Global seroprevalence and associated risk factors with Neospora caninum infection in sheep: a systematic review and meta-analysis

LUISA F. MENDOZA MORALES; VALENTINA LAGORIO; MARIANA G. CORIGLIANO; EDWIN SANCHEZ-LOPEZ; VICTOR A. RAMOS DUARTE; MARINA CLEMENTE; VALERIA A. SANDER

Los Angeles

Conferencia; 2nd Conference of Women in Bioinformatics and Data Science LA; 2021

Women in Bioinformatics and Datascience

Background: The increased demand for livestock products during the last decades has turned the sheep industry quite promising, particularly in developing countries, where the 80% of the total small ruminants population is placed. In those countries, sheep also play an important role in the survival, economic, and social livelihoods of many humans. However, there is a growing concern that low reproductive performance in ovine populations, mainly caused by infectious diseases, may progressively obstruct the industry. Recent experimental studies on ruminants have suggested that neosporosis, an infectious disease whose aetiological agent is the Apicomplexan parasite Neospora caninum, may be an important cause of abortion and reproductive losses among these animals. However, the epidemiological and clinical relevance of neosporosis in sheep remains to be elucidated. Objective: This meta-analysis aims to estimate the global seroprevalence and risk factors (RF) associated with N. caninum infection in ovines. Methodology: The current study was structured according to the recommendations of Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines, and the and is currently available at PROSPERO (CODE CRD42019121309). Searches for data were conducted in MEDLINE, PubMed, Scopus, LILACS, SciELO, Google Scholar and ScienceDirect. The inclusion criteria were (1) peer-reviewed original articles without geographical limitation; (2) cross-sectional investigations which estimated the N. caninum seroprevalence in sheep, (3) studies for which the full texts were available; (4) reports with information on the total sample size and positive samples. On the other hand, exclusion criteria were: (1) not a sheep study (2) not neosporosis diagnosis (3) prevalence of N. caninum infection evaluated by any other methodology than serological techniques (4) not a cross-sectional study. The meta-analysis was performed with the help of MetaXL2.0 software (Epigear International PtyLtd, Wilston, Queensland, Australia). The random-effects model described by DerSimonian and Laird (2015) was used for the meta-analysis.Results:The global pooled seroprevalence of anti-N. caninum antibodies in sheep was 13 % (95% C.I., 10-16) based on the random-effects model of meta-analysis (Fig. 2). The included studies demonstrated a strong heterogeneity (Q = 5147.15, I2 = 98%, P < 0.001). In order to assess the potential causes of heterogeneity, subgroup meta-analyses were conducted based on WHO regions and the diagnostic methodology used. Subgroup analysis of the WHO region showed that the African region depicted the highest pooled seroprevalence, reaching 43% (95% CI, 36-48) followed by the Region of the Americas with 17% (95% CI, 13-22). The seroprevalence in the remaining WHO regions were 10% (95% CI, 4-16) in EMR, 7% (95% CI, 4-12) in ER and 4% (95% CI, 1-7) in WPR. The overall N. caninum seroprevalence significantly differed among WHO Regions (X2 975.6, 4; p95%, each), with the exception of the African Region, which demonstrated homogeneity (I2 = 0%).Regarding the subgroup analysis of diagnostic methods, the enzyme-linked immunosorbent assay (ELISA) method was the most widely used diagnostic test to evaluate N. caninum antibodies in sheep, and the overall seroprevalence found by this methodology was 9% ( 95% CI, 7-12), whereas the pooled seroprevalence by IFAT was 17% ( 95% CI, 12-23), being significantly different (X2 686.2, 1; p