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Round worms (or nematodes) are parasites that most often cause diseases in humans. The routes of infection and the symptoms depend on which species you are dealing with. What are the symptoms of nematode infection and how is it treated?

Nematodesmeaningroundwormsmostly found in countries with a warm and humid climate, including Asia, Africa and South America and Central, although some species are found all over the world.

A person can become infected with nematodes in different ways, depending on the species of the parasite. The main routes of nematode infection are the consumption of water, vegetables and fruit contaminated with invasive forms of the parasite, as well as raw or undercooked meat.

Moreover, some nematodes can be infected even by walking without shoes on contaminated ground. Depending on the environment in which they parasite, there are 2 main groups: intestinal nematodes and tissue parasitic nematodes.

Worms that parasitize the intestines

  • Ascaris human

Human Ascaris (LatinAscaris lumbricoides ) is a worm parasitizing in the human small intestine, and its life span is about 12-18 months. It causes a disease called ascariasis or ascariasis. Man is its sole host.

Human roundworm is found all over the world, but most infections are observed in tropical countries, Southeast Asia, Africa, and South and Central America.

The human roundworm is a flesh-colored nematode with an elongated body. The adult parasite is 15-40 cm long (females are longer and larger than males) and approx. 0.5 cm in diameter.

  • Dear infection

A person becomes infected with human roundworm most often through the consumption of invasive parasite eggs with food, poorly washed vegetables, soil or contaminated drinking water.

  • Symptoms of infection

Infection with human roundworm in many cases is asymptomatic. During intense parasite infestations, disturbing symptoms from the respiratory system, severe dry cough, hemorrhages, a feeling of shortness of breath and increased body temperature are noticeable.

In addition, some patients report discomfortabdominal pain, nausea, vomiting, and diarrhea.

In children suffering from ascariasis, the presence of the parasite in the intestine can lead to vitamin deficiency and malnutrition, and consequently inhibition of physical and mental development.

  • Diagnosing infection

A faecal test, vomit test, or serological tests for parasites can be performed. the invasion may also be confirmed by an increased number of eosinophils in the peripheral blood.

  • Treating infection

Antiparasitic drugs are usually used in the therapy - pyrantel, mebendazole and albendazole, administered orally in a single dose (again after 2-3 weeks).

  • Hookworms

Duodenal hookworm (LatinAncylostoma duodenale ) andNecator americansare nematodes parasitic in the human small intestine, usually in its initial section, i.e. duodenum, where adults can live up to 15 years. They cause ankylostomosis and necatorosis, respectively.

Hookworms are parasites found in countries with tropical and subtropical climates.

The adult parasite is small (on average 0.7-1.8 cm long).

A characteristic feature of these nematodes is the presence of chitinous elements that resemble teeth or cutting plates at the entrance to the mouth pouch. They are used to incision the epithelium of the host's intestine.

The eggs of the duodenal hookworm are oval in shape and covered with a transparent shell.

A person is infected by invasive larvae, which enter the body through intact skin into blood vessels, and then into the lungs, and then go towards the trachea and pharynx, from where it goes to the gastrointestinal tract. It reaches adulthood and sexual maturity in the small intestine.

  • Dear infection

People become infected primarily by walking barefoot. It is suspected that there is a possibility of infection through contaminated food or water. The larvae can be transferred through the placenta to the fetus or via the mother's milk.

  • Symptoms of infection

Hookworm infection is in many cases asymptomatic. During intense parasite infestations, abdominal pain, nausea, vomiting, loss of appetite, weight loss, diarrhea with an admixture of blood and black stools draw attention. During the migration of larvae, many patients experience severe cough and inflammation of the bronchi and lungs. In addition, many patients have anemia and hypoproteinaemia.

  • Diagnosis of infection

Stool tests are performed, as well as serological tests for the presence of specific onesantibodies. There is an increased amount of eosinophils in the blood count.

  • Treating infection

Antiparasitic drugs are used. The treatment should be repeated after 2-3 weeks.

  • Intestinal nematode

Intestinal nematode (LatinStrongyloides stercoralis ) is a nematode parasitizing in the human small intestine. It causes a disease called vaginismus or strongyloidosis. The intestinal nematode is found all over the world, not only in humans, but also in dogs, cats and monkeys.

The adult parasite grows to a small size, females are about 2-3 mm long and males are smaller, about 0.9 mm.

