Parasitic infections: causes, symptoms, diagnostic testing, treatment and prevention

2024 Author: Curtis Blomfield | [email protected]. Last modified: 2023-12-16 20:44

Parasitic infections are a diverse range of symptoms and diseases that are caused by the ingestion of eggs or adult parasites into the human body. Often, the first signs of the disease cannot be detected for several days, and in some cases for several months and even years. This is due to the life cycle of parasites and their main functions: good camouflage and maintenance of their own life by obtaining nutrients from the host organism.

Types of parasites and their characteristics

Parasitic infections, depending on certain properties of their manifestation, are divided into three groups:

1. Ectoparasites.

The main localization is the surface of the human body. These include lice, fleas, ticks and bed bugs. They feed mainly on human blood, although in some cases, as, for example, with ticks that cause demodicosis, the main food is the secret of the sebaceous glands ordead epithelial (skin) cells.

The first signs of a parasitic infection are easy enough to recognize, as they cause itching and burning in their habitats. Some ectoparasites are carriers of serious diseases: typhus, anthrax, encephalitis and trypanosomiasis. They cause enormous damage to human he alth, even death.

2. Endoparasites (protozoa).

Mainly affect internal organs. In their structure, they are unicellular, hence the name - protozoa. Despite this, they can lead to severe forms of disease. The main diseases of this group are a parasitic infection of the blood caused by Toxoplasma, and intestinal infections provoked by amoeba or Giardia.

3. Helminths.

They are the causative agents of the most common forms of parasitic infections. In the human body, their development cycles mainly take place in the intestines and tissues, where the manifestation of disease symptoms begins.

Roundworms (nematodes)

These are parasites whose body is round in cross section. Easily distinguishable sexual characteristics. Females are usually larger than males. But also in representatives of this class there are hermaphrodites. All nematodes go through stages of development: egg, larva, adult. This class includes:

1. Pinworm. Causes the disease enterobiasis. Predominantly affects children of preschool and primary school age.
2. Vlasoglav. callstrichuriasis disease. Has a distinctive body shape. 2/3 of the body length has a thin diameter, resembling human hair or thread. The other end of the body is larger in diameter, it contains the intestines.
3. Ascaris. Causes ascariasis. Adults reach a size of 25 cm (males) and 40 cm (females). After the larva enters the human body, it passes through the stomach and enters the small intestine. From there, through the pores with the blood flow, it enters the liver, then to the heart and then to the lungs, where it develops within 7-10 days. Then the larvae begin to rise to the larynx. Having reached the oral cavity, they are re-swallowed. Once in the small intestine, the larvae can no longer re-enter through the pores into the bloodstream due to their large size. There they grow to adults within 2-3 months. After that, reproduction begins and the cycle repeats. A female can lay over 200,000 eggs per day.

Tapeworms (cestodes)

These are parasites whose body resembles the shape of a ribbon. A distinctive feature of this class is the lack of a digestive system. These include:

1. Echinococcus. Causes echinococcosis disease. This parasite is small (2-9 mm) and consists of several segments and suckers. The uterus of a sexually mature individual contains a large number of eggs, inside of which there are larvae. The main localization sites of echinococcus are the liver and lungs. There it causes a chronic disease called an echinococcal cyst.
2. Bullishtapeworm. Causes the disease teniarinhoz. At the larval stage, it has an intermediate host - cattle. Once in the human body, it develops in the small intestine to the tape stage. The body of an adult parasite has up to 1000 segments, and it can reach 4-10 meters in length.
3. Pork tapeworm. Causes taeniasis. Outwardly, it is very similar to a bull tapeworm. It also has intermediate hosts: pigs, dogs, camels, hares and rabbits. In humans, it parasitizes in the intestines. The size of an adult individual does not exceed 4 meters in length.
4. Ribbon is wide. Causes the disease diphyllobothriasis. Inhabits freshwater bodies of water. It uses crustaceans and fish as an intermediate host. In the human body, it parasitizes in the small intestine. In length, an adult can reach several meters.

