Spatiotemporal monitoring of myxomatosis in European wild rabbit (Oryctolagus cuniculus) in Spanish Mediterranean ecosystems

Abstract

A long‐term active epidemiological surveillance programme was conducted to determine seroprevalence to myxoma virus (MYXV), infection prevalence and spatiotemporal patterns and factors associated with MYXV circulation in wild rabbits (Oryctolagus cuniculus) in Spanish Mediterranean ecosystems. A total of 2376 animals were sampled over four study periods: 2009–2012 (P1), 2012–2015 (P2), 2015–2018 (P3) and 2018–2021 (P4). Antibodies against MYXV were detected by a commercial indirect ELISA in 59.9% (1424/2376; 95% CI: 58.0–61.9) of wild rabbits. At least one seropositive animal was detected on 131 (96.3%) of 136 game estates sampled. MYXV infection was confirmed by PCR in 94 of 1063 (8.8%; 95% CI: 7.3–10.7) wild rabbits. Circulation of the novel recombinant MYXV (ha‐MYXV) was not found in wild rabbits analysed during P4. Five statistically significant spatiotemporal clusters of high MYXV seroprevalence were identified using a Bernoulli model: one in P2 and four in P3. A generalized linear mixed model (GLMM) analysis identified sampling season (autumn), age (adult and juvenile), outbreaks of myxomatosis in the month prior to sampling, mean annual temperature, humidity and seropositivity to rabbit haemorrhagic disease virus as factors potentially linked with MYXV seropositivity. GLMM analysis identified outbreaks of myxomatosis in the month prior to sampling, MYXV seropositivity and presence of lesions compatible with myxomatosis as factors associated with MYXV infection. The results indicate high exposure, widespread but non‐homogeneous distribution, and endemic circulation of MYXV in wild rabbit populations in southern Spain during the last decade. Prevalence of antibodies against MYXV showed fluctuations both within the year and over the study periods, revealing variations in the immunity of wild rabbit populations in Mediterranean ecosystems that could increase the risk of MYXV re‐emergence in immunologically naïve populations. The present study highlights the importance of long‐term surveillance to better understand the epidemiology of MYXV in wild lagomorphs.

Dynamics of Humoral Immunity to Myxoma and Rabbit Hemorrhagic Disease Viruses in Wild European Rabbits Assessed by Longitudinal Semiquantitative Serology

“…The seroprevalence across study sites for MYXV (52.4%; CI 95 , 48.4 to 56.3%) was in accordance with results reported for Spain ( 8 , 43 , 44 ). In the log-LMM, the random effects “site” and “year” were associated with little variance in semiquantitative serological data, highlighting the endemic status of MYXV in wild populations.…”

“…In the log-LMM, the random effects “site” and “year” were associated with little variance in semiquantitative serological data, highlighting the endemic status of MYXV in wild populations. Annual outbreaks of MYXV occur predictably in every population in the Iberian Peninsula, in a stable endemic situation ( 8 , 43 , 44 ).…”