Parasites are a major public health problem in many countries. Tapeworms infect people around the world. The most common of these are bovine and pork tapeworm. As adults, these worms live in the intestines and usually do little harm. But if people become infected with cysts (immature stage), then cysticercosis can develop - a disease that can lead to brain damage.
What is a parasite?
A parasite is an organism that lives within the host organism and at its expense. Viruses are the smallest of all infectious agents; they average about 100 nanometers (100 billionths of a meter) in length. They have so few genes and their own protein that in order to produce offspring, they need to invade the alien cell structure. Bacteria vary widely in size and shape, but tend to be at least 10 times larger than viruses. They are unicellular organisms that reproduce independently. Multicellular parasites can be so large that they can be seen with the naked eye. Tape worms, for example, can reach a length of 6 meters or more. Food and water are the most common sources of parasite transmission. Since most of us eat three times a day and drink water throughout the day, the influence of these sources is constant. Animals, like humans, can become infected with parasites. And they are the main carriers of parasites. Experts believe that of the 110 million domestic dogs and cats in our country, more than half can be infected with at least one or more types of parasites. Given these data, the potential for transmission of parasitic infections from animals to humans is extremely high. Parasites are classified by structure, form, function and reproductive ability. These include microscopic organisms, roundworms, pinworms and worms (nematodes), tapeworms (cestodes) and flukes (trematodes).
Discovery story
Bull tapeworm is considered one of the earliest human parasites. He began to refer to tapeworms in the late 1700s. However, the exact life cycle of a bovine tapeworm was examined in detail in 1863, when cattle were identified as the direct owner.
Morphology and bull tapeworm: photos
The parasite has the form of a long flattened ribbon-like tapeworm of white color. Its diameter is about 6 to 7 millimeters. An adult worm typically has about 1000 segments called proglottids. Unlike scolex with 4 suction cups, these are relatively harmless organs of bovine tapeworm. Each proglottid contains both male and female reproductive organs, with the help of which eggs with embryos are produced, each of which has a size of 31-43 micrometers. The incubation period takes from 5 to 12 weeks.
Conditions for a successful completion of the life cycle
The life cycle of a bovine tapeworm includes one or more intermediate hosts. The distinctive morphological and physiological properties of the adult parasite reflect, on the one hand, their amazing ability to survive in the intestines of vertebrates, and on the other, their ability to reproduce offspring. The life cycle of a bull chain is complicated and has a number of essential conditions for successful completion:
1. Proglottids filled with eggs enter the environment through feces.
2. These “pregnant” segments enter the body of cattle eating infected vegetation, so they enter the digestive tract of the intermediate host. Enzymes and acids found in the gastrointestinal juice break the protective barrier and release up to 100,000 eggs.
3. Eggs develop into larvae that break through the intestinal epithelium and travel through the body of cattle. Then the larvae enter the muscle tissue, their oncosphere is filled with fluid, forming cysts.
4. In order to complete the difficult life cycle of a bull’s tapeworm (the diagram clearly shows this), infected undercooked beef meat must be eaten by a person (the final owner) to enter his digestive system. Digestive enzymes break down the membrane, the larvae are released, and the inverted scolex gets the opportunity to exit the capsule. Then it attaches to the intestinal wall. After which the parasite begins to grow and within three months can reach 5 meters in length. At the moment of maturity, he is already capable of releasing proglottids in order to resume the life cycle of a bull chain.
Life cycle diagram
The dimensions of the parasite in the adult stage are usually colossal and range from 4.5 to 9 meters. The bovine tapeworm worm lives in the small intestine. An infected person usually has only one or two individuals. To attach to the wall of the intestine, tapeworms use their head, which is called scolex. They have between 1,000 and 2,000 body segments called proglottids, each of which contains between 80,000 and 100,000 eggs that can survive for many months or years in the environment. When cattle eats vegetation contaminated by larvae, eggs penetrate through their intestinal walls, looking for peculiar burrows in the muscles and remain there in the form of a fluid-filled cyst, which is a protective capsule for them. If people eat raw or semi-raw beef meat containing cysts, cysts develop in adult tapeworms within 2 months. Adult bovine tapeworm can live for more than 30 years.
