Ascariasis lubricoides are nematode that lives in the lumen of small intestine,with male of 15-25 cm and female of 20-40 cm worms.
Each female worm puts thousands of eggs every day,to find exit in faeces.
Infective stage: passed eggs are not infective.They develop outside the body in 2-3 weeks to become embryonated.
Embryonated egg in polluted environment is the infective stage.It is resistant to desiccation and disinfectants and remains viable and infective under favourable environmental conditions for around three months.
Modes of Transmission:
Foodborne and hand to mouth infection (ingestion infection).
1.Foodborne infection: consuming embryonated egg in contaminated food,specially salad vegetables and pollutes water.
2.Hand to mouth infection: when the hand is contaminated with eggs-containing dust.Children are particularl affected,when hands get contaminated on playing in the road and are infected through either:
-putting contaminated fingers in the mouth
-taking food without handwashing.
How ascariasis eggs reach food?
-using fresh human fertilizer for vegetables
-contamination of food with eggs-containing dust (from human excreta)
-flies may have potential.
How ascariasis rech dust?
Through contaminating the soil with human excreta,by promiscuous defecation in underdeveloped areas.
Why there is no faeco-oral infection for ascariasis?
Because eggs passed in faecas are not infective,after developing in to embryonated egg in 2-3 weeks.That is also whyinfected food handlers do not spread infection .
Ascariasis cycle in the body:
Ingested infective eggs hatch in the small intestine to give larve that penetrate the intestine,to be carried by the circulation to the lungs where they reach the alveoli,then up in the airways to the pharynx,to be swallowed and backn to small intestine.
Migration cycle takes about 10 days.
Incubation period: about two months from ingestion of embryonated eggs until eggs first appear in stools.
Symptoms:
Manifest cases commonly show:
-Respiratory manifestation :spasms of coughing,usually nocturanl and pneumonitis due to petechial bleeding caused by migrating larve in the lungs.
-Intestinal disorders: abdominal discomfort and colic.
-Nutritional deficiency: du to anorexia,impaired digestion and protein absorption and loss of nutrientts consumed by parasite (proteins,vitamins).
-Others: restless sleep and griding of teeth,commonly in children.
Ascaris is diagnosed by indentifying the eggs in smear of faeces.
Predisposing Factors:
-Promiscuous defecation that contaminates the soil with ascaris eggs.
-Fertilizing vegetables with fresh human fertilizer.
-Ingestion of salad (fresh vegetables) without thorough washing.
-Neglecting care of children who play in the road and get hands contaminated with eggs carrying dust and not washed.
Prevention of Ascariasis:
1.Sanitation of environment:
-safe water supply,food sanitation.
-providing rural area with sanitary convenient latrines and sanitary disposal of wasters.
To be used for fertilization of vegetables human excreta must be stored in covered packed heaps for at least six weeks.
-fly control.
2.Health education of the public:
-using water closetof latrines and avoid promiscuous defecation.
-thorough washing of uncooked vegetables.
-handwashing on returning home and before food.
-supervision of children on playing outdoors and advise them to avoid putting fingers in the mouth and wash hands when necessary and before food.
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