Exploiting serological data to understand the epidemiology of foot-and-mouth disease virus serotypes circulating in Libya

Abstract

Sporadic outbreaks of foot-and-mouth disease (FMD) have occurred in Libya for almost fifty years. During the spring of 2013, a countrywide serosurvey was undertaken to assess the level of FMD virus circulation and identify FMD virus serotypes in the country. A total of 4221 sera were collected, comprising samples from large ruminants (LR; n=1428 samples from 357 farms) and small ruminants (SR; n=2793 samples from 141 farms). FMD sero-prevalence of NSP antibodies determined by ELISA were 19.0% (271/1428) with 95% CI (16.9 – 21.0) and 13.5% (378/2793) with 95% CI (12.3 – 14.8) for LR and SR samples, respectively. The sero-prevalence of NSP antibodies in LR was 12.3% and 19.8% for age group 2 year, respectively (X2= 118.1, P= 0.000). These observed NSP serologic profiles support the hypothesis of an endemic level of FMD circulation in Libya. All positive sera were tested for SP antibodies for O, A and SAT-2 FMD virus serotypes. Serotype O was the dominant circulating serotype followed by serotype A, while evidence of SAT-2 was not found. These data provide an insight into the wider epidemiology of FMD in Libya, and contribute to field and laboratory investigations that during 2013 recognized serotype O (O/ME-SA/Ind-2001 lineage) in clinical samples collected from the country.

Keywords

• Foot-and-mouth disease
• Large ruminants
• Libya
• Sero-prevalence
• Small ruminants