Information About

Ascariasis




  Name Ascariasis
  Image Ascaris lumbricoides - adult - CDC Division of Parasitic DiseasesJPG
  Caption '' Ascaris Lumbricoides ''
  ICD10
  ICD9
  ICDO
  OMIM
  DiseasesDB 934
  MedlinePlus
  EMedicineSubj
  EMedicineTopic
  MeshID D001196


Ascariasis is a and in areas of poor Hygiene . Other Species of the Genus '' Ascaris '' are parasitic and can cause disease in Domestic Animals .

Infection occurs through ingestion of food contaminated with Fecal Matter containing Ascaris Eggs . The Larvae hatch, burrow through the Intestine , reach the Lungs , and finally migrate up the Respiratory Tract . From there they are then reswallowed and mature in the intestine, growing up to 30 Cm (12 In. ) in length and anchoring themselves to the intestinal wall.

Infections are usually asymptomatic, especially if the number of worms is small. They may however be accompanied by Inflammation , Fever , and Diarrhea , and serious problems may develop if the worms migrate to other parts of the body.


PREVALENCE

Roughly 1.5 billion individuals are infected with this worm, primarily in Africa and Asia. Ascariasis is endemic in the United States including Gulf Coast ; in Nigeria and in Southeast Asia . One study indicated that the prevalence of ascariasis in the United States at about 4 million (2%) . In a survey of a rural Nova Scotia community, 28.1% of 431 individuals tested were positive for Ascaris, all of them being under age 20, while all 276 tested in metropolitan Halifax were negative.

Deposition of Ova (eggs) in Sewage hints at the degree of ascariasis incidence. A 1978 study showed about 75% of all sewage Sludge samples sampled in United States urban catchments contained Ascaris ova, with rates as high as 5 to 100 eggs per litre . In Frankfort , Indiana , 87.5% of the sludge samples were positive with Ascaris, Toxocara , Trichuris , and Hookworm . In Macon , Georgia , one of the 13 soil samples tested positive for Ascaris . Municipal wastewater in Riyadh , Saudi Arabia detected over 100 eggs per litre of wastewater and in Czechoslovakia was as high as 240-1050 eggs per litre .

Ascariasis can often be measured by examining food for ova. In one field study in Marrakech , Morocco , where raw sewage is used to fertilize crop fields, Ascaris eggs were detected at the rate of 0.18 eggs/kg in potatoes, 0.27 eggs/kg in turnip, 4.63 eggs/kg in mint, 0.7 eggs/kg in carrots, and 1.64 eggs/kg in radish. A similar study in the same area showed that 73% of children working on these farms were infected with Helminth s, particularly Ascaris, probably as a result of exposure to the raw sewage.


LIFE CYCLE

First appearance of eggs in stools is 60-70 days. In larval ascariasis, symptoms occur 4-16 days after infection. The final symptoms are gastrointestinal discomfort, colic and vomiting, fever; observation of live worms in stools. Some patients may have pulmonary symptoms or neurological disorders during migration of the larvae. However there are generally few or no symptoms. A bolus of worms may obstruct the intestine; migrating larvae may cause pneumonitis and Eosinophilia .


RESERVOIR/SOURCE

The source is direct transmission from humans by direct (skin) contact, and through soil and vegetation on which fecal matter containing eggs has been deposited. Ingestion of infective eggs from soil contaminated with human feces or transmission and contaminated vegetables and water is the primary route of infection. Intimate contact with pets which have been in contact with contaminated soil may result in infection, while pets which are infested themselves by a different type of roundworm can cause infection with that type of worm (Toxocara canis, etc) as occasionally occurs with groomers.

Transmission also comes through municipal recycling of wastewater into crop fields. This is quite common in emerging industrial economies, and poses serious risks for not only local crop sales but also exports of contaminated vegetables. A 1986 outbreak of ascariasis in Italy was traced to irresponsible wastewater recycling used to grow Balkan vegetable exports.


