Ascaridia galli

The parasitic roundworm A. galli belongs to the phylum Nematoda.

It occurs worldwide in galliform birds of all ages.

The body of the adult worms is semi-transparent, cylindrical, and has a creamy-white color.

Ascaridia galli has a direct life cycle that includes two phases, the free-living nematode eggs in the environment and the larvae and adult worms in the gastrointestinal (GI) tract of the host.

Infection takes place when birds ingest the embryonated parasite eggs that are found in their environment.

The prepatent period is about 4–8 weeks

Females (pic. on the left) are longer than males with a length of 72–116 mm and have a straight posterior terminal, whereas males (pic. on the right) are around 51–76 mm in length and possess a curved posterior terminal.

Upon maturation, the female worms produce massive numbers of eggs which are passed to the environment through the feces.

When laid, the eggs are covered with a resistant three-layered shell: the inner permeable layer called the vitelline membrane, a thick chitinous layer, and finally a thin, albuminous outer layer. The eggshell is important to protect the developing larva against harsh environmental conditions and to preserve infectivity.

The morbidity increases with the worm burden.

The clinical signs include diarrhea, sometimes with blood in the stools, impaired growth, reduced egg production, increased feed consumption, and, in some cases, death caused by intestinal obstruction

Hygienic measures between consecutive flocks aim to interrupt transmission of pathogens, prevent re-infection and gradually minimize the infection level on the farm to an acceptable level.

Cleaning of the barn with high-pressure hot water is recommended before the placement of new pullets to reduce the level of parasite egg contamination.

This together with a downtime period between consecutive flocks would theoretically reduce the infection level and delay the spread of the infection within the flock.

The free-living stages of most parasite species including A. galli need high relative humidity to develop to the infective stage and must survive until they are ingested by the host. Therefore, keeping the floor and the litter dry is of utmost importance.

Using disinfectants should be incorporated into the overall sanitation routine. It has been shown that chlorocresol (Interkokask®RTU) is effective against A. galli eggs in vitro.

Strict biosecurity routines such as disinfecting delivery vehicles before entering the production sites, using disinfection boxes and footwear exchange for personnel entering the barns, having a shower room and clean overalls, headgear, and footwear supplies will reduce the risk of introduction of new infective agents to farms and between flocks

For the treatment to be successful, it must be started as early as possible after confirmed parasite infection.

The first diagnostic sampling should be performed when hens are about 20-22 weeks old.

The birds are quickly re-infected after deworming therefore, the treatment should be repeated with 6-8 weeks intervals.