Onchocerciasis, also known as river blindness, is not an issue in Canada, but if you plan to travel internationally, you may be putting yourself at risk of contracting the disease. Here are five things you need to know about this sight-threatening eye disease.
What causes onchocerciasis?
Onchocerciasis is caused by Onchocerca volvulus, a type of parasite. These parasites are carried by Simulium blackflies, a type of blackfly that lives near fast-flowing water sources in some areas. When an infected blackfly bites you, it injects Onchocerca volvulus larvae into your body. Once inside, the larvae mature into worms. These worms can live in your body for as long as fifteen years. During this time, they produce about 1000 larvae a day which then crawl through your tissues. If they make their way to your eyes, you can develop eye complications.
Which travelers are at risk?
If you plan to travel to the tropics, you could be at risk of contracting onchocerciasis. It is found in many countries in sub-Saharan Africa, including popular vacation destinations such as Kenya, Mozambique, and Tanzania. It is also found in much of Central and South America. Visitors to Mexico, Venezuela, Brazil, and other nearby countries may also contract the disease.
Some travelers have a higher risk of getting infected than others. Since it takes many bites to get infected, people on short safaris or other trips that are less than three months long aren't likely to get sick. Long-term travelers like missionaries, researchers, or Peace Corps workers have a higher risk of getting infected.
Spending a lot of time on or near fast-flowing rivers is also a risk factor as the blackflies that spread the disease prefer these areas. If you plan to spend time camping beside a river or doing a lot of white-water rafting or kayaking, you may want to re-think your travel plans.
What are the symptoms of onchocerciasis?
If you have onchocerciasis, you may notice skin symptoms like an itchy rash or a change in your skin's pigment. If the worms reach your eyes, your eyes may become itchy as well. Your eyes may become red, swollen, and irritated, and you may experience sensitivity to bright lights. Vision changes like blurred vision can also occur as the worms damage structures within your eyes.
If your corneas, the lenses that cover your pupils, are damaged, you may develop cataracts. Cataracts are a clouding of your corneas, and as they progress, you can suffer serious vision loss or even become completely blind.
Can it be treated?
To confirm a diagnosis of onchocerciasis, your optometrist will look inside your eyes with a device known as a slit lamp. This device shines a bright light inside your eyes and makes it easier for your optometrist to identify possible problems. If you have onchocerciasis, your optometrist will be able to see the larvae or worms inside your eyes. Damage to the structures inside your eyes can also be seen with this lamp.
After the diagnosis has been confirmed, you'll need to take ivermectin, a drug that kills parasites. You need to take it every six months for the life span of the worms or until your eye symptoms go away, whichever comes first. If that doesn't work, you may be given doxycycline, a type of antibiotic. This treatment works by killing the bacteria inside your body that the worms feed on.
Can it be prevented?
The best way to avoid onchocerciasis is to avoid traveling to areas where the disease is endemic. If you can't avoid traveling, make sure to wear bug repellant, long pants, and long-sleeved shirts to keep the blackflies from biting you.
If you travelled to an onchocerciasis endemic area and are now noticing eye problems, see your optometrist immediately. For more information, contact a professional like Dr Gary Wetmore Optometrist.Share
10 December 2015
When a friend of mine started experiencing cloudy vision, they decided to put off a trip to their optometrist's office. Unfortunately, three months later, they found themselves completely blind in one eye—a condition that ended up being permanent. It turned out that they had an undiagnosed eye infection that destroyed their vision. After hearing about that problem, we realized that it might be smart to visit our eye doctor early—before permanent problems set in. Check out this blog for reasons not to skip out on early vision appointments, so that you can protect your family's vision and keep everyone happy and healthy.