A person is infected by invasive larvae, which enter the body through intact skin into blood vessels, and then into the lungs, then go towards the trachea and pharynx and enter the gastrointestinal tract. In the small intestine, they reach adulthood and become sexually mature.

  • Dear infection

Infection occurs primarily by walking without shoes on contaminated ground. It is possible to transfer the parasite larvae with the mother's milk, as well as the possibility of self-contamination.

  • Symptoms of infection

Clinical symptoms accompanying the intestinal nematode infection include not only skin changes (mainly redness, soreness, itching, swelling at the site of larvae penetration) and respiratory complaints in the form of severe cough and pneumonia, but also gastrointestinal complaints gastrointestinal in the form of, among others, inflammation of the intestines, abdominal pain, the presence of diarrhea with an admixture of blood, nausea or vomiting.

  • Infection diagnosis

Diagnosis is made on the basis of faecal or digestive examination taken directly from the duodenum, as well as by serological tests for the presence of specific antibodies against the parasite antigens.

  • Treating contagion

Antiparasitic drugs are usually used in the therapy - mebendazole, albendazole and ivermectin (first-line drug).

  • Human whipworm

Human whipworm (LatinTrichuris trichiura ) is a parasitic nematode in the large intestine of humans and monkeys. It causes a disease called trichuriasis or trichuriasis.

The human whipworm is a worldwide parasite, most common in countries with a warm, humid climate and poor hygiene. Most often, whipworm is diagnosed in preschool and early school-age children. An adult whipworm reaches approx.3-5 cm long, lives for several years and is characterized by an unusual body shape that resembles a whip. Females are able to lay 2,000 to 14,000 eggs per day.

After getting the eggs into the body, invasive larvae of the parasite hatch in the human intestines. For a few days they anchor in the intestinal mucosa (histotropic phase) and feed on the host's blood. They then go back to the lumen of the gut where they reach sexual maturity. In the human body, a whipworm can live for up to 5 years.

  • Dear infection

A person becomes infected with human whipworm, similarly to human roundworm, most often by ingesting invasive parasite eggs with food, poorly washed vegetables, soil or contaminated drinking water.

  • Symptoms of infection

Infection with human whipworm is asymptomatic in many cases. During intense invasions, increased body temperature and disturbing symptoms from the digestive system, abdominal pain, nausea, vomiting, diarrhea, as well as anemia and catarrhal or haemorrhagic colitis appear.

  • Infection diagnostics

The diagnosis of trichuriosis is based on the presence of parasite eggs in stool smears examined under the microscope.

  • Treating contagion

Antiparasitic drugs are usually used in the therapy - mebendazole, albendazole and oxantel. Drugs are administered orally for 3 days.

  • Human pinworm

The human pinworm (LatinEnterobius vermicularis ) is a worm parasitizing in the human large intestine. It causes a disease called enterobiasis or enterobiasis. Human worm is found all over the world, in countries of all climatic zones. The only host of this nematode is man. The greatest number of infections is observed in pre-school and early school-age children. In Poland, pinworm is considered the most common parasitic disease of the gastrointestinal tract.

Pinworms are small, white nematodes with a cylindrical and elongated body. The adult parasite is about 1 cm long, the females are larger (8-13 mm) and the males are smaller (2-5 mm).

Pinworm eggs are colorless, oval, covered with a sticky substance and resistant to drying out, and in the external environment they retain the ability to infect the host for about 2-3 weeks.

Pinworms live on the mucosa of the large intestine, there is also copulation, after which the males die. Females move to the anus, pass through the external anal sphincter, and lay eggs covered with a sticky discharge that causes thestick to skin.

Sometimes, in the presence of a large number of parasites, it is possible to observe white, mobile nematodes on the surface of the stool.

  • Dear infection

A person becomes infected with human pinworm most often by ingesting invasive larvae of the parasite with food, present on contaminated toys or by transferring the larvae on the fingers to the mouth from the anus area.

  • Symptoms of infection

The infection with human pinworm is primarily accompanied by severe itching in the anus, which is the dominant clinical symptom of the disease. The itching sensation increases in the evening and at night. It can lead to nervous disorders, weight loss, loss of appetite and even developmental delay. Children with pinworm disease tend to be hyperactive, have difficulty concentrating, suffer from insomnia, and grind their teeth. In the area of ​​the anus, skin lesions in the form of cross-cuts (caused by scratching) and eczema, which may be subject to bacterial contamination, occur.

