Infectious Diseases

Ascariasis Roundworm Infection



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Ascariasis is an infection caused by a particular type of roundworm, Ascaris lumbricoides.  Roundworms are a variety of parasitic worms with long, cylindrical bodies, also called nematodes.  Ascariasis is the most common parasitic infections found in human beings, known to infect more than a million people worldwide.  Most people who become infected are children under the age of ten.  It is not a common infection in the United States or other developed nations, although cases of Ascariasis are not unknown in these areas of the world.  It occurs with greater frequency in less-developed areas, where poor sanitation and crowded living conditions are commonplace, particularly those in tropical or sub-tropical climates. 

Ascariasis is usually contracted by eating unwashed vegetables from contaminated soil, or when unwashed hands that are contaminated with Ascarid roundworm eggs come in contact with a person’s mouth.  Ascarid roundworms cause a greater strain on their human host than do any other known human parasite.  Adult Ascarid roundworms can grow to be about a foot long and as thick around as a pencil.  They can release 200,000 eggs in a day.  Although some of these worms are removed from the body through defecation, many will remain in the body.  This means an infestation of these roundworms can multiply quickly in their host if left unchecked.  And, Ascarid roundworms can live for up to two years.

Once swallowed by their human host the Ascarid roundworm finds a perfect breeding ground.  In the digestive tract the eggs will release the larvae, which will penetrate the intestinal wall and travel through the body to the lungs by way of the bloodstream.  The larvae then migrate further into the host’s upper lung passages and airway, where they are swallowed again, this time entering the intestinal tract as mature adults.  The intestine now becomes a breeding ground for the Ascarid roundworm, and the cycle repeats itself.  This entire process takes about two months, from initial infection to reproduction and egg laying.

Symptoms of Ascariasis range from mild to severe.  Symptoms of a mild infection include obvious signs such as worms in a patient’s stool and coughing up worms, and less obvious signs such as fever, wheezing when breathing, and loss of appetite.  There may not even be any symptoms at all during the initial stages of infection.  And symptoms for children are likely to be more severe and pronounced, as children have smaller intestines and are more likely to develop intestinal obstruction as a result of a roundworm infestation.

Severe symptoms associated with Ascariasis include shortness of breath, vomiting, harsh coughing, blood in the phlegm, swelling of the abdominal area, severe stomach pains, and intestinal blockage.  This phase of the infection is marked by an accumulation of parasites in the lung tissue, and an abnormal increase in the number of a specific type of white blood cell as the body tries to fight the infection.

A doctor will diagnose Ascariasis in a patient by observation of any of the symptoms listed here.  Since many of the first symptoms of Ascariasis are common to a number of illnesses the doctor may perform other tests to rule out a parasitic infection, such as blood tests.  Adult Ascarid roundworms will be visible on x-rays and ultrasound tests.  A stool sample may also be obtained to check for the presence of worms, larvae, or eggs. 

Prevention is the best weapon against Ascariasis.  Sanitary disposal of human waste, cleaning and thoroughly cooking all foods before eating them, and proper hand-washing methods are all ways in which the spread of Ascariasis can be limited, and even eliminated. 

Treatment for an existing infection includes the use of drugs designed to target roundworms called anthelminthic medications.  Anthelminthic drugs kill the roundworm by either paralyzing them or by blocking them from feeding.  Symptoms will generally disappear within one week of starting the treatment regimen.  Nasogastric suction, by means of a tube inserted through the nasal passage, may be used to remove the worms from the intestinal tract.  If the suction fails to remove the worms, very invasive surgery will be necessary in order to prevent intestinal rupture or blockage.  Successful treatment of Ascariasis will not prevent future infections.

Ascariasis is the only roundworm infection in humans with a significant mortality rate.  Worldwide, it is estimated that 20,000 children die every year from this infection.

Sources:

mayoclinic.com

kidshealth.org

faqs.org

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