High feline parvovirus immunity in Australian cats after outbreaks

Abstract

Multiple, epizootic outbreaks of feline panleukopenia (FPL) caused by feline parvovirus(FPV) occurred in eastern Australia between 2014 and 2018. Most affected cats were unvaccinated.We hypothesised that low population immunity was a major driver of re-emergent FPL. The aim ofthis study was to (i) determine the prevalence and predictors of seroprotective titres to FPV amongshelter-housed and owned cats, and (ii) compare the prevalence of seroprotection between a regionaffected and unaffected by FPL outbreaks. FPV antibodies were detected by haemagglutinationinhibition assay on sera from 523 cats and titres ≥1:40 were considered protective. Socioeconomicindices based on postcode and census data were included in the risk factor analysis. The prevalenceof protective FPV antibody titres was high overall (94.3%), even though only 42% of cats wereknown to be vaccinated, and was not significantly different between outbreak and non-outbreakregions. On multivariable logistic regression analysis vaccinated cats were 29.94 times more likelyto have protective FPV titres than cats not known to be vaccinated. Cats from postcodes of relativelyless socioeconomic disadvantage were 5.93 times more likely to have protective FPV titres. Thepredictors identified for FPV seroprotective titres indicate targeted vaccination strategies in regionsof socioeconomic disadvantage would be beneficial to increase population immunity. The criticallevel of vaccine coverage required to halt FPV transmission and prevent FPL outbreaks should bedetermined.