As the spring blossoms and temperatures rise, are you planning to gear up, set up camp, and go out for picnics and flower viewing, maybe even dip your toes in the water to catch some shrimp?
Hold on a moment! Recently, the Chinese Center for Disease Control and Prevention (CDC) has issued consecutive reminders to beware of schistosomiasis!
Schistosomiasis can be contracted throughout the year, with the highest risk from April to October. It's particularly prevalent in spring and summer, so caution is advised when engaging in outdoor water activities to prevent infection.
Schistosomiasis is an infectious parasitic disease caused by schistosomes parasitizing in humans or mammals. It's characterized by its endemicity, infectivity, and natural foci. This neglected tropical disease is globally widespread and significantly impacts human health and socioeconomic development.
In China, the prevalent form is Japanese schistosomiasis caused by infection with the Japanese schistosome, categorized as a class B notifiable infectious disease. If left untreated or improperly treated, it can progress to advanced stages, damaging organs such as the liver and leading to portal hypertension, accompanied by symptoms like hepatosplenomegaly and ascites. This advanced stage is often characterized by a swollen abdomen, earning it the nickname "big belly disease."
Schistosomes, also known as blood flukes, are parasites that inhabit the blood vessels of vertebrates.
There are seven species of schistosomes capable of parasitizing humans and causing disease, with the Japanese, Mansoni, and Haematobium species being the most widespread and harmful.
The lifecycle of schistosomes comprises seven stages, with the cercariae (tail-end larvae) being the stage capable of infecting humans. Cercariae can penetrate the human body upon contact with the skin after exposure to contaminated water. Studies have shown that hosts can become infected by cercariae in just 10 seconds of contact.
When people refer to "blood-suckers," they often mean leeches, external parasites that feed on blood or dead flesh. Leeches, with their elongated, flattened bodies and two suckers for attaching to hosts, inhabit various aquatic environments and are widespread throughout China.
People or animals infected with schistosomes excrete feces containing schistosome eggs into water bodies. In these waters, intermediate hosts like snails facilitate the production of cercariae, which can then infect humans upon contact with contaminated water.
After contact with contaminated water, individuals may experience a prickling sensation on the skin, followed by papules and itching.
Within 1 to 5 days, symptoms such as coughing (often mistaken for a cold) may appear, with lung symptoms being more severe in recurrent infections.
After a latency period of 30 to 60 days, fever, hepatomegaly, increased eosinophils in peripheral blood, and symptoms like hepatalgia, splenomegaly, cough, abdominal distension, and diarrhea may develop. Without prompt treatment, severe cases can be fatal, and most patients progress to chronic infection.
Repeated, untreated infections can lead to advanced schistosomiasis.
Prevention: Avoiding contact with water bodies potentially contaminated with schistosome cercariae is crucial. When contact is unavoidable, protective measures such as wearing gloves, shoes, and clothing, applying repellents, and taking prophylactic medication can help prevent infection.
Treatment: If contact with contaminated water occurs and symptoms such as fever develop, seeking diagnosis and treatment at schistosomiasis control institutions or disease control agencies is essential. Praziquantel is currently the most widely used oral medication for schistosomiasis in endemic areas due to its high efficacy, low toxicity, and convenience. Adherence to medical advice and follow-up is essential during treatment.
With spring in full swing, it's imperative to take precautions when venturing outdoors!
