Mammomonogamus laryngeus (Railliet, 1899) infections in cattle from Sri Lanka

Additional characterization of the adult worm Mammomonogamus laryngeus (Railliet, 1899) and the tissue lesions caused by the infection in buffaloes

Mammomonogamus spp. are parasites with curious characteristics, such as the "Y" shape that results from male and female maintaining the permanent copulation position and the controversial presence or absence of spicules. These nematodes are hematophagous and cause damage to the upper respiratory tracts of cattle, sheep, goats, deer, wild yaks, and orangutans. Human infection is rare and most cases until now have been in the Caribbean Islands or in Brazil, and mainly in farmworkers but recently there have been reports affecting tourists. In the present work, the parasites were recovered from the laryngopharynx and larynx region of Bubalus bubalis on the island of Marajó, Pará, Brazil. Different microscopy methodologies were applied (bright field, fluorescence, and scanning electron microscopy) to explore the ultrastructural details of the anterior end, genital structures and the host tissue damage caused by the nematodes. The well-developed mouth is an important structure in the identification of these nematodes and used by the parasite to adhere to the host's tissue. Different methodologies in microscopy and molecular biology contributed to a detailed morphological description and showed the phenotypic position of Mammomonogamus laryngeus. Light and scanning electron microscopy (SEM) showed details of the papillae, amphids, festoons, ribs, and teeth. Fluorescence microscopy enabled a detailed characterization of different structures, such as the bursal rays and SEM enabled the visualization of the specialized features of the cuticle surface in the male and female. Histopathological analyses, cryofracture and environmental SEM experiments of the infected tissues were carried out in order to investigate the lesions resultant from the parasitism. In addition, the parasite couples were submitted to cryofracture and these results revealed details of the reproductive structures of both sexes, including the male spicule.

Mammomonogamus laryngeus (Railliet, 1899) infection in buffaloes in Rio Grande do Sul, Brazil

Parasites of the genus Mammomonogamus affect the respiratory tract of domestic animals. The present study was carried out to determine the presence of Mammomonogamus laryngeus infection and to analyze its lesions in infected buffaloes in Rio Grande do Sul, Brazil, between April and November 1999. The infection rate was 30.5%. In 32 infected buffaloes, the worm pairs collected per animal did not exceed 20. The microscopic diagnosis showed intense polypoid to intramucosal proliferation at the entrance to the pharynx, to which the parasites had adhered, with foci of multifocal hydropic degeneration of the epithelium or individual degeneration of epithelial cells with mild intraepithelial inflammatory infiltrate. The submucosa revealed intense lymphocyte infiltrate extending into the salivary glands. The submucosa also showed formation of structures that resemble lymphoid follicles.

Mammomonogamus laryngeus (Railliet, 1899) infections in cattle in Mindanao, Philippines

During one year, 597 cattle were examined for Mammomonogamus laryngeus infections in the abattoir of Cagayan de Oro, Philippines. The overall prevalence was 23% with no obvious seasonal variations. The infection rate was 19% in animals up to 4 years old and 24% in animals 4-12 years old. In infected animals up to 8 years old an average of eight parasite pairs was found; infected animals of 8-12 years old had 5.2 parasite pairs on average. All worms were located on the posterior side of the epiglottis. Field observations on cattle in Mindanao revealed that adult M. laryngeus had developed on the epiglottis of a tracer calf that had been on pasture for 30 days and then kept away from possible nematode infection for 28 days.