Family Toxocaridae

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Family Toxocaridae

• Toxocara canis (dog) and Toxocara cati (cat)
  common parasite of domestic dogs and cats and can
  be parasites of humans.
• Nearly 100 of puppies and kittens infected.
  98 puppies
• Adults able to repress worms. When females
  become pregnant, the worm is awaken and migrates
  to the offspring.

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Family Toxocaridae

• If unnatural host (small child) becomes infected,
  worms have a tendency to migrate throughout
  organs. This is known as visceral larval
  migrans.
• Can be a very important parasite depending upon
  which organs it migrates into.

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Family Toxocaridae

• Every child needs a puppy! Or does it?
• If you have a pet, it is your responsible to see
  that it gets proper treatment.
• Get it wormed and properly dispose of feces.
• Blanco

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Family Oxyuridae Pinworms

• Commonly called pinworms because female adults
  have long sharp pointed tail
• Very common, cosmopolitan worms, that do not have
  socio-economic barriers.
• Also have large esophageal bulb that helps in
  identification.

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Family Oxyuridae Pinworms

• Commonly called pinworms because female adults
  have long sharp pointed tail
• Very common, cosmopolitan worms, that do not have
  socio-economic barriers.
• Also have large esophageal bulb that helps in
  identification.

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Family Oxyuridae Pinworms

• Enterobius vermicularis
• Small worms of colon area.
• Females leave anus at night to lay eggs (contain
  embryonic juveniles. Severe rectal itching
  results.
• Children often reinfect themselves.
• If the anal folds are not cleaned, the worms may
  hatch and the larvae reenter the anus causing
  retroinfection.

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Family Oxyuridae Pinworms

• Epidemiology bedding, clothing, stuffed
  animals, become seeded with ova. Very light can
  be carried in the air.
• Children often scratch where it itches, then
  insert fingers in mouth.
• Footed pajamas, mittens, wash with very hot
  water, treat the whole family.

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Family Oxyuridae Pinworms

• Pathology often asymptomatic.
• Scratching can lead to secondary bacterial
  infections
• In females if worms hatch, they may enter vagina,
  uterus
• Other symptoms include nervousness,
  irritability, loss of sleep, nightmares, loss of
  appetite, bed wetting, grinding of teeth.

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Family Oxyuridae Pinworms

• Diagnosis and treatment
• Diagnosis is most easily performed by tongue
  blade technique
• Mebendazole (vermox) is the drug of choice.
  Usually entire family treated.

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Order Spirurata

• Parasites of all classes of vertebrates
• Usually have an arthropod intermediate host
• Very common in wild animals that include insects
  in diet.
• Just a few examples will be mentioned.

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Order Spirurata

• Gnarthostoma spingerum
• First described in tiger, found in may other
  vertebrate hosts. Eggs passed out in water,
  eaten by cyclop, cyclop eaten by fish frog (as
  many as 35 different paratenic hosts (see fig
  28.5, page 442). In humans can cause cutaneous
  larval migrans or creeping eruption. Rarely can
  invade brain and be fatal.

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Order Spirurata Spirocerca lupi

• Spirocerca lupi
• Bright pink to red worms that live in clusters in
  upper portion of esophagus
• Most common in hound dogs (see fig 28.10, page
  445.
• Dung beetles serve as intermediate hosts

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Order Spirurata Spirocerca lupi

• Pathology
• Hemorrhage from stomach mucosa,
• Leasions in aorta and other organs often leading
  to death
• Spondylosis fusion of vertebrae
• Hypertrophic pulmonary osteoarthropathy
  inflamed and enlarged joints
• Neoplasmic granulomas cancer formation.

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Order Filariata the Filarial Worms - Chapter 29

• Tissue dwelling worms
• All have intermediate host usually arthropod
• Most of little or no economic importance but 4 of
  major importance to man.

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Filarial Worms Wucheria bancrofti

• Causes disease known as Bancroftian filariasis or
  elephantiasis. Fig 29-2, page 449.
• Biology
• Adults live in major lymphatic ducts of humans
• Juveniles called microfilaria
• Major complication result of blockage of lymph
  capillaries causing build up of fluids in tissues.

