Bilharzia – also known as Snail Fever or Schistosomiasis – is a disease that is caused by a parasitic worm or fluke. This fluke has multiple species and mostly affects the urinary system and the intestine.
However, the fluke lives in the blood vessels, so its capable of causing harm to other body systems.
It is described as a chronic and acute disease by WHO(World Health Organization). The symptoms of the disease tend to appear when the individual’s body starts to react to the presence of the parasite, but complications can be long term.
The area of damage caused by the disease is based on the parasite species. The condition tends to affect a different part of the body, which includes the nervous system, the brain, and the lungs.
In children, the disease can lead to cognitive development problems and can also result in reduced or stunted growth. Although the disease may not be instantly fatal, it could cause damage to the internal organs since it is a chronic illness.
Some type of bilharzia can also affect birds and mammals like water Buffalo.
How is Bilharzia transmitted?
According to the World Health Organization, the infection begins when an individual is in direct contact with freshwater, where certain species of water snails carry the fluke.
The parasite penetrates the body when a person is paddling, swimming, or washing in contaminated water. The parasite can also be contracted by drinking contaminated water or eating foods washed in untreated water.
The infective form of the worm is known as Cercariae. The cercariae come out from the snails, penetrates the person’s skin when they are in the water, and later grows into adult worms that live person’s blood.
Depending on the worm type, bilharzia tend to affect;
- The spleen
- The brain
- The spinal cords
- The intestine
- The lungs
- The urinary system which can increase the risk of bladder cancer
- The lungs
The parasite’s infection cycle starts when the fluke’s eggs enter freshwater through the urine and faeces of an infected human.
The eggs then hatch in the water, releasing tiny larvae that get attached to and reproduce inside water snails.
After the water snails have been infected, the cercariae of the worm are released. The cercariae have a lifespan of about 48 hours.
The cercariae enter the bloodstream by penetrating the human skin. Then they make their journey to the veins around the bladder and bowel through the blood vessels of the lung and liver.
After taking a couple of weeks to mature, the worms start mating and producing eggs. These eggs travel through the bladder or intestinal walls, or both.
Eventually, they are passed out from the body through urine and faeces. From here, the cycle begins again.
Snail fever cannot be transmitted from one person to another. Humans can only contact schistosomiasis through contaminated water where the snails live.
Where does bilharzia occur?
The Centre for Disease Control and Prevention(CDC) estimates that more than 200million people worldwide are infected with bilharzia, although there is no presence of the parasite in the United States.
The places where it occurs include;
- Southeast Asia
- Africa, including the Nile Valley and Egypt
- The Middle East in Yemen
- Part of the Caribbean and South Africa
Bilharzia can affect people of any age range high-risk areas, but people who are mostly at risk include
- Individuals who work, swim and are in contact with freshwater rivers, streams, canals, and lakes.
The disease is extremely rare in the United States, although people have developed a rash known as cercarial dermatitis or swimmer’s itch after being exposed to a related species of schistosomes, the parasite responsible for Bilharzia.
Most reported outbreaks of the swimmer’s itch are from Stubblefield Lake in the northern part of New Mexico, and one from Prospect lake at the centre of Colorado Springs, Colorado.
Americans can get infected when they visit areas where this disease occurs. Be sure to check with your doctor before visiting any of these areas for any precautions you may need.
What are the symptoms of Bilharzia?
The effect of an infection is determined by the type of worm and the infection stage.
Symptoms may become noticeable between 14 to 84 days. The person may start experiencing any of the following symptoms after about three to eight weeks of infection:
- Breathing difficulties
- Body aches
At the early stage, most affected victims do not show symptoms but may start noticing signs as the disease progresses. These symptoms that occur later also depend on the parasite type.
When it affects the intestine and liver, the following symptoms may likely occur;
- Liver fibrosis
- Blood in the faeces
- Constipation and diarrhoea
- Intestinal ulcers
- High blood pressure around the digestive system or portal hypertension.
The following symptoms may occur if the parasite affects the urinary system
Anaemia can develop over time. In rare cases, the fluke may attack the central nervous system.
According to WHO, children may also suffer a reduction in the capability to learn and stunted growth.
How is bilharzia diagnosed?
Make sure to see your doctor if you start noticing symptoms of the disease or you feel you may have come in contact with contaminated water.
Your doctor may refer you to see a tropical medicine specialist or an infectious disease specialist.
You should be ready to give the following information to your doctor;
- Where you travelled to
- The duration of your stay there
- If you were exposed to contaminated water
- Noticeable symptoms and when they first appeared
- Whether you have noticed blood in your urine or have had an itchy rash.
A sample of the urine or stool will be able to indicate if eggs are present. The doctor may request a blood test.
It takes the worm up to forty days to mature, which means that the blood sample may not be able to give tangible results until at least six to eight weeks after infection.
Even if the blood tests result are negative, the individual may need a rectum biopsy if there are intestinal symptoms. A bladder biopsy may also be conducted.
It’s advisable to go for a checkup three months after returning home, even if they do not develop symptoms, as the symptoms do not appear until later.
What are the treatments for bilharzia?
Treatment can help to reduce the effect of bilharzia. However, there is no vaccine available for the treatment of the disease.
If a person’s tests result come out positive, a short course of medication known as praziquantel can be given as long as the person has not developed significant complications or damage.
Though praziquantel doesn’t prevent reinfection, it can help even at an advanced stage.
A single oral dose of the medication can help to reduce complication when taken by individuals who live in high-risk areas. This treatment may be administered yearly for several years.
Researches are still ongoing to develop a vaccine that will terminate the parasite’s life cycle in humans.
How can bilharzia be prevented?
The CDC advises people to avoid freshwater in places where the disease is present.
Individuals should be cautious when;
- Drinking water
- Eating food washed in water
- Swimming except in a chlorinated pool or seawater.
Anybody living or travelling to an area where exposure to the parasite is likely should either boil water for one minute beforehand or drink just bottled water. Treating water with iodine will not eliminate the parasites.
You can get infected if you get exposed to contaminated water. So it is advised that individuals boil and cool their bathing water before use. You can store the water safely for up to two days before using it for your laundry.
The authorities in high-risk areas can reduce the chances of people becoming infected by;
Snail control- this may entail clearing or redesigning irrigation schemes and use of chemicals to impede the proliferation of the snails. Another option is to introduce predators to the environment, such as crayfish.
Reducing infection levels: this can be achieved by providing drug treatment to the population.
Anybody who traveled to or spends time in an area with a high risk of bilharzia should seek medical attention if symptoms start surfacing or if they think they may have come in contact with freshwater or the parasite.