Overview

Elephantiasis, medically known as lymphatic filariasis (LF), remains a significant public health challenge in Sub-Saharan Africa and Southeast Asia, affecting millions and causing severe disability and stigma. The disease is primarily caused by filarial worms, including Wuchereria bancrofti, Brugia malayi, and Brugia timori, transmitted by mosquitoes such as Anopheles and Culex species. Epidemiological mapping has revealed varying prevalence patterns across endemic countries, with some regions achieving near-elimination while others continue to report high infection rates. Surveillance tools such as antigen-based diagnostic tests and Rapid Assessment of Geographical Distribution of Filariasis (RAGFIL) have been crucial in identifying high-risk areas and guiding mass drug administration (MDA) programs. Countries like Malawi and Tanzania have reported remarkable success through comprehensive MDA campaigns, drastically reducing transmission levels. However, nations such as Mozambique, Zambia, and Zimbabwe continue to face endemic conditions due to gaps in MDA supply and coverage. Integrated vector control, morbidity management, and sustained surveillance remain essential to achieving full elimination. The collective data from mapping studies highlight areas of progress and the need for continued investment and collaborative strategies to eliminate LF and improve the quality of life for affected communities.

Introduction

Elephantiasis is commonly known as lymphatic filariasis (LF). It is associated with thickening of the skin and underlying tissue. The areas such as the limbs, male genitalia, and female breasts are most at risk. The infection is caused by a parasitic filarial nematode worm. It belongs to the Filarioidea superfamily. The species named Wuchereria bancrofti accounts for 90% of cases globally. Two other species, such as Brugia malayi and Brugia timori, are also responsible for spreading elephantiasis. Elephantiasis is further classified into two types: lymphatic filariasis, caused by filarial worms, and non-filarial elephantiasis, which is frequently associated with irritating soil particles found in volcanic soils. Non-filarial elephantiasis can also be caused by tuberculosis, leprosy, and sexually transmitted infections like lymphogranuloma venereum.¹

It is the second most common vector-borne disease after malaria. Mosquitoes are the major vectors for this disease. In sub-Saharan Africa (SSA) the Anopheles and Culex species of mosquitoes are mainly responsible for spreading the disease. Whereas, in the tropical areas, the Anopheles species is the dominant vector, this species is also responsible for the spread of malaria disease. The main symptoms of this disease are swollen extremities and recurrent adenolymphangitis attacks. The reason behind the disease being endemic to sub-Saharan Africa is that the issue is generally neglected, with little information available.²

Epidemiology

The disease is endemic in 72 countries with an estimated at-risk population of 1.39 billion people. Approximately 120 million individuals are affected, who mainly reside in the areas around the tropics and subtropics of Asia, Africa, the Western Pacific, and parts of the Caribbean and South America.²

In Africa, 39 countries are endemic, with nearly 390 million at risk of infection. Sub-Saharan Africa accounts for 40% of the global LF burden, with reported cases ranging from 46 to 51 million in 2000 and 423 million at-risk individuals. In 2018, the total estimated at-risk population was 341 million, which required medical intervention.

Distribution Mapping

There are several tests used for mapping the distribution of the disease across various regions, some of these are as follows: The filarial antigen-based diagnostic test that can be used any time of the day and the Rapid Assessment of Geographical Distribution of Filariasis (RAGFIL) methodology by the Special Programme for Research and Training in Tropical Diseases (TDR) have accelerated the mapping of elephhantiasis in Sub-Saharan Africa. In the East-Southern African block, the endemicity levels are highest along the coastal areas and decline inwardly. In the West African block of countries, the pattern is variable about coastal endemicity levels along the whole coast, but generally, high prevalence rates are in inland countries. In Central Africa, the endemicity is relatively low.¹

Four countries- Burundi, Cape Verde Island, Mauritius, Rwanda, and Seychelles have been removed from the list of endemic countries.

Prevalence of elephantiasis in Angola

The Republic of Angola holds a prominent position as a priority nation for the elimination of onchocerciasis and Elephantiasis within the sub-Saharan African context. The country has adopted a proactive approach by implementing mass drug administration (MDA). The strategy involves the utilisation of a combination of ivermectin, albendazole, and diethylcarbamazine in various regimen combinations. In 2020, over three million people required MDA, 988,078 people received ivermectin plus albendazole, 86.8% of endemic regions were covered, and 47.3% of the individuals were treated as per the program target.¹

Prevalence of elephantiasis in the Democratic Republic of Congo (DRC)

It is claimed to be the largest endemic country for elephantiasis in Africa by the WHO. The clear extent of risk was unclear, as there were no clear recorded data. To ease the mapping of patients, a novel methodology called microstratification overlap has been developed. In 2022, over 45,243,848 people required MDA as part of DRC’s MDA, with over 36 million people treated with ivermectin plus albendazole; 100% of endemic regions were covered, and 97% of the individuals were treated as per the program target. The country is now declared to be under post-intervention surveillance.¹

Prevalence of elephantiasis in Mozambique

Mozambique is considered one of the countries with the highest neglected tropical disease (NTD) burden. Elephantiasis is endemic in Mozambique, where it is caused by W. bancrofti with Cx. Quinquefasciatus is the main vector. An investigation was conducted into the socio-environmental determinants and transmission risk associated with LF in Central and Northern Mozambique. The trend showed that the cases of elephantiasis increased in areas that showed higher mean maximum temperature, i.e., in areas that were closer to the equator. Whereas, the cases reduced as we moved away from the sea level or to higher altitudes. Poorer economic conditions, the prevalence of humid tropical areas, and the dominance of rice cultivation increase the risk of the disease. Even though all these factors proved to be a strong pillar for breeding of the transmission vector, it was not necessarily observed that these areas also bear the most affected patients. To further clarify the determinants of curbing the disease, a multiplex serology, a multiplex antibody-detection technology, was developed. This stated that the mass drug administration was a notable factor responsible for controlling the spread of the disease. In 2020, over 19 million people required MDA as part of Mozambique’s MDA, with over 14 million people treated with ivermectin plus albendazole. 98.9% of endemic regions were covered, and 76.9% of the individuals were treated as per the program target. However, due to the non-supply of MDA, over 9 million people are yet to be treated, making LF endemic in the country.¹

