Intestinal Helminthic Infestation

• Infections by helminths are one of the most common but neglected diseases, affecting more than 30% of the world’s population.
• The organisms are multicellular parasites comprising:
  • Nematodes (round worms)
  • Cestodes (tapeworms)
  • Trematodes (flukes)
• The intestinal nematodes are soil-transmitted but live in the intestine, hence the name. However, other parasites also pass through the intestine.

• Ascaris lumbricoides
• Ancylostoma duodenale (hookworm)
• Necator americanus (hookworm)
• Strongyloides stercoralis
• Enterobius vermicularis (pinworm)
• Trichuris trichuria (whipworm)

Ascaris lumbricoides: Ascariasis

Clinical Features

• Larvae stage occurs in the tissues and lungs and is usually acute.
• Allergic reactions
• Urticaria
• Loeffler’s syndrome (severe pneumonia, haemoptysis, bronchospasm, and eosinophilia)

Digestive and Nutritional Complications

• Chronic abdominal colic, contractions, and ischaemia of the gut mucosa
• Nausea and vomiting
• Malabsorption, lactose maldigestion, and impaired growth

Surgical Complications

• Intestinal obstruction and perforation are the most common.
• Biliary and pancreatic obstruction, hepatic abscess, appendicitis, peritonitis
• Wandering adult worms may be found in abnormal sites like the pleural cavity, heart, ear, nose, lachrymal duct, or reproductive tract.

Biology and Transmission

• Inhabit the lumen of the small intestine, with a lifespan of 10-20 months.
• Transmission is primarily hand-to-mouth but may also be through ingestion of contaminated raw fruits and vegetables.
• The worm produces 200,000 eggs per day.
• <5000 EPG is light infection, 5000-50000 EPG is moderate, and >50000 EPG is heavy infection.
• Activities of insects like house flies, bees, cockroaches, and ants help sustain the infectivity of the worms.
• Dust also plays a role in the dispersal of the ova, which can be airborne as well as food-borne.
• Poorly treated human fecal manures (used as fertilizers) in agricultural farms
• Rainfall carries the ova to streams and other water bodies

Ascaris lumbricoides

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Ascaris lumbricoides

Life cycle and transmission of ascaris

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Life cycle and transmission of ascaris

Diagnosis

• Eosinophilia of Loeffler’s syndrome
• Direct fecal smear with quantification of worms and by Kato thick smear method
• Abdominal X-rays: calcifications, shadows
• Barium enema: demonstrates worm as linear filling defects, either singly or in groups

Hookworm Infection

Lifecycle

• Eggs are passed in feces and develop into infective larvae in the appropriate soil.
• The infective larvae penetrate the skin and migrate through the lungs to reach the small intestine, similar to Strongyloides.
• The eggs may also be ingested.
• The larvae molt twice to develop into sexually mature male and female worms.
• Can remain in the intestine for 1-5 years by attaching to the mucosa and submucosa of the small intestine.
• A. duodenale produces more eggs (30,000 eggs/24 hrs) than N. americanus (10,000 eggs/24 hrs).
• Note: Transmission of Ascaris, Trichuris, and Enterobius is largely by ingestion of the ova, while that of hookworm and Strongyloides is by penetration of the skin by the larvae, often when walking barefoot.

Clinical Features

• Pruritic erythematous papules which may lead to vesiculation and edema, known as "ground itch."
• Eosinophilia occurs.
• Abdominal pain, anorexia, indigestion, failure to thrive, diarrhea, and melena.
• A constant feature is anemia (iron deficiency).
• Hypoalbuminemia (from blood and lymph loss, and loss of protein in stool).
• Chlorosis (yellow-green pallor from chronic hookworm disease).
• Cough and pharyngitis can occur when the worms pass through the lungs, causing laryngotracheobronchitis.
• Infection intensity:
  • Light infection (< 4000 EPG)
  • Moderate infection (4000-80,000 EPG)
  • Heavy infection (> 80,000 EPG)

Diagnosis

• Fecal smear: Requires prompt examination as the ova disappear within 1 hour.
• Kato thick smear
• Species identification:
  • N. americanus
  • A. duodenale

Hookworm

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Hookworm

Trichuris trichiuria: Trichuriasis

Lifecycle

• Larvae mature in the upper segment of the small intestine to adult worms, penetrate the villi, and move down to reside in the cecum and ascending colon.
• Produce 5000-20,000 eggs per day.
• Light infection: 1000-10,000 eggs per gram; heavy infection: >10,000 EPG.
• No migratory phase in the lungs.

