Freshwater snail: what kind of danger does it represent?

Few expect a trick from a snail. Many are accustomed to treat a bit of patience with these unusual animals. Who are they, these snails? And is a freshwater snail really dangerous?

Name

The snail is a representative of the animal kingdom. It is classified as a mollusk, a class of gastropods, or gastropods. The Latin name Gastropoda is formed from two ancient Greek words, the approximate meaning of which is "belly" and "leg". And the Russian name of this animal - "snail" - has old Slavic roots. It is consonant with the adjective "hollow". It turns out that each name reflected one of the characteristics of the mollusk. Latin concentrated on the mode of movement, and the Russian language emphasized the hollow house that the animal wears on its back.

Typical structure

A snail is a typical gastropod withan external shell and a trunk. It is amazing that the body simultaneously performs the functions of movement and abdomen. Above him is a special fold, which is called a mantle. The emptiness between the mantle and the body is called the mantle cavity. Inside it there is an entrance siphon, which lets in water, enriched with oxygen, and an outlet siphon, designed to remove the waste liquid. As you know, this applies to those snails that live in the water. If the animal is overland, then in the mantle cavity there is a primitive lung, and not gills.

Information about the species

In the nature of gastropods quite a lot. Scientists recorded more than 110 thousand species. All of them are divided into 3 main subgroups:

• marine species;
• freshwater species;
• land snails.

In fact, the division can be reduced to gill and pulmonary forms. But we will try to consider only one of the forms closer. It will be a freshwater snail.

Freshwater snails: danger

The most terrible murderers on earth are notlarge predators, and small innocent snails. Although how can you call an innocuous animal, on account of which about 10,000 deaths annually? This is not an exaggeration. You are interested in the danger of freshwater snails? How can an animal that does not have sharp fangs and long claws kill a person? Now we will explain.

Every day fresh wateramount of garbage, including waste products of livelihoods of animals and humans. Dirty water multiplies various parasites. On the body of freshwater snails settle microscopic parasites from the genus Schistosoma, which infect humans.

Freshwater snail killer causes terriblea disease called schistosomiasis. A huge number of parasites penetrate the skin and begin to multiply. According to the international classification, schistosomiasis is the second (after malaria) tropical disease in terms of prevalence in the world. It is estimated that more than 207 million people suffer schistosomiasis only on the African continent, but these are only those who could apply for help. According to statistics, 25% of the sick people die.

How does the infection occur?

Freshwater snails kill people, infectingreservoirs of larvae of schistosomes. It is in their organisms that the larvae undergo the first phase of development. The life cycle of schistosomes is quite complex. People bathe, wash, drink water from infected reservoirs, and sometimes just wade through them. In fresh water bodies there are snails, in the body of which sporocysts are settled, from which cecaria develop. They emerge from the body of the snails and move freely in the water, penetrating through the human skin into the circulatory system. On large vessels and capillaries, the cecaria migrate into the portal vein or into the bladder.

In the process of migration, the form of parasites in the regularonce they change, they become adult worms male and female. A special composition of the protein structure of schistosomes makes them unobtrusive or even invisible to the human immune system. This makes it possible for the parasites to breed in an incredible quantity. The immune reaction occurs only after the unisex individuals have mated and laid eggs. Through the intestine or bladder, eggs get back into the environment. From the water, the eggs again enter the body of the mollusks. And then the freshwater snails are killed again, continuing the cycle of development of schistosomes.

From the penetration of the cicar into the skin before developmentA sexually mature specimen capable of reproduction takes about 65 days to complete. The female is larger than the male. It can grow from 7 to 20 mm. Live schistosomes from 3 to 30 years, producing during this time billions of eggs.

The freshwater snail, which is a necessary step in the life cycle of schistosomes, is common in the waters of Africa, the Middle and Far East, South America and the Philippines.

How to understand what an infection has happened

Symptoms of schistosomiasis are dangerous because they areare not immediately apparent, but when a large number of parasite eggs accumulate in the body. Initially, after visiting dangerous areas, it is worth paying attention to the redness and irritation of the skin from contact with fresh water.

1-2 months after infection with parasitesthere are primary symptoms. They are expressed in a febrile state, chills, coughing and soreness of the muscles. But most of the infected primary symptoms do not feel. They understand that they are ill only when chronic schistosomiasis develops. Symptoms of this disease are:

• severe abdominal pain;
• ascites, that is, bloating;
• diarrhea with blood;
• pain during urination, blood in the urine;
• dyspnea;
• coughing attacks;
• heart palpitations, pain in the heart;
• partial or complete paralysis;
• mental disorders.

