Necator americanus is a species of human hookworm that is the predominant cause of hookworm infection in the Philippines and was historically responsible for cases of "laziness" in the southern United States. It is a slender worm up to 11mm long that lives in the small intestine. It has a buccal capsule with cutting plates and secretes anticoagulants. Females lay thousands of eggs daily that are passed in feces and can cause anemia if in large numbers. Diagnosis involves finding eggs in feces or larvae after preservation. It is treated with a single dose of albendazole or mebendazole.

1. Necator americanus

2. AMERICAN HOOKWORM
AMERICAN MURDERER
NEW WORLD HOOKWORM
Necator americanus
Synonym

3. NECATORIASIS
UNCINARIASIS
Necator americanus
Disease

4. Necator americanus
Historical Notes
Predominant human hookworm in the Philippines
Agent in the production of “laziness” in poor white
population in the Southern USA;
“Tropical Anemia” of Puerto Rico and tropical areas in
Western hemisphere

5. Necator americanus
Morphology
Adult Worm
• Attenuated anterior end w/ a buccal capsule
• Ventral and dorsal pair of semilunar cutting
plates
• Strongly flexed dorsal ward the anterior end

6. Necator americanus
Morphology
Adult Worm
• Amphidial (secretes anticoagulant), excretory
and esophageal glands for exodigestive function
• Grayish yellow at times reddish

7. Necator americanus
Morphology
Adult Male Worm
• 7-9mm long
• Long and wide bursa

8. Necator americanus
Morphology
Adult Male Worm
• Bipartite dorsal ray
• Long, slender and fused (forming delicate barb)
copulatory spicules

9. Necator americanus
Morphology
Adult Female Worm
• 9-11mm long
• Vulva is situated either in middle or somewhat
anterior

10. Necator americanus
Morphology
Eggs
• Resembles those of Ancylostoma duodenale
• Longer and more elongated than A.duodenale
• Daily egg output is 9,000 eggs

11. Necator americanus
Morphology
Diagnosis
• Subnormal level of hemoglobin with hookworm
eggs in the feces (Hookworm disease)
• Egg number estimation (Egg count)

12. Necator americanus
Morphology
Diagnosis
• Presence of Charcot Leyden crystals in the feces
(heavy infection : prepatent period)
• 24 hour fecal specimen preservation at room
temp for egg hatching to hookworm larvae

13. Necator americanus
Morphology
Treatment
• Single dose of Benzimidazole antihelminthic
• Such as
Albendazole or Mebendazole

14. Necator americanus
STORYANG BUTBOT
A. duodenale N. americanus
Strong Weak
Larger and thicker Smaller and more slender
Stunted Children Growth and Mental
Retardation
(I Have Enough Power)
Iron-deficiency anemia, Hypothermia,
Eosinophilia, Protein Malnutrition
Classic Hookworm Disease
6 Ventral Cutting Teeth 4 Ventral Cutting Plate
No Lung Migration Requires Lung Migration
Tripartite Dorsal Ray Bipartite Dorsal Ray
Present Spine Absent Spine
Anterior end bends in same direction Anterior end bends in opposite direction