Clinical Features

• Can be asymptomatic.
• Vague abdominal pain and distension.
• Heavy infection may cause anemia, bloody diarrhea with tenesmus, especially in undernourished children, rectal prolapse, or volvulus.
• Poor growth and cognitive deficits.
• Shigellosis may occur.
• No significant eosinophilia.

Diagnosis

• Stool smear reveals the characteristic eggs.

Trichuris trichiuria

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Trichuris trichiuria

Enterobiasis

Enterobiasis, caused by the intestinal nematode Enterobius vermicularis (pinworm), is a common parasitic infection, especially in children.

Clinical Presentation:

• Nocturnal Anal Pruritus: The primary symptom is itching around the anus, which is often most intense at night. This discomfort is caused by the female worms laying eggs in the perianal region.
• Sleeplessness: The itching can lead to disturbed sleep due to discomfort.

Associated Effects:

• Low IQ and Slight Growth Retardation: These effects may arise from the psychological stress and sleep disturbances associated with the infection, rather than direct physiological impact.

Perianal Granuloma:

• Granulomas: Rarely observed, these may contain live or dead worms. They are not a common finding in most cases of enterobiasis.

Enterobiasis is typically diagnosed through the detection of eggs on perianal skin using the "tape test" and can be effectively treated with antiparasitic medications such as mebendazole or albendazole.

Pinworms

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Pinworms

Taeniasis is an intestinal infection caused by tapeworms of the genus Taenia. The two primary species responsible for taeniasis are Taenia saginata (beef tapeworm) and Taenia solium (pork tapeworm).

Clinical Presentation:

• Asymptomatic: Many individuals are asymptomatic or experience mild symptoms.
• Gastrointestinal Symptoms: When symptoms occur, they may include abdominal pain, nausea, diarrhea, or weight loss.
• Proglottid Passage: Segments of the tapeworm, known as proglottids, may be visible in the stool.

Diagnosis:

• Stool Examination: Identification of eggs or proglottids in stool samples using microscopy.
• Serological Tests: May be used for diagnosis in certain cases, particularly for Taenia solium.

Treatment:

• Antiparasitic Medications: The treatment of choice includes praziquantel or albendazole, which effectively eliminate the tapeworm from the intestine.

Prevention:

• Food Safety: Proper cooking of beef and pork to kill tapeworm larvae and practicing good hygiene can prevent infection.

Note: While taeniasis is generally limited to the intestines, Taenia solium can cause cysticercosis if larvae migrate to tissues outside the intestine, leading to serious complications.

Tapeworm

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Tapeworm

Fluke worm infestation refers to infections caused by trematodes, commonly known as flukes. These parasitic worms can affect various organs, including the liver, lungs, and intestines.

Common Types of Fluke Worms:

• Liver Flukes: Fasciola hepatica (common liver fluke) and Clonorchis sinensis (Chinese liver fluke).
• Lung Flukes: Paragonimus westermani (oriental lung fluke).
• Intestinal Flukes: Fasciolopsis buski (giant intestinal fluke).

Clinical Presentation:

• Liver Fluke Infestation: Symptoms may include abdominal pain, jaundice, hepatomegaly, and fever. Chronic infection can lead to liver damage and fibrosis.
• Lung Fluke Infestation: Symptoms may include cough, chest pain, and hemoptysis. Chronic cases can cause pulmonary symptoms similar to tuberculosis.
• Intestinal Fluke Infestation: Symptoms include abdominal pain, diarrhea, and malabsorption.

