Blood & tissue nematodes

• Trichinella spiralis


  Largest intracellular parasite
• T. Spiralis Juvenile invasion


  1. Invade a muscle cell

  2. Convert it into a nurse cell
• Nurse cell

  • Secretes collagen coating
• Trichinella Spiralis host

  • swine
  • rats,
  • humans,
  • bear,
  • walrus,
  • other carnivores.
• Geographic distribution: cosmopolitan. More common in temperate areas than tropics
• T. Spiralis location:

  • adults in wall of small intestine
  • Juvenile instrained muscles and organs
• Trichinella spiralis Life Cycle


  1. Adults inside intestinal mucosa

  2. Female release juvenile

  3. Juvenile migrates to striated muscles

  4. Enter muscle cells

  5. Turns into nurse cell

  6. Ineffective in 4-8 wks

  7. Juvenile swallowed

  8. Reach small intestine

  9. Penetrates intestinal mucosa

  10. Four molts
• T. Spiralis transmission


  Ingestion of juvenile in under cooked meat
• T.Spiralis Initial phase: flu-like symptoms

  • Caused by females penetrating mucosa
• As T.spiralis worms mature, symptoms may include nausea, vomiting, sweating and diarrhea for five to seven days ( Body’s reaction to worm waste)
• T.spiralis symptoms

  • pneumonia,
  • pleurisy,
  • encephalitis,
  • meningitis,
  • nephritis,
  • deafness,
  • peritonitis, brain and eye damage
  • , muscle stiffness,
  • weak pulse
  • difficulty breathing
  • hallucinations
• T.spiralis death is rare

  Usually due to inflammation of heart muscle, respiratory complications or kidney malfunction
• T.spiralis Diagnosis:

  • antigenic and serological tests,
  • muscle biopsy plus case history
• T.spiralis has no effective treatment
• T.spiralis Prevention: cook meat well
• T.spiralis Larvae ( 125 um in Length x 7 um in width), many are

  encysted found in striated muscle tissue
• T.spiralis Adults range up to 1mm in length and reside in the intestinal tract
• T.spiralis Laboratory test reveals, leukocytosis, eosinophilia and

  increase in Creatine Kinase (CK) and Lactate Dehydrogenase (LDH
• D.Medinensis Causative agent of dracunculosis (Medina or Guinea
• Male Dracunculus medinensis worms are 1–4cm long, the females measure 50– 100cm in body length
• D.Medinensis life cycle

  • Female moves to just under the skin
  • Create blisters which ruptures the skin
  • Female release J1 into water when definitive host puts blister in the water
  • J1 eaten by copepod
  • Penetrate hemocoel
  • J2
  • J3
  • Copepod ingested by human
  • Mature
  • Mates & males die
• D.medinensis caused three factors

  • Emerging worms causes severe allergic reaction to worm waste
  • Bacterial infections are common at site of emergence
  • Nonemergent “dead” worms can causes inflammatory response
• D. Medinensis prevention

  • Supplying safe drinking water
  • Education about transmission in unclean water
  • Early case containment and keeping infected body parts out of drinking water
  • Vector control- using chemical that kills copepods but had very little effect on other animals
• FILARIAL PARASITES

  • Nematodes consisting of adult threadlike worms which inhabit the circulatory and lymphatic system, found also in muscles, connective tissue and serous cavities
• FILARIAL PARASITES

  Primary species that infect humans:

  • W.bancrofti ,
  • B.malayi,
  • Loaloa
  • O.volvulus
• Filarial parasites Diagnosis:

  examination of blood or tissue for Microfilariae, some species migrate at day time, others migrate at night (nocturnal periodicity)
• Filarial parasites Blood sample is best collected between 10:00 A.M. and noon (morning) and between 10:00 PM and midnight (evening
• WUCHERERIA BANCROFTI


  mosquito-borne tissue nematodes found lymphatics of humans
• W.BANCROFTI


  endemic in Bicol, Samar-Leyte, Mountain province, Quezon and all provinces in Mindanao
• W. Bancrofti

  Male (2-4 cm length) Female (8-10 cm length
• W. Bancrofti mosquito vectors

  • Anopheles minimus flavirostris,
  • Aedes poecilus
  • genus Culex,
  • genus Mansonia (Brugia malayi)
• Wuchereria bancrofti life cycle

  • Adults in lymph channel
  • Female release microfilaria
  • Microfilaria are swept into blood
  • Microfilaria in peripheral blood at night
  • Mosquito pick up microfilaria in blood meal
  • J1, J2, J3
  • Move to proboscis
  • Injected with blood meal
  • Molt & migrate to lymph vessels
• 3 phases of filariasis

  • Asymptomatic phase
  • Inflammatory acute phase
  • Obstructive phase
• Large number of microfilaria in blood. Some have swelling of lymph nodes


  Asymptomatic phase of filariasis
•  Attacks are marked by sudden onset of fever, chills, rigors, sweating, swollen, warm skin over lymph nodes, painful lymph nodes. May also show orchitis (swelling of testes) and epididymitis


  Inflammatory (acute) phase of filariasis
• W. Bancrofti Pathology

  • Lymphatic filariasis; chronic > edema >fibroblastic hyperplasia > encapsulation of parasite causing obstruction> elephantiasis
  • Hydrocele (male) Lymphedema of vulva (female)
  • Tropical pulmonary eosinophilia
  • Chyluria
• W. Bancrofti treatment

  Ivermectin prevents infection (Cheaper and fewer side effects)
• W. Bancrofti treatments

  Hetrazan or DEC (diethylcarbamazine) used to kill adults

  • Nasty side effects
  • Repeated treatment needed
• W. Bancrofti prevention

  • Avoid mosquito bites at night
  • Annual or semiannual doses of DEC (diethylcarbamazine) and ivemectin
• Life cycle of loa-loa

  • Adults under the skin
  • Female release microfilaria
  • , microfilaria to bloodstream
  • Deer fly pick up microfilaria in tissue fluids
  • Goes to fat body
  • J1, J2, J3
  • Moves to proboscis
  • Enters wound made by fly
  • Molt