DIAGNOSIS

The diagnosis is usually incidental when the host passes a worm in the stool or vomit. Stool samples for ova and parasites will demonstrate Ascaris eggs. Larvae may be found in gastric or respiratory secretions in pulmonary disease. Blood counts may demonstrate peripheral Eosinophilia . On X-ray , 15-35 cm long filling defects, sometimes with whirled appearance (bolus of worms).


SYMPTOMS

Patients can remain asymptomatic for very long periods of time. As larval stages travel through the body, they may cause visceral damage, Peritonitis and Inflammation , enlargement of the Liver or Spleen , toxicity, and Pneumonia . A heavy worm infestation may cause nutritional deficiency; other complications, sometimes fatal, include obstruction of the bowel by a bolus of worms (observed particularly in children) and obstruction of the Bile or Pancreatic duct. More than 796 Ascaris lumbricoides worms weighing 550  G ounces were recovered at autopsy from a 2-year-old South African girl. The worms had caused torsion and gangrene of the Ileum , which was interpreted as the cause of death.

Ascaris takes most of its nutrients from the partially digested host food in the associated with some other Roundworm infections.


TREATMENT

Pharmaceutical treatments include:
  • Mebendazole (Vermox) (C16H13N3O2). Causes slow immobilization and death of the worms by selectively and irreversibly blocking uptake of glucose and other nutrients in susceptible adult intestine where helminths dwell. Oral dosage is 100 Mg 12 hourly for 3 days.

  • Piperazine (C4H10N2.C6H10O4). A flaccid paralyzing agent that causes a blocking response of ascaris muscle to acetylcholine. The narcotizing effect immobilizes the worm, which prevents migration when treatment is accomplished with weak drugs such as thiabendazole. If used by itself it causes the worm to be passed out in the feces. Dosage is 75 mg/kg (max 3.5 g) as a single oral dose.

  • Pyrantel Pamoate (Antiminth, Pin-Rid, Pin-X) (C11H14N2S.C23H16O6) Depolarizes ganglionic block of nicotinic neuromuscular transmission, resulting in spastic paralysis of the worm. Spastic (tetanic) paralyzing agents, in particular pyrantel pamoate, may induce complete intestinal obstruction in a heavy worm load. Dosage is 11 mg/kg not to exceed 1 g as a single dose.

  • Albendazole (C12H15N3O2S) A broad-spectrum antihelminthic agent that decreases ATP production in the worm, causing energy depletion, immobilization, and finally death. Dosage is 400 mg given as single oral dose (contraindicated during pregnancy and children under 2 years).

  • Thiabendazole . This may cause migration of the worm into the Esophagus , so it is usually combined with piperazine.


Also, Corticosteroids can treat some of the symptoms, such as inflammation.

Native Americans have traditionally used Epazote (''Chenopodium ambrisioides'') for treatment, which was not as powerful as pharmaceutical compounds, but spontaneous passage of Ascarids provided some proof of efficacy .

Some recent studies exist in the medical literature suggesting that sun-dried Papaya and watermelon seeds may reduce infections by a large factor. The adult dosage is one tablespoon of the seed powder in a glass of Sugar water once a week for two weeks. The sugar makes the bitter taste palatable and acts as a Laxative .


PREVENTION

Prevention includes; use of Toilet facilities; safe excreta disposal; protection of food from dirt and soil; thorough washing of produce; and hand washing.

Food dropped on the floor should never be eaten without washing or cooking, particularly in endemic areas. Vegetables originating from third-world countries should always be washed thoroughly before consumption.


ANIMAL MODELS FOR ASCARIS INFESTATION


There are two animal models for studying Ascaris infection:
  • Mouse-'' Ascaris Suum '' test model. (Howes HL Jr. J Parasitol. 1971 Jun; 57(3): 487-93.)

  • ''Ascaris suum'' in experimentally infected pigs. (Lichtensteiger CA et al; 1999)



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