PARASITOLOGY

• Parasitology


  A science that deals with organisms that takes up their abodes
• Parasites


  An organism that lives on or in a host organism and gets its food from or at the expense of its host
• Host


  Where parasite depends for survival, harbouring species, a living organism that acts as a harbour for invading pathogenic organisms
• Types of Parasites


  • Nemanthelminthes (roundworm)
  • Platyhelminthes (flatworm)
  • Protozoa
• Effects of Parasites on the Host

  • Pathogenic
  • Non-pathogenic
• Types of Association of Living Organisms

  • Symbiosis
  • Mutualism
  • Commensalism
  • Parasitism
• Special Types of Parasites

  • Ectoparasites
  • Endoparasites
  • Incidental Parasites
  • Temporary Parasites
  • Permanent Parasites
• Types of Host


  • Difinitive Host (Final host)
  • Intermediate Host
  • Paratenic Host
  • Dead-end Host
  • Reservoir Host
• Major Methods of Transmission of Parasites to Man

  • Thru Digestive System
  • Thru Skin
  • Thru Reproductive System
  • Thru Respiratory Tract
  • Thru Placenta
  • Contact with Animals
• Entry of Parasites (Infective Stage)

  • Oral
  • Skin
  • Sexual Intimacy
  • Intranasal
• Exit of Parasites (Diagnostic Stage)

  • Urine
  • Stool
  • Sputum
  • Blood
  • Tissue Biopsy
  • Tissue Aspirate
  • Orifice Swab
• Methods of Parasites Control

  • Reduction of the sources of infection in human beings by drug treatment or therapeutic measures
  • Sanitary control of water, food, living and working conditions and waste disposal
  • Insecticide spraying
  • Meat inspection
  • Public education in personal prophylaxis to prevent dissemination of infection
• Nemanthelminthes (roundworm)


  • Females larger than males and have a straight tail
  • Males have a curved tail with spicule used for copulation
  • Unsegmented
  • Round, elongated from a few millimeters in length
  • Complete digestive tract (mouth to anus)
  • Have separate sexes
  • Found in intestine, blood and tissue
• Classification of Nematodes


  • Presence/Absence of Caudal Receptors (phasmid nematodes and aphasmid nematodes)
  • Habitat (intestinal nematodes and extraintestinal nematodes)
  • Infective Stage of Intestinal and Extraintestinal Nematodes
• Nematodes (Groundworm)


  • Ascaris Lumbricoides
  • Enterobius Vermicularis
  • Trichuris Trichiura
  • Strongyloides Stercoralis
  • Necator Americanus
  • Ancylostoma Doudenale
  • Ancylostoma Brazilienze
  • Ancylostoma Caninum
  • Trichenella Spiralis
  • Capillaria Philippinensis
  • Wucheriria Bancrofti
  • Brugia Malayi
  • Loa-loa
  • Onchocerca Volvulus
  • Dipetalonema Perstan
  • Manzonella Ozzandi
• Ascaris Lumbricoides


  Largest nematodes, no intermediate host needed, smooth, finely striated cuticle, conical anterior and posterior extremities and the terminal mouth has 3 oval lips with sensory papillae
• Ascaris Lumbricoides Eggs


  The eggs measure 45 – 70 u, there is an outer coarsely mamillated, the egg proper has a thick, transparent, hyaline shell, the typical fertile eggs measure 88 – 94 u x 39 – 44 u, have a thinner shell with an irregular coating of albumin
• Pathology and Symptomology of Ascaris Lumbricoides

  • Larval Migration
  • Intestinal Obstruction
  • Causes pneumonia, cough, fever, eosinophilia during larva migration
• Loeffler's Syndrome


  A disease in which a certain type of white blood cells (eosinophils) accumulates in the lungs in response to a parasitic infection
• Diagnosis of Ascaris Lumbricoides


  Depend on the identity of worm or eggs, stool examination for seeing the adult worm or egg
• Treatment of Ascaris Lumbricoides


  Piperazine Citrate, an anti-helminitic medication that kills the worms
• Life Cycle of Ascaris Lumbricoides


  1. Adult worms lays eggs in small intestine, passes out undeveloped eggs through feces

  2. Embryonated egg developed in 3 weeks in moist, warm and shaded soil

  3. Embryonated egg will hatch in small intestine

  4. Larva will release from the eggs and begins with larva migration in intestinal wall, blood vessels, liver, blood vessel, lungs, alveoli, small intestine and mature to adults
• Enterobius Vermicularis


  Male and female possess an alae cephalic expansion, alae with longitudinal cuticular ridges which aid in identification, adults are provided with cephalic alae expansion, prominent esophageal bulb and pointed tail, adult female is small 8 – 13 mm, male is smaller 2 – 5 mm, ivory white in color, body resembles question mark
• Life Cycle of Enterobius Vermicularis

  1. Adults worm inhabit in colon

  2. Gravid female migrates in perianal skin to deposit embryonated eggs

  3. Embryonated egg lifespan is 4-6hrs (infective stage)

  4. Egg ingested or inhaled and the egg hatches in small intestine

  5. Infection of the same person by hand to mouth transmission (scratching perianal areas)

  6. Eggs inhaled from airborne dust

  7. Retroinfection to the anus

  8. Largest number of eggs found in the bedroom
• Diagnosis of Enterobius Vermicularis

  Done by demonstrating eggs on scotch tape slide or cellophane anal swab taken from the peri-anal skin in the morning on waking, the egg resembles letter D, eggs should not find in a fecal specimen unless it encounters the peri-anal skin
• Trichuris Trichiura


  Whipworm, highest incidence is found in the regions of heavy rainfall, subtropical climate, and highly polluted soil
• Trichuris Trichiura Eggs


  Lemon shaped with plug-like translucent polar prominences, barrel shaped, Japanese lantern
• Trichuris Trichiura life cycle

  1. Egg ingested or inhaled

  2. Egg hatches in small intestine

  3. Infection of same person via hand to mouth transmission (scratching perianal areas)

  4. Inhalation of airborne eggs in dust

  5. Retroinfection to the anus

  6. Largest number of eggs found in the bedroom (Dormitory worm)
• Trichuris Trichiura is the most common helminth infection worldwide
• Trichuris Trichiura diagnosis


  1. Demonstrate eggs on scotch tape slide or cellophane anal swab taken from the perianal skin in the morning on waking

  2. Egg resembles letter D

  3. Eggs should not be found in a fecal specimen unless it encounters the perianal skin
• Trichuris Trichiura


  Also known as Whipworm
• Trichuris Trichiura has the highest incidence in regions of heavy rainfall, subtropical climate, and highly polluted soil
• Trichuris Trichiura eggs


  • Lemon shaped with plug-like translucent polar prominences
  • Barrel shaped, Japanese lantern egg, football shape, golden brown in color
• Trichuris Trichiura adult worm

  • Has a parallel prevalence of Ascaris
  • Adult posterior end is very thin and attenuated whip like structure
  • More robust posterior
• Trichuris Trichiura male


  • 30-45 mm long, thin anterior end, posteriorly straight
• Trichuris Trichiura female


  • 35-55 mm long, posterior end is curved/coiled
• Heavy chronic Trichuris infections present frequent, small, blood streaked diarrheal stool, abdominal pain and tenderness, anemia, and rectal prolapse
• Trichuris Trichiura


  Referred to as the whipworm because it looks like a whip with wide handles at the posterior end
• Trichuris Trichiura treatment


  1. Sanitary and disposal of human feces

  2. Instruction of children for sanitation

  3. Not washing the vegetables
• Strongyloides Stercoralis


  Also known as Threadworm