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Filarial Worms Wucheria bancrofti

• Microfilaria often display a periodicity in which
  the microfilaria are only found circulating in
  the blood during specific times. Usually
  associated with the time of insect feeding
  vectors (at least 77 species of mosquitoes can be
  vectors).
• Microfilaria ingested by feeding mosquitoes, on
  to new host.

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Filarial Worms Wucheria bancrofti

• Pathology 3 phases
• Incubation between infection and presence of
  microfilaria
• Acute inflammatory stage mature female begins
  releasing microfilaria. Allergic
• Obstructive phase microfilaria block lymphatic
  vessels causing fluid to accumulate in the
  tissues. (scrotum, legs, breasts, etc.)
• Chylura is accumulation of lymph in the urine.

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Filarial Worms Wucheria bancrofti

• Prevention protection from infected mosquitoes
  (screening, netting, insect repellents, insect
  destruction)
• Treatment
• Chemotherapy
• Surgical removal of elephantoid tissue
• Pressure dressings

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Filarial Worms Onchocerca volvulus

• Causes a disease known as river blindness in
  parts of Africa and a few limited areas in South
  America.
• In some communities in Africa, almost all of the
  elder members are blind as a result of this
  organism
• Over 30 million people infected.

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Filarial Worms Onchocerca volvulus

• Disease called river blindness because the people
  are always located near flowing rivers.
• Vector is black fly of genus Simulium. The
  larvae of these develop in fast flowing water.
• Humans infected by bite of vector injecting
  filariaform larvae into person.

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Filarial Worms Onchocerca volvulus

• Main symptoms include
• Fibrous nodule adult worms become encapsulated
  under skin (pgs. 452-456).
• Hanging groin
• Severe dermititis
• Depigmentation
• Dwarfism damage to pituitary gland
• River blindness damage to eye

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Filarial Worms Onchocerca volvulus

• Diagnosis and Treatment
• Best diagnosis is done by skin snips. Small bit
  of skin (buttock preferred site) is cut off and
  placed in saline. If microfilaria are observed
  this solidifies diagnosis.
• Microfilaria in blood
• Treatment chemotherapy with ivermectin
• Prevention prevent is by elimination of vectors

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Filarial Worms - Loa loa

• Eye worm of Africa produces loaisis or fugitive
  or Calabar swellings
• Primarily found in rain forest area of West
  Africa
• Adults live in subcutaneous tissues of of back
  chest, axilla, groin and eyes.
• Can attack brain and cause death
• Vector is deer fly of genus Chrysops.

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Filarial Worms Dirofilaria immitis

• Dog heartworm
• Common in this area
• Transmitted by mosquitos
• Dogs given prophylactic doses of ivermectin or
  milbemycin once a month.

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Occurs in areas shown in red, maybe in yellow,
not in blue
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Camallanidae Guinea Worms

• Dracuncullus medinensis
• Known from ancient times (read page 462)
• Females are large (up to 800 mm) while males are
  only 40 mm.
• Ovoviviparous with young developing within the
  mothers uterus.
• Adult worm migrates close to the skin and
  ruptures releasing young under skin.

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Camallanidae Guinea Worms

• Dracuncullus medinensis
• Blister forms when blister ruptures, it releases
  the juveniles usually in water.
• Juvenile eaten by crustacean (cyclops)
• Definitive host becomes infected by ingesting
  infected cyclop.
• After elaborate migration, adults end up in the
  axillary and groin areas where sexual
  reproduction occurs.

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Camallanidae Guinea Worms

• Dracuncullus medinensis
• Male dies shortly after mating.
• Usually between 10-14 months after this the
  female migrates to skin to repeat cycle.

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Camallanidae Guinea Worms

• Dracuncullus medinensis
• Pathology
• When adult worm ruptures there is often severe
  allergic reaction.
• Blister rupture is often site of secondary
  bacterial infection
• If worm migrates to CNS may cause paralyaia
• Worm can be in joint causing arthritis

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Camallanidae Guinea Worms

• Dracuncullus medinensis
• Epidemiology
• Life cycle highly dependent upon water
• Parasite of some very arid and dry regions. Why?
• Must have concentration of people and water.
  People step down in step wells, blister ruptures,
  cyclops become infected, people ingest cyclops.

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Camallanidae Guinea Worms

• Dracuncullus medinensis
• Diagnosis
• Blisters with juveniles
• Worm begins to emerge wind out on stick
• Proper maintenance is best prevention.

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