Statistics show that 7-23% of chronic schistosomiasis cases present symptoms of pulmonary hypertension caused by inflammation of the pulmonary vascular endothelium and granulomatous obstruction of the pulmonary vessels. The disease progresses to severe fibrosis of lung tissue, resulting in fatigue, severe hypoxemia, chest pain, and other symptoms.
What is schistosomiasis?
Schistosomiasis (also known as Bilharzia or snail fever) is a disease caused by infection with parasitic trematodes of the genus Schistosoma.
Although not typically life-threatening, the disease can become chronic and damage multiple organs, particularly the lungs.
In children, infection with schistosomes can cause stunted growth, weight loss, and even intellectual impairment.
What is schistosomiasis?
Causes of pulmonary schistosomiasis
The cause of pulmonary schistosomiasis is the parasitic worm Schistosoma, which includes several species such as S. mansoni, S. mekongi, and S. hematobium.
The male schistosome measures around 4-15mm in length and 1mm in width, while the female is longer at around 20mm. They live as parasites in the blood, and can survive for up to 26 years in the human body.
Schistosome life cycle
Within the human body, schistosome eggs travel through the venous system into the intestinal tissue and bladder, and are then excreted in feces and urine.
Upon entering water, the eggs hatch into miracidia, which parasitize intermediate hosts such as snails. Here, they develop into cercariae (tailed larvae) before leaving the snail and entering water.
When they come into contact with human skin, they penetrate it and travel through the venous system to the hepatic portal vein, where they develop, reproduce, and cause disease.
Clinical manifestations of lung hydatid disease
Lung hydatid disease can have acute, subacute, or chronic clinical manifestations as follows:
Acute lung hydatid infection
When hydatid larvae enter the body, they can cause acute lung damage within 2-4 weeks.
Clinical symptoms include fever, cough, wheezing, and red rash on the skin. Blood tests may show increased eosinophil count.
In addition, some cases may have symptoms of chills, headache, enlarged liver, and peripheral lymphadenopathy.
Chest X-ray may show small nodular infiltrates, thickening of the bronchial walls, and sometimes a dense pulmonary nodule (rarely).
Subacute lung hydatid infection
After entering the body, the hydatid cysts travel through the blood vessels to the site of egg deposition. The eggs move against the flow of venous blood into tissues, causing an inflammatory reaction and formation of granulomas. The inflammatory reaction can either spread or be localized.
In the lungs, the hydatid cysts or worms can cause pulmonary arterial obstruction and invade lung tissue. This is usually caused by adult worms moving from the pelvic veins to the lungs.
Clinical manifestations may include cough, dyspnea, and worsening of the condition due to hypoxia, even leading to death. Chest X-ray may show infiltrates in the form of diffuse shadows.
Chronic lung hydatid infection
The most common lesions are granulomas or interstitial damage due to inflammation of the blood vessels. This is the result of the deposition and wide spread of egg granulomas in the pulmonary blood vessels.
Chest X-ray may show infiltrates in the interstitial tissue, small blurred nodules, and possibly fibrosis.
Statistics show that 7-23% of cases of chronic lung hydatid disease exhibit symptoms of pulmonary hypertension due to inflammation of the vascular endothelium and obstruction of blood vessels by cysts. The disease can progress, causing fibrosis of the lung tissue. Patients may feel tired, have severe hypoxia, chest pain, etc.
Diagnoses of schistosome disease
The diagnosis is determined through epidemiology, clinical symptoms, and tests as follows:
Patients living, traveling, or moving through areas where katayama Fever disease is prevalent or in contact with contaminated water sources.
Clinically, patients have prolonged cough symptoms.
Blood test: Increased eosinophils, anemia, and decreased platelets.
Chest X-ray: There are infiltrative lesions.
IgG ELISA test with 97% specificity is the fastest diagnostic method.
Finding fluke eggs in samples of specimens (stool, urine, sputum, …) under a microscope.
It is necessary to differentiate diagnosis from other diseases such as: eosinophilic pneumonia, mild bronchitis, pulmonary or portal hypertension, …
Schistosome disease treatments
Praziquantel
The most commonly used drug to treat Katayama Fever disease is Praziquantel.
Praziquantel has a broad spectrum of activity against many types of flukes, including liver flukes, intestinal flukes, and blood flukes that cause diseases in humans. It affects both adult flukes, immature flukes, and fluke eggs.
Usage:
The dose of Praziquantel in treatment is a single dose of 40 mg/kg. The success rate of treatment is up to 85-90%.
Side effects:
About ⅓ of people using Praziquantel experience unwanted effects such as nausea, dizziness, headaches, abdominal pain, diarrhea, and itching.
These symptoms may be due to the drug or to the body’s immune response to the parasites that have been destroyed.
Cautionary groups:
Drivers, machine operators need to stop doing this within 24 hours of taking the drug because its side effects may affect nerve activity.
Pregnant women are not recommended to use this drug.
Breastfeeding mothers need to stop this action for 3 days after taking the drug. Milk must be discarded.
Schistosome disease treatments
Oxamniquine
This drug is only used to treat intestinal flukes in Africa and South America with the following doses:
Children under 30kg: use a dose of 20mg/kg/day, divided into 2 doses per day.
Adults take a single dose of 12-15 mg/kg or 30-60 mg/kg divided into 2-4 equal doses, 2 times/day.
The treatment time is 1-3 days. Take the medicine after eating.
Metrifonate
This drug is indicated for the treatment of bladder fluke disease with a dose for both adults and children of 7.5 mg/kg per dose, taken 3 doses apart at 2-week intervals.
Usually, people only use a single dose of 10mg/kg and then repeat it after 3, 6, or 12 months.
Ways to prevent schistosome disease
Keep the living environment clean, especially the water source.
Handle waste properly according to regulations, do not discharge untreated waste and domestic water into the environment.
Avoid contact with polluted water sources, especially in Katayama Fever disease epidemic areas.
Use clean water for daily living.
Eliminate harmful snails living in water to destroy the habitat of Katayama Fever larvae.
When necessary to wade into polluted water, use protective gear to protect the skin.
Use clean water sources.
Although Katayama Fever disease has a low mortality rate, it has a significant impact on internal organs in the body. Therefore, one should not be complacent about this disease and should find effective ways to prevent and control it.
Johnny Jacks was born in 1985 in Texas, USA. He is the founder of Good Health Plan and is passionate about helping people improve their health and physical well-being. With over a decade of experience working in the healthcare industry, he currently works at Goodheathplan.com – a blog that shares knowledge on beauty and health.