Epidemiology 

Ascariasis, caused by the roundworm Ascaris lumbricoides, is a widespread parasitic infection affecting approximately 1.5 billion individuals worldwide, with the highest prevalence observed in regions of Africa and Asia.

This parasitic disease is considered endemic in various parts of the world, including the United States, particularly in areas along the Gulf Coast, as well as in countries like Nigeria and across Southeast Asia.

The transmission of ascariasis is closely linked to poor sanitation and hygiene practices, as the eggs of the roundworm are commonly found in contaminated soil, water, and food. Lack of access to clean water sources and inadequate sewage disposal systems contribute to the persistence of this parasitic infection in endemic regions.

Efforts to control ascariasis include public health interventions aimed at improving sanitation infrastructure, promoting hygiene education, and implementing mass deworming programs in affected communities.

In addition, increased awareness and surveillance are essential for the early detection and treatment of ascariasis cases to prevent the spread of infection and reduce the burden of this parasitic disease on affected populations.

Causes of Ascariasis

Ascariasis is primarily caused by the parasitic roundworm, Ascaris lumbricoides. The transmission of this infection occurs when you ingest soil contaminated with human feces containing Ascaris lumbricoides eggs.

This contamination of soil commonly arises due to poor sanitation practices, inadequate sewage disposal systems, and a lack of access to clean water sources in affected regions.

Modes of Transmission

Ascariasis can be transmitted to humans through various modes:

1. Direct Ingestion: Patients may become infected with Ascaris lumbricoides through direct ingestion of contaminated soil. This can occur during activities like hand-to-mouth contact or the consumption of food that has been in contact with contaminated surfaces.
2. Indirect Ingestion: Indirect transmission can occur when individuals consume raw vegetables or fruits that have been grown in soil contaminated with Ascaris eggs and inadequately washed before consumption.

Risk Factors

Several factors increase the risk of ascariasis transmission, including:

1. Poor Sanitation: Areas with poor sanitation practices and inadequate sewage disposal systems are more likely to have contaminated soil and water sources, increasing the risk of Ascaris infection.
2. Lack of Clean Water: Limited access to clean water for drinking and sanitation purposes can contribute to the persistence of Ascaris contamination in the environment.
3. Consumption of Raw Vegetables: Consuming raw vegetables or fruits grown in contaminated soil without proper washing increases the risk of ingesting Ascaris eggs.

Life Cycle of Roundworms (Ascariasis)

• Egg Ingestion: The life cycle of roundworms begins when Ascaris lumbricoides eggs, present in contaminated soil or food, are ingested by humans.
• Hatching in the Intestines: Once ingested, the eggs hatch in the small intestine, releasing larvae that penetrate the intestinal wall and enter the bloodstream.
• Migration to the Lungs: The larvae then migrate through the bloodstream to the lungs, where they penetrate the lung tissue and enter the airways.
• Coughing and Swallowing: The larvae are coughed up from the airways and swallowed, returning to the small intestine, where they mature into adult worms.
• Maturation and Egg Production: In the small intestine, the larvae develop into adult worms, which can grow up to 30 centimeters in length. Adult female worms begin to produce eggs, which are then passed in the feces of the infected individual.
• Contamination of Environment: The eggs are released into the environment through the feces, contaminating soil, water, and food sources.
• Cycle Continuation: The contaminated environment perpetuates the cycle of infection as new hosts ingest the eggs, restarting the life cycle of Ascaris lumbricoides.

Signs and Symptoms of Ascariasis

Ascariasis, caused by the parasitic roundworm Ascaris lumbricoides, can manifest with a range of signs and symptoms, including:

• Vague Stomach Discomfort: Patients infected with roundworms may experience mild to moderate stomach discomfort, often described as vague or generalized abdominal pain.
• Vomiting or Passing Worms in Stool: In some cases, infected patients may vomit or pass live worms in their stool, which can be a distressing and alarming symptom.
• Restlessness: Ascariasis may lead to feelings of restlessness or discomfort, particularly as the worms migrate within the digestive tract.
• Disturbed Sleep: Infected patients may experience disrupted sleep patterns due to discomfort or restlessness caused by the presence of roundworms in the gastrointestinal tract.
• Signs of Intestinal Obstruction: Severe cases of ascariasis can result in intestinal obstruction, characterized by symptoms such as severe abdominal pain, bloating, and constipation.
• Weight Loss: Chronic ascariasis can lead to weight loss, particularly in cases where the worms cause significant intestinal obstruction or interfere with nutrient absorption.
• Impaired Growth: In children, chronic or severe ascariasis can impair growth and development, leading to stunted growth and developmental delays.
• Fever: Some individuals may develop a low-grade fever as the body mounts an immune response to the parasitic infection.
• Abdominal Distension: Ascariasis can cause abdominal distension or swelling, especially in cases of intestinal obstruction or severe worm infestation.
• Other Symptoms: Additional symptoms may include nausea, diarrhea, fatigue, and weakness, depending on the severity of the infection and its complications.

