The living creatures that extract sustenance and safeguard from other living beings are parasites. Those organisms on which they depend are the host. They may be either small, single celled like protozoa or large as worms like helminths. The life cycle of the parasites may either get completed in one host or go through different stages in different hosts. The pathogenicity also varies from mild uneasiness to unbearable illness or even death at times.
They may be transmitted from person to person, through contaminated food and water, unclean hands and through animals. Some of them are responsible for food borne illness. These parasites depend on the host in all aspects and it multiplies and completes the life cycle inside the body and even come out through the excreta.Some common parasites and diseases they cause are; Giardia duodenalis, Cryptosporidium parvum, Cyclospora cayetanensis, Toxoplasma gondii, Trichinella spiralis, Taenia saginata (beef tapeworm) and Taenia solium (pork tapeworm).

1. Giardiasis:  caused by Giardia duodenalis. Responsible for the majority of food illness. The parasite lives inside the human and animal intestine. The disease is spread through contaminated water and also by the consumption of cysts contaminated meat. Nausea, abdominal cramps, weight loss, diarrhea, dehydration, etc. are symptoms which start after 1-2 weeks of consumption of cysts.

2. Cryptosporidiosis: causative agent; Cryptosporidium parvum is usually seen inside the intestine of sheep, goat, cow, etc. Parasite reaches humans when food contaminated with the oocysts ( an egg cell having the capacity to develop into a new organism) in the feces of these animals reach the body. 2-10 days after consumption of oocysts symptoms such as stomach problems, watery diarrhoea, cramps in the abdomen, etc. starts to appear.

3. Toxoplasmosis: caused by Toxoplasma gondii. The parasite completes a part of the lifecycle inside the cat’s gut. The oocyst, which is the infective stage is shed through feces into the environment. When contaminated food with the parasite is taken in, the disease is contracted. Raw and undercooked meat also causes the infection. An infected mother can pass on the disease to the fetus. Swollen lymph glands, muscle pain are common symptoms. Stillbirth can occur in pregnant women. Severe cases may cause damage to the eyes and brain.

4. Taeniasis: this is the common name given for the diseases caused by T. solium (pork tapeworm) and T. saginata (beef tapeworm). Both the parasites complete the reproduction and cyst formation inside the human intestine. Disease is caused when improperly cooked beef and pork are consumed.Digestive problems, abdominal pain, intestinal obstruction, excreting parasitic body segments in the feces, etc. are symptoms.

5. Cyclosporiasis: caused by Cyclospora cayetanensis. When food or water contaminated with the oocysts of this parasite causes the disease. Onset of symptoms occurs after 1week of consumption, which includes watery diarrhoea, muscle pain, cramps in the stomach, fever, tiredness, etc.

6. Trichinellosis: the causative agent is Trichinella spiralis. Improperly cooked meat, especially of wild animals is the main reason for this disease. Horse, fox, wolf, pork, etc. bear this parasite.

After 1-2 days of consuming such meat, symptoms appear. It includes painful joints and muscles, total weakness, headache, lack of coordination, itching over the skin, etc.

 
Precautions:

1. Avoid taking in of uncooked meat.
2. Avoid using night soil as manure.
3. Do not consume raw vegetables without proper cleaning.
4. Avoid swimming in contaminated pools.
5. Take medical attention upon the onset of symptoms.