  • Infection diagnostics

Pinworm infection can be suspected on the basis of quite characteristic clinical symptoms. Confirmation of the diagnosis makes it possible to detect adults on the surface of the stool or around the anus, as well as parasite eggs deposited on the skin of this area. It is very important to collect the material for the test in the morning immediately after waking up, before the morning bath and defecation, and to repeat the procedure several times, because female pinworms do not lay eggs every day.

  • Treating contagion

Antiparasitic drugs are usually used in the therapy - pyrantel, mebendazole and albendazole, taken orally in one dose. It is worth noting that the treatment should be repeated several times (after about 2 weeks) and should cover all family members and people who may be potential carriers (e.g. children in kindergarten, boarding school or orphanage) in order to prevent reinvasions.

Nematodes that parasite in tissues

  • Filarie

The nematodes responsible for causing a group of diseases called filarioses areWuchereria bancrofti ,Brugia malayi ,Brugia timori,Onchocerca volvulusand Loa loa.

Filariasis are parasitic diseases caused by nematodes living in human tissues, transmitted by blood-sucking insects (usually mosquitoes or other blood-sucking arthropods). They have been divided into 3 groups depending on the clinical symptoms caused by particular parasites. They are:

  • derm althe figure of filariasis (Loa loa, Onchocerca volvulus)
  • lymphatic form of filariasis (Wuchereria bancrofti, Brugia malayi, Bruges timori)
  • the form of filariasis in which symptoms originating from body cavities dominate (Mansonella species)

The disease occurs most often in people living in the subtropics, as well as in people traveling to these parts of the world. Pillars are typically found in Asia, especially India and China, Indonesia, Africa, and South and Central America.

In Poland, these nematodes do not occur in the natural environment.

The only known method of preventing filariasis is effective protection against mosquitoes and other blood-sucking insects during a stay in tropical countries.

It is recommended to use repellants, mosquito nets and to wear clothes with long sleeves and legs, especially after dark.

  • Medina worm

The Medina worm, otherwise also known as the Guinean worm (LatinDracunculus medinensis ) is a nematode parasitizing in human subcutaneous tissue. It causes a disease called Dracunculosis. The worm is a parasite found in Asia and Africa, especially in countries south of the Sahara. The vast majority of cases are reported in Sudan, and a mature female breaks through human tissue and skin. A small wound forms, usually on the lower limbs, through which the female extends part of her body to be able to release the numerous larvae directly into the aquatic environment. There, they are swallowed by freshwater crustaceans, in which the larvae of the parasite develop into invasive forms (so they are intermediate hosts).

A person becomes infected with the Medina worm by consuming water infected with eyelids. Invasive nematode larvae enter the digestive tract, pierce the intestinal wall and enter the connective tissue. Mature parasites most often travel to the superficial layers of the skin of the lower limbs, especially the feet.

  • Dear infection

A person becomes infected with the Medina worm most often through the consumption of water contaminated with eyelids. They are small freshwater crustaceans that are intermediate hosts of the nematode and develop invasive parasite larvae.

  • Symptoms of infection

Infection with the Medina worm is usually asymptomatic. The first symptoms of infection appear when the parasite moves towards the superficial layer of the skin of the lower limb, which is accompanied by significant limb swelling. General symptoms, which include fever, pain,nausea is not specific, but is often associated with the female nematode piercing the skin. A characteristic picture of the disease is red and taut skin and swelling of the subcutaneous tissue of the limb, on which a blister forms after some time, and then a slight ulceration.

  • Infection diagnosis

Diagnosis of worm infection is usually based on the characteristic clinical symptoms - lower limb edema and ulcer formation.

  • Treating infection

Antiparasitic drugs show little effectiveness in the treatment of dracunculosis, so their use is not recommended. The treatment of choice is surgical removal of the female nematode from the subcutaneous tissue. In African countries, an independent, mechanical removal of the parasite is practiced. For this purpose, a protruding piece of nematode is wound from the wound, a few centimeters a day on a match or a small stick.

  • Infection prevention

To prevent contamination with the Medina worm, avoid drinking water from bodies of water that may be contaminated with the parasite.

