Neglected Tropical Diseases: River Blindness In Focus

6 min readFeb 12, 2023

River blindness, also known as Onchocerciasis, is a neglected tropical disease affecting millions worldwide, primarily in sub-Saharan Africa. The disease is caused by the filarial parasite Onchocerca volvulus and is transmitted through the bite of infected blackflies (Simulium spp.).

The consequences of river blindness can be devastating, leading to skin lesions, eye damage, and eventually blindness. Despite the significant impact of river blindness, it has received limited research attention, making it a disease in dire need of further investigation.

This article aims to provide a comprehensive overview of river blindness, including its causes, symptoms, impact, and efforts to eradicate it. By the end of this article, you will have a better understanding of this neglected tropical disease and the ongoing efforts to control and eliminate it.

What is River Blindness?

River blindness, or Onchocerciasis, is a parasitic disease caused by the filarial parasite Onchocerca volvulus. The parasite is transmitted through the bite of infected blackflies of the genus Simulium, which breed near fast-flowing rivers and streams (WHO, n.d.).

The parasites reproduce and multiply within the human body, eventually reaching the skin and eyes, causing skin lesions and eye damage. In severe cases, the disease can cause complete blindness and vision loss, leading to significant economic and social consequences for affected communities (Kim et al., 2015).

Infected individuals may experience symptoms such as skin itching, rashes, and eye damage (Kim et al., 2015). In some cases, nodules may develop in the subcutaneous tissue, which can be used as a diagnostic tool for river blindness (Duerr et al., 2008).

The progression of the disease varies from person to person, with some individuals remaining asymptomatic while others may develop severe symptoms (Kim et al. 2015).

The Devastating Impact of River Blindness in Africa

River blindness is a neglected tropical disease primarily found in Africa, particularly in rural and remote communities. In sub-Saharan Africa, an estimated 37 million people are infected with the parasite, while around 220 million people are at risk of infection (WHO, 2022).

Victims of river blindness include both genders, but women are at particular risk of being bitten by infected blackflies while working in riverside fields (Bokarie and Davies, 1990; Mackenzie et al., 2018).

The disease has devastating effects on affected communities, leading to reduced agricultural productivity, lower economic growth, and decreased social and economic mobility (Meludu and Ajayi, 2005).

In addition to the human toll, river blindness also has a significant economic impact on affected countries, leading to diminished economic growth and decreased economic competitiveness.

The disease also perpetuates poverty, as affected individuals often cannot work and support themselves or their families (Afework et al., 2016).

Given the high burden of river blindness in Africa, it is critical to take action to control and eradicate the disease in the region. Effective control strategies and programs will improve health outcomes and contribute to socio-economic development in affected communities and countries.

Efforts to Eradicate River Blindness Worldwide

Global efforts to control and eradicate river blindness have been underway for several decades and have made significant progress in reducing the burden of disease. However, there is still much work to be done to reach the goal of a world free from river blindness.

The Mectizan Donation Program

One of the key initiatives in the fight against river blindness is the Mectizan Donation Program, which was established in 1987 by Merck & Co., Inc. (Mectizan, 2021). The program provides free treatment with the drug ivermectin to all individuals in endemic communities who need it.

To date, the program has distributed over two billion treatments, helping to control and reduce the burden of river blindness in endemic communities (Mectizan, 2021).

Combination Therapy with Doxycycline and Ivermectin

More recent efforts to control river blindness have focused on combination therapy with doxycycline and ivermectin. This approach has been shown to be more effective in reducing the transmission of the disease and the load of infective parasites in the skin and eyes of affected individuals (Abegunde et al., 2016).

Community-Directed Treatment with Ivermectin (CDTI)

In many endemic communities, local leaders and health workers are trained to deliver ivermectin treatment to those in need through the Community-Directed Treatment with Ivermectin (CDTI) program (Amazigo et al., 2001).

This approach has effectively increased access to treatment and improved coverage in remote and rural areas, where access to health services may be limited (Colebunders et al., 2019).

Diagnosis and Prevention

In addition to treatment, efforts are also underway to improve diagnosis and prevention of river blindness. Nodule palpation, a simple and non-invasive method of diagnosing the disease, has been shown to be highly effective in identifying infected individuals (Duerr et al., 2008). Preventive measures, such as avoiding blackfly bites and wearing protective clothing, can also help reduce infection risk (CDC, 2019).

