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HOOKWORM INFECTION
Brandy Kragness & Kerbe Norberg
Geographical Range
Necator americanus Sub Saharan Africa
Southeast Asia China
Indonesia the Americas
Ancylostoma duodenale Middle East North Africa
India
Morphology
Necator americanus “New World Hookworm” Pair of dorsal and ventral cutting plates surrounding the
buccal cavity Also have subdorsal and subventral teeth near the rear of the
buccal cavity Males:
7-9 mm long Copulatory Bursa with needle-like spicules forming a distal hook
Females: 9-11 mm long Vulva located in middle of body Produce 5,000-10,000 eggs per day (Life Span = 5 Years!) Eggs: 65-75 μm by 36-40 μm, thin shelled
Necator americanus
dorsal and ventral cutting plates
Morphology
Ancylostoma duodenale “Old World Hookworm” Two ventral cutting plates with two large teeth fused
at their base A pair of small teeth are located in the capsule as well
Males: 8-11 mm long Copulatory Bursa with needle-like spicules that are NOT
fused distally Females:
10-13 mm long Vulva located about 1/3 of the body length from the
posterior end Produce 10,000-30,000 eggs per day (Life Span= 1 year) Eggs: 56-60 μm by 35-40 μm, thin shelled
Ancylostoma duodenale
cutting plates with two large teeth fused
Transmission
Ancylostoma duodenale Fecal Oral Route Penetration of filariform
larvae upon human skin Transplacentally and
through mother’s milk Necator americanus
Penetration of filariform larvae upon human skin
Hosts
Definitive Host Humans (Children more commonly than
adults)
Paratenic Host A. duodenale can be transmitted through
ingestion of undercooked meat (rabbit, pork, beef, lamb)
Pigs can serve as a transport host for N. americanus
Other Forms
Ancylostoma caninum dogs, fox intestinal
Ancylostoma braziliense canines, felines Cutaneous larval migrans
Humans act as accidental hosts for both species
Pathogenesis
Cutaneous Phase: Occurs when the juvenile penetrates
human skin Ground Itch (“Creeping Eruption”)
Pulmonary Phase: Occurs when juveniles break out of lung
capillaries and into the throat Usually asymptomatic Dry coughing or sore throat may occur Pneumonitis (Rare)
Pathogenesis
Intestinal Phase: Occurs when worms reach the small
intestine and attach themselves Iron deficiency anemia:
N. americanus can suck approximately 0.03 L of blood per day (1000 worms)
A. duodenale can suck approximately 0.26 L of blood per day (100 worms)
Abdominal Pain Loss of normal appetite Cognitive Impairments
Diagnosis
Eggs or Worms in Feces Must use concentration
technique Differentiating between
N. americanus & A. duodenale: Use PCR-RFLP method
Treatment & Prevention
Treatment: Mebendazole- Drug of choice
Removes both species of Hookworm Single dose therapy is efficient and cheap
Prevention: Education Persuasion of sanitary disposal of feces (use of
latrines) Avoid using nightsoil for fertilization Mass Drug Administration (Distributing
Benzimidazole Anthelmintic Drugs)
Public Health Concern
Approximately 22.1 million DALY’s (Daily Adjusted Life Years) have been lost due to Hookworm Infection
Research: Vaccines currently being clinically tested for
targeting: Larval worm stage Adult worm stage
References
http://www.cdc.gov/ncidod/dpd/parasites/hookworm/factsht_hookworm.htm
https://health.google.com/health/ref/Creeping+eruption
Roberts, Larry S. and Jr. John Janovy. Foundations of Parisitology. 8th Edition. November 30th, 2008.