  • Curly hair

The spiral hair (Latin Trichinella spiralis) is a parasitic nematode both in the digestive system (adults) and in the muscle tissue (larvae) of humans. It causes a disease called trichinellosis. Curly hair is a parasite that occurs all over the world, especially in forest areas inhabited by carnivores. Among its hosts, apart from humans, there are birds of prey and other mammals, e.g. domestic pig, wild boar, rat, dog or common fox. Adult parasites are 1-4mm long, males around 1-2mm, while females are on average twice as long - around 2-4mm in length. Females give birth to live larvae which are placed in the muscles of the host. A characteristic feature of Trichinella larvae is the ability to encyst in the muscles. After eating meat containing encysted Trichinella larvae, they are released from the shell under the action of gastric juice. Then they penetrate the intestinal epithelial cells. After moulting four times, they reach adulthood and become sexually mature. Females lay live larvae into the submucosa of the intestine, from where they enter various tissues and organs of the human body through the lymphatic and blood vessels. In the striated muscle, the larvae penetrate the muscle cells and encapsulate. This is a process that usually takes 4-6 weeks. Over time, the capsule surrounding the larva can calcify and the larvae remain alive for a long time (even up to 30 years!).

  • Dearinfections

A person becomes infected with trichinella by eating raw or undercooked meat (usually pork or venison) in which there are invasive parasite larvae. For this reason, it is not recommended to eat pork or wild boar, e.g. in the form of tartare, raw.

  • Symptoms of infection

In many cases, Trichinella infection is initially asymptomatic. The appearance of the first clinical symptoms and the severity of the disease course largely depend on the intensity of the parasite invasion and the rate of its reproduction. There are two main phases of invasion: intestinal and parenteral.

The gut phase usually takes about a week. In some patients, it is asymptomatic, while others report increased body temperature, abdominal pain, nausea, vomiting, and diarrhea.

The parenteral phase of the disease usually begins seven days after eating the meat that is contaminated with larvae and lasts about 1 to 6 weeks. Disturbing clinical symptoms occurring in patients most often concern the musculoskeletal system, respiratory system and skin. These include stiffness and muscle aches, shortness of breath and difficulty breathing, fever and skin rash.

In some cases, trichinosis infection may be complicated and pose a threat to human life, especially when meningitis or myocarditis develops. Trichinellosis is rarely a fatal disease and in most cases it heals completely.

  • Infection diagnosis

Diagnosis of trichinosis is established on the basis of the presence of larvae in muscle biopsies (a section is taken from the deltoid muscle), as well as by serological tests examining the presence of specific antibodies against parasite antigens.

In laboratory tests of peripheral blood, attention should be paid to eosinophilia (i.e. increased values ​​of eosinophilic granulocytes), leukocytosis and increased levels of lactate dehydrogenase, myokinase and keratin phosphokinase in the blood serum. Creatinuria is noteworthy in the laboratory test of urine.

  • Treating infection

Antiparasitic drugs are usually used in the therapy - mebendazole and albendazole (the most effective), administered in combination with prednisolone.

  • Infection prevention

The most important methods of trichinosis prevention include proper heat treatment of meat from a proven source and that has been veterinary tested (it is especially importantcareful consumption of pork and game!). Trichinella spiralis larvae are sensitive to high temperatures (above 80 degrees C) and die quickly when cooking or frying meat. However, they are resistant not only to drying and curing, but also to quite low temperatures - they die only during deep freezing of meat (down to -25 degrees C) for 10-20 days. It is also worth remembering not to feed pets and pigs with raw meat waste.

Nematodes - larvae invasions of different species of nematodes

Larvawanderingskin

Cutaneous larva migrans externa (Latin larva migrans externa) is a parasitic disease usually caused by hookworm larvae (genus Strongyloides), which usually feed on animals (especially dogs and cats - genus Ancylostoma braziliense, Ancylostoma caninum), and the human was infected accidentally.

  • Dear infection

Invasive larvae of the hookworm species are found in the soil. They penetrate the human skin in places that are in direct contact with contaminated soil, usually they are feet or hands.

  • Symptoms of infection

Infection with invasive skin wandering larvae causes severe itching, inflammation and the formation of lumps at the point of penetration of the parasite through the skin. They travel through the dermis, creating in it numerous, winding corridors about 1 cm long, but it is worth noting that they do not pass to other organs. The larvae usually live in the skin for a few weeks, and then they die without reaching the adult form in the human body.

  • Infection diagnosis

The diagnosis of cutaneous larvae syndrome is usually established on the basis of the presented clinical symptoms and the presence of numerous tortuous corridors in the dermis.

  • Treating infection

The therapy usually includes antiparasitic drugs that act locally in the form of ointments (thiabendazole). Sometimes ethyl chloride is also used, which is used to freeze existing corridors and oral treatment with albendazole or ivermectin.

