One of the most important parasitic diseases in pig production is the ascariasis, caused by Ascaris suum. Its relevance is due to, not only its frequency, but also to its economic and clinical impact.

This introductory article will focus on the essentials about the aetiology, epidemiology and relevance of this parasitic infection in pig production.

Aetiology

Ascaris suum is a nematode (round worm) that affects swine, although in can also infest other species (ovine, amongst others) without finishing its biologic cycle.

It’s a large parasite (adults can reach 40 cm) that affects the intestine and migrates through theblood, firstly to the liver and then to the lungs.

Epidemiology

A. suum has a cosmopolitan distribution; in fact, there are only a few farms free of this parasite.  Prevalence rates vary according to the geographic area (its frequency is higher in damp, tropical and warm climates) and the management and hygienic practices of the farms.

Higher prevalence occurs in piglets from 2 to 5 month-old, and decreases as animals grow, due to the acquisition of specific immunity.

Ascariasis’ importance

Economic losses due to ascariasis in swine are of great importance and are mainly caused by two causes: on one hand, a worsening of the feed conversion ratio, which leads to production losses. On the other hand, it causes losses in meat industry due to the seizure of injured organs, especially because of the hepatic lesions called “milk spots”.

For years, Ascaris suum has been thought to be the only cause of ascariasis infection in human, although recent scientific studies confirm that there is a specie that affects humans more specifically called A. lumbricoides.