools. Conclusions Malawi’s elimination of LF will ensure that future generations are not infected and suffer from the disfiguring and disabling disease. However, it will be critical that the Malawi LF Elimination programme remains vigilant, focussing on post-elimination surveillance and MMDP implementation and integration into routine health systems to support long-term sustainability and ongoing success. Summary Lymphatic filariasis, also known as elephantiasis, is a disabling, disfiguring, and painful disease caused by a parasite that infected mosquitoes transmit to millions of people worldwide. Since 2000, the Global Programme to Eliminate Lymphatic Filariasis (GPELF) has supported endemic countries such as Malawi in south-eastern Africa, to eliminate the disease as a public health problem. The Malawi National LF Elimination Programme has worked tirelessly over the past two decades to implement the GPELF recommended strategies to interrupt the transmission with a two-drug regime, and to alleviate suffering in patients with lymphoedema and/or hydrocoele through morbidity management and disability prevention. Additionally, the LF Programme has collaborated with national and international stakeholders to implement a range of supplementary operational research projects to address outstanding knowledge gaps and programmatic barriers. In 2020, the World Health Organisation validated that Malawi had successfully eliminated LF as a public health problem, making it the second country in sub-Saharan Africa to achieve this, which is remarkable given that Malawi previously had very high infection rates. The LF Programme now remains vigilant, putting its efforts towards post-elimination surveillance and the continued implementation of care for patients with chronic conditions. Malawi’s elimination of LF will ensure that future generations are not affected by this devastating disease.

The national distribution of lymphatic filariasis cases in Malawi using patient mapping and geostatistical modelling

“…arabiensis and A . gambiae have been categorised as main LF vectors [ 11 , 40 ]. Along Lake Malawi shore, antigenaemia prevalence was observed to be higher compared to in-land areas, thus likely due to mosquito breeding sites driving W .…”

“…LF clinical case data was collected across 90 TA areas approximately 35% of Malawi, between 2014 and 2017. National health surveillance assistants, trained to identify and report individual clinical cases (lymphoedema and hydrocoele) using an innovative phone reporting tool [ 11 , 26 , 27 ]. Data were reported by health facility catchments, which were generally aligned with TA administrative boundaries defined by Humanitarian Data Exchange [ 28 ].…”

“…All geostatistical analyses were performed in R programming software using the PrevMap R package [ 36 , 37 ]. To assess the goodness of fit of the geostatistical model 2 predictions, the mean predicted LF clinical cases were compared to programme-collected clinical cases numbers within TAs observations [ 11 ]. Within S2 File , the goodness of fit of the geostatistical model 1 predictions were assessed by comparison against antigenaemia prevalence.…”

“…The Malawi LF Elimination Programme has achieved certification of LF elimination as a public health problem in 2020 from the WHO [ 3 , 11 ]. Over the past two decades the programme successfully implemented prevalence mapping, effective anti-filarial mass drug administration (MDA), impact assessments, morbidity management and disability prevention (MMDP) and operational research activities as outlined in Chiphwanya et al [ 11 ].…”

“…More recently, attention has focussed on obtaining better estimates of clinical burden, and the programme conducted a series of large-scale house-to-house mapping activities, across 23 districts in 90 sub-district administrative areas known as Traditional Authorities (TAs) between 2014–2021. The extensive clinical case mapping covered an area of over 33,000km 2 populated by 5.6 million people, representing approximately 35% of the geographical area of Malawi, identifying 8,856 clinical cases: male hydrocoele = 6,333 (71.5%; average age 50.5); male lymphoedema = 854 (9.6%; average age 54.4; female lymphoedema = 1,585 (17.9%; average age 50.5); male both = 84 (1.0%; average age 58.8) [ 11 ].…”