Flatworms (trematodes)

During their life cycle, these parasites can change several intermediate hosts. In humans, they can parasitize in any organ. This group includes:

1. Schistosomes. They cause the disease schistosomiasis. They can enter the human body through contact with contaminated fresh water. The parasite penetrates the skin and enters the circulatory system, where it begins to multiply actively. Females can produce from 300 to 3000 eggs per day. Further, with the blood flow, the eggs are carried throughout the body and continue their development in any organ. Their body length does not exceed 0.1-0.2 cm.
2. Liver flukes. Cause the disease opisthorchiasis. The length of an adult variesfrom 3 to 5 cm. When it enters the human body, it parasitizes in the bile ducts, gallbladder, liver and pancreas. It is fixed in these organs with the help of suction cups located on the body.

Ways of penetration of parasites into the human body

1. The alimentary route of infection is considered the most common. A person becomes infected with the parasite when eating poorly washed vegetables and fruits. Of particular danger is meat that has not undergone sufficient heat treatment. Also, human infection with a parasitic infection occurs if the rules of personal hygiene are not followed. For example, do not wash your hands before eating.
2. Transplacental route. Parasitic infection is transmitted from a pregnant woman through the placenta to the child. For example, these are diseases such as toxoplasmosis, malaria or hookworm.
3. Percutaneous path. The parasite enters the human body through the skin. These are mainly schistosomes and hookworms.
4. Contact way. The parasite is transmitted through dirty hands, contaminated personal belongings, linen. This is how lice, scabies, pinworms are most often transmitted.
5. Transmissive way. Infection occurs after the bite of insects that are carriers of parasites. For example, malaria.

Symptoms

Many parasitic diseases are asymptomatic in the early stages. This is due to the stages of development of the pathogen. Each individual species of parasite manifests itself differently as it grows. To the common general symptoms of parasiticinfections include:

1. Itching.
2. Redness of the skin like urticaria.
3. Diarrhea.
4. Constipation.
5. Meteorism.
6. Nausea, vomiting.
7. Spasms and pain in the gastrointestinal tract.
8. Loss of body weight without diets and increased physical activity
9. Feverish condition.
10. High body temperature (38-40˚C) for an extended period.
11. Prolonged attacks of dry cough.
12. Swollen lymph nodes.
13. Pain in the muscles.
14. Psycho-emotional disorders.

Diagnosis

If you suspect the presence of parasitic diseases, you must pass a series of tests. Diagnosis of parasitic infections allows you to determine the presence or absence of the parasite, its type and location in the body. The data obtained will help the doctor to make the correct diagnosis and prescribe the correct treatment.

Diagnostic methods include:

I. Study of feces. Allows you to determine the presence of most types of parasites that live in the intestines. With faeces, their eggs, larvae and body segments are excreted. There are two types of analysis:

1. A stool sample is examined for eggs and larvae of helminths. The analysis is delivered to the laboratory, where the doctor makes smears and examines them under a microscope. This method is often used, but it is not accurate enough. In order to make a final diagnosis, the patient must take this analysis up to three times.with small time intervals. This is due to the life cycle of parasites and egg laying, which are detected by this method of research.
2. Scraping (flushing) from the folds of the anus. This analysis is used to detect only one type of helminth - pinworms. Parasitic infections are more common in children than in adults. For this reason, such an analysis is carried out mainly for children. The laboratory assistant moistens a cotton or glass eye stick in water or glycerin and flushes from the perianal folds. Next, the resulting material is applied to a glass slide and examined under a microscope. Also, this analysis is done by a different method: the laboratory assistant sticks a piece of adhesive tape to the anus, presses it and peels it off. Then the adhesive tape is glued to the glass slide and also examined under a microscope. The parasite is diagnosed quite accurately. Using these methods, the laboratory assistant manages to examine not only helminth eggs, but sometimes adults as well.

II. Examination of cerebrospinal fluid, sputum, duodenal contents (bile), urine. Assign according to the results of a patient survey in order to determine the presence of the parasite and determine its localization. The analysis of these biological fluids is examined using microscopy and macroscopy. First, the resulting sample is examined for the presence of adults, and then microscopy is performed to detect eggs and larvae of parasites.

