Today is our topic of discussion Definition of Ascariasis
Definition of Ascariasis
Definition:
Infection of intestinal tract with Ascaris lumbricoides is called ascariasis.
Geographical distribution:
Worldwide in distribution. Most common helminthic infestation.
Reservoir of infection:
Man is the only reservoir.
Infective material:
Facces containing fertilized eggs.
Period of infectivity:
Until all fertile females are destroyed and stool are negative.
Host:
In children –
1. Infection rate is high lugn o
2. Responsible for most dissemination
3. Malnutrition and growth retardation
In adult-
1. Gain some resistance
2. There is high degree of host-parasite tolerance.
Environment:
1. Ascaris is a soil transmitted helminth. Also called ‘Geohelminths’.
2. The eggs remain viable in soil for months to years under favourable conditions.
3. Low temp inhibits, but clay soil favours the growth and development of eggs.
Life cycle:
Eggs excreted in faeces → Undergo development in soil → Embryonated eggs within 2-3 weeks which is infective → Ingestion with contaminated food and drinks →→ Pass to intestine → Eggshell is destroyed and larva comes out → Penetrate the gut wall and carried to liver and then to lungs by blood→ Break through alveolar walls and migrate into bronchioles Coughed up through trachea and swallowed → Mature into adult in intestine in 60-80 days (life span of adult is 6 – 12 months) → Adults discharge eggs.
Human habits:
1. Open air defaecation which contaminates soil.
2. Soil pollution occurs mostly around house due to irregular defaecation habit of children.
3. Children gain Ascaris infection during playing with infected soil.
Fig: A) Ascaris B) lumbricoides & B) expulsion of ‘ascaris worm’ bolus after anti-helminthic therapy
Period of communicability:
until all fertile females are destroyed and stools are negative.
Mode of transmission:
Faccal oral route:
Ingestion of food and drinks contaminated with eggs.
Other methods are:
Contaminated fingers, eating contaminated soil, contaminated dust.
Incubation period:
About two months
Clinical feature:
Due to larva: Ascaris pneumonia/Loeffler’s syndrome:
fever, cough, dyspnoea, urticarial rash with eosinophilia.
Due to adult worm:
1. Spoliative The worm eats the nutrients, proteins & vitamins – causing PEM (Protein malnutrition) especially in children.
2. Toxic-Toxic metabolites of worm are absorbed and allergic manifestation – urticaria, oedema of face.
Energy
3. Mechanical – Intestinal obstruction, intussusception, perforation of ulcer etc.
4. Ectopic – Vomited out & pass to respiratory tract causing blockage of respiratory passage, appendicitis.
Complications:
1. Breathlessness
2. Intestinal obstruction (Ascariatic crisis)
3. Cholestasis, extrahepatic
4. Pancreatitis, acute
5. Short stature
Treatment:
Deworming (contraindicated in pregnancy):
Any of the following drugs are used-
a. Albendazole: 200 under ≤ 6 yrs and 400 mg> 6 yrs and adult
b. Mebendazole: 100 mg twice daily for 3 days irrespective of age.
c. Levamisole: Single oral dose of 2.5mg/kg body wt.(maximum 150 mg)
d. Pyrantel: Single dose of 10mg/kg body wt. Maximum1 gm.
Vitamin A supplementation:
For growth & development of children.
Drug therapy affects only adult worms. Patient is re-evaluated in 3 months and retreated.
Control and preventive measures:
Primary prevention –
1. Sanitary disposal of faeces
2. Provision of safe drinking water
3. Food hygiene habits
4. Health education of community regarding: use of sanitary latrines, personal hygiene, and changing
behavioural patterns.
Secondary prevention:
1. Effective treatment of human reservoir is needed.
2. Mass treatment: Periodic deworming at interval of 2-3 months in highly prevalent area reduce worm load of the community.
[Mechanism of action of antihelminthics: The drugs cause paralysis of the worms which are expelled by
normal intestinal motility]
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