Anatrichosomiasis in African Monkeys

Abstract

Approximately 29% of 298 African monkeys belonging to 5 species (Erythrocebus patas, Cercopithecus talapoin, C. aethiops, Cercocebus galeritus, and Papio sp.) obtained from various parts of Africa were found to be infected with species of Anatrichosoma. The adult worms were found in the nasal epithelium. The embryonated eggs which accumulate on the epithelial surface were easily removed with a cotton-tipped applicator stick, nasopharyngeal swab, or similar implement. Eggs were rarely found in the feces by routine diagnostic methods. Swabbing of the nasal mucosa was found to be the most reliable and accurate procedure for diagnosis of infections in living animals. Although specific determinations were not made, it appeared that the parasites from the African monkeys were different from A. cutaneum and A. cynamolgi described previously from Asian monkeys. The anatrichosomes are relatively rare and poorly known trichuroids which, to date, have been found in the skin and nasal mucosa of Asian monkeys (Swift et al., 1922; Smith and Chitwood, 1954; Chitwood and Smith, 1958; Allen, 1960) and on two occasions in man (Morishita and Tani, 1960; Le-Van-Hoa et al., 1963). Infections have been recognized more frequently as a result of recovery of adult worms at necropsy than from finding the eggs of the parasite. The latter have been found in scrapings of the nasal mucosa and occasionally in feces (Allen, 1960; Reardon and Rininger, 1968). Reports concerned with this parasite are so few that our knowledge of the species, their host range, and geographical distribution is very limited. Recently, in the course of histological examination of nasal tissues from an African patas monkey (Erythrocebus patas), Dr. Herman Seibold of the Pathology Laboratories, Delta Regional Primate Research Center, observed sections of a nematode in the mucosa and referred the slides to the author for identification. Examination of the sections of worms revealed that they were trichuroids. Their location and the morphology of the fully embryonated eggs found in the tissues indicated that they were a species of Anatrichosoma. Examination of intact worms subsequently recovered from animals at necropsy confirmed the tentative diagReceived for publication 14 January 1970. * Presented at the Forty-fourth Annual Meeting of the American Society of Parasitologists in Washington, D. C. 3-7 November 1969. This investigation was supported by U. S. Public Health Service grants FR 00164, DRFR and Al 06828, NIAID, NIH. nosis. Because there are no existing reports of anatrichosomes in African primates and because routine stool examinations in the past have failed to demonstrate the presence of the parasite in colony animals except rarely, studies were undertaken to ascertain the prevalence of this parasite in African primates and to determine the most suitable method for its diagnosis. MATERIALS AND METHODS The monkeys utilized in the study were maintained in the Delta Primate Center's animal colony or, in some cases, at other institutions. The nasal passages of each animal were swabbed with a dampened, cotton-tipped applicator stick or commercially prepared, sterile, nasopharyngeal swab (Calgiswab?), or rectal swab (SWUBE?), depending on the size of the nostrils. The swabs were examined under a binocular dissecting microscope with incident light to determine whether or not eggs were present. Stool examinations were made by direct-smear, formalin-ether, and zinc sulfate flotation techniques. At necropsy, portions of the nose and upper lip were removed from infected monkeys and fixed in Bouin's solution or 10% formalin. These tissues were processed by routine methods, sectioned at 7 ,i, and stained with hematoxylin and eosin. Worms removed from the tissues in toto were fixed in glacial acetic acid, transferred to 70% alcohol to which glycerin was added gradually, and were brought to pure glycerin by evaporation for microscopic study. RESULTS AND DISCUSSION Histological examination of tissues from infected animals revealed that adult worms usually are located in that portion of the nasal cavity lined with stratified squamous epithelium (Fig. 1). The female worms make extensive burrows in the epithelium as they wander through the tissues, depositing eggs in their wake. The eggs remain in these burrows or