Microsporidia as a Potential Threat to the Iberian Lynx (Lynx pardinus)

Simple Summary The Iberian lynx, which inhabits the Iberian Peninsula, is one of the most endangered felines in the world. Wild Iberian lynx populations have suffered a constant regression over the past century, with a rapid decline of 90% in the last 20 years. Infectious diseases are one of the most critical threats that cause the population decline of these animals, either in the wild or captivity. Different studies have revealed positive seroprevalence against various pathogens, confirming contact and exposure to bacteria, viruses, and parasites. In this sense, searching for pathogens related to the depopulation of the Iberian lynx is vital for conserving and maintaining this threatened species. The present work confirmed the presence of microsporidia, opportunistic intracellular parasites recently related to fungi, in the lynx environment. Also, different species of microsporidia were determined for the first time in the urine, feces, and tissue samples of Lynx pardinus. Further studies are needed to establish the impact of microsporidia infection on the survival of the Iberian lynx. These studies would contribute to the endurance and conservation of this feline by implementing new prevention strategies. Lynx pardinus is one of the world's most endangered felines inhabiting the Iberian Peninsula. The present study was performed to identify the presence of microsporidia due to the mortality increase in lynxes. Samples of urine (n = 124), feces (n = 52), and tissues [spleen (n = 13), brain (n = 9), liver (n = 11), and kidney (n = 10)] from 140 lynxes were studied. The determination of microsporidia was evaluated using Weber's chromotrope stain and Real Time-PCR. Of the lynxes analyzed, stains showed 10.48% and 50% positivity in urine and feces samples, respectively. PCR confirmed that 7.69% and 65.38% belonged to microsporidia species. The imprints of the tissues showed positive results in the spleen (38.46%), brain (22.22%), and liver (27.27%), but negative results in the kidneys. PCR confirmed positive microsporidia results in 61.53%, 55.55%, 45.45%, and 50%, respectively. Seroprevalence against Encephalitozoon cuniculi was also studied in 138 serum samples with a positivity of 55.8%. For the first time, the results presented different species of microsporidia in the urine, feces, and tissue samples of Lynx pardinus. The high titers of anti-E. cuniculi antibodies in lynx sera confirmed the presence of microsporidia in the lynx environment. New studies are needed to establish the impact of microsporidia infection on the survival of the Iberian lynx.