We would also like to thank the pig suppliers involved in the research and Sietske Ruijgh for editing the paper. Author contribution RM wrote the manuscript, conducted sampling and data analyzes. MG conducted viral diagnostic screening. CJ coordinated and planned the study. MP contributed to conducting viral screening in the virology laboratory of UNA. EJ participated in the selection of the pig farms and sample collection. BL conducted data analysis and provided feedback on the study. JMC offered technical advice to support laboratory assays. LRC offered technical assistance. AU supplied laboratory protocols for the study and critical guidance. AVN contributed to study design and provided technical and management guidance. AS contributed to study design and provided technical and management guidance. HV contributed to data analysis. JJR contributed to study design and data analysis. Funding RM was a recipient of ML 171 a scholarship from the Ministry of Science and Technology and Telecommunications (MICITT) PND-018C15-2 from PINN POSGRADOS of Costa Rica to conduct doctoral studies. well as gilts based on the pilot study. In total 1281 ML 171 pigs were sampled across all 25 farms. The aim of the cross-sectional study was to quantify the seroprevalence of PRRSV in Costa Rican pig farms and to describe its geographical distribution in this tropical country. The prevalence of positive farms was 44% (11/25), and these farms were located in six of the seven provinces of Costa Rica. Overall, 58% (344/596) of the pigs were seropositive to PRRSV. The age of the pigs and the ecozone where farms were located were significantly related with PRRSV seroprevalence in animals and herds, respectively. strong class=”kwd-title” Keywords: Epidemiology, Prevalence, PRRS, Reproduction, Serological diagnosis, Swine production, Computer virus Introduction Porcine reproductive and respiratory syndrome virus (PRRSV) is one of the most important pig pathogens worldwide from an economic perspective. Holtkamp et al. (2010) calculated the costs associated with this disease to be around 663 million USD/12 months in the USA. In Europe, common losses related to PRRSV outbreaks were estimated to be around two piglets per sow per year (Nieuwenhuis et al., 2012). As climate may influence the computer virus spread within and between farms, it is difficult to infer the occurrence and distribution of PRRSV in a tropical country from observations in countries with a more moderate climate. In the past, some studies have been carried out to assess the PRRSV contamination prevalence in Central America, Mxico (Morilla et al., 2003), Colombia (Mogolln et al., 2006), Venezuela (Diaz, 2006), and the Dominican Republic,(Ventura et al., 2013), but there are no recent reports about the disease. This also holds for Costa Rica, a tropical country located in Central America between Nicaragua and Panama, where PRRSV was first detected in 1996 but which has received little attention since. Holdridge (1987) has identified various climate zones (ecozones) in Costa Rica: moist-low mountain forest, moist-pre mountain forest, very moist-low mountain forest, very moist-pre mountain forest, very wet tropical forest, and rainy-low mountain forest. This research aimed to assess the seroprevalence of PRRSV in pig farms of Costa Rica and to estimate its association with the age of the pigs, farm size, geolocation, distance, time, and ecozones. According to the Livestock National Census (INEC, 2014, 2015), there are 14,600 pig holders in Costa Rica, but most of them have backyard farms. There are only around 150 commercial pig farms, and these farms produce Rabbit Polyclonal to SHANK2 80% of the countrys pork. The total number of sows in Costa Rica ML 171 is usually approximately 39,000, and the number of pigs slaughtered per year rounds 780,000. Material and methods Sample size In the first phase, a total of 260 pigs (1 to 15?weeks of age) from 9 highly PRRSV computer virus infection-suspected farms were sampled. All samples were tested in parallel with a commercial enzyme-linked immunoassay (IDEXX Laboratories: 100.0% Se, 99.7% Sp) and endpoint PCR (Zorzetto- Fernandez, 2016). The second phase, a serological analysis was performed using the IDEXX PRRS X3 kit (cat. 99C40,959). Only 87 out of all of the 150 pig commercial farrow-to-finish farms were affiliated to the National Chamber of Pig Farmers. These 87 farms were classified as large ( ?500 sows, n?=?14), medium-sized (200 to 500 sows, n?=?62), or small ( ?200 sows, n?=?11). Twenty-five of these farms were selected using stratified sampling. Vaccination against PRRSV has never been applied on these farms. The sample size to determine presence of contamination in each farm was based on 5% within-herd prevalence (95% confidence level), resulting in 50 to 60 samples, depending on herd size (Cannon et al., 1982). We sampled pigs of 8, 10, and 12?weeks of age, as well as gilts. A total of 450 blood samples were obtained from the eight large farms, 550 from 12 medium farms, and 278 from 5 small farms. The starting point for the distance and time determinations was the Juan Santamaria International Airport, located in the middle of the central zone of the country (Alajuela). Based on this, distances and journey length (time determinations) from each farm to the designated starting point were estimated and retrieved using Google Maps. Laboratory testing Blood samples analysis The blood samples collected were placed in portable coolers that maintained refrigeration temperatures (4?C) and were transported to the laboratory within 8?h. Once in the laboratory, the samples were centrifuged for 10?min at 14,000?rpm. The sera.