Ascaris lumbricoides is a large parasitic roundworm of the genus Ascaris. It is the most common parasitic worm in humans. An estimated 807 million–1.2 billion people are infected with Ascaris lumbricoides worldwide. People living in tropical and subtropical countries are at greater risk of infection. Infection by Ascaris lumbricoides is known as ascariasis.
It has been proposed that Ascaris lumbricoides and Ascaris suum (pig roundworm) are the same species.
Soil-transmitted helminthiasis is a type of worm infection (helminthiasis) caused by different species of roundworms. It is caused specifically by worms transmitted through soil contaminated with faecal matter and are known as soil-transmitted helminths. Three types of soil-transmitted helminthiasis can be distinguished: ascariasis, hookworm infection and whipworm infection. These three types of infection are therefore caused by the large roundworm A. lumbricoides, the hookworms Necator americanus or Ancylostoma duodenale and by the whipworm Trichuris trichiura.
It has become the most common parasitic disease of humans worldwide. Approximately two billion people (about a fourth of global population) are infected as of the latest estimate, and four billion at risk, surpassing even the all-time most prevalent parasitic disease, malaria. The largest numbers of cases occur in impoverished rural areas of Sub-Saharan Africa, Latin America, Southeast Asia, and China. Its main cause, like for many types of helminth infections, is lack of sanitation, such as the practice of open defecation, lack of hygiene such as hand washing and walking barefoot on contaminated soil. It is regarded as one of the world's most important causes of intellectual and physical retardation.
Ascariasis is a disease caused by the parasitic roundworm Ascaris lumbricoides. Infections have no symptoms in more than 85% of cases, especially if the number of worms is small. Symptoms increase with the number of worms present and may include shortness of breath and fever at the beginning of the disease. These may be followed by symptoms of abdominal swelling, abdominal pain, and diarrhea. Children are most commonly affected, and in this age group the infection may also cause poor weight gain, malnutrition, and learning problems.
Infection occurs by ingesting food or drink contaminated with Ascaris eggs from feces. The eggs hatch in the intestines, the larvae burrow through the gut wall, and migrate to the lungs via the blood. There they break into the alveoli and pass up the trachea, where they are coughed up and may be swallowed. The larvae then pass through the stomach a second time into the intestine, where they become adult worms. It is a type of soil-transmitted helminthiasis and part of a group of diseases called helminthiases.
Francesco Redi (18 February 1626 – 1 March 1697) was an Italian physician, naturalist, biologist, and poet. He is referred to as the "founder of experimental biology", and as the "father of modern parasitology". He was the first person to challenge the theory of spontaneous generation by demonstrating that maggots come from eggs of flies.
Having a doctoral degree in both medicine and philosophy from the University of Pisa at the age of 21, he worked in various cities of Italy. A rationalist of his time, he was a critic of verifiable myths, such as spontaneous generation. His most famous experiments are described in his magnum opus Esperienze intorno alla generazione degl'insetti (Experiments on the Generation of Insects), published in 1668. He disproved that vipers drink wine and could break glasses and that their venom was poisonous when ingested. He correctly observed that snake venoms were produced from the fangs, not the gallbladder, as was believed. He was also the first to recognize and correctly describe details of about 180 parasites, including Fasciola hepatica and Ascaris lumbricoides. He also distinguished earthworms from helminths (like tapeworms, flukes, and roundworms). He possibly originated the use of the control, the basis of experimental design in modern biology. A collection of his poems first published in 1685 Bacco in Toscana (Bacchus in Tuscany) is considered among the finest works of 17th-century Italian poetry, and for which the Grand Duke Cosimo III gave him a medal of honour.
Ascaris is a nematode genus of parasitic worms known as the "small intestinal roundworms". One species, Ascaris lumbricoides, affects humans and causes the disease ascariasis. Another species, Ascaris suum, typically infects pigs. Other ascarid genera infect other animals, such as Parascaris equorum, the equine roundworm, and Toxocara and Toxascaris, which infect dogs and cats.
Their eggs are deposited in feces and soil. Plants with the eggs on them infect any organism that consumes them. A. lumbricoides is the largest intestinal roundworm and is the most common helminth infection of humans worldwide. Infestation can cause morbidity by compromising nutritional status, affecting cognitive processes, inducing tissue reactions such as granuloma to larval stages, and by causing intestinal obstruction, which can be fatal.
Ascaris suum, also known as the large roundworm of pig, is a parasitic nematode that causes ascariasis in pigs. While roundworms in pigs and humans are today considered as two species (A. suum and A. lumbricoides) with different hosts, cross-infection between humans and pigs is possible; some researchers have thus argued they are the same species. Ascariasis is associated with contact to pigs and pig manure in Denmark.
A. suum is distributed worldwide and grows up to 40 cm (16 in) in length. Ascaris infections are treated with ascaricides. A. suum is in the family Ascarididae, and is one of the oldest associations to mankind.