Are there parasites on humans?

Parasites can appear in many places, such as in food, and also on the human body. These are human parasites. Human parasites can be divided into two types: internal parasites and external parasites. They are generally eaten and transmitted through some food. These include various types such as protozoa, nematodes, and trematodes. The treatment method should be chosen according to the type of parasite.

Human parasites are parasites that use humans as hosts.

They can be divided into two categories: internal parasites and external parasites. Most of them belong to protozoa, nematodes, flatworms, annelids and arthropods. In parasitology, protozoa are usually called protozoa, and nematodes and flatworms are collectively called helminthes. Most of the important types of internal parasites are included in the classes of protozoa, nematodes, trematodes and helminths.

Parasites are usually ingested. Some larval cysts are also distributed in the lungs, subcutaneous tissue, and even the brain and eyes. Parasites are harmful to the human body. They mostly cause damage to the body by robbing it of nutrients, causing inflammation, and blocking blood vessels. Most of them belong to protozoa, nematodes, flatworms, annelids and arthropods.

In parasitology, protozoa are usually called protozoa, and nematodes and flatworms are collectively called helminthes. Most of the important types of internal parasites are included in the classes of protozoa, nematodes, trematodes and helminths.

hookworm

Basic Introduction

Hookworm is a general term for nematodes of the family Ancylostoma, and the well-developed oral sac is its morphological characteristic.

Among the nematodes that parasitize the human digestive tract, hookworms are the most harmful

Human parasites

The most serious type is hookworm parasitism, which can cause long-term chronic blood loss in the human body, leading to anemia and anemia-related symptoms in patients. Hookworms are distributed worldwide, especially in tropical and subtropical regions, where infection is more common among the population. It is estimated that hookworm infection affects approximately 900 million people worldwide. In our country, hookworm disease is still one of the parasitic diseases that seriously endangers people's health.

The hookworms that parasitize the human body mainly include Ancylostoma duodenale Dubini (1843), also known as Ancylostoma duodenale, and Necator americanus Stiles (1902), also known as American hookworm. In addition, the Ceylon hookworm (Ancylostoma ceylanicumLoose, 1911), which occasionally parasitizes humans, is similarly harmful to the first two hookworms. The infective larvae of Ancylostoma caninum Ercolani (1859) and Aucylostoma braziliense Gomez de Faria (1910) can also invade the human body and cause cutaneous larva migrans (CLM).

Because the larvae migrate in a winding manner, the rash appears in the form of creeping lines, so it is called creeping eruption. But the larvae cannot develop into adults.

form

The adult body is about 1 cm long, translucent, flesh-red, and turns grayish white after death. The front end of the insect body is thinner, with a well-developed oral sac at the top, which is made of tough cuticle. Because the front end of the insect body is bent toward the back, the upper edge of the oral sac is the ventral side and the lower edge is the dorsal side. The oral pouch of the duodenal hookworm is flat and oval in shape, with two pairs of hooked teeth on its ventral edge. The outer teeth are generally slightly larger than the inner teeth. There is a semicircular deep depression in the center of the dorsal side, with slight protrusions on both sides. The oral sac of Necator americanus is oval in shape. There is a pair of plate teeth on its ventral margin and a conical sharp tooth on its dorsal margin. The hookworm's pharyngeal tube is about 1/6 of its body length, its rear end is slightly swollen, and the pharyngeal tube wall is well-developed with muscles. The intestinal wall is thin and composed of a single layer of epithelial cells. The inner wall has fine villi, which facilitate the absorption and diffusion of oxygen and nutrients.

Life History

The life cycle of Ancylostoma duodenale is essentially the same as that of Ancylostoma americanum.

The adult worms parasitize in the upper part of the human small intestine. After the eggs are excreted from the body with feces, the cells inside the eggs continue to divide in warm (25-30℃), humid (relative humidity is 60%-80%), shaded, and oxygen-rich loose soil, and the first-stage rhabditiformes will hatch within 24 hours. The larvae at this stage feed on bacteria and organic matter, grow rapidly, and undergo their first molt within 48 hours, developing into second-stage rhabditiformes. After that, the worm continues to grow and can store the ingested food in the intestinal cells. After 5 to 6 days, the worm's mouth closes, it stops feeding, its pharyngeal tube becomes longer, and it undergoes a second molt to develop into filariform larvae, which are the infectious larvae. The vast majority of infectious larvae live in the surface soil 1 to 2 cm deep and often move in clusters. In a small piece of heavily contaminated soil, thousands of larvae can sometimes be found. The larvae at this stage can also use the surface tension of the water film covering their bodies to crawl up along plant stems or grass branches, reaching a height of about 20 cm.