Ascariasis - Ascaris Lumbricoides

The ascariasis is an intestinal parasitic disease caused by helminth Ascaris lumbricoides, a worm that can get to measure up to 40 cm long. Estimates suggest that, worldwide, more than 1 billion people are infected with Ascaris lumbricoides, but many of them unaware of this fact because it does not have relevant symptoms.

Ascaris Lumbricoides female and male
Ascaris Lumbricoides female and male

What is ascariasis

The Ascaris lumbricoides, popularly known as tapeworm, is a nematode (roundworm), a light red color, cylindrical body and thinner ends, which usually has between 15 and 30 cm long.

Infection with Ascaris lumbricoides occurs worldwide, but it is more prevalent in countries with hot climate and poor sanitation conditions. The ascariasis can occur at any age but is most common in children between 2 and 10 years.

Most individuals infected with Ascaris no symptoms, except that the intestines are infested with hundreds of worms.

How do you get ascaris

An individual infected by the worm daily eliminates thousands of eggs of Ascaris faeces. In places without proper sanitation, these feces contaminate soil and water. Transmission of Ascaris occurs when a healthy person accidentally ingests these eggs in the environment.

Children often become infected while playing in contaminated soil. Dirty hands can take the eggs directly into the mouth or contaminated toys or objects that enter later in contact with the mouth of other children. The adults usually become infected by ingesting contaminated food or water.

Once in the environment, the eggs of Ascaris are very resilient and can remain viable for several years if have suitable conditions of humidity and temperature. Filtering water, cooking food properly and wash raw fruits and vegetables are sufficient to remove the eggs and prevent contamination of new individuals.

Prior infection Ascaris does not guarantee immunity, it is quite possible the same person develop parasitosis several times throughout life.

Life cycle of ascaris lumbricoides

Eggs shed in the feces contain embryos Ascaris inside. After a few days in an environment, even into the egg, the embryo becomes larvae, which, after passing through 2 changes, it becomes able to infect who ingest. Therefore, Ascaris egg is only able to infect mature human being contains larvae inside, called L3 larvae, which process takes 2 to 4 weeks to occur. If the larvae are still in the egg L1 or L2 phase, the worm can not survive in the digestive tract, it is unlikely to contamination who ingested.

The ingested infective larvae L3 egg release the duodenum, the first part of the small intestine. After become free, the larvae L3 crossing the wall of the small intestine and reach the bloodstream, where, within 4 to 5 days, will migrate to the liver, heart and finally lungs.

In the lungs, the larvae L3 suffer most 2 changes over 10 days and become L5 larvae. After being mature, the larvam migrate to the upper respiratory system, until close to the oral cavity and can be expelled through the mouth by coughing or swallowed, returning to the digestive system. Again the small intestine, L5 larva undergoes its last change, becoming an adult worm.

An adult worm usually live 1-2 years within the gastrointestinal tract. The Ascaris adults do not multiply in the intestines. The eggs of females need to be disposed in the environment to develop viable larvae. Therefore, the number of worms in a person only if it increases ingest new eggs throughout their life. If there is no new contamination after two years, all the worms die and the patient is no longer contaminated.

Symptoms of ascariasis

In most cases, the infection Ascaris lumbricoides are asymptomatic. However, patients with high numbers of worms in their gastrointestinal tract may present symptoms in the migration phase of the larva or during adulthood the worm.

The most common clinical manifestations of ascariasis are:

Pulmonary manifestations

An inflammatory condition of the lungs (pneumonitis) during the short passage of the larvae through the respiratory system is quite common. Manifestations such as dry cough, bronchitis, fever and chest pain are called Loeffler's syndrome. In CBC, the increase in the number of eosinophils is typical of this syndrome.

During episodes of coughing, it is possible that the patient expels one or more larvae of Ascaris the mouth.

Gastrointestinal Manifestations

The symptoms of ascariasis related to the gastrointestinal system are: abdominal pain, nausea, vomiting, diarrhea, bloating and weight loss. infected children may have malnutrition and stunted growth due to reduced absorption of important nutrients from the gut. Elimination of adult worms in the stool may also occur.

In cases of heavy infestation of worms, a "cake" of Ascaris can cause bowel obstruction requiring surgical or endoscopic intervention for removal of the worms.

Diagnosis of ascariasis

The diagnosis of ascariasis is usually done by identification of eggs Ascaris lumbricoides faeces. The problem of stool testing is that the first eggs only appear in the stool about 40 days after the patient has been infected. So in the early stages, such as during lung infection, the stool test is usually negative.

In cases of elimination of the worm through the mouth or feces, it must be collected and taken for recognition of the physician.

Treatment of ascaris lumbricoides

Various drugs can be used in the treatment of ascariasis, the most common options are:
  • Albendazole 400 mg, single dose.
  • Mebendazole 100 mg, 2 times daily for 3 consecutive days.
  • Levamisole, 150 mg, as a single dose.

In the case of intestinal obstruction by Ascaris, the indicated drugs are Piperazine, 50 to 100 mg / kg / day plus mineral oil, 40 to 60 ml / day for 2 days.

The drugs mentioned above are more effective against adult worms than against larvae. So, after three months, the patient should be retested to ascariasis. If positive, a new treatment should be indicated. It is also important to test people who live in the same household as contamination of family members is very common.
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