Myiasis and perforation of the rumen of calves by larvae of Cochliomyia hominivorax (Coquerel, 1858). Economic significance

Abstract

The authors describe a new type of myiasis which occurs in calves from one to two months old, caused by the larvae of the “screw-worm fly” — Cochliomyia hominivorax (Coquerel, 1858), Sin. C. americana (Cushing and Patton, 1933) — with localization in the rumen. The larvae, probably removed from external myiasis by the common calf’s habit of licking wounds are swallowed and set themselves up in the atrium of the rumen, there piercing the mucosa and subjacent layers, causing peritonitis and often invading the abdominal cavity. From some hundreds of post-mortem examinations made with the intention of establishing the various causes of death of calves in the “Fazendas Almeida
Prado” , belonging to the “Condomínio Almeida Prado” , Araçatuba, it was found that myiasis of the rumen accounted for eight (winter) to fifteen (summer) percent of the total, this variation probably due mainly to seasonal circumstances. The economic significance of this type of myiasis is emphasized by the fact
that, in these “Fazendas” more than 100 calves are dying yearly from perforation of the rumen. On the other hand, this paper points out the possibility of the internal localization of the larvae of C. hominivorax.