Classification
Tapeworms, including bull tapeworm (see photo in the review), belong to the class of cestodes. This is a group of parasitic flatworms, which includes about 5000 species. Tapeworms are found all over the world and have a size range from 1 mm to more than 15 m. They are internal parasites of certain species of invertebrates and all types of vertebrates, including humans, domestic animals. Some worms exist apart, while others require one or more intermediate hosts during their life cycle. The structure of the bovine tapeworm, like other tapeworms, suggests bilateral symmetry (i.e., the right and left sides are identical). Some consist of one long segment, others have a pronounced head, followed by a series of identical segments called proglottids.
Body of the tapeworm
The body of a bovine tapeworm is presented in the form of a tape, flattened both from top to bottom and bilaterally (symmetrically). It is characterized by the presence of three germ layers (ectoderm, mesoderm and endoderm), the respiratory and circulatory systems are not developed. The body is covered with a rigid and at the same time flexible cuticle, there are also no cardiovascular and respiratory systems, but there is a bilateral nervous system. Even large tapeworms consist almost entirely of reproductive structures with a small “head” for attachment. Adults usually have the same body structure. The latter consists of scolex, the neck and a large number of proglottids, which are sometimes called segments. The neck of the tapeworm is a clearly defined, short, narrow and non-segmented area behind the scolex. It consists of a relatively undifferentiated mass of cells. This is a zone of growth and distribution of the segmentation region, since it is here that new proglottids are formed. The structure of the bovine tapeworm also includes nerve rings and lateral nerve endings running along the entire length of the body. Food previously digested in the small intestine is the main source of nutrition for tapeworm. The total surface area of the parasite increases significantly due to the presence of microvilli.
Breeding
Like any other, the life cycle of a bull chain has as its main task a continuation of a kind. Tapeworms are hermaphrodites, because they contain both male and female genital organs in one body, and male maturation occurs first, so the front part of mature proglottids consists only of male genital organs. Thus, they are a complete reproductive unit that produces eggs either through self-fertilization or cross-fertilization with other mature proglottids. After this, disconnection from the rest of the body occurs. This phenomenon serves to limit the length of the parasite. The developing embryo leaves with the feces of the host.
Signs, symptoms and diagnosis of infection
Bovine tapeworm infection is accompanied only by mild symptoms, including diarrhea, constipation, flatulence, abdominal pain and weight loss. How do doctors diagnose and treat the infection? Eggs and proglottids can be seen in stool samples during microscopic examination. To accurately determine that the tapeworm is bovine or pork, it is necessary to remove and study their scolexes. This is rarely done, as doctors usually prescribe the same drugs for both types of infection. Helminth larvae in tissue cysts of tissues can be detected using the method of x-ray, as well as computed tomography (brain cysts). Control is also carried out at 3 and 6 months after treatment to ensure that the infection is completely gone.
Bull tapeworm causes teniarinhoz
Bovine tapeworm belonging to the group of tapeworms is a rather large specimen that causes an infection called teniarinhoz. He got his name due to the fact that he uses cows as intermediate owners. People are only the ultimate carriers. The disease is often asymptomatic. In a severe stage, it can sometimes cause inflammation of the appendix and bile ducts. Infection can also endanger the immune system. The effects of infection can have a particularly profound effect on the health of young children. Teniarinhoz is ubiquitous and is relatively common in Africa, Eastern Europe, Latin America and the Philippines.
Treatment
Treatment is traditionally carried out with special medications. This is, as a rule, “Fenasal”, “Praziquantel”, “Nicklozamide”. Endoscopic treatment is the introduction of the drug directly into the small intestine. This causes the parasite to exit completely naturally.
Prevention
Tapeworms can cause intestinal diseases and other serious pathologies. Infection with bovine tapeworm can be prevented by careful preparation of the meat, this ensures that any tapeworm cysts are destroyed. Alternatively, you can freeze the meat and hold it at a temperature below -5 ° C for several days. Eating cattle is also prevented from eating in areas where vegetation cannot be contaminated with human feces. A reliable method of preventing endemic spread is the detection of infected livestock. It is also important to observe the rules of hygiene and maintain cleanliness, which involves regular hand washing, especially after going to the toilet. Proper sanitation is the key to eliminating infection worldwide.