Have you ever heard of a terrible disease that silently afflicts people living along some beautiful, fast-flowing river valleys, even causing blindness? This is Onchocerciasis, also known as 'river blindness.' The name may sound a bit complicated, but let's talk about this dangerous disease in a simple way that you can understand.
What is Onchocerciasis? Also known as "river blindness"
Simply put, onchocerciasis is a disease caused by a parasitic worm . The scientific name of this worm is ``Onchocerca volvulus``. This parasite is transmitted to humans through the repeated bites of infected blackflies of the genus ``Simulium``. These blackflies breed near fast-flowing rivers and streams, especially in difficult, tropical, agricultural areas.
This disease can cause severe damage to your skin and eyesight , and sometimes even lead to permanent blindness . That's why it's also called "river blindness." Imagine how dangerous that is!
How common is this disease?
Did you know that this disease, called onchocerciasis, is most common in sub-Saharan Africa and parts of South America, such as Brazil and Venezuela? According to the Pan American Health Organization, which works in partnership with the World Health Organization, about 18 million people worldwide suffer from this disease. Of these, about 270,000 are completely blind.
But, there is good news. Some countries have eliminated this disease by spraying insecticides and giving medicine to large populations. That is really encouraging.
Who is more likely to develop this disease?
The infected ``(Simulium)`` flies that transmit this disease live near fast-flowing rivers and streams, in remote, rural, agricultural villages in Africa and South America. So, people living in such areas are most at risk.
Also, people who travel to these areas for long periods of time are also at risk of contracting this disease. For example, field researchers, missionaries, and Peace Corps volunteers. In Sri Lanka, we do not usually travel to these areas very often, so we are not at high risk. However, if someone is traveling to a country like this, especially a rural area, for work or for any other specific reason, it is very important to be aware of this.
How does onchocerciasis develop?
This is something that needs a little explanation. Think about it this way.
When a black fly bites a person with onchocerciasis, it ingests microscopic worm larvae , which are tiny baby worms, that cause the disease. The larvae then develop inside the fly's body.
Now, when that infected fly bites another healthy person, it injects those developed larvae into the new person's body. However, usually, this disease is not transmitted by just one bite; several flies, several times, are required to cause infection. After entering the new body, these larvae develop into adult worms, which join together to produce more larvae. These larvae then spread to the skin, eyes, and other organs.
The important thing is that when these larvae become too numerous in the body, our body starts to react. That is, the body starts to fight against these invaders. We call this an inflammatory response . That's when symptoms start to appear.
What are the symptoms of river blindness?
Onchocerciasis mainly affects your skin and eyes . Symptoms may include:
- Excessive itching of the skin: This is the main symptom and the first symptom that most people notice. Sometimes the itching is unbearable.
- Lesions on your eyes: Lesions can occur inside the eyes.
- Scars, blisters, or bumps on the skin: Sometimes, nodules can form under the skin around the worm infestation. These can sometimes even appear on the face, giving it an unsightly appearance.
- Visual impairment, low vision, or permanent blindness: As the disease progresses, the eyes become damaged and vision gradually decreases, eventually leading to complete blindness. This is the most dangerous outcome of this disease.
How long after infection do symptoms appear?
A person infected with onchocerciasis usually does not feel any discomfort at first. Symptoms begin to appear after the larvae have multiplied in the body. This process can take about 12 to 18 months, that is, a year or a year and a half . Therefore, it may be some time before a person realizes that they have been infected with the disease.
Is this onchocerciasis disease contagious?
Onchocerciasis is not transmitted directly from one person to another . This means that it cannot be spread by talking to, shaking hands with, or eating with someone who has the disease.
But, this is how this disease spreads: Black flies bite someone who has the disease and suck out the larvae that are in their body. Then, when those flies go and bite someone who doesn't have the disease, they infect the new person with those larvae. So, this is spread through flies .
How do you accurately diagnose this disease?