Examination, analysis, treatment

If after returning from vacation orbusiness trips from countries where schistosomiasis is very common, a person begins to experience strange ailments, then you should immediately contact a parasitologist or infectious disease specialist. Especially if during a survey of local attractions a person contacted with water of rivers or lakes. In this case, in a pond where a freshwater snail is found, it is not necessary to swim. It is enough to sit on the shore, lowering your feet into the water, or for a long time to dip your hand into the water during a boat excursion.

Symptoms of schistosomiasis are similar to othersinfectious diseases, therefore it is necessary to pass several analyzes of feces and urine. Blood tests (PCR) show the presence of the problem only in the advanced stage of the disease, since the immune reaction does not immediately manifest itself.

In difficult cases, you may need a colonoscopy, a cystoscopy or a biopsy. To identify the degree of infection, ultrasound, X-ray, MRI and other examinations can be used.

As treatment is appointed reception"Prazikvantela." Dosage is calculated based on the weight of the patient, the duration of the appointment is determined by the doctor. To enhance the effect, it is possible to combine with the "Artesunat" preparation.

After the course of treatment, the patient should receive an appointment for feces and urine tests to make sure that the parasites died.

Freshwater snails. Predator-Helena

There are a variety of freshwater speciessnails, living both in open water bodies, and in freshwater aquariums. One of the species is the snail helen. This dangerous beauty lives in Southeast Asia. It has a bright and attractive appearance and is able to eat smaller gastropods.

The shell of the Helena is decorated with contrasting stripesblack-amber color. The head of the mollusk is elongated, like a proboscis. The Helen's body is speckled, it is covered with thousands of black dots. Nature has provided this dangerous predator with special lamellar protection. In dangerous situations, the snail closes the entrance to the sink with a solid "door".

Shellfish are often found as freshwater aquarium snails. They help reduce the number of algae, tadpoles, pond snails and other types of snails.

Horned snail

These freshwater mollusks belong to the well-knownthe Neritina family. They are distributed in the southern latitudes. They are found in the water bodies of Japan, Thailand, the Philippines, China and Indonesia. Mollusc prefers estuaries of rivers with a stone or sandy bottom.

The snail has a natural protection in the form of sharp growths. The horns discourage predators trying to grab a snail.

The color of the shells consists of two colored bands. One of them is yellow, the second is black. Small bright inhabitants often get to the owners of freshwater aquariums. They clean excess seaweed from snags, scenery and glasses. Horned mollusks live well with other inhabitants of aquariums, except, perhaps, only a snail of Helena.

Ampulary snail

Freshwater ampullaria occurs in water bodiesSouth America and Asia. These are beautiful multicolored mollusks with four sharp mustaches on the body. The color range of the ampullar is surprisingly diverse. This is a whole family of mollusks, in which there are at least 120 species, each of which has its own color. The body of the molluscan can reach 7 cm in length. Of the characteristics of the species can be called gills and lungs. This is due to the fact that the species lives in shallow waters. Ampularia have a special process, stretching which, they can breathe atmospheric air, even being in the water.

Ampularies like warm water (up to 28 ° C) and nottoo whimsical in the diet. They are suitable and frayed vegetables, and fish food, and small fish pieces. If the water in the aquarium is cold, then the ampularia will hibernate, covering the shell with a lid.

Aquarists love the representatives of this family for maintaining cleanliness in the bowl. The ampullarians pick up pieces of food that have settled on the bottom and dead algae.

Snail of Melania

This type of gastropod spread across Africa andhas a very wide range. In natural conditions, prefers small ponds with a slow current. But melania does not like a stony bottom, prefers a silt pillow or sand. The basis of the diet of this cochlea is inferior algae and semi-decomposed organics. The melanion shell is elongated with a sharp tip. The color range varies from black to light brown.

Virtually any freshwater snail, photowhich you will find, will look beautiful and attractive. However, we must not forget that these mollusks are a great danger. If the owner of the aquarium wants to make a similar pet, having settled it to other fish, then he should understand that it is necessary to take security measures.

Regardless of whether you caught the snails themselves orbought them in a pet store, all mollusks must be kept in quarantine. Freshwater snails are planted in an empty aquarium (without algae and other inhabitants) and aged for about 4 weeks in a weak solution of potassium permanganate. Then the animal is washed in clean water and only after this procedure is allowed into the common aquarium. Although, remembering what a freshwater snail is dangerous for a person, it is undesirable to catch this animal in natural reservoirs. Why expose yourself to the danger of becoming infected with schistosomiasis?