PARASITIC NEMATODES
KAGIRA JM
,PARASITIC NEMATODES:
• Generally light cream-white colored
• Life cycle includes: egg, larvae & adult
• Divided into:
Intestinal nematodes
Intestinal nematodes with tissue stage
• Ascaris lumbricoides
• Hookworms
• Strongyloides stercoralis
Intestinal nematodes without tissue stage
• Enterobius vermicularis
• Trichuris trichuira
Tissue and blood dwelling nematodes
• Filarial worms
• Dracunculus medinensis
• Trichinella
• Larva migrans
,NEMATODES WITH TISSUE STAGE
ASCARIS LUMBRICOIDES (roundworm)
• Superfamily: Ascaridoidea
Geographical distribution
• One of the most common & widespread human infections
• Infects 1.2 billion people & causes 12 million cases of acute illness, 10 000 deaths
annually
• Shares similar global distribution with T. trichiura
Morphology:
Adult:
• Male - 15-20 cm, posterior end curved ventrally
• Female - 20-40 cm & posterior end is straight
• Both: pale brown with whitish longitudinal lines & round tapering ends
• Mouth has 3 lips with finely denticulated ridges
• Genital tubules - 27 million eggs, the average daily output being 200 000 eggs
• Adult life span of 10–12 months
Egg
• Elliptical encased in a rough albuminous coat- mamillated appearance
• Stained by faecal pigments
, Infective stage and modes of infection:
• Egg containing L2 - ingested with contaminated raw vegetables, soil ...
Life cycle: Migratory
• Ingested eggs (L2) hatch in the duodenum
• Larvae penetrate the intestinal wall & circulate in the blood
• From the heart they migrate to the lungs, ascend to the trachea, descend
to the esophagus and finally reach the small intestine to become adult
• Female pass immature eggs which pass to the soil and mature in 2 weeks
• Larva devps within the egg
• IP = 60-70 days
KAGIRA JM
,PARASITIC NEMATODES:
• Generally light cream-white colored
• Life cycle includes: egg, larvae & adult
• Divided into:
Intestinal nematodes
Intestinal nematodes with tissue stage
• Ascaris lumbricoides
• Hookworms
• Strongyloides stercoralis
Intestinal nematodes without tissue stage
• Enterobius vermicularis
• Trichuris trichuira
Tissue and blood dwelling nematodes
• Filarial worms
• Dracunculus medinensis
• Trichinella
• Larva migrans
,NEMATODES WITH TISSUE STAGE
ASCARIS LUMBRICOIDES (roundworm)
• Superfamily: Ascaridoidea
Geographical distribution
• One of the most common & widespread human infections
• Infects 1.2 billion people & causes 12 million cases of acute illness, 10 000 deaths
annually
• Shares similar global distribution with T. trichiura
Morphology:
Adult:
• Male - 15-20 cm, posterior end curved ventrally
• Female - 20-40 cm & posterior end is straight
• Both: pale brown with whitish longitudinal lines & round tapering ends
• Mouth has 3 lips with finely denticulated ridges
• Genital tubules - 27 million eggs, the average daily output being 200 000 eggs
• Adult life span of 10–12 months
Egg
• Elliptical encased in a rough albuminous coat- mamillated appearance
• Stained by faecal pigments
, Infective stage and modes of infection:
• Egg containing L2 - ingested with contaminated raw vegetables, soil ...
Life cycle: Migratory
• Ingested eggs (L2) hatch in the duodenum
• Larvae penetrate the intestinal wall & circulate in the blood
• From the heart they migrate to the lungs, ascend to the trachea, descend
to the esophagus and finally reach the small intestine to become adult
• Female pass immature eggs which pass to the soil and mature in 2 weeks
• Larva devps within the egg
• IP = 60-70 days
