Worms – pinworm, hookworm, roundworm, whipworm

Pin Worm

Thread worm/pinworm/Entrobius vermicularis

• commonest of the human helminthes affecting mainly children.

•  
• Infestation is due to
  • ingestion of food
  • drinks contaminated with the eggs of the parasite
  • infested fingers
• The eggs mature in the rectum where after two weeks the eggs hatch and the female migrates out of the anus especially at night to lay more and more eggs .
• During its migration, it causes intense itching, where by scratching the eggs may be carried under the nails or on the finger to cause a common way for re-infection.
• Methods of Infestation
  • Ingestion of the nematode eggs, most commonly carried by finger nails contaminated during scratching the anal area.
  • Infested dust, in which eggs may survive for up to 13 days.
• Clinical Features
  • Skin manifestations
  • Skin excoriation and urticarial lesions.
  • Nocturnal pruritus: anal , vaginal and perineal itching at night which may be severe causing sleep disturbances and irritability.
  • Perineal intertrigo, secondarily infection and nocturia due to severe itching vulvar irritation and mucoid discharge.
• General manifestations
  • irritability
  • insomnia
  • enuresis
  • Peritonitis and salpingitis are rare complications
• Diagnosis
  • Peri-anal itching and the detection of worms in the stool are diagnostic.
  • Scotch tape is fixed on the peri-anal area better in the morning then removed and mounted on a glass slide and examined by the low power microscope may show the ova of the worm.
• Treatment
  • General measures
    • General hygiene – the children should be instructed to wash their hands thoroughly after using the toilet and before eating.
    • Keeping the nails shortly cut.
    • General hygiene for the bed linen, toilets and houses to eradicate the ova. Changing the underwear and bed linens. Boiling of suspected clothes and linens at least during treatment.
    • The bedroom vacuum is cleaned especially if the floor is covered with carpets.
  • Specific treatment
    • Mebendazole 100 mg (child 10 kg or less: 50 mg) orally, as a single dose OR
    • Pyrantel (adult and child) 10 mg/kg up to 1 g orally, as a single dose OR
    • Albendazole 400 mg (child 10 kg or less: 200 mg) orally, as a single dose.
  • Antihistamine syrup may be needed to relieve severe distressing itching
  • Topical steroid cream can be used if itching is severe and persistent

 

Care at home:

You can talk to a pharmacist about over-the-counter treatment options. Drugs such as pyrantel (Combantrin) or mebendazole (Banworm) are very safe and often recommended. Follow the instructions on the packet, bearing in mind special precautions may be given for children under two years of age and for pregnant women.

• Treat all the family members at the same time, even if they aren’t showing any symptoms. Adults can also get threadworm.
• If possible, your child should have a shower on the night they have the medicine, and again the next morning to remove the eggs laid during the night.

Unfortunately, repeat threadworm infection is very common. To help reduce this and to prevent the threadworms from spreading to others, you can take the following precautions:

• Despite the itching, encourage your child not to scratch their bottom. If they must scratch, make sure it is over their underpants and not directly on their skin.
• Keep your child’s fingernails clean and trimmed. Try to stop your child from biting their nails or sucking their thumb.
• Have your child wash their hands and under their nails thoroughly after going to the toilet.
• Wash your child’s bedding, towels and toys in hot water.
• Vacuum your floor often to remove any eggs. 
• Clean surfaces in your house that your children may touch, in particular door handles.
• Discourage your child from eating food that has fallen on the floor.

 

 

 

ANCYLOSTOMIASIS (Hookworm Disease)

 

• The adult worms live in the jejunum with the head firmly attached to the mucosa and cause bleeding.
• Bleeding leads to
  • anemia
  • hypoproteinemia
  • digestive disturbances
  • retarded development.
• Thousands of eggs are passed in the feces, which can resist dryness.
• Under favorable conditions of warmth and humidity, eggs are hatched into motile rhabditiform larvae. A
• fter 5 days and further they molt into infective filariform larvae.
• They migrate upwards through soil and grass, and after a period of contact with human skin, the larvae penetrate the skin.
• Walking barefoot is the commonest method of infection.
• Favorable places for transmission include soil around houses such as plantations, cultivated fields, and mines.

• Clinical Manifestation
  • After penetrating the skin, larvae migrate within a day or two via the blood stream to the lungs, pass up the bronchial tree where they are swallowed and pass down to the esophagus, reaching the duodenum and jejunum. These mature in 4-6 weeks.
  • In passing through the lungs they cause acute alveolitis or pneumonitis.

