However, parasitic infections also affect persons living in developed countries, including the United States. Contact Us. Skip directly to site content Skip directly to page options Skip directly to A-Z link. Section Navigation. Facebook Twitter LinkedIn Syndicate. About Parasites. Minus Related Pages.
An adult Ascaris lumbriocoides worm. They can range from 15 to 35 cm. Those with a compromised immune system are more susceptible, and fetuses can suffer serious or fatal effects from infection. Giardia lamblia is a flagellated protozoan parasite. It lives and reproduces in the intestine, causing an infection of the small intestine known as giardiasis.
When it takes up residence in a human's gut, it results in inflammation and and other damage, reducing the gut's ability to absorb nutrition and causing diarrhoea. The parasite is highly resistant to water treatment and is known to exist in drinking water. Entamoeba histolytica This single-celled organism causes a disease called amoebiasis.
It predominantly infects humans and other primates. It can be found in water , damp environments and in soil, and can contaminate fruits and vegetables. It spreads through faecal contamination. Other than the malarial parasite, it causes more deaths than any other protozoan. New Scientist investigates some of the most common human parasites and the damaging effects they can have Hookworm Necator americanus This parasitic nematode worm begins life outside the body and is transmitted through contaminated water, or fruits and vegetables.
Scabies mite Sarcoptes scabiei var. Roundworm Ascaris lumbricoides These are the largest of the intestinal nematodes affecting humans, growing to centimetres in length. Flatworm blood fluke Schistosoma mansoni , S. It can also affect dogs and cats, but these are different kinds. Dogs, cats, and humans cannot normally infect each other.
This is caused by the parasite Entamoeba histolytica. It affects the intestines. It is more likely in tropical regions and in areas with high population density and poor sanitation. It is transmitted through the fecal-oral route. If humans ingest food or water contaminated with feces, dormant cysts may infect the body. This disease is caused by the Cystoisospora belli , previously known as Isospora belli. It affects the epithelial cells of the small intestine. It exists worldwide and is both treatable and preventable.
It is passed on through the fecal-oral route. This is a disease that is passed on by parasites of the Leishmania family. It can affect the skin, the viscera, or the mucous membranes of the nose, mouth, and throat. It can be fatal. The parasite is transmitted by types of sandflies. This is passed on through a free-living ameba known as Naegleria fowleri. It affects the brain and the nervous system, and it is nearly always fatal within 1 to 18 days.
It is transmitted through breathing in contaminated soil, swimming pools, and contaminated water, but not from drinking water. Different types of plasmodium affect the red blood cells.
It exists in tropical regions and is transmitted by the Anopheles mosquito. This is caused by Rhinosporidium seeberi. It mainly affects the mucous of the nose, conjunctiva, and urethra. It is more common in India and Sri Lanka but can occur elsewhere. Polyps result in nasal masses that need to be removed through surgery. Bathing in common ponds can expose the nasal mucous to the parasite. This is a parasitic pneumonia caused by the parasite Toxoplasma gondii.
It affects the liver, heart, eyes and brain. It occurs worldwide. People can become infected after ingesting raw or undercooked pork, lamb, goat, or milk, or though contact with food or soil that is contaminated with cat feces.
A person with a healthy immune system will not usually have symptoms, but it can pose a risk during pregnancy and for those with a weakened immune system. It affects the female urogenital tract. It can exist in males, but usually without symptoms. This is passed on when the tetse fly transmits a parasite of the Trypanosoma family.
It affects the central nervous system , blood, and lymph. It leads to changes in sleep behavior, among other symptoms, and it is considered fatal without treatment. It can cross the placenta and infect a fetus during pregnancy. This affects the blood , muscle, nerves, heart, esophagus and colon. It is transmitted through an insect bite. Over , people in the U. Anisakiasis : This is caused by worms that can invade the intestines or the stomach wall.
The worms are passed on through contaminated fresh or undercooked fish and squid. Roundworm : Ascariasis, or a roundworm infection, does not usually cause symptoms, but the worm may be visible in feces. It enters the body through consuming contaminated food or drink. Raccoon roundworm : Baylisascaris is passed on through raccoon stools. It can affect the brain, lungs, liver, and intestines. It occurs in North America. People are advised not to keep raccoons as pets for this reason.
Clonorchiasis : Also known as Chinese liver fluke disease, this affects the gall bladder. Humans can become infected after ingesting raw or poorly processed or preserved freshwater fish. Dioctophyme renalis infection : The giant kidney worm can move through the wall of the stomach to the liver and eventually the kidney. Humans can become infected after eating the eggs of the parasite in raw or undercooked freshwater fish.
Diphyllobothriasis tapeworm : This affects the intestines and blood. Humans can become infected after eating raw fish that live wholly or partly in fresh water. Prevalence has increased in some parts of the developed world, possibly due to the growing popularity of sushi, salted fillets, ceviche, and other raw-fish dishes.
Guinea worm : This affects subcutaneous tissues and muscle and causes blisters and ulcers. Diagnosis of neurocysticercosis is difficult due to the lack of specific clinical symptoms. The disease — which normally affects people in South America, Asia and sub-Saharan Africa — has been exceptionally rare in Western countries, however a few cases have been reported in the UK and the US.
Naegleria fowleri — commonly known as brain-eating amoeba — is single-celled and free-living and thrives in warm bodies of water. This parasite can cause a rare brain infection called meningoencephalitis, which causes severe brain inflammation. If water containing the amoeba enters the nose, the parasite can travel via the olfactory nerves, which are responsible for detecting odour molecules and transmitting them as signals to the brain. Initial symptoms appear in less than a week after infection and include fever, headache, nausea, stiffness in the neck, and vomiting.
As infection progresses patients develop lack of attention, loss of balance, seizures, hallucinations, and finally coma and death. Naegleria fowleri infection is diagnosed based on microscopic examination of the fluid present the central nervous system, where active amoebae may be detected.
Sappinia pedata , another free-living amoeba found in water was reported in a year-old patient with neurological symptoms from Texas.
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