Diversity of parasitic worms
Echinococcus is a tapeworm (only 3–6 mm) living in the intestines of dogs, wolves and foxes. Cattle, sheep, horses or people (intermediate hosts) who take in eggs with contaminated fodder or hands develop large bladders – finnas – in the liver and lungs; if predators (definitive hosts) eat these organs, the worm matures in their intestine. A person can pick up eggs from the fur of a sick dog. The pork tapeworm resembles the beef tapeworm: its larva is in pig muscle, the adult in the human intestine, and people catch it from poorly cooked meat. The pinworm (5–10 mm) lives in the intestine of young children; the female lays eggs at night around the anus, which itches, and eggs spread by dirty hands, clothes and bedding. The guinea worm lives under the skin in tropical countries and spreads through water with cyclops; in Uzbekistan it has been eliminated among people thanks to clean drinking water. The root-knot nematode forms swellings on plant roots and reduces the harvest. Parasitic worms have developed attachment organs, simplified or lost digestive organs and strongly developed reproductive organs, and they lay huge numbers of eggs. They are studied by helminthology.
Make a poster: “We avoid parasitic worms” – 6 rules (wash hands, wash greens and fruit, cook meat well, do not drink puddle water, do not touch stray dogs, see a doctor). Safety: do not approach dogs and cats, especially strays, and never touch them.