Treatment and prevention of onchocerciasis
At the present time, there is no drug or vaccine available that prevents or establishes immunity to Onchocerciasis. However, there is a very effective oral drug available to those infected named ivermectin (trade name of Mectizan). Ivermectin is an anti-parasitic drug taken once or twice per year for a span of 10-15 years. This drug is effective in paralysing and then killing the Onchocerca volvulus larvae, which although initially causes the usual symptoms such as fever and intense itching due to the toxins released by the dead larvae, stops the disease/symptoms from progressing and helps to stop transmission. However, ivermectin does not kill the adult worms. The mature worms may remain alive for 10-15 years in the patient, which is why the treatment continues for a time period that long and specific. Most clinicians recommend that nodules underneath the skin should be removed, thereby removing the adult worms and stopping the production of larvae. The drug ivermectin is donated in mass to the diseased by organisations such as OCP (Onchocerciasis Control Program). Unfortunately, some people in developing areas still do not have access to these treatment measures.
Conscious measures can also be taken to avoid infection by preventing blackfly bites. This can be done by using insect repellent and wearing long sleeved shirts and long pants in areas where the blackfly is endemic. Large scale prevention of the disease involves using pesticides against the blackfly larvae – known as vector control – by helicopters and aeroplanes.
Currently, world-wide organisations are trialing a number of new treatments as well as possible vaccines for Onchocerciasis. A new drug capable of killing the adult worms of Onchocerciasis is under study for use in humans named moxidectin, but has not yet been approved for use in humans. As well as this, a vaccine to prevent Onchocerciasis infection for cattle is being trialed. Cattle injected with a modified and weakened form of Onchocerca volvulus larvae have developed very high levels of protection against infection. The findings suggest that it could be possible to develop a vaccine that protects people against river blindness using a similar approach. Unfortunately, a safe and effective vaccine to protect humans is probably still many years away.
Conscious measures can also be taken to avoid infection by preventing blackfly bites. This can be done by using insect repellent and wearing long sleeved shirts and long pants in areas where the blackfly is endemic. Large scale prevention of the disease involves using pesticides against the blackfly larvae – known as vector control – by helicopters and aeroplanes.
Currently, world-wide organisations are trialing a number of new treatments as well as possible vaccines for Onchocerciasis. A new drug capable of killing the adult worms of Onchocerciasis is under study for use in humans named moxidectin, but has not yet been approved for use in humans. As well as this, a vaccine to prevent Onchocerciasis infection for cattle is being trialed. Cattle injected with a modified and weakened form of Onchocerca volvulus larvae have developed very high levels of protection against infection. The findings suggest that it could be possible to develop a vaccine that protects people against river blindness using a similar approach. Unfortunately, a safe and effective vaccine to protect humans is probably still many years away.
Picture showing ivermectin (Mectizan), the drug taken to help treat Onchocerciasis
