Capillaria

• Capillaria philippinensis


  A zoonotic disease that primarily affects animals but humans eventually become infected

  
• Capillaria philippinensis


  • One of the four species of Capillaria that affects humans
  • First discovered in the Philippines, hence the name
  • Habitat: Small Intestine

  
• Natural hosts


  Fish-Eating birds
• First infection reported by Chitwood et al. in a 29 year old in Northern Luzon


  1963
• Epidemic in Pudoc West, Tagudin, Ilocos Sur with over 1000 cases and 77 deaths


  1966
• Cause of 1966 epidemic: Washing of fecally contaminated bed sheets in lagoons in Tagudin
• Mystery disease in Monkayo, Compostela Valley province leading to death of villagers due to misdiagnosis


  1988
• The med techs there found an organism that look like T. trichiura and they diagnosed and treat them under such assumptions, with mebendazole for 3 days. C. philippinensis requires 20 days treatment
• Male adult


  1.5 - 3.9 mm long with one unspine spicule
• Female adult


  2.3 - 5.3 mm long with vulva located at the junction of anterior and middle thirds
• Esophagus


  Rows of secretory cells called Stichocytes, entire esophagus is Stichosome
• Ova


  Size: 36 - 45 um by 20 um, Peanut-shaped with striated shell and flattened bipolar plugs, Passed in feces as unembryonated egg, Embryonation: Soil or water
• Life Cycle of Capillaria philippinensis

  1. Embryonated eggs hatch in the intestines of fish to become infective larvae

  2. Ingestion of raw or undercooked contaminated fish

  3. Infective stage: Encysted larva in freshwater fished

  4. First generation female worms produce larvae to build up the population (larviparous)

  5. Subsequent generations of female worms predominantly produce eggs (oviparous), few produce both eggs and larvae

  6. There is hyperinfection and autoinfection

  
• Pathogenesis and Clinical Manifestations


  • Flattening of villi
  • Abdominal pain and borborygmi
  • Chronic diarrhea: 8 - 10 voluminous stools per day
  • Protein losing enteropathy, electrolyte imbalance, intestinal malabsorption
  • Malabsorption is due to micro-ulcers in the intestinal epithelium as well as due to the mechanical compression of intestinal cells leading to cellular degradation
  • Weight loss, malaise, anorexia, vomiting, edema
  • Potentially fatal
• Clinical diagnosis is difficult as it may be negative even on the first and second attempts, but positive on the third
• Laboratory diagnosis


  • Demonstration of Ova in direct fecal smear or wet mount, stool concentration technique
  • Larva and adult worms may be seen in the feces
  • Enzyme-Linked Immunosorbent Assay (ELISA)
  • Immunoblot assay
• If C. philippinensis is diagnoses as T. trichiura, the course of treatment prescribed would be different which can possible kill the patient

  
• Treatment


  • Drug of choice: Mebendazole 200 mg BID x 20 days
  • Alternative: Albendazole 400 mg OD x 10 days
  • Relapse may occur if treatment regimen is not followed and completed
  • Adjunctive treatment: Electrolyte replacement, High protein diet
• Prevention and Control


  • Improvement of sanitation and health educational programs
  • Prevent indiscriminate disposal of human waste
  • Discourage eating raw or undercooked fish
  • Capacity building for health personnel for early and accurate diagnosis
• Typically, unembryonated, thick-shelled eggs are passed in the human stool and become embryonated in the external environment in 5-10 days; after ingestion by freshwater fish, larvae hatch, penetrate the intestine, and migrate to the tissues

  
• Ingestion of raw or undercooked fish results in infection of the human host

  
• The adults of Capillaria philippinensis are very small (males: 2.3 to 3.2mm; females: 2.5 to 4.3 mm) and reside in the human small intestine, where they burrow in the mucosa
• In addition to the unembryonated, shelled eggs which pass into the environment, the females can also produce eggs lacking shells (possessing only a vitelline membrane), which become embryonated within the female's uterus or in the intestine
• The released larvae can re-invade the intestinal mucosa and cause internal autoinfection, which may lead to hyperinfection (a massive number of adult worms)