Strongyloides stercoralis By: Mahamed Yassin & Zakariya Salah By: Mahamed Yassin & Zakariya Salah

Fun Facts!! Carries 60-85% mortality rate for immunocomprimised patients. Carries 60-85% mortality rate for immunocomprimised patients. Adult females may live up to 5 years and continue the reproductive cycle. Adult females may live up to 5 years and continue the reproductive cycle. Strongyloides is the only helminth to secrete larvae (and not eggs) in feces Strongyloides is the only helminth to secrete larvae (and not eggs) in feces Unlike most parasitic worms, Strongyloides stercoralis has a heterogonic life cycle. Unlike most parasitic worms, Strongyloides stercoralis has a heterogonic life cycle. First described in the nineteenth century in French soldiers returning home from expeditions in IndoChina. First described in the nineteenth century in French soldiers returning home from expeditions in IndoChina.

Taxonomy Kingdom: Animalia Kingdom: Animalia Phylum: Nematoda Phylum: Nematoda Class: Secernentea Class: Secernentea Order: Rhabditida Order: Rhabditida Family: Strongyloididae Family: Strongyloididae Genus: Strongyloides Genus: Strongyloides Species: S. stercoralis Species: S. stercoralis

Morphology (parasitic vs. free- living) Parasitic females can grow up to 2.5mm long with blunt ends and males = 0.9mm. Parasitic females can grow up to 2.5mm long with blunt ends and males = 0.9mm. females filariform esophagus covers 1/3 of body length. Ovary is didelphic and opens at vulva (2/3 of bodies length) females filariform esophagus covers 1/3 of body length. Ovary is didelphic and opens at vulva (2/3 of bodies length) Free living adults approx. 1 mm long. *female slightly larger than male Free living adults approx. 1 mm long. *female slightly larger than male Both sexes have rhabditiform esophagus. Female has didelphic ovary with vulva mid way of body. Both sexes have rhabditiform esophagus. Female has didelphic ovary with vulva mid way of body.

Geographic Range Endemic Tropics and subtropics Endemic Tropics and subtropics Also can occur in temperate climates Also can occur in temperate climates Likes warm moist climates Likes warm moist climates significance significance Africa, Tropical America, Pacific Islands and parts of North America Africa, Tropical America, Pacific Islands and parts of North America Widespread in Eastern Europe and Mediterranean region. Widespread in Eastern Europe and Mediterranean region. *about 1% of world population is infected

Host Definitive host: Humans, dogs,cats Definitive host: Humans, dogs,cats Intermediate Host: None Intermediate Host: None Reservoir Host: Dog, monkey. Reservoir Host: Dog, monkey. Might use other mammals, like the two above. Might use other mammals, like the two above.

Life Cycle

L3 stage penetrates skin L3 stage penetrates skin Enters bloodstream and migrates to pulmonary capillaries Enters bloodstream and migrates to pulmonary capillaries Once in alveoli of lung, it is taken to throat where it is swallowed Once in alveoli of lung, it is taken to throat where it is swallowed Inside small intestine it matures into adult female by molting 2X Inside small intestine it matures into adult female by molting 2X Female undergoes asexual reproduction and lay eggs that will hatch into rhabditiform. Female undergoes asexual reproduction and lay eggs that will hatch into rhabditiform. From there they either exit the body or molt 2X more into filariform. From there they either exit the body or molt 2X more into filariform. Filariform either penetrates intestinal wall or perianal skin, thus starting the infection all over again. Filariform either penetrates intestinal wall or perianal skin, thus starting the infection all over again.

Life Cycle Rhabditiform in the soil either develop into filariform (2X molting) or adults (4X molting). Rhabditiform in the soil either develop into filariform (2X molting) or adults (4X molting). The free-living male and female produce eggs The free-living male and female produce eggs Eggs can either molt into infective filariform or adults Eggs can either molt into infective filariform or adults The adult worms only live through one copulation cycle in the wild. But inside humans (only females there) adults can survive longer. The adult worms only live through one copulation cycle in the wild. But inside humans (only females there) adults can survive longer.

Pathogenesis Acute strongyloidiasis Acute strongyloidiasis Wheezing Wheezing Low-grade fever Low-grade fever Epigastric tenderness Epigastric tenderness Chronic strongyloidiasis Chronic strongyloidiasis Chronic urticaria Chronic urticaria Larva currens Larva currens Severe strongyloidiasis Severe strongyloidiasis Diffuse abdominal tenderness; abdominal distension; hyperactive, hypoactive, or absent bowel sounds; vomiting; hematemesis; and hematochezia Diffuse abdominal tenderness; abdominal distension; hyperactive, hypoactive, or absent bowel sounds; vomiting; hematemesis; and hematochezia Altered mental status and meningismus (if CNS involvement) Altered mental status and meningismus (if CNS involvement) Rash, Cough, respiratory distress, wheezing, hemoptysis, and crackles Rash, Cough, respiratory distress, wheezing, hemoptysis, and crackles Fever, chills Fever, chills

Symptoms Minor infections can be asymptomatic but usually one or more of the following symptoms occur: Minor infections can be asymptomatic but usually one or more of the following symptoms occur: Anemia, cough, constipation, diarrhea, nausea, stomach ach, vomiting, weight loss Anemia, cough, constipation, diarrhea, nausea, stomach ach, vomiting, weight loss Immunosupressed and immunocomprimised patients: DEATH, distension, shock, septicemia, neurological and pulmonary commplications

Treatment and diagnosis stool samples will confirm the presence of this parasite. Other techniques used include direct fecal smears, culturing fecal samples on agar plates, serodiagnosis through ELISA. stool samples will confirm the presence of this parasite. Other techniques used include direct fecal smears, culturing fecal samples on agar plates, serodiagnosis through ELISA. Treatment includes Ivermectin is the drug of first choice for treatment because of higher tolerance in patients. Treatment includes Ivermectin is the drug of first choice for treatment because of higher tolerance in patients. Thiabendazole and Albendazole are also sometimes used. Thiabendazole and Albendazole are also sometimes used.

Control The ideal method would be prevention by improved sanitation (proper disposal of feces), practicing good hygiene (washing of hands), etc.. The ideal method would be prevention by improved sanitation (proper disposal of feces), practicing good hygiene (washing of hands), etc.. Stay away from moist soil, do not work or play with contaminated water/soil. Stay away from moist soil, do not work or play with contaminated water/soil.

References y/Strongyloidiasis_il.htm y/Strongyloidiasis_il.htm y/Strongyloidiasis_il.htm y/Strongyloidiasis_il.htm unts/information/Strongyloides_stercoralis.html unts/information/Strongyloides_stercoralis.html unts/information/Strongyloides_stercoralis.html unts/information/Strongyloides_stercoralis.html overview overview overview overview stercoralis.html stercoralis.html