River Blindness (Onchocerciasis)

River blindness is a disease. Onchocerciasis is another name for this disease. It is caused by the Onchocerca volvulus worm. The worm is a parasite, this means that it lives in another organism to survive. The worm lives in blackflies. When the blackflies bites people many times, the worm is spread to people too. The worm makes larvae (known as microfilariae). It travels under skin and also travels to eyes and other organs. The adult worm can hide from the immune system by living in a nodule (hard lump) under the skin. The microfilariae can move around the body. When the microfilariae die, our immune system is so strongly activated. This causes many symptoms like bad itching, skin nodules and changes in skin colour and eye disease. The eye disease can cause blindness. This can become permanent without treatment. In some villages around half of the adults are blind because of this. This can be very bad for the economy and growth of the village. Once infected, it can take months or years for symptoms to show.


This disease is found in areas where there are rivers with fast flowing water. Usually where land is fertile and often used for growing food. This is because the blackflies breed near water. To get infected, you must be bitten many times. So short term travellers are unlikely to get onchocerciasis. However, people who live there for many months are at risk. Onchocerciasis is found in many countries in Sub-Saharan Africa including Ethiopia, Ghana and Nigeria. The World Health Organisation (WHO) says that at least 23 million people have been infected.


Unfortunately, there is no medicine you can take to prevent onchocerciasis. However, you can take steps to stop being bitten by blackflies. Such as using insecticides with DEET on bare skin. Also wearing long sleeve shirts and full-length trousers can help.


There are a few ways to test for microfilariae (the larvae). One method is by taking small cuts of skin from near the nodules. A microscope is then used to look at the skin for microfilariae.


Onchocerciasis can be treated with a medicine called ivermectin. It is also called Mectizan. Ivermectin works by killing the microfilariae. It also stops the adult worms from making more microfilariae for some time. The ivermectin can stop the itching and the eye disease too. Ivermectin is free. This medicine is given yearly. Sometimes ivermectin is taken for 10 years. This is to make sure that the worm and the microfilariae are completely gone. It is important to get help early. This will stop this disease from getting worse and spreading to other people.


This article is part of Right for Education’s Eye Health Week.



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