To determine if you have onchocerciasis, a doctor usually performs skin biopsies . This means taking small pieces of skin from different parts of the body and examining them under a microscope to see if there are any worm larvae.
To check for an eye infection, the doctor will examine your eyes for any lesions or other things. They will use a special device called a ``slit lamp.'' It's like a microscope with a bright light attached.
Additionally, blood tests can be done to detect whether the body has antibodies that are trying to fight the infection.
What are the treatments?
The treatment for river blindness is an oral anti-parasitic drug called ivermectin . This is a very important drug.
But here's a little something to understand. Ivermectin only kills the larvae, not the adult worms . An adult female worm can live for about 10 to 15 years. During that time, they can produce millions of new larvae! Imagine how dangerous that is.
Therefore, this medicine must be taken for 10 to 15 years, at least once a year . Only by continuing treatment can the number of larvae in the body be controlled, until the adult worms die naturally.
How can we protect ourselves from this?
The best way to protect yourself from this disease is to avoid traveling to areas where the infection is still present. However, if you absolutely must travel to such an area, it is important to follow these safety measures:
- Wear clothes that have been treated with an insecticide called ``Permethrin.'' Some stores sell these clothes, or you can spray them on your clothes yourself.
- Spray your body and clothes with an insect repellent containing `(DEET).` This will help repel flies as well as mosquitoes.
- Wear your pants tucked into your socks. This way, your ankles won't be exposed and there will be less chance for flies to bite you.
- Wear long-sleeved shirts and long pants. It's best to cover as much skin as possible.
Imagine that you are going to a village in Africa for work. You will have to stay near a river. Then how important it is to follow these safety measures when you go out in the morning and evening!
What happens if you get onchocerciasis?
Onchocerciasis is the second leading cause of blindness in the world and can cause severe skin lesions and problems, as well as permanent blindness.
However, seeking medical attention as soon as possible after infection can help prevent more serious infections. Therefore, it is important to be aware of the symptoms and see a doctor as soon as possible if you have any concerns.
Can't the blindness caused by this be cured?
Unfortunately, once blindness occurs due to onchocerciasis, it is irreversible. That is, the vision that has been lost cannot be regained . That is the saddest part of this disease. That is why early detection and treatment, and prevention of the disease before it occurs, are so important.
What should I do if I think I have this disease?
If you have recently traveled to a remote area in Africa or South America, especially along rivers, and were bitten by black flies, or if you have symptoms of onchocerciasis (such as severe skin itching, eye discomfort), please seek medical advice immediately .
A doctor can test your skin and blood to see if there is an infection. Remember, the sooner you start treatment, the better your chances of preventing serious consequences.
Onchocerciasis, also known as "river blindness," is a disease caused by a parasite called Onchocerca volvulus. This parasite is spread by infected flies that live near rivers and streams in remote areas of Africa and South America. If you've been to such areas and have been bitten by black flies, it's best to talk to a doctor.
Remember the most important thing! (Take-Home Message)
Okay, so I hope you now have a better understanding of what we've been talking about, onchocerciasis, or river blindness. Here are some key points to remember:
- This is a disease caused by a parasitic worm and spread by black flies .
- It is most commonly seen in parts of Africa and South America .
- The main symptoms are severe itching, skin problems, and vision loss/blindness .
- Treatment can be done with a medicine called `(Ivermectin)` , but it has to be taken for a long time.
- If traveling to areas where the disease is prevalent, it is imperative to take special precautions to protect yourself from flies .
- If in doubt, seek medical advice immediately, as early detection can prevent serious conditions such as blindness.
Although this disease is not common in Sri Lanka, when you consider how much people in other parts of the world suffer from it, it is very important to be aware of such diseases, isn't it? Also, if you or someone you know ever has to travel to such a high-risk area, I believe this information will be useful.
` Onchocerciasis, river blindness, parasitic worm, black flies, blackflies, skin rash, vision loss, ivermectin
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