First Study of Pharingomyia picta and Cephanemyia auribarbis in Wild Populations of Red Deer (Cervus elaphus) in Portugal

SIMPLE SUMMARY: This study aimed to provide the first epidemiological data on nasopharyngeal myiasis in wild red deer from Portuguese territory. This parasitosis consists of the infestation of the host nasopharynx by Diptera larvae. In this study, the first scientific report in Portugal, a high level of prevalence (50.6%) and mean intensity of parasitism (11.38 larvae) were found. The following two larvae species were identified: Pharyngomyia picta and Cephenemyia auribarbis. The life cycle of this species can be summarised in the following series of stages: one adult stage, three larval stages, and one pupa stage. The larvae are the parasitic form, living and growing inside the host. With their spicules and hooks, they progress into the host’s nasal cavities causing sinusitis, sneezing, purulent mucous exudates, dyspnea, and swallowing. In addition, they can also cause neurologic symptomatology derived from erratic larvae migrations. Therefore, it would be important to develop further studies to estimate the sublethal effect of this parasitosis, for example, investigate whether it interferes with the roar and the reproductive performance, or if it leads to losses in carcass quality. For now, many doubts remain. ABSTRACT: Nasopharyngeal myiasis in red deer has never been studied in Portugal. For this reason, from December 2015 to February 2016 a study was derived on hunted red deer in Idanha-a-Nova county to evaluate the Diptera larvae presence. During the initial examination on the spot, the larvae was analysed at the nasopharynx. When present, larvae were collected for further species identification. The infestation prevalence was 50.6 ± 7.61% (CI 95%), and the mean parasitism intensity was 11.38 larvae per affected host. Two larvae species were found, Pharyngomyia picta and Cephenemyia auribarbis, both on single or concomitant infection, with the first species having a higher prevalence and mean infestation intensity than the second. The larvae’s prevalence was significantly higher (X(2) = 4.35; p = 0.0370) in males (62.16 ± 11.05%) than in females (41.30 ± 10.06%). Within age groups, younger animals showed a higher prevalence. This study shows the presence of P. picta and C. auribarbis larvae in the wild red deer population in Portugal for the first time. The high parasitic prevalence and mean intensity highlight the importance of this parasitosis in this wild species. For this reason, more scientific research is required to accurately assess its prevalence in other geographic areas, and evaluate the risk factors as well effects of this parasitosis on the deer population.