  • Infection prevention

In order to prevent cutaneous larvae infections, remember to wear appropriate footwear and do not walk without it on soil that may be contaminated with larvae (e.g. beaches!).

Migratory visceral larva

Visceral larva migrans interna (Latinlarva migrans interna , English: visceral larva migrans VLM) is a parasitic disease caused byusually by nematode larvae that feed on animals.

Toxocara canis(or roundworm dog) parasitizes on dogs, wolves and foxes,Toxocara cati(roundworm cat) on cats, while nematode larvaeAnisakidaeparasitize marine mammals.

In the human body, the larvae travel to internal organs, such as the central nervous system, liver, lungs and eyes, and may cause their failure. The most common diseases caused by wandering visceral larvae are toxocarosis and anisakiosis.

  • Toxocara

NematodesToxocaraoccur all over the world, especially in wooded areas. Its natural hosts include dogs, cats and foxes. Man is the random host of this parasite. The nematodesToxocaraparasite in the small intestine of animals. Only in their organisms does it complete its full life cycle and reach sexual maturity. In eggs released into the external environment, invasive larvae develop, which infect humans through accidental ingestion of invasive eggs.

In the human digestive tract, the larvae are released from the eggs, pierce the wall of the small intestine and enter the blood vessels. Together with the blood, they travel to various internal organs, especially the liver, the central nervous system of the lungs and the eyeball.

The larvae encapsulate in most organs and can live for many years in this form. It is worth noting that man is a host not specific to these parasites, therefore in his body they never reach the adult form and for many years they migrate in tissues and internal organs in the larval form, which does not reach sexual maturity.

  • Dear infection

A person becomes infected with toxocarosis by accidental ingestion of invasive eggs, which are found in soil contaminated with animal faeces (including sandboxes, home gardens, parks). Especially often these are small children playing on playgrounds, putting dirty hands and toys in their mouths, as well as people who eat unwashed fruit and vegetables (especially from home gardens).

  • Symptoms of infection

Toxocarosis is a parasitic disease that usually takes the form of one of 4 syndromes: asymptomatic, migratory visceral larvae, latent, or localized with ocular or central nervous system involvement. The appearance of the first clinical symptoms and the severity of the disease course largely depend on the location and degree of pathological changes.

Among the symptomsreported by patients are distinguished primarily by an increase in body temperature, abdominal pain, nausea, vomiting, diarrhea, dyspnea, and disturbances in the central nervous system, especially convulsions and paralysis. Nematodes

Toxocara may also cause symptoms associated with parasitic invasion of the eye (wandering optic celiac larvae syndrome), which include granulomatous retinoblastitis, choroiditis, intraocular optic neuritis, pus in the anterior chamber of the eye, and vitreous clouding .

  • Infection diagnosis

The diagnosis of toxocarosis is established by serological tests examining the presence of specific antibodies against the antigens of the parasite. It is also important to conduct a thorough epidemiological interview, which may lead the doctor to the correct diagnosis. It is not possible to test the presence of nematode eggs in the stool of the patient because he does not reach adulthood and sexual maturity in the human body. In laboratory tests of peripheral blood, attention should be paid to eosinophilia (i.e. elevated eosinophilic granulocytes) and leukocytosis (i.e. elevated amount of leukocytes - white blood cells). It is also worth remembering to perform an ophthalmological examination and imaging tests in order to exclude the form of a localized disease.

  • Treating infection

The antiparasitic drug albendazole is usually used in the therapy. In ocular toxoplasmosis, glucocorticosteroids and surgical treatment are additionally used.

  • Infection prevention

In order to prevent Toxocara nematode infections, you should follow the rules of personal hygiene and remember to wash your hands, vegetables and fruit frequently. Regular deworming of pets, especially puppies and kittens, is also especially important. In addition, remember to protect parks, playgrounds and sandboxes from contamination of the ground with animal faeces, due to the high risk of infecting young children.

  • Anisakis

Anisakis are a genus of nematodes which are usually hosted by marine mammals and birds. Man becomes infected with them by eating raw or undercooked meat of a sick animal. Among the main symptoms reported by patients with anisakiosis are gastrointestinal complaints due to the formation of gastric and intestinal granulomas. An effective way to prevent infection with Anisakis nematodes is to heat-treat meat before eating it, and also to freeze it (for about 24 hours at a temperature of-20 degrees C minimum).

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Parasitic diseases