Strongyloides stercoralisStrongyl: cylinder oides: like stercoralis: faecal

In the soil Free-living cycle

Indirect cycle

male female

Mature egg

Hatching rhabditiform

larva

Infective filariform larva

Optimum environmental conditions

Unfavorable environmental conditions

In man Parasitic cycle

Direct cycle4 moults

2 moults

In the soil

Contains rhabditiform

larva

Parasitic Cycle in Man

Venous blood

3rd moult

4th moult♂ ♀

Rhabditiform larvae in stool

On the groundInfective filariform larva

Free-living adult

Duodenum & upper jejunum

Skin lesion

Larva is swallowed Pulmonary

lesion

Intestinal lesion

Diagnostic Stage Infective Stage

Rhabditiform larva Filariform larva

Notched tail

end

Filariform oesophagus

fills anterior ½ of larva

250µ long 500-600µ long

Rhabditiform oesophagus

Pathogenesis and Clinical Picture

due to penetration of larvae into the skin. Itching and dermatitis.

due to migration of larvae.Verminous pneumonitis,

minute haemorrhage.(Loeffler’s syndrome) Fever, cough, dyspnea, haemoptysis

Skin lesion

Lung lesion

Duodenitis causing burning epigastric pain with tenderness.

Diarrhoea alternates with constipation

Constipation gives enough time for rhabditiform larvae to develop into infective filariform larvae

Rhabditiform larvae

Intestinal lesion

Larvae penetrate mucosa of large intestine causing

internal autoinfection

Larvae penetrate perianal skin after coming out of the

anus causing external autoinfection

Larva currens

Larva of S.stercoralis left on skin of buttock or thigh move in the skin at a rate of 5-10 cm / hour causing linear eruption

Long standing heavy infection causes:

Dysentery, malabsorption امتصاص عدمالدهون steatorrhoea ,الغذاء هضم andعدمweight loss

Autoinfection increases worm burden (( عدد كثرة.and leads to persistent infection الديدان

Currens: fast running

Disseminated منتشرة Strongyloidiasis

Venous blood Systemic circulation

Strongyloides: an Opportunistic parasite

Larvae penetrate extra intestinal organs

Occurs more in patients

with impaired immunity

Aorta

Diagnosis

1- Examination of faeces or duodenal contents for larvae.

2- Examination of sputum for larvae.

3- Eosinophilia.4- Serological tests.

Treatment Thiabendazole OR Ivermectin

Prevention and Control

As in Ancylostoma

250µ

Question

Autoinfection : an infected person re-infects himself by the same

parasite either externally (hand to mouth) or internally.

Enumerate helminths transmitted by autoinfection. Enterobius vermicularis Strongyloides stercoralis Hymenolepis nana Taenia solium eggs

Name one that is transmitted through skin penetration. Strongyloides stercoralis.Name one that is common among children. Enterobius vermicularis Hymenolepis nana

Prepared by :

1- Mohamed Fathy Helmy2- Mohamed Nabil Badawy3- Mohammd Metwelly4- Mohamed Mamdouh5-Mohamed M Elkhabaza