Answer:
The transmission is fecal-oral, by direct contact of the host-host and through water or food contaminated with oocysts, infectious at the time of being eliminated with the fecal matter of the host. It is worth mentioning that cryptosporidiosis has been identified in epidemic outbreaks due to contamination of drinking, surface and recreational water networks.
Explanation:
It is recognized that despite the careful washing of green leafy fruits and vegetables, the oocysts, due to their cover and, therefore, their resistance, can be found in the stoma of these fruits. Cryptosporidium oocysts remain viable in seawater for 1 year. Its concentration in bivalve molluscs has also been documented and there is growing evidence that the parasite can multiply in host-free environments.
Cryptosporidium oocysts, with double wall and 4 naked sporozoites inside, survive in the environment for long periods of time (between 20-30 ° C, for weeks / months). Once in the digestive tract, mainly at the level of the small intestine, the sporozoites (invasive form) are released through a groove in the oocysts in solution.
Sporozoites have an apical complex, which aids in adhesion to the host cell membrane, which involves invasive forms of the parasite and results in a parasitic vacuole. This vacuole, which encompasses the sporozoite in a special extracytoplasmic (epicellular) niche, has an electrodense region at the base, called a feeding organelle or epimerite.
Further development includes the transformation of sporozoite into trophozoite and reproduction asexually, by merogonia (cell division is by endopolinnya: formation of daughter cells by budding), which results in merones of two types: merones I with 8 merozoites, which they invade other cells, with repetition of the cycle and formation of other merons I, or merons II, with 4 merozoites; the latter give rise to sexual stages and sexual reproduction occurs through gametogonia, with micro and macrogamets. The resulting zygotes go through a final stage of development (sporogonia), which culminates in the production of oocysts; Cryptosporidium has two functional types of oocysts: a) thick-walled infectious, with 4 bare sporozoites (no sporocysts), eliminated with feces; b) thin-walled oocysts, involved in intestinal autoinfection
The 3 phases of reproduction cover between 12 and 24 h, with a new generation of parasites and self-infecting forms on each occasion. Given such an amount of organisms, it is not surprising that in immunocompromised subjects, parasitic forms can spread to the bile and pancreatic ducts, the stomach and the respiratory tract.