Diagnosis:

• Stool Examination: Identification of eggs or adult flukes in stool samples.
• Imaging: Ultrasound, CT scans, or MRI may be used to detect fluke-induced damage in the liver or other organs.
• Serological Tests: Can help diagnose specific fluke infections.

Treatment:

• Antiparasitic Medications: Praziquantel and triclabendazole are commonly used to treat fluke infestations. The choice of medication depends on the specific type of fluke and the infection site.

Prevention:

• Sanitation and Hygiene: Ensuring proper sanitation and avoiding consumption of raw or undercooked aquatic plants and animals can help prevent fluke infections.

This can be achieved by applying the five levels of prevention.

1. General Protection

• Health Education: Promoting awareness and knowledge about the prevention of helminth infections.
• Sanitary Practices:
  • Hand-washing before eating or handling food.
  • Vegetables and fruits should be washed thoroughly.
  • Efficient sewage disposal system:
    • Avoid unhygienic and indiscriminate defecation or dumping excreta at refuse depots.
    • Untreated sewage should not be used as fertilizer.

2. Specific Protection

• Integration of worm control into already established health-care programs, such as family planning schemes. This control can also be used to introduce communities to Primary Health Care, where they can become both the managers and clients. Examples of such programs include:
  • Construction of pit latrines and improved neighborhood sanitation.
  • Wearing shoes when in contact with soil to protect against Strongyloides and hookworm infestation.
  • Genetically engineered hookworm antigen for vaccination (currently in progress for hookworm prevention).
  • Chemotherapy schemes for control in the community:
    • Mass chemotherapy for everybody who comes for treatment (population-based).
    • Selective chemotherapy for patients predisposed to large worm burdens.

Targeted for preschool and school-age children (groups). Helminth control using chemotherapy can be introduced at relatively low cost into established health care programs.

Prevention and Control

This can be achieved by applying the five levels of prevention.

1. General Protection

• Health Education: Promoting awareness and knowledge about the prevention of helminth infections.
• Sanitary Practices:
  • Hand-washing before eating or handling food.
  • Vegetables and fruits should be washed thoroughly.
  • Efficient sewage disposal system:
    • Avoid unhygienic and indiscriminate defecation or dumping excreta at refuse depots.
    • Untreated sewage should not be used as fertilizer.

2. Specific Protection

• Integration of worm control into already established health-care programs, such as family planning schemes. This control can also be used to introduce communities to Primary Health Care, where they can become both the managers and clients. Examples of such programs include:
  • Construction of pit latrines and improved neighborhood sanitation.
  • Wearing shoes when in contact with soil to protect against Strongyloides and hookworm infestation.
  • Genetically engineered hookworm antigen for vaccination (currently in progress for hookworm prevention).
  • Chemotherapy schemes for control in the community:
    • Mass chemotherapy for everybody who comes for treatment (population-based).
    • Selective chemotherapy for patients predisposed to large worm burdens.

3. Early Diagnosis and Prompt Treatment

• Patients presenting with infection should be promptly diagnosed and treated by doctors and health workers. Due to the high rate of re-infection, chemotherapy may need to be repeated at three to six-month intervals. The feasibility and cost of such a regimen should be evaluated before widespread implementation.
• Repeated treatments are necessary for institutionalized children to prevent enterobiasis.
• Individuals who will be given immunosuppressive drugs before organ transplantation or cancer chemotherapy should be screened for Strongyloides stercoralis and treated before immunosuppression is induced.

4. Limitation of Disability

• Iron Supplementation: Use iron supplementation for individuals with learning disabilities and intellectual impairment due to iron deficiency anemia.
• Psychosocial Therapy: Provide psychosocial therapy for those with pruritus ani.

5. Rehabilitation

• Nutritional Rehabilitation: Offer nutritional rehabilitation for those with poor growth.
• Educational Support: Provide educational support for individuals affected by adverse effects on cognitive development.