III. Blood study. Modern methods of blood testing for parasitic infections make it possible to determine the presence and type of pathogen with a highaccuracy. There are three types of such diagnostics:

1. Serological reactions. Allow to determine the presence of parasite antibodies in the patient's blood serum. This method is considered highly specific, but inferior to PCR diagnostics.
2. PCR diagnostics. This method is based on the detection of parasite DNA in any biological fluid taken for analysis.
3. Genetic research. It consists in the detection of the parasite genome in a patient's blood sample. This method is used much less often than all the others, but has high accuracy.

IV. Examination of biopsy material and lymph nodes. For this analysis, the doctor performs excision of a small section of an organ, tissue, or an entire lymph node and sends it for histological examination. Thus, the presence or absence of parasites is diagnosed.

Recommendations for preparing for testing

Before you get tested for parasitic infections, you need to properly prepare for them. If the recommendations are followed, the accuracy of diagnostics increases, since there are no interfering factors in the material that affect the effectiveness of research methods.

Preparing for a stool test:

1. Antibiotics, anti-inflammatories and antacids should be stopped. It is also unacceptable to use drugs and other drugs containing bismuth and iron.
2. If a barium x-ray or colonoscopy was performed, in which a colon cleansing enema was performed, then a fecal analysis can be taken only after 2-3days.
3. It is not recommended to donate feces in case of the onset of menstrual bleeding or exacerbation of hemorrhoids.

Preparing for a blood test:

1. It is necessary to stop taking pharmacological drugs that affect the blood count.
2. Three days before the test, you should follow a light diet, do not eat fatty foods, give up alcohol.
3. A blood test for parasitic infections is taken on an empty stomach. A small amount of clean drinking water is allowed.

For the rest of the tests, most often no special preparation is required. It will only be necessary to follow the recommendations of the doctor.

Treatment

Unfortunately, the symptoms of parasitic infections can not always be detected in the initial stages of the disease. In such cases, treatment begins late. It is important to understand: the longer the parasite is in the body, the more difficult it will be to get rid of it.

Therapy of infectious and parasitic infections is divided into two areas:

1. Symptomatic treatment. It is aimed at eliminating the clinical manifestations of the disease. These include a decrease in body temperature, getting rid of redness and itching, normalization of the gastrointestinal tract.
2. Etiological treatment of parasitic infections is aimed at getting rid of the causative agent of the disease.

Surgical intervention may be necessary in some cases. It is applicable for alveococcosis, echinococcosis and some types of trematode infection.

When dehydration is prescribeds alt-containing solutions: Trisol, Disol, Regidron, 0.9% sodium chloride solution.

To reduce irritation, hyperemia and itching of the skin, the following creams are used: Fenistil, Hydrocortisone, Gistan, Advantan.

Anthelminthic therapy is carried out using the following drugs: Nemozol, Vermox, Pirantel, Decaris, Vermakar, Mebendazole.

Antimalarial drugs: Delagil, Primaquine, Quinine sulfate, Malarone, Fansidar.

Only a doctor can prescribe treatment for parasitic infections based on laboratory data and patient interviews.

Prevention

It is very important to observe the prevention of parasitic infections. In most cases, this will help to avoid pathogens entering the body.

Preventive measures include:

1. Compliance with the rules of personal hygiene: it is necessary to wash hands before eating, after visiting the toilet room, entering the house from the street.
2. Vegetables and fruits should be washed well.
3. Be sure to carry out sufficient heat treatment of meat, fish and seafood.
4. Tap water should not be used as drinking water, as it cannot always be purified from parasites. The use of home filters will not help as an additional cleaning. The best option would be to drink boiled or bottled water.
5. If pets live at home, then they need to be dewormed once every six months. Alsoyou should limit contact with the pet if it has signs of parasitic diseases and contact the veterinary clinic.
6. You should iron underwear (especially children's) after washing.
7. After visiting exotic countries, when working with the land, as well as employees of children's institutions, it is recommended to be examined once a year for the presence of parasitic infections and, if necessary, carry out prophylaxis with drugs.