Seroprevalence of Foot-and-Mouth Disease in Susceptible Wildlife in Israel

Abstract

Foot-and-mouth disease (FMD) epidemics recur in Israel almost every year. Wild even-toed ungulates are seldom affected during these epidemics. The seroprevalence of FMD in wild ungulates during 2000 and 2005-2013 was estimated using anti-non-structural proteins ELISA. Overall, 209 samples were tested, comprising sera of 120 wild boar (Sus scrofa lybicus), 64 mountain gazelles (Gazella gazella gazella), 6 water buffaloes (Bubalus bubalis), and 19 Persian fallow deer (Dama dama mesopotamica). None of the tested animals presented clinical signs of FMD during blood collection. Sixteen samples [7.7% (95% confidence interval (CI95%) = 4.4-12.1%)] were found to be seropositive. Fifteen out of 120 samples (12.5%) from wild boar were seropositive, compared with only 1 out of 89 samples (1.1%) from all other species combined (Fisher's exact test: p = 0.003). Most of the positive samples obtained from wild boar [13/15 (86.7%)] were collected during 2007, and analysis was restricted to that year and species only. The seroprevalence of FMD in this species during 2007 was estimated at 54.2% (CI95% = 32.8-74.5%; n = 24). A significant infection cluster, comprising nine seropositive samples collected in three different locations, was identified in the north-eastern part of Israel. These findings indicate that wild boar was affected during the 2007 FMD epidemic, even though wild boar presenting FMD typical clinical signs were not observed during that year. The actual role of wild boar in the spread of FMD virus in this epidemic, however, could not be determined. The negligible seroprevalence of FMD found for all other surveillance years indicates that ongoing circulation of FMD among wildlife in Israel is unlikely. It is concluded that while the role of wildlife species in the dynamics of FMD in Israel is usually limited, there might be occasions, in which wildlife plays a part in the spread of the virus.

Keywords: FMD; NSP; prevalence; wild boar; wildlife.

Figure 1

The seroprevalence of foot-and-mouth disease virus in wildlife species in Israel during 2000 and 2005–13. The approximate locations from which samples were collected are indicated. Wildlife species and the number of collected samples are illustrated by different shapes and sizes, respectively. A collection location was considered positive (marked red) if at least one of the species samples was found to be positive. Otherwise, the location was considered negative (marked blue).

Figure 2

The seroprevalence of FMD in wild boar in Israel during 2007. The approximate locations from which samples were collected are indicated (samples collected from the same location were manually scattered around the location in order to allow better visualization). Positive samples are marked red and negative samples marked blue. FMD outbreak locations (during 2006–2007) are indicated by stars. Additionally, the approximate area of the main mountain gazelle population that was affected by FMD during 2007 (“Ramot Yissakhar”) is indicated by a gray polygon filled with diagonal lines. Significant prevalence cluster is indicated by a purple circle.