Conclusion

Despite the progress made in controlling river blindness, more work needs to be done to reach the goal of eradication. With continued research and implementation of effective control measures, river blindness can be eliminated from sub-Saharan Africa. However, it is important to continue monitoring and surveying the disease to ensure that it does not reemerge in the future.

Research into the disease must continue to prioritize developing better diagnostic methods, as well as more effective treatments. With collaboration and dedication, river blindness can become a thing of the past.

Disclaimer: This article is for informational purposes only and should not be used as a substitute for seeking medical attention. If you have any symptoms of river blindness, it is important to seek medical attention immediately.

Written by: Emmanuel J. Osemota

References

Abegunde, A.T., Ahuja, R.M. and Okafor, N.J. (2016) “Doxycycline plus ivermectin versus ivermectin alone for treatment of patients with onchocerciasis,” Cochrane Database of Systematic Reviews, 2016(1). Available at: https://doi.org/10.1002/14651858.cd011146.pub2.

AMAZIGO, U.V. et al. (2002) “The challenges of community-directed treatment with ivermectin (CDTI) within the African programme for Onchocerciasis Control (APOC),” Annals of Tropical Medicine & Parasitology, 96(sup1). Available at: https://doi.org/10.1179/000349802125000646.

Bockarie, M.J. and Davies, J.B. (1990) “The transmission of onchocerciasis at a forest village in Sierra Leone. II. man — fly contact, human activity and exposure to transmission,” Annals of Tropical Medicine & Parasitology, 84(6), pp. 599–605. Available at: https://doi.org/10.1080/00034983.1990.11812515

CDC — Onchocerciasis — Prevention & Control (2019) Centers for Disease Control and Prevention. Centers for Disease Control and Prevention. Available at: https://www.cdc.gov/parasites/onchocerciasis/prevent.html (Accessed: February 8, 2023).

Colebunders, R. et al. (2019) “From river blindness to river epilepsy: Implications for onchocerciasis elimination programmes,” PLOS Neglected Tropical Diseases, 13(7). Available at: https://doi.org/10.1371/journal.pntd.0007407.

Duerr, H.P., Raddatz, G. and Eichner, M. (2008) “Diagnostic value of nodule palpation in onchocerciasis,” Transactions of the Royal Society of Tropical Medicine and Hygiene, 102(2), pp. 148–154. Available at: https://doi.org/10.1016/j.trstmh.2007.10.009.

Kim, Y.E. et al. (2015) “Control, elimination, and eradication of river blindness: Scenarios, timelines, and ivermectin treatment needs in Africa,” PLOS Neglected Tropical Diseases, 9(4). Available at: https://doi.org/10.1371/journal.pntd.0003664.

Mackenzie, C.D. et al. (2018) “A serological survey of human onchocerciasis in Yemen,” The American Journal of Tropical Medicine and Hygiene, 99(4), pp. 1049–1052. Available at: https://doi.org/10.4269/ajtmh.18-0051.

Meludu, N.T. and Ajayi, O.O. (2006) “Effect of onchocerciasis on farming activity in Oyo State, Nigeria,” African Journal of Biomedical Research, 8(3). Available at: https://doi.org/10.4314/ajbr.v8i3.35743.

Onchocerciasis (river blindness) (no date) World Health Organization. World Health Organization. Available at: https://www.who.int/health-topics/onchocerciasis (Accessed: February 8, 2023).

Onchocerciasis (river blindness) (2022) World Health Organization. World Health Organization. Available at: https://www.who.int/news-room/fact-sheets/detail/onchocerciasis (Accessed: February 8, 2023).

Tekle, A.H. et al. (2016) “Progress towards onchocerciasis elimination in the participating countries of the African programme for Onchocerciasis Control: Epidemiological Evaluation Results,” Infectious Diseases of Poverty, 5(1). Available at: https://doi.org/10.1186/s40249-016-0160-7.

What is the program? (2022) Mectizan Donation Program. Mectizan. Available at: https://mectizan.org/what-is-the-program/ (Accessed: February 8, 2023).