Parasitosis is one of the most dangerous human diseases. Only Malaria kills hundreds of thousands of people every year. But eating wild animals and even walking barefoot can be dangerous, too. Three stories show the range of the topic “Parasitosis of humans”.
Hidden Life in Meat and Fish
It tastes good, but there may be consequences – humans are afflicted by herring worms (Anisakis), liver flukes (Opisthorchis), and fish tapeworms (Diphyllobothrium). Freshwater shellfishes and crustaceans give us lung flukes (Paragonimus), while
liver flukes (Fasciola) hide on unwashed water plants. Insufficiently cooked pork and beef is the source for tapeworms (Taenia). The larvae of the pork tapeworm cause serious damage (cysticercosis) if they infect the brain. Pigs, wild boars, bears, and other animals can harbor trichinae that can wait for up to 30 years to be eaten. The food safety guidelines protect consumers within the EU from such risks.
Malaria – the Insidious Epidemic
Plasmodium, the protozoan pathogen of malaria (mala aria = bad air), enters into the bloodstream through the bite of a mosquito. Science took half a century to explain the whereabouts of the protozoa during the following 8–35 days in which no symptoms of the disease appear. They hide in the liver and reproduce there before reappearing in the blood, entering the red blood cells, and reproducing further. After 48 to 72 hours the erythrocytes all burst simultaneously, leading to a serious fever spike. If untreated, the dangerous malaria tropica can quickly lead to death. In areas with high infection rates sickle cell anemia – an inherited disease – provides protection from malaria. The greatest problem with medicinal prevention and treatment is the increasing resistance of the plasmodia. A vaccination would be worthy of a Nobel Prize.
Intestinal Worms Hide in the Ground
Primarily in the tropics and subtropics humans become infected via contaminated soil. The resistant eggs of roundworms (Ascaris) and the human whipworm (Trichuris) are swallowed unnoticed. The larvae of bloodthirsty hookworms (Ancylostoma, Necator) and threadworms (Strongyloides) pass directly into the skin when walking barefoot and then wander through the heart, lungs, and throat until, finally, they are swallowed. The distribution is fostered by inappropriate disposal of faeces or the use of dung as a fertilizer. Intestinal worms profit from poor hygiene, warms, and humidity.
During the construction of the Gotthard tunnel in Switzerland, miners died of the tunnel disease, an infection with hookworms (Ancylostoma duodenale). The parasites, which actually come from the tropics, lurked in the waste water that could not be removed during construction. Conditions were reported to be catastrophic, with workers sometimes standing ankle-deep in human feces.
Here you get back to the overview.