The broad tapeworm is the largest of the helminths that parasitize humans. Lives in the intestines. Its length is 3-15 meters, and can reach 20-30 meters.
Content
The structure of a wide tapeworm
The body of the worm is white and consists of a head (scolex), a narrow short neck and a strobila (body), consisting of 4000 proglotids (segments). There are two suction slits on the head.
The wide tapeworm has hermaphroditic segments in which fertilization of eggs occurs. Mature segments in the posterior part take on a rectangular shape, their width is greater than their length.
How does a worm develop?
When they reach maturity, the eggs emerge from the segments and enter the feces. The eggs are oval, 75 microns long, grayish-yellow in color, released into the external environment and must enter the water for final development.
Under favorable conditions (water temperature 10-20ºС, sufficient oxygen content), after 2-3 weeks spherical larvae, coracidia, covered with cilia and having 3 pairs of hooks, appear in the eggs. The lid of the egg opens and the larva enters the water, where it swims freely.
In water, coracidia are ingested by the first intermediate hosts of the broad tapeworm - several species of copepods. After 2-3 weeks, worm larvae, procercoids, develop in the body of the crustaceans.
The second intermediate hosts of the parasite are fish. In the body of fish, procercoids penetrate the muscles and internal organs (in perches and ruffes only into the muscles) and develop into a stage that is infectious to humans - the plerocercoid.
If a small fish is eaten by a larger one, the plerocercoids accumulate in its tissues.
Once in the body of the final host - humans, piscivorous domestic and wild animals - plerocircoids attach to the mucous membrane of the initial section of the small intestine and after 14-30 days they begin to secrete eggs. They are found in quantities of up to 2000 pieces in one gram of feces.
A person's intestines are usually inhabited by one or several individuals, but there are cases of parasitism of up to 100 worms.
Diphyllobothriasis
Diphyllobothriasis is a helminthiasis caused by broad tapeworms and occurs mainly with lesions of the gastrointestinal tract.
A characteristic feature of the disease is its prevalence in areas of cold and temperate climates, predominantly in the northern hemisphere, more often in large freshwater bodies of water.
The incubation period is 20-60 days.
Routes of infection
Human infection occurs
- when consuming fresh, insufficiently salted caviar,
- raw fish,
- poorly cooked fish.
Infection occurs especially often through fish species such as
- pike,
- burbot,
- perch,
- ruff.
Impact of helminth on health
Parasitism of tapeworm in the intestines has a detrimental effect on human health for the following reasons:
- at the site of attachment of the worm to the intestinal wall, death of the muscles and tissues of the intestine occurs,
- the body of the parasite irritates the internal receptors of the intestine, disrupting reflex reactions, and leads to neurotrophic disorders,
- metabolic products secreted by the worm and poisoning the human body cause allergic reactions,
- The development of hypovitaminosis is caused by the fact that, on the one hand, the wide tapeworm feeds on food bolus, and on the other hand, due to damage to the intestinal mucosa, the absorption of vitamins is disrupted.
Symptoms
Diphyllobothriasis can manifest itself acutely or with a gradual increase in symptoms. The initial stage of the disease is characterized by symptoms such as:
- nausea,
- vomit,
- pain in the stomach area,
- pain all over the abdomen,
- loss of appetite,
- stool disorder,
- low-grade fever.
With a long period of the disease, symptoms such as:
- general weakness,
- increased fatigue,
- dizziness,
- vitamin B₁₂ deficiency,
- pain and numbness of the tongue,
- in severe cases, bright red painful spots, cracks on the tongue.
Later, the papillae of the tongue atrophy, the tongue becomes smooth, shiny (varnished),
tachycardia develops, and the borders of the heart may expand.
Blood test changes:
- a sharp decrease in the number of red blood cells and hemoglobin,
- increase in ESR.
Intestinal obstruction may develop due to a large accumulation of worms.
Diagnostics
The most informative is stool analysis, which reveals tapeworm eggs or fragments of strobila (body). Excretion of parts of helminths with feces is observed in 70-80% of patients.
The helminth can be detected by endoscopic examination.
Treatment
Diphyllobothriasis is treated with antiparasitic drugs. The most common drug recommended is niclosamide. It causes paralysis of tapeworms and reduces their resistance to gastrointestinal enzymes.
Niclosamide is prescribed once after a light dinner or in the morning on an empty stomach.
Before taking the drug, it is necessary to carry out preparations, which are described in the article “ Teniarinhoz: treatment ”.
If niclosamide is ineffective, praziquantel is used.
In case of severe anemia, treatment with cyanocobalamin is carried out intramuscularly until blood counts normalize.
Prevention
3 months after treatment, a stool test must be taken twice with an interval of 2-4 days. If fragments of tapeworm or its eggs are detected in the analysis, repeated treatment is carried out.
To avoid infection, you must eat well-processed fish:
- boiled,
- fried,
- salted,
- smoked,
- frozen.
Lightly salted or fresh pike caviar is especially dangerous.
Rules for processing fish:
- when fried, the larvae die within 20-40 minutes,
- when boiling - instantly,
- when salting - after 1-2 weeks,
- freezing fish weighing 2 kg at temperatures from -10⁰С to -12⁰С disinfects it after 3 days,
- freezing at temperatures from -21⁰С to -22⁰С leads to the death of the larvae after 18 hours.
An important factor in the spread of the disease is pollution of water bodies with sewage.
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