Medical Management

History

• Symptom Inquiry: Ask about symptoms such as stomach discomfort, vomiting worms, disturbed sleep, restlessness, weight loss, fever, and abdominal distension.
• Exposure History: Ask about potential exposure to contaminated soil, water, or food sources, especially in areas where ascariasis is endemic.
• Travel History: Ascertain any recent travel to regions with poor sanitation practices or a high prevalence of ascariasis.
• Past Medical History: Determine if the individual has a history of previous parasitic infections or intestinal disorders.
• Occupational History: Ask about occupations or activities that may involve contact with contaminated soil or water, such as farming or gardening.

Physical Examination

• Abdominal Examination: Perform a thorough abdominal examination to assess for tenderness, distension, and palpable masses suggestive of intestinal obstruction or worm infestation.
• Vital Signs: Measure vital signs, including temperature, pulse, respiratory rate, and blood pressure, to assess for signs of infection or systemic illness.
• Skin Examination: Inspect the skin and sclera for signs of jaundice, which may indicate liver involvement secondary to ascariasis.
• Stool Examination: Collect stool samples for laboratory analysis to detect the presence of roundworm eggs or adult worms, confirming the diagnosis of ascariasis.
• General Examination: Conduct a general examination to evaluate overall appearance, hydration status, and signs of systemic illness such as fatigue or malaise.
• Respiratory Examination: Perform a respiratory examination to assess for signs of respiratory involvement, such as coughing or wheezing, which may occur during larval migration to the lungs.
• Neurological Examination: Assess neurological status, especially in severe cases or cases with complications, to evaluate for signs of neurological involvement or impairment.

Diagnosis of Ascariasis

• Incidental Discovery: Ascariasis is often diagnosed incidentally when individuals pass worms in their stool or vomit.
• Stool Examination: Stool samples are collected and examined for the presence of Ascaris eggs using microscopic techniques. This method confirms the diagnosis of ascariasis.
• Respiratory Secretions: In cases of pulmonary involvement, larvae may be detected in respiratory secretions obtained through sputum samples or gastric lavage.
• Peripheral Eosinophilia: Blood tests, including a complete blood count (CBC), may reveal elevated levels of eosinophils, indicating an immune response to the parasite.
• Radiographic Findings: X-ray imaging may show characteristic findings such as filling defects measuring 15–35 cm in length. These defects may exhibit a whirled appearance, suggestive of a bolus of worms within the gastrointestinal tract.
• Clinical Symptoms: Clinical presentation, including symptoms such as vomiting worms, stomach discomfort, and signs of intestinal obstruction, can also contribute to the diagnosis of ascariasis.
• Travel or Exposure History: A history of travel to endemic regions or exposure to contaminated soil, water, or food sources can further support the diagnosis.

Pharmaceutical Treatment for Ascariasis

• Mebendazole (Vermox): Mebendazole acts by selectively and irreversibly blocking the uptake of glucose in roundworms, leading to their slow immobilization and death. The oral dosage regimen typically involves 100 mg taken every 12 hours for a duration of 3 days.
• Piperazine: Piperazine functions as a flaccid paralyzing agent, causing a blocking response of the roundworm muscle to acetylcholine. This narcotizing effect immobilizes the worm, preventing migration. When used alone, piperazine may cause the expulsion of the worm in feces. The recommended dosage is 75 mg/kg (maximum 3.5 g) administered as a single oral dose.
• Pyrantel Pamoate: Pyrantel pamoate induces depolarization of ganglionic and blockage of nicotinic neuromuscular transmission, resulting in spastic paralysis of the roundworm. However, in cases of heavy worm loads, spastic paralyzing agents like pyrantel pamoate may lead to complete intestinal obstruction. The typical dosage is 11 mg/kg, not exceeding 1 g, administered as a single dose.
• Albendazole: Albendazole is a broad-spectrum antihelminthic agent that decreases ATP production in roundworms, causing energy depletion, immobilization, and eventual death. The standard dosage is 400 mg given as a single oral dose. However, albendazole is contraindicated during pregnancy and in children under 2 years of age.

Other Drugs

• Thiabendazole: Thiabendazole is sometimes used in combination with piperazine to prevent the migration of the roundworm into the esophagus. It is effective as a single dose.
• Hexylresorcinol: Hexylresorcinol is effective when administered as a single dose.
• Santonin: Santonin is another drug option for the treatment of ascariasis.