No abstract

Foot‐and‐mouth disease (FMD) is widely distributed in Sudan where outbreaks occur on an annual basis especially during the winter months (December‐February). This study aimed to increase our understanding of the epidemiological patterns of FMD in Sudan and connections to neighbouring countries by characterizing the genetic sequences of FMD viruses (FMDV) collected from samples collected in 10 Sudanese states over a 10‐year period (between 2009 and 2018). FMDV was detected in 91 of the 265 samples using an antigen‐detection ELISA. Three serotypes were detected: O (46.2%), A (34.0%), and SAT 2 (19.8%). Fifty‐two of these samples were submitted for sequence analyses, generating sequences that were characterized as belonging to O/EA‐3 (n = 17), A/AFRICA/G‐IV (n = 23) and SAT 2/VII/Alx‐12 (n = 12) viral lineages. Phylogenetic analyses provided evidence that FMDV lineages were maintained within Sudan, and also highlighted epidemiological connections to FMD outbreaks reported in neighbouring countries in East and North Africa (such as Ethiopia and Egypt). This study motivates continued FMD surveillance in Sudan to monitor the circulating viral lineages and broader initiatives to improve our understanding of the epidemiological risks in the region.

Foot-and-mouth disease (FMD) is widely distributed in Sudan where outbreaks occur on an annual basis especially during the winter months (December-February). This study aimed to increase our understanding of the epidemiological patterns of FMD in Sudan and connections to neighbouring countries by characterising the genetic sequences of FMD viruses (FMDV) collected from seven Sudanese states over a 10-year period (between 2009 and 2018). FMDV was detected in 91 of the 265 samples using an antigen-detection ELISA. Three serotypes were detected: O (46.2%), A (34.1%), and SAT 2 (19.8%). Fifty-three of these samples were submitted for sequence analyses, generating sequences that were characterised as belonging to O/EA-3 (n=18), A/AFRICA/G-IV (n=23) and SAT 2/VII/Alx-12 (n=12) viral lineages. Phylogenetic analyses provided evidence that FMDV lineages were maintained within Sudan, and also highlighted epidemiological connections to FMD outbreaks reported in neighbouring countries in East and North Africa (such as Ethiopia and Egypt). This study motivates continued FMD surveillance in Sudan to monitor the circulating viral lineages and broader initiatives to improve our understanding of the epidemiological risks in the region.

Like other East African countries, Sudan experienced circulation of several SAT2 topotypes. In Sudan, topotype XIII and VII of SAT2 virus were recorded. This work meant to evaluate the impact of such diversity on diagnosis and control. A Sudanese SAT2 foot-and-mouth disease virus (FMDV) of topotype VII originated in 2010 showed poor antigenic relationship (r1 value ≈ 0.00) with Sudanese SAT2 FMDV from 2008 when topotype XIII was circulating. After one or three doses of a vaccine derived from SAT2 virus in 2010, heterologous antibody titres with SAT2 virus in 2008 were ≤ 1.2 log 10, not consistent with likely protection, while homologous titres were 1.65 (after one dose) or 1.95 and 2.55 log10 (after 3 doses). SAT2 positive eld sera from Sudan in 2016 were not unvaryingly identi ed by virus neutralization tests (VNT) employing SAT2 viruses from 2010 and 2008. Proportions of positive sera by SAT2 virus from 2010 were always higher than those by viruses from 2008; consistent with the more frequent and recent circulation of topotype VII prior to 2016. Proportions by SAT2 virus from 2010 were 0.68 (±0.1) in one location (n=72), 0.39 (±0.1) in another one (n=94) and 0.52 (±0.1) in the whole test group (n=166). Corresponding values by viruses of 2008 were 0.53 (±0.1), 0.27 (±0.1) and 0.38 (±0.1). In the whole test group, differences were statistically signi cant (p=.02339). Like post-vaccination sera, eld sera (natural immunity) showed no considerable cross neutralization between topotype VII and presumably XIII; almost 45% (43/96) of SAT2 positive eld sera were positive to one topotype but not to the other. Experimental and surveillance ndings emphasized the implication of SAT2 diversity in Sudan. It is concluded that it is di cult to control SAT2 infection in Sudan using a monovalent vaccine. Beside a prophylactic vaccine from topotype VII, stockpiling of antigens from topotype XIII and rapid genotyping and matching studies are necessary approaches. When more frequent circulation of more than one topotype occurs, retrospective diagnosis by serological surveys could be problematic or imprecise.