Brandy Kragness & Kerbe Norberg Hookworm Infection Kerbe Brandy Kragness & Kerbe Norberg

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

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 Kerbe

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 Brandy

Ancylostoma duodenale cutting plates with two large teeth fused

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

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

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.

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

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

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

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

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

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

References http://www.cdc.gov/ncidod/dpd/parasites/hookworm/fact sht_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.