Onchocerciasis, or river blindness, is a parasitic disease caused by the Onchocerca volvulus worm. It is spread by blackflies that carry the parasite. It can cause visual impairment, blindness, itching, and other skin diseases.(Learn More)

River blindness is a tropical disease, most common in specific parts of sub-Saharan Africa, but it’s also found in some parts of the Americas and Yemen. It usually takes many fly bites to contract the disease, so those living in these areas for less than three months are usually not affected. (Learn More)

At least 25 million people are currently infected, according to the World Health Organization, with an estimated 800,000 experiencing problems with vision.

Treatment usually consists of ivermectin, a drug that can kill worm larvae in the body. It is taken in six month increments until the adults in the body have had time to die off. More recently, some doctors have also been treating river blindness with doxycycline, a drug that kills a bacteria key to the adult worms’ survival. (Learn More)

Ivermectin’s side effects are generally well understood, as the drug has been in use for some time. However, doxycycline is a newer treatment for river blindness, and it is under researched to a notable degree. While it can undeniably help, talk to a doctor about what to expect and what warrants medical care. If you’re ever unsure about the severity of a symptom, it is better to contact your doctor than risk not getting help when you need it. (Learn More)

Onchocerciasis is a neglected tropical disease (NTD). This is a category of diseases that primarily affect poor communities, often devastating those affected.

Due to the vision problems and painful skin conditions it can cause, river blindness has the potential to almost completely destroy a person’s ability to work if they can’t afford help or do not live near a trained doctor.

Neglected tropical diseases do not often get the attention needed for a variety of sociopolitical and economic reasons. As a result, research is the area is somewhat lacking. (Learn More)

blackfly bites

What Is River Blindness?

Onchocerciasis, also known as river blindness, is a parasitic disease caused by the worm Onchocerca volvulus. These worms get into people through the bites of blackflies, specifically those of the genus Simulium. These flies live and breed near rivers, hence the river part of the disease’s name.

Onchocerciasis is the second most common cause of blindness from infection; the first is trachoma.

River blindness can be debilitating, especially to those too poor or far from medical care to get help. Onchocerciasis can cause the following:

  • Visual impairment
  • Blindness
  • Nodules under the skin
  • Debilitating itching
  • Other skin diseases

If you have reason to suspect you may have been infected with river blindness, seek help from a doctor right away to prevent long-term vision and skin problems as a result of the infection.

Who Is at Risk?

Onchocerciasis is a tropical disease, mainly affecting 30 sub-Saharan African nations. It also affects some parts of the Americas and Yemen, which is a Middle Eastern nation. While significant efforts have been made in a variety of countries in the Americas to limit its spread, it is still not totally eradicated.

Unfortunately, many people in poverty do not have the luxury of avoiding risky areas. The World Health Organization (WHO) estimates at least 25 million people are currently infected with onchocerciasis. An estimated 800,000 suffer from some visual impairment, and 300,000 are blind.

The people most at risk are those who live in rural areas, near rivers or streams, in sub-Saharan Africa. The CDC notes that many fly bites are usually needed to contract the disease, so people traveling in at-risk areas for less than three months have a low chance of being affected. If you intend to travel to a tropical area, especially if you will be near a river, research if you will be at risk for river blindness so you can take proper precautions.

Travelers most at risk are those who will be in a risky area for a long time, including missionaries, volunteers, and field researchers.


Treatments for Onchocerciasis

The traditional treatment for onchocerciasis is to administer ivermectin. The treatment will be given every six months for the duration of the adult worms’ lifespan or until there is no more evidence of an eye and/or skin infection.

Ivermectin kills only the parasitic larvae in the body, not the adults. As a result, the person being treated has to wait out any adults already in their body.

A new treatment has had promising results in killing the adult worms by targeting Wolbachia bacteria, which the worms depend on. This medication, doxycycline, is increasingly being used in conjunction with ivermectin. One medication kills the larvae, and the other targets adults. Because of this dual approach, patients may see faster recovery rates with less permanent damage.

It should be noted that before any of the above treatments are administered, doctors must make sure a patient is not infected with Loa loa, another parasite common in many African regions where Onchocerca volvulus is found. If a person who has Loa loa is treated in a traditional manner for river blindness, they could suffer severe and potentially dangerous side effects.

Side Effects of Treatments

Both ivermectin and doxycycline come with risks and side effects.

As with most medications, it is unlikely you will experience all of a medication’s side effects. Contact your doctor if a side effect seems especially severe or is greatly impacting your quality of life.

Ivermectin has been linked to the following side effects when treating river blindness:

  • Common side effects
    • Fever
    • Skin rash
    • Itching
    • Unusually rapid heartbeat
    • Tenderness or pain in the glands in the groin, armpits, or neck
  • Uncommon/rare
    • Headache
    • Swelling in the feet, legs, hands, arms, or face
    • Lightheadedness
  • Concerning (contact a doctor as soon as possible)
    • Pain, swelling, or redness in the eyes or eyelids

Doxycycline is less fully understood than ivermectin, as it has only been used to treat river blindness relatively recently. Because of this, it’s difficult to say how common particular symptoms are and which are the most concerning. If you experience any concerning symptoms, contact your doctor.

The following are some symptoms thought to be linked to doxycycline use:

  • Bowel problems that are sometimes fairly severe
  • Digestion problems
  • Nausea and vomiting
  • Weight loss
  • Drowsiness
  • Redness, blistering, or loosening of the skin
  • Inflammation
  • Joint pain
  • Increased thirst
  • Yellowing of the skin

Many of the less concerning symptoms of doxycycline are very similar to those that are concerning. As such, it is best to talk with a doctor about what to expect and when to give them a call.

While you should familiarize yourself with the dangers of any prescription medication you take, it’s especially important to do this with doxycycline. While the medication can be of genuine help in combating river blindness, it is not without risks, and some of those risks are not yet entirely understood.

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A Neglected Tropical Disease

Onchocerciasis is a neglected tropical disease (NTD), a category of disease that tends to specifically devastate the underprivileged. Common in many poorer areas, river blindness can condemn those who cannot afford or find treatment for blindness and serious pain. This in turn can impact their ability to work and support themselves and their families.

NTDs can trap people in poverty, even leading them to die if they cannot afford basic necessities like food and water. Because these diseases primarily affect the poor, their research is sometimes underfunded compared to diseases that impact more prosperous communities.


Parasites - Onchocerciasis (Also Known as River Blindness). (August 2015). Centers for Disease Control and Prevention.

Epidemiology & Risk Factors. (May 2013). Centers for Disease Control and Prevention.

Treatment. (May 21, 2013). Centers for Disease Control and Prevention.

Ivermectin (Oral Route). (February 2019). Mayo Foundation for Medical Education and Research (MFMER).

Doxycycline (Oral Route). (February 2019). Mayo Foundation for Medical Education and Research (MFMER).

Neglected Tropical Diseases. (June 2018). Centers for Disease Control and Prevention.

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