Ascaris is a genus of parasitic nematode worms known as the "giant intestinal roundworms". One species, A. suum, typically infects pigs, while another, A. 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 helminth 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.
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.
Passing of worm in stool
Complete blood count
Stool ova and parasite exam
A.lumbricoides is known as Ascaris pneumonitis. In the lung it causes hemorrhage, inflammation, bacterial infection. It also causes allergy in areas with seasonal trasmission. Typically occurs at 6–14 days after initial exposure.
The intestinal phase causes malnourishment, intestinal blockage, verminous intoxication. A.lumbricoides will move around in the body in response to chemotherapy or fever. Typically occurs at 6 to 8 weeks after initial exposure.
Early diagnosis can be performed by examination of stool for the worm eggs. The spread or infection of A.lumbricoides can be controlled by proper disposal of faeces and proper washing of food. Control of helminthiasis is based on drug treatment, improved sanitation and health education.
As part of the parasite defense strategy, Ascaris roundworms secrete a series of inhibitors to target digestive and immune-related host proteases, which include pepsin, trypsin, chymotrypsin/elastase, cathepsins, and metallocarboxypeptidases (MCPs). Ascaris inhibits MCPs by releasing a enzyme known as Ascaris carboxypeptidase inhibitor (ACI). This enzyme binds to the active site of MCP and blocks the cleavage of its own proteins by the host MCP (Sanglas et al., 2008)
Infections with A.lumbricoides are easily treated with a number of anthelmintic drugs:
The drugs main target is the absorbing cells of the worm. The drugs prevent the worm from absorbing sugar in the intestine which is essential for its survival. This process leads to depletion of energy in worm and its eventual death within few days. The dead worm is then excreted from the gut in the stool. Albendazole is not well absorbed by the intestines and a high fat food or meal should be consumed with each dose.
Many parasitic disease specialists are seeing increased initial incidence and recurrence of roundworm in the U.S. and are thereby increasingly recommending follow up courses of medication to treat internal eggs which have not yet hatched, in addition to the initial treatment period as above. This consists of sporadic treatment with albendazole or similar for a period of three days each month for up to five months after the initial treatment period.
More severe cases, blockage of intestine or pancreatic ducts require surgical removal of worms.
See ascariasis for more information.
Esophagus of an Ascaris worm.
Ascaris Cross Section 40X
Ascaris Cross Section 40X
antivaisa Cross Section 400X
Species: A. lumbricoides - A. suum
Ascaris is a genus of parasitic nematode worms known as the "giant intestinal roundworms". One species, A. suum, typically infects pigs, while another, A. lumbricoides, affects humans, typically in sub-tropical and tropical areas with poor sanitation. A. lumbricoides is the largest intestinal roundworm and is the most common worm infection of humans, 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.