Helminths ( worms)
Taenia is also known as pig tapeworm. This infection is caused by ingestion of eggs shed in the faeces of a human tapeworm carrier. Pigs and humans become infected by ingesting eggs or gravid proglottids. Humans are infected either by ingestion of food contaminated with faeces containing eggs, or by autoinfection. In the latter case, a human infected with adult T. solium can ingest eggs produced by that tapeworm, either through faecal contamination or, possibly, from proglottids carried into the stomach by reverse peristalsis. Once eggs are ingested, oncospheres hatch in the intestine, invade the intestinal wall, and migrate to striated muscles, as well as the brain, liver, and other tissues, where they develop into cysticerci. In humans, cysts can cause serious problems if they localize in the brain, resulting in neurocysticercosis. The parasite life cycle is completed, resulting in human tapeworm infection, when humans ingest undercooked pork containing cysticerci. Cysts evaginate and attach to the small intestine by their scolex. Adult tapeworms develop, (up to 2 to 7 m in length and produce less than 1000 proglottids, each with approximately 50,000 eggs) and reside in the small intestine for years.
Taenia saginata, also known as the Beef tapeworm, is a parasite of both cattle and humans, but which can only reproduce asexually in humans. Taenia saginata occurs where cattle are raised by infected humans maintaining poor hygiene, human faeces is improperly disposed of, meat inspection programs are poor, and where meat is eaten without proper cooking.
Taenia saginata are normally 3m to 5m in length, but it can become very large, over 20m in some situations. The scolex is composed of 4 powerful suckers.The segments are made up of mature and gravid proglottid. The mature proglottid contains the uterus,(unbranched), ovary, genital pore, testes and vitelline gland. In the gravid proglottid the uterus is branched and is filled with eggs. The gravid segments detach and are passed in the faeces. Each of these segments can act like a worm. When they dry up the proglottid ruptures and the eggs are released. The egg can only infect cattle, the intermediate host Inside the cow's duodenum the oncosphere hatch with the help of the gastric and intestinal secretions and migrates through the blood to the muscle. There it develops into infective cysticerci.
Humans become infected when they eat beef that is not cooked fully. Prevention is easy. Cook beef until it is no longer pink inside because cysticerci die at 56 degrees Celsius. Also, if beef is frozen at -5 degrees Celsius it is considered to be safe to consume.
This parasite is found anywhere where beef is eaten, even in countries like the United States where there are strict federal sanitation polices. In the U.S. the incidence of becoming infected is low, however, 25% of infected cattle are still sold.
Ascarides ( Round worms)
Ascaris is a genus of parasitic nematode worms known as the giant intestinal roundworms. One species, Ascaris lumbricoides affects human populations, typically in sub-tropical and tropical areas with poor sanitation. A. lumbricoides is the largest intestinal roundworm and is the most common roundworm infection of humans worldwide, an infection known as ascariasis. Infestation can cause morbidity, and sometimes death, by compromising nutritional status, affecting cognitive processes, inducing tissue reactions, such as granuloma, and provoking intestinal obstruction or rectal prolapse.
What do they look like?
Adult: cylindrical shape, creamy white or pinkish in color.
Male: average 15-31 cm and is more slender than female.
Female: average 20-35 cm in length.
The hookworm is a parasitic nematode worm that lives in the small intestine of its host, which may be a mammal. Two species of hookworms commonly infect humans, Ancylostoma duodenale and Necator americanus. Hookworms are also bilateral, meaning that if cut in half, the worm would be the exact same on each side. Necator americanus predominates in the Americas , Africa, Southeast asia, and China, and Indonesia while A. duodenale predominates in the Middle East, North Africa and India and (formerly) in southern Europe. Hookworms are thought to infect more than 600 million people worldwide.
Hookworms are much smaller than the large roundworms, and the complications of tissue migration and mechanical obstruction so frequently observed with roundworm infestation are less frequent in hookworm infestation. The most significant risk of hookworm infection is anaemia, secondary to loss of iron in the gut. The worms suck blood voraciously and damage the mucosa. However, the blood loss in the stools is not visibly apparent.
A. duodenale worms are grayish white or pinkish with the head slightly bent in relation to the rest of the body. This bend forms a definitive hook shape at the anterior end for which hookworms are named. They possess well developed mouths with two pairs of teeth. While males measure approximately one centimeter by 0.5 millimeter, the females are often longer and stouter.
There are many protozoan parasites that infect humans. These parasites are much smaller than worms and are unlikely to be seen by the naked eye. A sample of faeces must be submitted for laboratory analysis to detect the infestation.
Cryptosporidium is a microscopic single celled parasite somewhat smaller than a red blood cell, which, if swallowed, can cause gastroenteritis. It is not a bacterium or a virus, but belongs to a group of micro-organisms known as protozoa. It infects humans, animals such as cattle and sheep, and sometimes, dogs, cats, rodents, birds etc.. Most of the infections in man and livestock are with just one species, Cryptosporidium parvum.
Cryptosporidium can grow only in a living host and does not multiply in the environment. The parasite develops mainly in the cells lining the gut where it goes through a complex life cycle. The last stage of this cycle is the production of oocysts, the infective stage. These are passed out of the body in the stools and can survive (but not multiply) in the environment, especially in cool moist conditions. Oocysts contain four motile (free moving) banana-shaped bodies known as sporozoites. When oocysts are swallowed, the sporozoites are released and attach to the cells lining the gut and start the life cycle over again.
Giardia lamblia (synonymous with Lamblia intestinalis and Giardia duodenalis) is a flagellated protozoan parasite that colonises and reproduces in the small intestine, causing giardiasis. The Giardia parasite attaches to the epithelium by a ventral adhesive disc, and reproduces via binary fission. Giardiasis does not spread via the bloodstream, nor does it spread to other parts of the gastro-intestinal tract, but remains confined to the lumen of the small intestine. Giardia trophozoites absorb their nutrients from the lumen of the small intestine, and are anaerobes. If the organism is split and stained, it has a very characteristic pattern that resembles a familiar "smiley face" symbol.
Giardia infection can occur through ingestion of dormant cysts in contaminated water, food, or by the faecal-oral route (through poor hygiene practices). The Giardia cyst can survive for weeks to months in warm water, and therefore can be present in contaminated wells and water systems, especially stagnant water sources such as naturally occurring ponds, storm water storage systems, and even clean-looking mountain streams. They may also occur in city reservoirs and persist after water treatment, as the Giardia cysts are resistant to conventional water treatment methods such as chlorination and ozonolysis.
more info: http://en.wikipedia.org/wiki/Giardia_lamblia
Treatment will vary according to the parasite detected. If you are diagnosed with having a parasitic infection, it will be important to consult a medical practitioner to receive the appropriate treatment.
Images can be seen by typing in the name of the parasite at http://www.flickr.com/