Parasitic diseases. How to suspect and diagnose?

Parasitic diseases are a widespread, diverse group of diseases caused by helminths and protozoa that go through the life cycle in the human body, feeding and reproducing at the expense of the “host” and causing damage to various organs and systems. Given the effect on the entire body as a whole, it is rather difficult to suspect and recognize them.

How does the infection take place?
Before entering the human body, helminths and protozoa go through a development cycle in other environments or living organisms.

Eggs and larvae of roundworm, strongyloid, hookworm remain in the soil under certain conditions of temperature and humidity. A person becomes infected when contaminated soil enters through dirty hands, water, unwashed fruits and vegetables, directly from the ground.
In living organisms, the following helminths undergo developmental cycles: opisthorchis (cat fluke), clonorchis, trichinella, toxocara, echinococcus, pork and bovine tapeworm. Before reachi

ng maturity, in order to parasitize in a person, a change of one or two intermediate hosts is possible. These are molluscs, crustaceans, fish, insects. Eating insufficiently thermally processed fish and meat, raw water leads to infection.
Another way of infection is through direct contact of people through handshakes, common hygiene and household items, or by self-infection. We are talking about contagious helminths: enterobiasis, strongyloidosis, cysticercosis, giardiasis.

How can a parasitic disease be s

uspected?

Manifestations can be varied, from mild to severe. Rarely there are typical signs that give out a specific pathogen. Often there are no signs, or they disguise themselves as other diseases, or disappear as one cycle of development of the parasite ends and the beginning of another. For example, ascaris larvae first enter the human lungs, where they mature and migrate to the intestines. The child may be bothered by a short cough (similar to a cold), which does not alarm the parent.

Nevertheless, the acute and chronic phases of the course of the parasitic disease are usually distinguished.

Acute manifestations occur as a result of a general effect on the body:

The effects of toxins – an increase in temperature up to 37 – 37.5 degrees, weakness, headaches, decreased mood and performance, sleep disturbances;
Allergic reactions – itching, urticaria, bronchospasm, shortness of breath, less often Quincke’s edema;
Immune system activation – muscle and joint pain; enlarged lymph nodes, liver and spleen
Mechanical impact – if you look under a microscope, each helminth can see devices for fixing in the body, injuring the mucous membrane: teeth, hooks, suction cups. The result is abdominal pain, frequent bowel movements, and dyspepsia.
The chronic phase is characterized by damage to certain organs and systems. Most often, the intestine suffers, prolonged mechanical action leads to its inflammation, impaired absorption and digestion of food. Anemia, a lack of vitamins and minerals develops, and in young children, growth and weight gain are delayed. The gallbladder and biliary tract (giardiasis) may be affected; cardiovascular system, lungs, nervous system (usually trichinosis); lungs and liver (echinococcosis) and so on. With a long course, immunity is suppressed and secondary infections join.

So, we have many ways of infection, mechanisms of development and manifestations of parasitic diseases. It turns out that every second person has a risk of getting sick, right? But sometimes helminths may not stay in the body: die and leave, or pass “in passing” without beginning to parasitize (that is why the detection of a “worm” in the feces does not prove the presence of the disease). Much depends on the stage of the helminth, its invasive properties and the human immune system. More susceptible to the development of helminthiasis are children under 5 years of age, actively learning the world “on the tongue” and people with chronic diseases and weakened immunity.

If you find any of the listed signs, take a clinical blood test with a leukocyte count. An increase in eosinophils up to 7-10% or more will become another suspicious criterion.

How to identify a parasitic disease?
Study of feces for protozoa and helminth eggs, preferably the enrichment method – PARASEP Determines the eggs of all types of helminths and protozoa that live in the intestines
The criterion for disease activity is the detection of eggs! This means the passage of the cycle of development of the helminth in the body, its parasitism and reproduction. These are mainly intestinal helminthiases, when a person is the final host, the “permanent residence” of the parasite, and eggs are needed for further spread and the beginning of the next cycle.

You should pay attention to the following points:

Each helminth has its own development cycle, so a single study is not enough. If the result is negative, a three-time study is recommended with an interval of 3-7 days.
There are such forms of helminthiases, when a person is an intermediate host (carrier of helminth larvae) or a “biological dead end”, when the larvae have confused the host and cannot develop further at all. In such cases, eggs will never appear in the feces, the disease can only be detected by determining antibodies (see below)
Examination of scraping for enterobiasis – reveals only pinworm eggs in the perianal folds. Female pinworms lay eggs, leaving the intestines exclusively at night, when a person is relaxed. Therefore, the study is carried out strictly after sleep BEFORE WASHING!
The study of the antigen of lamblia in the feces is a high-precision method for the detection of lamblia. For better detection, it is recommended to adhere to a choleretic diet before testing.
The study of antibodies to helminths (immunoglobulins) is aimed at assessing the immune system against pathogens. Basically, the most persistent immunoglobulins are determined – class G (IgG), reflecting the fact of infection, but not allowing to understand whether there is a helminth in the body now or not, since IgG is stored in the body for a long time in the “memory archive”.
What should you pay attention to?
The presence of manifestations and the simultaneous detection of IgG may indicate a chronic phase of helminthiasis
In doubtful cases, it is recommended to retest IgG after 2 weeks. An increase in the level of antibodies by 2 times or more indicates the activity of the helminth
With trichinosis, echinococcosis, cysticercosis, the determination of antibodies is the only possible method of laboratory diagnosis, since a person is an intermediate host for these helminths.