• Diagnosis can be reached by:
  • Clinical manifestations
  • Pneumonitis seen radiologically (characterized Leoffler‘s syndrome).
  • Eosinophilia
  • Diagnosis can be confirmed by detection of the characteristic eggs in the feces.
• Treatment
  • Ground itch is treated symptomatically, with an antipruritic cream such as crotamiton and 1% hydrocortisone.
  • Oral antihistamines.
  • Pulmonary symptoms, if severe, respond to corticosteroids.
  • Oral iron is given for iron deficiency anemia
  • Albendazole 400 mg (child 10 kg or less: 200 mg) orally, as a single dose OR
  • Mebendazole 100 mg (child 10 kg or less: 50 mg) orally, 12-hourly for 3 days OR
  • Pyrantel (adult and child) 10 mg/kg up to 1 g orally, daily for 3 days.

 

 

AMOEBIASIS

• Amoebiasis is a very common disease caused by Entemeba histolytica
• The disease is endemic in all warm and temperate parts of the world with low standard of living and low sanitary conditions .
• The prognosis is serious in neglected case particularly in infants.
•  
• Clinical Manifestations:
  • Amoebic dysentery
    • this is due to invasion of the trophozoites to the mucosa of the large intestine .
  • Metastatic lesions
    • these are blood born due to escape of amoebae from the bowel to blood stream causing metastatic abscesses particularly in the liver.
  • Skin lesions:
    • begin as deep abscesses, which rupture and form ulcerations with distinct raised , cord-like and thickened edges , surrounded by an erythematous halo .
    • The base of the ulcer is covered with necrotic tissue and hemopurulent pus in which amoebae are present.
    • Cutaneous Amoebiasis
      • when invasive amoebae escape from the bowel to skin mainly on the trunk, abdomen, external genitalia and buttocks.
      • Cutaneous Amoebiasis can spread very rapidly and may terminate fatally, so early diagnosis and treatment is important.
      • A solitary lesion may be mistaken for an epithelioma, tuberculosis and verrucosa cutis
    • Mucous membrane lesions
      • Mucous membranes may be involved when amoebae are implanted in the mucosa, most commonly that of the vagina, cervix uteri or glans penis and rarely in the mouth
• Diagnosis
  • Fresh smears :
    • Examination of fresh material from the cutaneous lesion regularly discloses amoebae.
    • Material should be taken from the edge of the ulcer avoiding necrotic tissue, and examined at once under the microscope.
    • The demonstration of motile trophozoites containing red blood cells is diagnostic.
  • Serological tests:
    • Are helpful for rapid screening especially in school children.
    • Serial stool examinations should be performed.

Treatment

• Local cleaning of cutaneous ulcers with antiseptic solutions may be necessary.
• Hepatic abscess needs to be drained, this is most safely done by needle aspiration.
• Effective treatment is usually followed by complete healing of the skin lesion without any need for plastic surgery

• Asymptomatic carriage of Entamoeba histolytica
  • Treatment of asymptomatic carriage of Entamoeba histolytica (with a luminal agent only) is recommended to minimise transmission and the risk of developing invasive disease. Use:
    • Paromomycin 500 mg (child: 10 mg/kg up to 500 mg) orally, 8-hourly for 7 days : Paromomycin is not registered for use in Australia but is available via the Special Access Scheme.
• Invasive amoebiasis
  • For acute amoebic colitis (dysentery), use:
    • Tinidazole 2 g (child: 50 mg/kg up to 2 g) orally, daily for 3 days [ If tinidazole dosing is difficult in children, use metronidazole instead, Tinidazole was discontinued in Australia in February 2020.] OR
    • Metronidazole 600 mg (child: 15 mg/kg up to 600 mg) orally, 8-hourly for 7 days.
  • For severe amoebic colitis (eg frequent blood-stained stools, perforation, peritonitis or toxic megacolon), use:
    • Tinidazole 2 g (child: 50 mg/kg up to 2 g) orally, daily for 5 days  OR
    • Metronidazole 800 mg (child: 15 mg/kg up to 800 mg) orally, 8-hourly for 7 days   OR (if the patient is unable to tolerate oral therapy)
    • Metronidazole 750 mg (child: 15 mg/kg up to 750 mg) intravenously, 8-hourly for 7 days