Worm Infestations (Helminthiasis)

(a) Causes of Worm Infestations

1. Nematodes (Roundworms) - most common group

2. Cestodes (Tapeworms)

3. Trematodes (Flukes)

Predisposing/Risk Factors

• Poor personal hygiene - not washing hands before eating or after defecation
• Open defecation and lack of proper sanitation/latrine facilities
• Using night soil (human feces) as fertilizer on vegetable gardens
• Eating raw or undercooked meat/fish
• Walking barefoot on contaminated soil
• Drinking contaminated water
• Overcrowding and poor socioeconomic conditions
• Low literacy and lack of health education
• Tropical/subtropical climate - warm, moist soil favors egg and larval survival

(b) Clinical Manifestations of Worm Infestation

General / Systemic Features

• Malnutrition and growth retardation - worms compete for host nutrients; especially in children
• Anemia (iron deficiency) - particularly severe with hookworm (blood-sucking worms cause 0.03-0.15 mL blood loss per worm per day)
• Vitamin B12 deficiency - with fish tapeworm (Diphyllobothrium latum) competing for cobalamin-intrinsic factor complex
• Weight loss and weakness
• Eosinophilia (raised eosinophil count on blood film) - a hallmark of helminth infections
• Fatigue and pallor due to anaemia

Gastrointestinal Manifestations

• Abdominal pain and discomfort - colicky or vague
• Nausea and vomiting
• Diarrhea (may be bloody in whipworm - Trichuris)
• Rectal prolapse - in heavy whipworm infection in children
• Bowel obstruction - mass of roundworms can cause mechanical obstruction
• Biliary obstruction / biliary colic - Ascaris can migrate into the bile duct
• Hepatic abscess - from migrating Ascaris
• Appendicitis - Ascaris entering the appendix
• Perianal itching (pruritus ani) - characteristic of pinworm (Enterobius); worse at night when female worms migrate to lay eggs around the anus

Pulmonary Manifestations (Larval Migration - Löffler's Syndrome)

• Cough, wheeze, and breathlessness during larval migration through lungs (Ascaris, hookworm)
• Transient pulmonary infiltrates on chest X-ray
• Haemoptysis (rare)
• Tropical pulmonary eosinophilia - nocturnal asthma in lymphatic filariasis

Cutaneous / Dermatological Manifestations

• Pruritic (itchy) skin rash at site of larval entry (hookworm, Strongyloides)
• Creeping eruption (Cutaneous Larva Migrans) - erythematous, serpiginous, tracking skin lesions caused by Ancylostoma braziliense larvae migrating under the skin; intense pruritus, sleeplessness
• Urticaria and allergic skin reactions

Lymphatic / Systemic Manifestations (Filariasis)

• Recurrent "filarial fevers" - bouts of fever with lymphangitis lasting 2-3 weeks
• Lymphadenopathy and lymphedema
• Elephantiasis - gross swelling of limbs, scrotum, breasts from chronic lymphatic damage
• Retrograde lymphangitis

Neurological Manifestations

• Neurocysticercosis - seizures, headache, focal neurological deficits when Taenia solium larvae (cysticerci) lodge in the brain
• Hydrocephalus (in severe neurocysticercosis)

Urinary Manifestations

• Haematuria (blood in urine) - pathognomonic of urinary schistosomiasis (Schistosoma haematobium)

Ocular Manifestations

• Subconjunctival worms visible in the eye (e.g., Loa loa)

(c) Preventive Measures of Worm Infestation

1. Personal Hygiene

• Thorough handwashing with soap and water before eating, after using the toilet, and after handling soil
• Keeping fingernails short and clean (especially in children) to prevent egg accumulation under nails
• Avoid nail-biting
• Bathing regularly

2. Food Safety

• Thoroughly cook meat and fish before eating (kills tapeworm larvae and Ascaris eggs)
• Wash fruits and vegetables thoroughly before eating, especially those grown with organic/human fertilizer
• Drink safe, treated water - boil or filter water in endemic areas
• Avoid eating raw or undercooked pork, beef, or fish
• Avoid street food in high-risk endemic areas

3. Environmental Sanitation

• Proper construction and use of latrines/toilets - preventing open defecation is the single most effective measure for soil-transmitted helminths
• Safe disposal of human excreta - do not use untreated night soil (human feces) as crop fertilizer
• Proper sewage treatment
• Clean water supply - provision of safe piped water
• Wearing footwear (shoes/sandals) when walking outdoors, especially on soil in endemic areas - prevents hookworm and Strongyloides skin penetration

4. Chemoprophylaxis / Mass Drug Administration (MDA)

• Periodic deworming programmes - WHO recommends regular anthelmintic treatment (albendazole 400 mg or mebendazole 500 mg once or twice yearly) for school-age children and high-risk groups in endemic areas
• Treating infected individuals promptly reduces environmental contamination
• Pre-travel prophylaxis for travelers to endemic regions

5. Vector Control (for Filariasis)

• Mosquito control - eliminating breeding sites, insecticide spraying
• Use of insecticide-treated bed nets
• Protective clothing to prevent mosquito bites
• Repellents (DEET)

6. Health Education

• Educating communities - especially in rural and low-income settings - about:
  • Transmission routes
  • Importance of hygiene and sanitation
  • Safe food preparation
  • Regular deworming of children

7. Veterinary Measures

• Regular deworming of pet animals (dogs, cats) to reduce environmental contamination
• Meat inspection at slaughterhouses to detect and condemn cysticercus-infected carcasses (Taenia)
• Control of stray dogs to reduce Echinococcus (hydatid disease) transmission

• (a) Causes: 2 marks - cover the main organisms and routes of entry
• (b) Clinical manifestations: 8 marks - cover all organ systems (GI, pulmonary, skin, lymphatic, neurological, general)
• (c) Preventive measures: 5 marks - cover hygiene, food safety, sanitation, MDA, and health education