Parasitic food infections

Overview

Many foods can cause parasitic infections. These include meat and seafood, as well as some so-called exotic foods (frogs legs, snails and slugs). The same is true of some plant foods such as lettuce, celery or parsley contaminated larvae following the irrigation of contaminated water.

Parasites capable of food-borne infections can be classified into 4 groups: nematodes, cestodes, trematodes and protozoa.

Nematodes

Nematodes are parasites which adults live in the intestines, kidneys or other organs of mammals or birds. Copepods, worms and mollusks are usually the first guests, while fish, reptiles, birds and mammals serve as second and third host.

The nematode is best known Trichinella spiralis which causes trichinosis. The life cycle of this parasite is relatively simple: enkystés and larvae in the striated muscles are released after consumption of muscle and their digestion in the stomach of the host. The larvae mature males and females for about 5 days, and then invade the intestinal mucosa and copulent. Females then deposit larvae in the lymphatic ducts. These larvae reach the blood via the thoracic duct and are then transported to various body organs, including striated muscles where they encyst and remain latent for months. The cycle is complete when the flesh of such a host is eaten raw by a predator or by any other person after undercooking.

The meat of pig and pork was implicated in most human trichinosis. These are manifested by gastroenteritis during the first 4 to 5 days during which the larvae invade the intestinal mucosa. The second stage begins when the larvae invade the muscles sewing acute muscle pain, fever, edema and transient myocarditis. Symptoms last a few days to several weeks and their severity depends on the number of larvae ingested, they disappear when the larvae encyst in the muscles.

Cestodes

Cestodes are the tapeworms measuring 1.5 cm (dog tapeworm) to 10 m (tapeworm pork and beef) and parasitizing the digestive tract of vertebrates.

In humans, infection by cestodes resulting from consumption of contaminated meat, beef, pork or fish, raw or lightly cooked.

The most well-known cestodes is the tapeworm that is the cause of parasitic infection in humans. This worm may measure several meters long and remains attached to the intestinal wall of its host by the scolex, a head fitted with suction cups and hooks. His body is made up of thousands of segments (proglotids), those of the tip is filled with eggs, is posting regularly and pass into the feces. They feed on partially digested nutrients to diffuse through the surface of his body and grows by increasing the number of proglotids.

The human infection by the tapeworm is manifested by the presence of proglotids in the feces, causing abdominal pain, nausea, weakness, weight loss, stomach pains due to hunger, nervousness. It is treated by taking medication.

Trematodes

The trematodes are parasitic flatworms with and elongated soft-bodied with windy. They have a complex life cycle often involving one or two hosts. The final hosts are mainly domestic or wild animals. They infect humans following consumption of raw or inadequately cooked.

Among the food trematodes interest include Clonorchis sinensis, Opisthorchis sp. Which are common to the liver. They form in the human bile duct where they induce inflammation, abdominal cramps and diarrhea.

Protozoa

Protozoa are unicellular without cell wall, some live in colonies. Most of them live in an aquatic environment, ocean, lake, river, pond. Their length varies between 2 and 70 microns. They feed by ingesting bacteria, waste excreted by other organisms, algae or other protozoa.

Some protozoa are responsible for infections in humans mainly due to consumption of contaminated water or food irrigated by wastewater.

Protozoa are the most famous Entamoeba histolytica, Giardia lamblia, Dientamoeba fragilis. The first (Entamoeba histolytica) causes a severe amoebic dysentery can be fatal if the parasite invades tissues of organs such as liver, lungs or brain. The other two protozoa are not generally able to cross the intestinal mucosa and cause mainly gastroenteritis.

Prevention of parasitic infections

Prevention of parasitic infections through the use of water as it is for consumption, irrigation or cleaning of food. Them when they are contaminated by domestic wastewater, should not be eaten.

A food cooking before consumption reduces the risk of parasitic infections. Fruits and vegetables that are eaten raw, must be thoroughly washed before consumption.