1. Brandy Kragness & Kerbe Norberg
Hookworm Infection
Kerbe
Brandy Kragness & Kerbe Norberg

2. Ancylostoma duodenale
Geographical Range
Necator americanus
Sub Saharan Africa
Southeast Asia
China
Indonesia
the Americas
Ancylostoma duodenale
Middle East
North Africa
India
Brandy

3. 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: μm by μm, thin shelled
Kerbe

4. Necator americanus
dorsal and ventral cutting plates

5. 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: μm by μm, thin shelled
Brandy

6. Ancylostoma duodenale
cutting plates with two large teeth fused

7. Transmission Ancylostoma duodenale Necator americanus Fecal Oral Route
Penetration of filariform larvae upon human skin
Transplacentally and through mother’s milk
Necator americanus
Kerbe

8. Hosts Definitive Host Paratenic 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
Brandy

9. 1. Eggs are passed in the stool and under favorable conditions (moisture, warmth, shade), larvae hatch in 1 to 2 days. 
2. The released rhabditiform larvae grow in the feces and/or the soil , and after 5 to 10 days (and two molts)
3. they become filariform (third-stage) larvae that are infective .  These infective larvae can survive 3 to 4 weeks in favorable environmental conditions.
4. On contact with the human host, the larvae penetrate the skin and are carried through the blood vessels to the heart and then to the lungs.  They penetrate into the pulmonary alveoli, ascend the bronchial tree to the pharynx, and are swallowed .  The larvae reach the small intestine, where they reside and mature into adults.  Adult worms live in the lumen of the small intestine, where they attach to the intestinal wall with resultant blood loss by the host .  Most adult worms are eliminated in 1 to 2 years, but the longevity may reach several years.
Some A. duodenale larvae, following penetration of the host skin, can become dormant (in the intestine or muscle).  In addition, infection by A. duodenale may probably also occur by the oral and transmammary route.  N. americanus, however, requires a transpulmonary migration phase.

10. Other Forms Ancylostoma caninum Ancylostoma braziliense
dogs, fox
intestinal
Ancylostoma braziliense
canines, felines
Cutaneous larval migrans
Humans act as accidental hosts for both species
Brandy

11. Pathogenesis Cutaneous Phase: Pulmonary 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)
Kerbe

12. 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
Brandy

13. Diagnosis Eggs or Worms in Feces
Must use concentration technique
Differentiating between N. americanus & A. duodenale:
Use PCR-RFLP method
Why differentiate?
N. americanus has drug sensitivity to Ivermectin, A. duodenale does not have senstitivity
Kerbe

14. Treatment & Prevention
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)
Brandy

15. 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
Kerbe

16. References
sht_hookworm.htm
Roberts, Larry S. and Jr. John Janovy. Foundations of Parisitology. 8th Edition. November 30th, 2008.