Mcq and answers

• Helminths


  Parasitic worms that can infect humans
• Types of intestinal nematodes

  • Hookworms
  • Nematodes that survive as eggs in soil
• Ancylostomiasis (hookworm)

  A leading cause of anaemia in the tropics, caused by Ancylostoma duodenale and Necator americanus
• Hookworm life cycle

  1. Passage from soil through skin via bloodstream to lungs

  2. Ascent of bronchi and swallowing

  3. Adult worm inhabits duodenum and jejunum

  4. Eggs passed in faeces, develop to infective stage in soil
• Clinical features of hookworm infection

  • Cutaneous: allergic dermatitis
  • Pulmonary: paroxysmal cough, blood-stained sputum
  • GI: vomiting, epigastric pain, diarrhoea
  • Systemic: symptoms of anaemia
• Investigations for hookworm

  • Stool sample: ova
  • Fecal Occult Blood (FOB) testing
  • Full Blood Count: eosinophilia

  
• Albendazole

  Treatment of choice for hookworm
• Mebendazole

  Alternative treatment for hookworm
• Ascaris lumbricoides (roundworm)

  Pale yellow nematode 20-35cm long, causes up to 35% of intestinal obstructions in tropics
• Ascaris life cycle

  1. Ingestion of mature ova

  2. Larvae hatch in duodenum, migrate through lungs, ascend bronchial tree, swallowed and mature in small intestine
• Clinical features of ascariasis

  • GI: abdominal pain, obstructive complications, intussusception, volvulus, haemorrhagic infarction and perforation
  • Hepatobiliary: blockage of bile or pancreatic duct
  • Generalised hypersensitivity: pneumonitis, bronchial asthma, urticaria
• Investigations for ascariasis

  • Stool sample: adult worms, ova
  • FBC: eosinophilia
  • Barium studies: may demonstrate worms
• Albendazole

  Effective single-dose treatment for ascariasis
• Alternative treatments for ascariasis

  • Pyrantel pamoate
  • Ivermectin
  • Mebendazole
• Enterobius vermicularis (threadworm)

  Common helminthic infection, especially in children
• Threadworm life cycle

  1. Ova swallowed

  2. Worms develop in small intestine

  3. Adult females lay eggs around anus, causing itching, leading to autoinfection
• Clinical features of threadworm

  • Intense itch in perianal or genital area
• Investigations for threadworm

  • Ova collected on adhesive tape from perianal area
• Mebendazole, albendazole, piperazine

  Treatments for threadworm, with repeat dosing after 2 weeks
• General hygiene measures help prevent spread of threadworm
• Lymphatic filariasis

  Caused by Wuchereria bancrofti and Brugia malayi, with different geographic distributions
• Clinical features of acute lymphatic filariasis

  • Filarial lymphangitis: fever, pain, tenderness, erythema along lymphatic vessels
  • Inflammation of spermatic cord, epididymitis, orchitis
• Clinical features of chronic lymphatic filariasis

  • Persistent oedema, regional lymphadenopathy
  • Progressive enlargement, coarsening, corrugation and fissuring of skin and subcutaneous tissue (elephantiasis)
  • Chyluria and chylous effusions
• Tropical pulmonary eosinophilia

  Allergic response when filariae enter pulmonary capillaries, presenting with cough, wheeze and fever
• Investigations for lymphatic filariasis

  • FBC: massive eosinophilia
  • Indirect immunofluorescence and ELISA: filarial antibodies
  • Wet blood film: microfilariae at night
  • Radiology: calcified filariae
• Diethylcarbamazine (DEC)

  Kills microfilariae and adult filarial worms
• Severe allergic response may occur in first 24-36 hours of DEC therapy, proportional to filarial load</b>
• Schistosomiasis

  Major cause of morbidity in the tropics, spread by irrigation schemes
• Schistosoma species causing human disease

  • S. haematobium
  • S. mansoni
  • S. japonicum
  • S. mekongi
  • S. intercalatum
• Investigations for S. haematobium

  • Dipstick urine testing: blood and albumin
  • Microscopy of centrifuged urine: eggs
  • USS: bladder wall thickening, hydronephrosis, bladder calcification
  • Cystoscopy: 'sandy' patches, bleeding mucosa, distortion
• Investigations for S. mansoni and S. japonicum

  • Stool microscopy: characteristic eggs
  • Rectal biopsy: schistosomes
  • Sigmoidoscopy: inflammation or bleeding
• Praziquantel

  Drug of choice for schistosomiasis, 80% parasitological cure
• The multiple response format in MCQs allows students to select more than one correct answer from a list of options.
• Pancreatic enzymes are produced by the exocrine cells of the pancreas and play an important role in digestion.