Prevalence of elephantiasis in Zimbabwe

As of 2022, over eight million people in Zimbabwe require MDA. This is a result of the non-rollout of MDA, hence making LF endemic in the country. Prevalence of elephantiasis in Zambia: It is important to note that LF is now prevalent in 96 out of the 116 districts within Zambia. These endemic areas, inhabited by approximately 11 million individuals, face an increased risk of LF transmission. The government has followed the policy of MDA. However, due to the shortage of MDA, over 12 million people are now expected to be treated, making LF endemic in Zambia.¹

Prevalence of elephantiasis in Malawi

Malawi has undertaken extensive initiatives to control lymphatic filariasis (LF) through nationwide surveys, vector studies, and large-scale treatment programs. Early epidemiological studies in regions like Lower Shire and Karonga revealed high endemicity, with CFA prevalence reaching up to 64.6% and microfilaremia rates as high as 30.8% in some villages. Clinical assessments also recorded significant morbidity, including hydrocele prevalence of up to 17.9% and lymphedema in both male and female populations. Vector studies identified Anopheles funestus as the primary carrier of LF, highlighting the need for integrated mosquito control. Nationwide mapping showed prevalence variations from 0% to 35.9%, with priority areas including lakeshore regions, the Phalombe Plain, and the Lower Shire Valley. Sentinel surveillance in Chikwawa documented lower-than-expected microfilaremia prevalence, around 1.5%. Further studies reported lymphedema incidence at 32 cases per 10,000 population, predominantly at advanced stages.

The National LF Elimination Program successfully implemented annual mass drug administration (MDA) with ivermectin and albendazole, achieving full coverage of endemic regions and treatment targets. These interventions drastically reduced transmission levels and disease burden. By the latest reports, Malawi has treated its entire at-risk population, reaching 100% coverage and successfully eliminating LF as a public health problem.¹

Prevalence of LF in Tanzania

Tanzania has made substantial progress in controlling lymphatic filariasis (LF) through its National Lymphatic Filariasis Elimination Program (NLFEP), initiated in 1997. Mass Drug Administration (MDA) began in 2000, initially treating 45,000 individuals, and expanded to cover six regions and 34 districts, reaching 9.2 million people over nine years. By 2022, a total of 16 MDA rounds had been implemented. Studies have shown significant reductions in LF indicators, with circulating filarial antigen (CFA) prevalence dropping by over 75% and microfilariae prevalence by nearly 90% after multiple MDA cycles, while CFA in schoolchildren fell by over 90%. In Rufiji District, CFA prevalence decreased from 14.3% to 0.0% between 2012 and 2015 following 12 MDA rounds. However, transmission persists in some coastal regions, where endemicity ranges from 45% to 60%, compared to 2% to 4% in Western Tanzania. Morbidity surveys reported lymphedema and hydrocele prevalence rates of around 20% in certain areas. Despite progress, low-level transmission remains due to suboptimal compliance during MDA. Currently, about 34 million people remain at risk, and six million are affected by LF in Tanzania.¹

Summary

The disease, though non-fatal, takes a substantial toll through the pronounced impairment. The epidemiological mapping of elephantiasis across Sub-Saharan Africa and Southeast Asia underscores both significant progress and persisting challenges in disease control. Countries like Malawi have successfully eliminated LF as a public health problem, while Tanzania has achieved substantial reductions in transmission through sustained MDA campaigns. However, incomplete drug distribution and logistical gaps in nations such as Mozambique, Zambia, and Zimbabwe continue to sustain transmission in high-burden areas. Vector studies, diagnostic advancements, and socio-environmental assessments have proven invaluable in guiding targeted interventions, ensuring resources are directed to the most affected regions.

Despite being a non-fatal disease, elephantiasis causes profound physical disability, social stigma, and economic hardship, further underlining the urgency of eliminating it. Sustained surveillance post-elimination, strengthened health systems, and community-based care for affected individuals are crucial to prevent resurgence. Additionally, expanding public health education and improving compliance with MDA programs can accelerate elimination efforts. While progress has been encouraging, coordinated international support, research innovation, and long-term commitment are necessary to ensure that LF is fully eradicated from all endemic regions. The combined success stories and lessons learnt provide a strong foundation for a future where elephantiasis no longer burdens communities across these regions.

References

1. Lamula SQ, Aladejana EB, Aladejana EA, Buwa-Komoreng LV. Prevalence of elephantiasis, an overlooked disease in Southern Africa: a comprehensive review. J Venom Anim Toxins Incl Trop Dis. 2024;30:e20240007. Published 2024 Oct 14. doi:10.1590/1678-9199-JVATITD-2024-0007 [2]Sodahlon, Y.K., Dorkenoo, M.A., Gyapong, J.O. (2024).
2. Lymphatic Filariasis (Elephantiasis). In: Gyapong, J.O., Boatin, B.A. (eds) Neglected Tropical Diseases - Sub-Saharan Africa. Neglected Tropical Diseases. Springer, Cham. https://doi.org/10.1007/978-3-031-53901-5_8