The below mentioned article provides a short note on Class Nematoda, Strongyloides Stercoralis (Thread Worm).
Morphology of Class Nematoda, Strongyloides Stercoralis (Thread Worm):
The cylindrical muscular oesophagus (Fig. 109.9) of the parasitic female (109.10, 11) occupies the anterior third of the body, whereas the intestine fills up the posterior two-third. The anus opens mid-ventrally. The parasitic males are similar to the free living males (Fig. 109.12) and have two spicules (sp.) and a gubernaculum (Fig. 109.13).
Life cycle of Class Nematoda, Strongyloides Stercoralis (Thread Worm):
When man walks barefoot on soil contaminated with eggs (Fig. 109.14) of S. stercoralis containing filariform larvae. These filariform larvae (Fig. 109.16, 17, 18) penetrate directly through the skin enter into the circulation and break out of pulmonary capillaries into the alveoli, then migrate to the bronchi, trachea, larynx and epiglottis.
They are swallowed and reenter the intestine. They develop into parasite females and males. The females penetrate the intestinal mucosa and begin to deposit eggs.
Clinical Features of Class Nematoda, Strongyloides Stercoralis (Thread Worm):
There will be petechial haemorrhage at the site of entry of larvae followed by intense pruritus, congestion, oedema and urticarial rash. There will be bronchopneumonia with consolidation of the lobules. Frequent coughing, pleural effusion and pyothorax are the symptoms.
Three types of enteritis may occur:
(a) Catarrhal enteritis;
(b) Oedematous enteritis; and
(c) Ulcerative enteritis.
There is accompanying diarrhoea with mucus and blood which may be very painful. Laboratory diagnosis is by the recovery of active rhabditiform larva (Fig. 109.15) from the stool, sputum, duodenal washing. Serology is not quite satisfactory. Direct smear (cheapest), modified Baermann techniques agar plate culture (costly) method can be used.
Treatment of Class Nematoda, Strongyloides Stercoralis (Thread Worm):
Thiabendazole, mebendazole and the current albendazole are drugs of choice.
Prophylaxis:
(1) The human body must be protected from infective soil and from contaminated faeces;
(2) Constipation should be avoided by use of cathartics;
(3) Careful cleaning of hands.