hookworm infection brandy kragness & kerbe norberg

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.