Ascaris lumbricoides - Intestinal Nematodes

Largest intestinal nematode - mouth with 3 lips

Causes Ascariasis, about one fourth of world population is infected.
World wide distribution - where human feaces are used as fertilizer.
Children more often and heavily infected.

Diagnostic stage -> Eggs in feaces (Fertilized & Unfertilized)
Infective stage -> Embryonated egg (L2)

Pathogenesis:
-Effects of visceral larval migration (VLM)
-Abdominal pain, nausea, diarrhoea and vomiting
-Impaired absorption & Malnutrition.

Larvae migration:

Larva hatches in intestine -> Portal circulation -> Lungs(L3)
-> Trachea -> Pharynx -> Adults in small intestine.

*Mechanical -> inflammatory, bacterial infection & hypersensitive reaction.
*In lung -> Loeffler's syndrome (Ecdysis occur in lung)

Heavy infection:
-Intestinal obstruction & perforation.
-Bile duct and pancreatic duct obstruction.
-Can be fatal.

Atopic Ascariasis:
-Bile duct, pancreatic duct, liver, peritoneal cavity, kidney.
-Appendix, pleural cavity, upper respiratory tract.
-Atopic ascariasis causes granuloma.

Laboratory Diagnosis:
-Finding eggs in feaces
--Fertilized egg & unfertilized egg & decorticated egg
-Identifying worms expelled through anus or mouth

A. lumbricoides eggs:
-Fertilized egg & unfertilized egg & decorticated egg.
-Embryonated egg -> contains larva (R-form, 1st or 2nd stage)
--infective

Prevention and control:
-Preventing soil becoming feacally pulluted:
--avoid using human feaces as fertilizer.
-Preventing eggs from ingestion:
--wash hands before eating.
--avoid eating uncooked vegetables, salad or fruits.

Treatment:
-Levamisole & Albendazole & Mebendazole