Strongyloides, a parasitic nematode, contains 50 varieties that infect birds, amphibians, mammals, reptiles and humans. Currently 100 to 200 million people suffer infestation infections from strongyloides. Normally, infections produce mild gastrointestinal upset in humans, but if an infected person suffers from a low immune system, the infestation can prove deadly. Two types of larvae live within the soil awaiting a host, filariform infective and free-living rhabditiform.
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Infestation
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When the skin of a host comes into contact with infected soil, the larvae burrows through the skin and penetrate the lymphatic system, making their way toward the pulmonary system of the host. Once in the pulmonary system, the larvae cause irritation and obstructions to the airway, causing the host to cough them up and swallow them.
Digestive Tract Life
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Once swallowed, the larvae make their way into the digestive tract of the host. The larvae mature to adults. Inside the small intestine, concentrating primarily in the top 1/2 to 1/3 of the small intestine. The female lays eggs within the intestine. A female can live up to five years.
Egg to Larvae
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Once the eggs are laid in the intestine, they hatch into larvae. The larvae exit the body in fecal matter to contaminate soil. Once a host comes into contact with larvae-infested soil and becomes infected it takes only one month before the host is producing infectious larvae in its fecal matter.
Larvae Within the Body
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Many times the larvae do not exit during defecation because of factors such as constipation. When the larvae find themselves trapped in the large intestine, they molt into filariform larva. Once the transformation occurs, the larvae penetrate the wall of the intestine and make their way through the host's body and take up residence in the liver, central nervous system and lungs.
Multiple Generation
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Most hosts are unaware of the infection. A host can carry the parasites for decades before diagnosis is achieved. The prevalence of infection tends to occur in tropical, sub-tropical and temperate climates. Regions of Tennessee, Kentucky and West Virginia show wide spread strongyloide infection rates.
Treatment
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Control of an infestation is easily achieved when a positive diagnosis is made. In humans, the dewormer Ivermectin is administered with a 97 percent cure rate and rarely requires additional treatment. Thiabendazole has also been administered with success for humans infested with the parasite. In cases of Strongyloides in animals, the preferred treatment is administration of either fenbendazole or Ivermectin.
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