10 Infectious Diseases Still Considered Endemic in Specific Regions

5. Schistosomiasis - The Water-Associated Chronic Infection

Schistosomiasis, caused by parasitic flatworms of the genus Schistosoma, remains endemic in 78 countries, primarily in Africa and the Middle East, with some species also found in South America and Asia. This chronic disease affects over 240 million people worldwide, with the majority of cases concentrated in sub-Saharan Africa. The complex life cycle involves freshwater snails as intermediate hosts, making the disease intrinsically linked to water bodies used for domestic, agricultural, and recreational purposes. Endemic transmission is sustained by poor sanitation infrastructure, lack of access to clean water, and behavioral practices that bring people into contact with contaminated freshwater sources. Children are particularly vulnerable due to their frequent contact with water during play and daily activities. The chronic nature of schistosomiasis leads to long-term health consequences, including bladder cancer, liver fibrosis, and kidney damage, significantly impacting quality of life and economic productivity in endemic communities. Climate change and water development projects can alter snail habitat distribution, potentially expanding or contracting endemic areas. Mass drug administration programs using praziquantel have shown success in reducing disease burden, but reinfection rates remain high without improvements in water, sanitation, and hygiene infrastructure.

6. Onchocerciasis - River Blindness in African Communities

Onchocerciasis, commonly known as river blindness, is caused by the parasitic worm Onchocerca volvulus and transmitted through the bites of infected blackflies of the genus Simulium. The disease remains endemic in 31 countries, with 99% of cases occurring in sub-Saharan Africa, though small endemic foci persist in Yemen and previously in parts of Latin America. Approximately 21 million people are infected worldwide, with over 1 million suffering from vision impairment or blindness as a result. The disease's endemicity is closely tied to fast-flowing rivers and streams where blackflies breed, earning it the name "river blindness." Rural agricultural communities living near these water sources face the highest risk of infection and subsequent complications. The chronic nature of onchocerciasis leads to severe skin disease, visual impairment, and eventually blindness, devastating both individual lives and community productivity. The African Programme for Onchocerciasis Control and subsequent elimination programs have achieved remarkable success through mass drug administration with ivermectin, donated by Merck & Co. However, the recent emergence of ivermectin resistance in some areas of Ghana and Cameroon poses new challenges to elimination efforts. The complex relationship between the parasite, vector, and human host, combined with the long lifespan of adult worms, makes sustained treatment and surveillance essential for maintaining progress toward elimination.