image source, photo by Teresa Zgoda.
This alien monster is actually our very close neighbour - Taenia solium (pork tapeworm). The photo shows the front section of its body: the eyes (two suction cups), two more are on the other side of the head. And mouth- the chitin hooks, through which the tapeworm is attached to the walls of the small intestine. The final carrier of this parasite is a human.
A full cycle of this parasite involves 4 main stages:
- The eggs fall into the environment through the feces of the final carrier, waiting for the pig will eat contaminated food (plants).
- In the intestine of a pig, under the influence of bile and digestive enzymes, the larvae hatch from the eggs. The larvae move from the intestines into the bloodstream and spread throughout the body of the animal
- Entrenched in animal tissues, the larvae go into a dormant stage, taking the form of сysticercoid- a small "bubble" with a worm germ inside
- If a human eats the infected meat without proper heat treatment, surviving сysticercoids, reacting to enzymes in the stomach, unfold into an adult worm and attach to the walls of the intestine
A more detailed description of the cycle source
The worm absorbs nutrients from the host organism through a thin veil of internal tissues and can grow to 2-3 meters. The period of life of Taenia Solium is several years, but its closest relative- Taenia saginata (beef tapewor), can live up to 28 years in the human body and reach a length of 10 meters.
In the final stage of the worm, the parasite does not cause serious harm to the human, because he is unprofitable to harm his carrier. But sometimes, our body can become an intermediate carrier of pork tapeworm in the egg stage. The eggs enter the human body from unwashed vegetables and fruits. In this case, numerous foreign entities are formed in the internal organs, which must be surgically removed.
Adult worm. image source. I decided not to put pictures of this parasite inside the body, it looks pretty repulsive, especially if you are eating.
Curious the fact that these parasites have chosen humans as the final carries. Our immune system and our species are one of the youngest on the planet. While parasites are one of the oldest creatures, which are primarily suited for survival inside the animal that appeared with them in the same era.
Previously it was thought that Taenia Solium began to adapt to the human body about 10,000 years ago, when we domesticated pigs... it is logical. But there is also a version according to which these parasites have paid attention to us much earlier, before the advent of hopo sapiens.
Presumably our ancient African ancestors were infected with worms by eating the carrion (buffaloes, antelopes and wild boars), which remained after the hunting of hyenas and lions. Results of molecular analysis showed that pork tapeworm descended from ancestors, the final hosts of which were hyenas, and intermediate hosts- boars.
Parasites have evolved together with intermediate hosts (wild boars) and were distributed along with the new final hosts (humans) around the world, through the migration of peoples and the development of animal husbandry.
According to preliminary estimates, about 5-6% of the world's human population are infected with Taenia Solium.
Hundreds of scientific discoveries occur around the world every day. But they may contain insufficient data to create a full-fledged article or seem rather boring for usual readers, because of the strong scientific specifics. Although, I see that steemit community loves science in all its manifestations.
#Sciencepop - science popularization. I suggest you use this tag in order to share interesting news, photos, stories from the world of science in a short format. Perhaps, in time, in this way, we will be able to create a powerful news and encyclopedic database. And use the links not to the external resources, but to sources inside the Steemit platform. This will significantly improve the indexation of the site and improve its position in search results.
