WORM INVESTITION
Intestinal human nematodesThere are two types:1-have a soil stage in which develop into larvae that then penetrate thehost2-in the soil as eggs that have to be ingested for their lifeANCYLOSTOMIASIS (HOOKWORM)
caused by parasitisation of the small intestine with Ancylostoma duodenale or Necator americanus
In the early stages of infection eosinophilia is common
It is one of the main causes of anaemia in the tropics.
The larvae may cause allergic inflammation at the site of entry through the skin
When infection is heavy, the passage through the lungs may cause pulmonary eosinophilia.
withdraw blood from intestine after attachment . The mean daily loss of blood from one A. duodenale is 0.15 ml and from N. americanus 0.03 ml.
Clinical features: Dermatitis at the time of infection. The passage of the larvae through the lungs in a heavy infection causes a paroxysmal cough with blood-stained sputum . When the worms have reached the small intestine, vomiting and epigastric pain . Iron deficiency anaemia, protein-losing enteropathy and hypoproteinaemia may develop in the undernourished. High-output cardiac failure may result from the chronic iron deficiency anaemia. development of children may be retarded. A well-nourished person with a light infection may be asymptomatic.
Investigations
There is eosinophilia
ovum can be recognised in the stool.
when sufficient to cause anaemia, faecal occult blood testing will be positive
Management
single-dose treatment albendazole is the best choice but Mebendazole is preferred. Anaemia associated with hookworm infection responds well to oral iron even when severe; blood transfusion is rarely required
The management of anaemic heart disease is best accomplished by treatment with antihelmintics and iron.
ASCARIS LUMBRICOIDES (ROUNDWORM)
Humans are infected by eating food contaminated with mature ova. The tissue migration until it reach the intestine again from the lung can provoke both local and general hypersensitivity reactions with pneumonitis, eosinophilic granulomas, bronchial asthma and urticaria.
Normally, the adult worms are located in the small intestine. In unusual circumstances, such the worms may migrate to ectopic sites where they may give rise to severe disease.
Clinical features
symptoms ranging from abdominal pain to malnutrition. The large size of the adult worm and its tendency to aggregate and migrate can result in severe obstructive complications.. Obstruction can be complicated further by intussusception, volvulus, haemorrhagic infarction and perforation. Other complications include blockage of the bile or pancreatic duct and obstruction of the appendix by adult worms.Investigations
microscopically by finding ova in the faeces.
Adult worms are frequently expelled rectally or orally.
barium examination.
There is eosinophilia.
Management
Mebendazole , Albendazole or piperazine or ivermectin
Obstruction due to ascariasis should be treated with nasogastric suction, piperazine and intravenous fluids.
Enterobiasis
caused by Enterobius vermicularis infestation.Children are more often involved than adults. It occurs in groups such as families living together .
development takes place in the small intestine, but the adult worms are found chiefly in the colon.
Clinical features
The gravid female worm lays ova around the anus, causing intense itching, especially at night.
In females the genitalia may be involved.
Investigations:
Ova are detected by applying the adhesive surface of cellophane tape to the perianal skin in the morning. This is then examined under the microscope.
A perianal swab, is an alternative method for diagnosis.
Management:
A single dose of mebendazole or albendazole or piperazine is given and may be repeated after 2 weeks to control auto-reinfection.
all nightclothes and bed linen are laundered.
Fingernails must be kept short and hands washed carefully before meals.