Daniel Peromingo Fernández defended this Degree Final Project

September 14^th, 2023

Wild birds are important reservoirs of zoonotic pathogens, although the risk of transmission to humans is quantitatively lower than for other mammalian host groups, due to their phylogenetic distance. The main epidemiological determinants of wild birds in relation to zoonoses include migratory movements and their association with emerging and re-emerging diseases, and their ability to adapt to urban environments, which is associated with increased exposure to humans. Both psittacosis and West Nile fever are zoonoses of great public health relevance and share their reservoir in birds. The aim of the present study is the laboratory detection and determination of the prevalence of Chlamydia psittaci and West Nile Virus (WNV) in the wild bird population of the community of Madrid in 2022 and of C. psittaci in the urban pigeon population of Madrid in the same year on the one hand. On the other hand, to evaluate the evolution of these agents in the aforementioned populations in recent years. For this purpose, laboratory diagnosis was carried out using molecular techniques (PCR and real-time RT-PCR) on samples from the aforementioned bird populations. The presence of WNV and C. psittaci was ruled out in the samples from the 61 wild birds tested, and the absence of C. psittaci was also determined in the samples from the 50 urban pigeons. A retrospective longitudinal descriptive study covering 6 years in wild birds was able to detect a single C. psittaci-positive individual, resulting in a mean prevalence of 0.46%, and consistent negativity for WNV detection. Previous studies show variable results on the prevalence of C. psittaci in wild birds, while similar trends are observed for WNV. The design of surveys with larger sample sizes could be key in the surveillance of these agents. The same retrospective study carried out in the urban pigeon population in the last 5 years showed a mean prevalence of C. psittaci of 3.44% and a low interannual variation that could be contrasted with previous studies in the same population. The low prevalence of C. psittaci in urban pigeons in Madrid in recent years and its absence in the individuals tested in 2022 are determinants of a very limited risk for the human population. Even so, the reservoir role of urban pigeons must be taken into account when implementing surveillance strategies