Hookworm

• Ancylostoma duodenale common name is old world hookworm
• Geographical distribution of A. duodenale - Europe, Asia, becoming worldwide
• pathogenesis of A. duodenale - lesions of intestinal mucosa, anemia, eosinophilia, pneumonitis, erythema, dyspnea
• habitat of A. duodenale - small intestine
• reservoir host of A. duodenale - dogs, cats, lions, hogs, tigers, and gorillas
• infective form of A. duodenale - penetration of the skin
• specimen of choice of A. duodenale - feces
• cross infection of human and dogs are possible for A. duodenale
• eggs gain nutrition from host feces and feed on blood from the host's intestine
• heavy infections of A. duodenale can led to fatalities fue to infection, malaria, excess blood loss, and other complications
• hookworm disease is more prevalent in females than in males
• morphology of A. duodenale

  • shape - s-shaped
  • color - pinkish-white color
  • Females - vulva located 1/3 of body length
  • Males and Females both have two powerful ventral teeth
• Necator americanus common name is new world hookworm
• N. americanus is a nematode with a cylindrical body and a cuticle with three outer layers
• N. americanus are distinguishable from A. duodenale
• N. americanus have 4 larval stage

  1. eggs
  2. Rhabditiform larvae
  3. filariform larvae
  4. Adult
• • mortality rate of N. americanus is around 0.005%
  • morbidity rate is 12%
• morphology of N. americanus

  • adult females - 9 mm - 11 mm
  • males - 7 mm - 9 mm
  • adults have 2 pairs of cutting plates in their mouth
• males of N. americanus have spicules on the bursa
• • copulatory bursa - Male
  • paired copulatory spicules - fused with a terminal barb
  • small paired dorsal rays - bipartite
• N. americanus can be differentiated with A. duodenale during their adult stage specifically in comparison of their Buccal structures
• 1. N. americanus has cutting plates
  2. duodenale has 2 sets of teeth
• Ancylostoma duonenale is more pathogenic
• • Ancylostoma duodenale - has 4 hook like teeth on ventral surface & 2 knob - like teeth on dorsal surface
  • Necator americanus - has 4 chitinous plates (2 each on vental & dorsal surfaces)
• Ova

  • shape - oval with a blunty rounded ends
  • color - hyaline
  • operculum - absent
  • content - yolk mass incleavage (larva)
  • shell wall - thin, single layer
• intestinal hookworm are asymptomatic, causing abdominal pain, nausea, and anorexia
• iron deficiency may occur due to blood loss at the site of intestinal attachment
• eggs are passed in stool image, hatching in 1 - 2 days. After 5 - 10 days, larvae become filariform (infective). After contact with human, larvae penetrate the skin, reach heart and lungs, ascend bronchial tree to the pharynx, and swallow.
• adult worms live in small intestine lumen, attach to intestinal wall and live for several years
• Some larvae can beccome dormant, reactivating and establishing infections. Infection may occur via oral and transmammary route.
• • Ancylostoma ceylanicum - emerging parasite infecting humans in some regions (found among cats)
  • Ancylostoma caninum - can cause eosinophilic enteritis in humans, but does not reach reproductive maturity

  
  

  • Ancylostoma braziliense, Ancylostoma caninum, Uncinaria stenocephala - canine larva migrans can penetrate human skin
• characteristics of hookworm

  1. Necator Americanus - semi lunar cutting plate
  2. Ancylostoma duodenale - 2 pair of teeth
  3. Ancylostoma braziliense - 2 pair of teeth
  4. Ancylostoma caninum - 3 pairs of teeth