What is that
L"Ascaris lumbricoides it is a parasitic worm capable of infesting many mammals (pig, horse, dog, cat, etc.), including humans.
The average size of an adult female is about 30cm by 5mm, while the smaller male measures "only" 20cm by 4mm.
Transmission and Contagion
Imagining a few dozen adult Ascaris intent on wandering in our intestines is certainly not exciting, especially for those subjects who, living in poor sanitary conditions, run a serious risk that the horrifying eventuality will materialize.
The infestation is contracted by ingestion of contaminated food (especially fruit and vegetables) with the mature eggs of the worm, which can reach the small intestine even after the introduction of earth-smeared hands into the mouth.
Biological cycle
Once in the upper part of the small intestine, the eggs hatch, letting out the larvae that enter the bloodstream after having perforated the intestinal wall.
Carried by the blood, the Ascaris larvae reach the right heart which, contracting, pushes them little by little up to the pulmonary capillaries, where they settle and begin their development cycle. After about 10 days the larvae, further developed, go up the respiratory tree until they reach the back mouth, where they are partly swallowed and partly eliminated externally, through the sputum, sneezing and coughing.
Once again in the small intestine, the ingested larvae complete their maturation becoming adult specimens within two or three months. Each female, after mating with the male, lays about 200,000 eggs per day, which are then emitted with the faeces and dispersed in the soil, where in suitable climatic conditions (humid, ventilated, temperate but not directly exposed to the sun) soils, they can survive for a long time before being ingested through water or vegetables. During this period inside the eggs develop the larvae which, in a period of time ranging from 18 days to several weeks, undergo two mutations before reaching the stage pest for man.
Prevention
The prevention of ascariasis (the disease caused by the infestation of an Ascarid is so called) is based on compliance with elementary hygiene rules, often disregarded in third world countries: it is necessary to wash and cook the vegetables carefully before consumption (heat kills Ascaris eggs), but also reduce environmental contamination with faeces and their use as fertilizer.
Symptoms
Sometimes the presence of a limited number of specimens does not determine specific symptoms and represents a casual finding. More frequently, Ascaris lumbricoides infestation causes gastrointestinal pain (pain, nausea, vomiting and diarrhea alternating with constipation).
Considering the size of the worm it is possible that one or more specimens, moving inside the digestive tract, go up to the liver obstructing the biliary tract (through which the organ pours bile into the intestine). This can lead to the onset of violent pains, jaundice from stasis, stones, hepatitis and acute cholecystitis; also possible appendicitis and intestinal obstructions.
At whatever level it occurs, the persistent obstruction gradually determines the necrosis of the affected tissue, with consequent organ perforation, a complication that is very dangerous for the survival of the individual. The young age and the state of malnutrition increase the risk of poor prognosis.
In the early stages, when the larvae are localized in the respiratory tract, the disease is characterized by an irritating cough, not very productive, and by frequent chest pain, which is aggravated by coughing sometimes accompanied by the expulsion of bright red blood.
Diagnosis
The examination of the faeces, through which the presence of eggs is sought, constitutes the main diagnostic form. Radiological and endoscopic tests are necessary if there is suspicion of Ascaris inside the duodenum and biliary tract. Sometimes the infestation is testified by the emission of worms with the feces or with the vomit; sometimes they can also spontaneously go up the digestive tract and come out of the nose or mouth.
Treatment
The treatment of ascariasis is based on antibiotic therapy which, when it does not produce immediate results, is the prelude to surgery.
Drugs recommended by the World Health Organization for the treatment of ascaradiasis include: albendazole, mebendazole, levamisole and Pirantel Pamoate
The prognosis is poor only in the most severe cases, neglected and complicated by late diagnosis.
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