Ascariasis

Overview

Ascariasis is a common type of roundworm infection that primarily affects the intestine. It is prevalent in regions with poor sanitation worldwide, where individuals may carry the parasite responsible for the infection. These parasites rely on the human body as a host to progress from larvae or eggs to fully grown adult worms. The adult worms can reach lengths exceeding one foot (30 centimeters) and are capable of reproduction.

Ascariasis is classified as a soil-transmitted helminth (STH) infection since it spreads through contaminated soil. While many infected individuals experience mild cases and remain asymptomatic, a severe infestation can lead to significant symptoms and complications.

Generally, treatment is necessary only for infections that cause noticeable symptoms, as some cases of ascariasis may resolve spontaneously over time.

Symptoms

Most people who have ascariasis don’t experience any signs or symptoms. However, if the infection becomes more severe, it can cause various symptoms depending on which part of the body is affected.

In the lungs

After being swallowed, the ascariasis eggs hatch within the small intestine, and the resulting larvae migrate through the bloodstream or lymphatic system towards the lungs. During this stage, individuals may experience symptoms resembling asthma or pneumonia, including:

• Chronic coughing
• Shortness of breath
• Wheezing

After a period of 10 to 14 days residing in the lungs, the larvae proceed towards the throat, where they are expelled through coughing and subsequently ingested when swallowed.

In the intestines

In the case of mild or moderate ascariasis, the larvae develop into adult worms within the small intestine, where they reside until their natural lifespan ends. This intestinal infestation can lead to various symptoms, including:

• Generalized abdominal discomfort
• Nausea and the urge to vomit
• Diarrhea or the presence of blood in stools

However, when a person is heavily infested with a large number of worms, more severe symptoms may arise, such as:

• Intense abdominal pain
• Persistent fatigue
• Swelling of the abdomen
• Frequent episodes of vomiting
• Restlessness and difficulty sleeping
• Growth problems, particularly in children
• Weight loss or malnutrition due to the worms consuming nutrients
• The potential presence of worms in vomit or stool samples

Roundworm infestations may initially be asymptomatic when only a small number of worms are present. However, in severe instances, these parasites can cause partial or complete obstruction of the small intestine, leading to potential complications such as pancreatic inflammation and even life-threatening conditions.

Causes

Ascariasis does not pass from one person to another directly. An individual must instead come into touch with water that is contaminated with ascariasis or soil that has ascariasis eggs combined with pig or human excrement. In certain underdeveloped nations, human waste is mixed with the soil in yards, ditches, and fields, or it is utilized as fertilizer because of inadequate hygienic conditions. Infected pig or chicken liver that has not been fried can likewise cause infection in humans.
Small children frequently play in the dirt, and if they put their dirty fingers in their mouths, it could cause an illness. Unwashed produce cultivated in contaminated soil has also been shown to spread ascariasis eggs.

Life cycle of a worm

• Ingestion. In order for the minuscule eggs of ascariasis to become infectious, they require contact with soil. Accidental ingestion of contaminated soil can occur through hand-to-mouth contact or by consuming raw fruits or vegetables cultivated in soil that is contaminated.
• Migration. Larvae emerge from the eggs within your small intestine and proceed to migrate through the intestinal wall, using the bloodstream or lymphatic system as their means of transportation to reach the heart and lungs. Following a maturation period of approximately 10 to 14 days in the lungs, the larvae rupture into the airway, making their way up the throat. Eventually, they are expelled through coughing and subsequently swallowed.
• Maturation. After returning to the intestines, the parasites undergo growth and develop into either male or female worms. Female worms can reach lengths of over 15 inches (40 centimeters) and have a diameter of approximately a quarter inch (6 millimeters), while male worms are typically smaller in size.
• Reproduction. When both male and female worms reside in the intestines, the female worms have the ability to produce around 200,000 eggs per day. These eggs are then excreted from the body through feces. However, for the fertilized eggs to become infective, they need to spend a minimum of two to four weeks in the soil. During this period, they undergo necessary maturation processes before becoming capable of causing infection.

The complete lifecycle of ascariasis worms, from the ingestion of eggs to the deposition of new eggs, generally spans a duration of approximately two to three months. Once inside the body, these worms have the ability to reside and survive for a period of one to two years.

Risk factors

Ascariasis risk factors include:

• Age. Children aged 10 years and younger are more susceptible to ascariasis, a condition caused by the infestation of the roundworm Ascaris lumbricoides. This higher risk can be attributed to their tendency to engage in outdoor activities, including playing in dirt or soil.
• Warm climate. The Southeast of the United States is where ascariasis is more prevalent. However, it happens more frequently in developing nations with warm weather all year long.
• Poor sanitation. In impoverished nations where human waste is let to interact with the soil, ascariasis is common.