Parasitic Infections

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Schistosomiasis

Description

  • Schistosomiasis is an acute or chronic parasitic disease caused by blood flukes (trematode worms) of the genus Schistosoma.
  • Infection larval forms of the parasite released by freshwater snails penetrate the skin during contact with infested water.

There are 2 major forms of schistosomiasis that are caused by 5 main species of blood fluke:

  • Intestinal: Schistosoma mansoni, Schistosoma japonicum, Schistosoma mekongi and Schistosoma intercalatum
  • Urogenital: Schistosoma

Signs and Symptoms

In the acute infection, mild, maculopapular skin lesions may develop within hours after exposure.

  • Intestinal schistosomiasis
    • Acute: Abdominal pain, diarrhoea, blood in the stool,
    • Chronic: hepatomegaly, splenomegaly ascites, portal, and pulmonary
  • Urogenital Schistosomiasis
    • Acute: Haematuria, dysuria, urinary
    • Chronic: Fibrosis of the bladder and ureter, kidney dysfunction, bladder cancer (later stages).
    • Adolescent girls: genital lesions, vaginal bleeding, dyspaurenia nodules in the
    • Adolescent boys: pathology of the seminal vesicles, prostate, and other

Investigations

  • Stool/Urine M/C/S for blood and Schistosoma
  • FBC, DC-
  • Urea, Electrolytes,
  • Chest x-ray
  • Plain abdominal x rays
  • Abdominal ultrasound
  • Blood culture
  • Rectal Snip

Treatment

  • Praziquantel is the treatment of choice for all forms of Schistosomiasis (children >2 years and adults: 40mg/kg as a single dose). Consider steroid therapy if very severe disease.
  • Adverse effects of praziquantel include dizziness, headache, nausea, vomiting, diarrhea, abdominal discomfort, bloody stool, urticaria, and fever following initiation of These are usually mild and last about 24 hours.
  • Prevention: Praziquantel 40/mg/kg as a single dose.

Taeniasis/Cystercercosis

Description

Intestinal infection with tapeworm acquired from eating raw or not-well cooked food. Causative organisms include; Taenia saginata (beef tapeworm), Taenia solium (pork tapeworm), Diphyllobothrium latum (fish tapeworm) and Hymenolepsis nana (faecal oral contamination from human and dogs) leading to chronic malnutrition (Taeniasis) or infection of tissues with larval parasites (Cysticercosis). The larvae (cysticerci) are most often located in subcutaneous and intramuscular tissue, followed by the eye and brain. The CNS is involved in 60-90% of patients resulting in neurocystercosis.

Signs and Symptoms

Taeniasis

  • Colicky abdominal pain
  • Body Weakness
  • Loss of or increased appetite
  • Constipation or diarrhea
  • Pruritus ani or hyperexcitability

 Neurocystersercosis

  • Seizures
  • Intracranial hypertension: Headache, nausea, vomiting, vertigo, and
  • Personality and mental status changes (Neuropsychiatric changes).
  • Behavioural changes and learning

Investigations

  • Stool M/C/S- Evidence of characteristic ova, proglottides or scolex in the wet mount stool examination
  • Brain CT scan or MRI

NB: Refer the patient to high centers for further investigation and expertise.

Treatment

  • Taeniasis A: Praziquansstel (PO) 5–10mg/kg single
  • Neurocystercercosis: Albendazole 15mg/kg/day for 15 days in 2 divided doses plus corticosteroids- prednisolone 1-2mg/kg/day or dexamethasone
  • Praziquantel 50mg/kg /day for 15 days
  • Surgical removal of cysts depending on site of infection e.g eyes, spine, or subcutaneous tissue.

Albendazole or praziquantel should not be used to treat ocular or spine cysts as resulting inflammation may cause permanent damage.

Further treatment:

  • Anti-epileptic drugs if seizure Carbamazepine, phenobarbitone or sodium valproate. Treatment is recommeded until the patient has been seizure free for 2 years.
  • Osmotic diuretics for Intracranial
  • Ventricle- peritoneal shunt placement for hydrocephalus.