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Biological sex is an important risk factor for the occurrence and severity of infectious and parasitic diseases. Although various studies and reviews have described sex differences in infectious diseases of humans, wildlife and laboratory animals, there has been little focus on biological sex as a risk factor for infectious and parasitic diseases of domestic animals. We aim to identify and synthesise evidence in dogs for the hypothesis that biological sex and gonadectomy status are determinants of occurrence and severity of disease across taxa of pathogens. This systematic review follows the Preferred Reporting Items for Systematic reviews and Meta-analyses (PRISMA) guidelines. We will search Web of Science, Scopus and PubMed for peer-reviewed studies published in English from database inception through 2021. All study designs for infectious and parasitic diseases of dogs will be included. This review will include the outcomes prevalence or incidence of infection or disease; and severity of disease as measured by case-fatality, time to death or recovery, hospitalisation time, pathogen burden (e.g. viral load or parasitaemia) or relevant clinicopathological parameters. Two reviewers will jointly assess the first 500 records from all three databases. Subsequently, one reviewer will screen the remaining records, and then the second reviewer will verify all records excluded by the first reviewer. Full-texts of all included records will be retrieved and assessed for eligibility by the first review author, and then the second author will review those records excluded by the first author. The risk of bias in individual studies will be assessed using the Risk of Bias Assessment tool for Nonrandomized Studies. We will synthesise the information from the studies and present this as a narrative in the text. The findings will be presented by outcome type and also grouped by pathogen type. Evidence on sex-specific effects will expand our understanding of infectious disease pathogenesis and underlying mechanisms, and this may be of importance in implementation of disease control interventions.

African swine fever (ASF) is a highly contagious, lethal and economically devastating haemorrhagic disease of domestic pigs. Insights into the dynamics and scale of virus transmission can be obtained from estimates of the basic reproduction number (R0). We estimate R0 for ASF virus in small holder, free-range pig production system in Gulu, Uganda. The estimation was based on data collected from outbreaks that affected 43 villages (out of the 289 villages with an overall pig population of 26,570) between April 2010 and November 2011. A total of 211 outbreaks met the criteria for inclusion in the study. Three methods were used, specifically; (i) GIS- based identification of the nearest infectious neighbour based on the Euclidean distance between outbreaks, (ii) epidemic doubling time, and (iii) a compartmental susceptible-infectious (SI) model. For implementation of the SI model, three approaches were used namely; curve fitting (CF), a linear regression model (LRM) and the SI/N proportion. The R0 estimates from the nearest infectious neighbour and epidemic doubling time methods were 3.24 and 1.63 respectively. Estimates from the SI-based method were 1.58 for the CF approach, 1.90 for the LRM, and 1.77 for the SI/N proportion. Since all these values were above one, they predict the observed persistence of the virus in the population. We hypothesize that the observed variation in the estimates is a consequence of the data used. Higher resolution and temporally better defined data would likely reduce this variation. This is the first estimate of R0 for ASFV in a free range smallholder pig keeping system in sub-Saharan Africa and highlights the requirement for more efficient application of available disease control measures.

Bartonella bovis is commonly detected in cattle. One B. bovis strain was recently isolated from a cow with endocarditis in the USA, suggesting its role as an animal pathogen. In the present study, we investigated bartonella infections in 893 cattle from five countries (Kenya, Thailand, Japan, Georgia, and Guatemala) and 103 water buffaloes from Thailand to compare the prevalence of the infection among different regions and different bovid hosts. We developed a multi-locus sequence typing (MLST) scheme based on nine loci (16S rRNA, gltA, ftsZ, groEL, nuoG, ribC, rpoB, ssrA, and ITS) to compare genetic divergence of B. bovis strains, including 26 representatives from the present study and two previously described reference strains (one from French cows and another from a cow with endocarditis in the USA). Bartonella bacteria were cultured in 6.8% (7/103) of water buffaloes from Thailand; all were B. bovis. The prevalence of bartonella infections in cattle varied tremendously across the investigated regions. In Japan, Kenya, and the Mestia district of Georgia, cattle were free from the infection; in Thailand, Guatemala, and the Dusheti and Marneuli districts of Georgia, cattle were infected with prevalences of 10-90%. The Bartonella isolates from cattle belonged to three species: B. bovis (n=165), B. chomelii (n=9), and B. schoenbuchensis (n=1), with the latter two species found in Georgia only. MLST analysis suggested genetic variations among the 28 analyzed B. bovis strains, which fall into 3 lineages (I, II, and III). Lineages I and II were found in cattle while lineage III was restricted to water buffaloes. The majority of strains (17/28), together with the strain causing endocarditis in a cow in the USA, belonged to lineage I. Further investigations are needed to determine whether B. bovis causes disease in bovids.