Spirocerca lupi

The esophageal worm ( Spirocerca lupi ) is a roundworm that can infect as endoparasite the esophagus of dogs.

Description

Esophagus worms are bright red roundworms of cylindrical shape. Male adult worms are about 40 mm long, female worms measure about 70 mm. The mouth has six lips. The mouth capsule is highly developed and has thick walls. The formed precipitates of the epidermis cuticle has three layers and is composed of collagen and other substances; it serves to protect the worms before digestion.

Dissemination

The esophageal worm is particularly widespread in the southern United States, but occurs worldwide in tropical and subtropical regions. As a final host are primarily affected dogs, but also in brown hyena, the infection is described. Veterinary Medical relevance of the parasite is especially the house dog.

Life cycle

Adult worms lodge themselves in the esophageal wall ( occasionally also in the stomach wall ), where they mate and give eggs into the esophagus, which are excreted in the feces. The eggs are oval along, measure about 11-15 × 30-38 microns, and already contain a larva. Eggs are laid in batches, so that infected animals are only intermittent shedders, which can complicate the parasitological diagnosis.

The eggs in the feces of koprophagen insects ( mostly dung beetles ) was added as intermediate hosts. The larvae molt still in the egg to larva 3 ( L3), the slip form and in the intermediate host cysts. The intermediate hosts can infect the definitive host directly, often it happens but also for the enrichment of the parasites in collecting hosts such as lizards, chickens or mice.

If the definitive host an intermediate or collection host to so penetrate the infective L3 in the stomach wall and migrate from there through the wall of the celiac artery into the aorta, where they arrived about 20 days after infection. After two to three months, they migrate out of the aortic wall in the esophageal wall, where they molt into adult worms mate and turn excrete eggs, can infect through the new intermediate hosts. The prepatent period is five to six months.

In response to the parasites develop in the esophagus wall granulomas, which can degenerate into malignant tumors; usually it involves sarcomas ( fibrosarcoma and osteosarcoma ), squamous cell carcinomas occasionally. During the walk in the aortic wall, the parasites can also lead to the formation of aneurysms.