Schistosomiasis, also known as Bilharzia or snail fever, is a disease caused by a parasite known as flukes that belong to the Schistosoma family. The disease has been considered as one of the world’s most severe tropical diseases. The parasitic disease was first discovered by a German surgeon named Theodore Bilharz, of which he discovered a particular species Schistosoma haematobium.
The disease occurs because of immune system reaction caused by the eggs of flukes inside the body tissues. The type of antigen that the eggs release can cause the immune system to form granulomas. Granulomas are only formed when there is inflammation in the body. The symptoms vary a lot on how much eggs are inside the tissue and where the eggs are situated.
Main Types of Schistosomiasis
There are three main types of schistosomiasis; eastern schistosomiasis, intestinal schistosomiasis, and urinary schistosomiasis. Eastern schistosomiasis, also known as japonica schistosomiasis, is caused by a specific species called Schistosoma japonicum. Intestinal schistosomiasis, also known as Manson’s schistosomiasis, is caused by Schistosoma mansoni and is a chronic form of schistosomiasis Lastly, urinary schistosomiasis, also known as vesical schistosomiasis, is caused by Schistosoma haematobium. They live and releases the eggs the blood vessels found in the bladder. This type of infection can bring about blood in urine. Worst cases that can possibly happen if this symptom is not attended to are kidney failure, cancer in the bladder, and anemia.
Different Species of Schistosoma
The most common cases of schistosomiasis are caused by Schistosoma haematobium, Schistosoma japonicum, and Schistosoma mansoni. The uncommon cases of schistosomiasis are caused by Schistosoma mekongi and Schistosoma intercalatum. There are also some species that target hosts like birds and mammals that can cause dermatitis when humans acquire it.
This species is considered as the most widespread among all other species that cause diseases to humans. It is also the only species that can cause urinary schistosomiasis. It is also one of the main reasons for most bladder cancer cases.
- japonicum Is considered as the most contagious among the three common species. When infected by s. japonicum, you will also experience Katayama fever. If this is left unattended, the case can turn into a chronic disease. Worst case that can happen with this species is that it can cause neurological diseases because of the eggs reaching the brain through blood vessels.
- mansoni is a parasite that can be acquired through infected water. They are transmitted through freshwater snails that belong to the Biomphalaria genus. When infected with this species, it will live in the mesenteric veins (blood vessels near the intestines). S. mansoni is the main cause of intestinal schistosomiasis. To avoid acquiring this parasite, avoid unclean waters.
This is considered as uncommon because this type of species is found only in the Mekong river. The primary host of this parasite are humans and can cause damages on your spleen, liver, esophagus and digestive tract. They are transmitted through freshwater snails called Neotricula aperta, which is the reason why schistosomiasis is also called snail fever. S. mekongi may appear similar to s. japonicum, but S. mekongi is milder.
The S. intercalatum is one of the uncommon species because it is nearing endangerment since various species have already invaded its natural habitat. There are two strains of s. intercalatum, the Lower Guinea strain, and Zaire strain. Lower Guinea strain is transmitted through a species of freshwater snail called Bulinus forskalii. The Zaire strain is transmitted through another species of freshwater snail called Bulinus africanus.
Signs and Symptoms
A lot of those who initially have schistosomiasis are asymptomatic or the symptoms only appear a few months or years after initial infection. You will not notice that you have already been infected or at times you get small skin bumps that are itchy which are caused by the worms. A few weeks after being infected with Schistosoma species, a few people may show symptoms of cough, diarrhea, pain in the abdomen, a fever that’s above 38°C, an itchy raised rash or muscle pain. When you’ve experienced these symptoms, you already have Katayama fever, but it heals by itself in a couple of weeks. However, leaving it untreated can increase risks of the disease developing to chronic schistosomiasis.
In diagnosing schistosomiasis, you may take samples of urine or stool and have it checked under the microscope to see if there are any species of Schistosoma found in your stool and urine. Eggs of S. japonicum and S. mansoni can be detected by taking the stool analysis and eggs of S. haematobium can be detected through urinalysis. There are instances when there are no eggs detected because they pass through occasionally and in small portions. To get a clearer detection, it is suggested that a serological test is taken.
Methods to Prevent Schistosomiasis
You might be situated in an area where there is a transmission of schistosomiasis. Here are some tips that can best help you avoid schistosomiasis:
- When in an unfamiliar place, refrain from going in freshwater, like lakes or ponds, as Schistosoma species are transmitted through these waters. You may want to swim in the sea or treated pools because they are free from schistosomiasis.
- Make sure that you drink water that is filtered or disinfected by boiling the drinking water for a minute. The water that you’re drinking might be from bodies of freshwater that are contaminated with various parasites, including Schistosoma parasites. Boiling water will kill the parasites in the water, making it safe to drink. You may not get infected when you swallow water with Schistosoma parasites, but the problem is when your mouth or lips get in contact with the contaminated water as the risk of infection is high.
- When in an area where water supply is from freshwater, make sure that the water you’ll use for taking a bath is disinfected. Disinfection is done by heating the water and bring it to a rolling boil for 1 minute to kill the parasites. Make sure that the water is cooled down to avoid burns from the hot water. You may store the water for a couple of days to ensure the safe use of water.
- When accidentally got in a brief contact with freshwater that is contaminated with Schistosoma parasites, strenuously dry the skin area with a towel to keep parasites from getting through the skin. However, it is not a guarantee that you will not be infected with schistosomiasis even after strenuously drying the area with a towel.
It would be best to treat schistosomiasis in its acute form because it would be easy to kill the parasites at this stage. There are drugs that aid in killing the parasites. Examples are schistosomicides and corticosteroids, commonly known as steroids.
The most common medication used to treat various types of schistosomiasis is Praziquantel. It helps paralyze and expose the worm to immune system attacks. It is known to work effectively on acute schistosomiasis, but less effective on chronic schistosomiasis. It is also safe for pregnant and breastfeeding patients to use the treatment. When using Praziquantel, you may experience one or more side effects such as headache, vomiting, fever, nausea, diarrhea, discomfort in the abdomen after the treatment. The side effects will not last longer than a day and are mild as these are just effects of worms dying inside the body.
There are some cases that the anti-inflammatory properties of the garlic have been used to treat schistosomiasis. It seems that the garlic was providing relief to the inflammation only and not necessarily making effects on the parasite.