Parasitology: diseases — симптомы, диагностика и лечение

Giardiasis is an intestinal infection caused by a single-celled parasite that lives in the small intestine. They become infected through water, unwashed food and dirty hands, so the disease is especially common among preschool and primary school children. More myths have accumulated around Giardia than around any other intestinal infection: they are accused of allergies, of “slagging in the liver”, they are treated prophylactically by the whole family and are found “in everyone” in a blood test. The truth is different. Giardia does not live in the liver or gallbladder, but in the small intestine; their presence in the body does not equal disease; and the diagnosis is made by detecting the parasite itself or its antigen in the stool, and a single negative test does not exclude anything.

Helminth infections are a group of diseases caused by parasitic worms that live in the intestines or, less commonly, in other organs. Each species has its own route of infection, its own symptoms and its own treatment, and combining them into the general word “worms” is only convenient in conversation. In a medical sense, these are different diseases. Hence the main practical conclusion, which contradicts the common habit: “taking a pill for worms once a year with the whole family for prevention” is not prevention. The drug acts on specific parasites, does not protect against subsequent infection, has side effects and is completely useless if there are no helminths. The correct sequence is the reverse: first, examination if there are indications, then treatment according to the result.

Echinococcosis is a parasitic disease in which a slowly growing cyst with tapeworm larvae forms in organs, most often in the liver. For Central Asia, this is not exotic, but a real regional problem: infection is associated with keeping dogs and breeding sheep and cattle. The key feature of the disease is that it is asymptomatic for years: the cyst grows several millimeters per year, and a person finds out about it by chance, during an ultrasound for another reason. That is why an early finding on ultrasound is luck and not a reason for panic.

Amoebiasis is an intestinal infection caused by the protozoan Entamoeba histolytica. Infection occurs when cysts are ingested with unboiled water, unwashed vegetables and herbs, or through dirty hands. In the colon, the amoeba penetrates the wall and forms ulcers, hence the main symptom is prolonged diarrhea with mucus and blood, abdominal pain and painful urges. The danger is that the parasite is able to enter the liver with the blood and form an abscess there, which is manifested by fever and pain in the right hypochondrium without intestinal complaints. Amoebiasis can be treated with special medications, but requires proper diagnosis: conventional antidiarrheals and broad-spectrum antibiotics do not work here.

Ascariasis is a parasitic disease caused by the roundworm Ascaris. Infection occurs when parasite eggs are ingested with unwashed vegetables, herbs, water, or through dirty hands, especially if undisinfected feces were used to fertilize the garden. Once in the intestines, the larvae enter the bloodstream, pass through the lungs, causing a cough, rise through the respiratory tract and are swallowed again, after which they transform into adults in the intestines. Because of this journey, the disease has two phases with completely different symptoms, and complications may require the help of a surgeon.

Blastocysts are single-celled microorganisms that are often found in the intestines of healthy people. Infection occurs through water and food contaminated with feces and through dirty hands. For a long time they were considered absolute parasites, but today the view has changed: in most carriers, blastocysts do not cause any symptoms and do not require treatment. Some people experience bloating, unstable stools, abdominal discomfort, and itchy skin. The difficulty is that such complaints include irritable bowel syndrome, lactose intolerance, and celiac disease. Therefore, the discovery of blastocysts is not a reason to immediately take medication, but a reason to be examined and exclude other causes.

Hymenolepiasis is an intestinal helminthiasis that is caused by the dwarf tapeworm, the most common tape parasite in children. Unlike other tapeworms, infection does not require meat or an intermediate host: the eggs are transmitted directly from person to person through dirty hands, pots, toys and shared towels. Self-infection is also possible, when the eggs mature directly in the intestines and the number of parasites grows. Therefore, the disease often breaks out in families and children's groups and tends to return. Manifested by abdominal pain, unstable stool, nausea, weakness, decreased appetite and irritability; Children may experience slower weight gain. Treatment and monitoring are prescribed by a doctor.

Strongyloidiasis is caused by the small nematode Strongyloides stercoralis, which is called the intestinal eel. Its larvae live in moist, warm soil and actively penetrate the skin of the feet when walking barefoot. Then they enter the lungs with the blood, rise into the pharynx, are swallowed and populate the small intestine. The main feature of the parasite is the ability to self-infect: some of the larvae mature directly in the intestine and reintroduce themselves into the wall, so the invasion persists for decades without new contact with the soil. People with weakened immune systems and those taking hormones can develop a life-threatening disseminated form. Therefore, before hormonal and antitumor therapy, it is important to exclude strongyloidiasis.

Taeniasis and teniarinhoz are diseases caused by tapeworms: pork and bovine tapeworms. A person becomes infected by eating undercooked or fried meat with parasite larvae. In the intestines, the worm grows up to several meters and lives for years, separating segments that come out with feces or crawl out on their own. Symptoms are often scant: nausea, unstable stools, abdominal pain, weakness, weight loss with good appetite. The main danger of pork tapeworm is that when its eggs are ingested, the larvae can enter the muscles, eyes and brain, causing cysticercosis. Therefore, treatment is always carried out under the supervision of a doctor.

Toxocariasis is a parasitic disease caused by the larvae of roundworms in dogs and cats. A person becomes infected by ingesting Toxocara eggs with particles of soil and sand, unwashed greens, or after contact with contaminated animal fur. In the human body, the larvae do not grow into adult worms and are not passed in the feces, so the usual stool test for helminth eggs does not find them. Instead, the larvae migrate through the blood to the liver, lungs, eyes and nervous system, causing allergic inflammation. Preschool children who play in the sandbox get sick more often. Characterized by a prolonged cough, rash, abdominal pain and persistently high eosinophils in the blood; the doctor prescribes the treatment.