A serological survey for antibodies against foot-and-mouth disease virus (FMDV) in domestic pigs during outbreaks in Kenya

Foot and mouth disease vaccine efficacy in Africa: a systematic review and meta-analysis

Background

Several factors, such as diverse serotypes, vaccination methods, weak biosecurity, and animal movements, contribute to recurrent Foot-and-Mouth Disease Virus (FMDV) outbreaks in Africa, establishing endemicity. These outbreaks cost over $2 billion annually, prompting a high-priority focus on FMDV vaccination. Despite extensive efforts, vaccine efficacy varies. This study aims to evaluate routine foot and mouth disease (FMD) vaccines in Africa via systematic review and meta-analysis.

Methods

A systematic review and meta-analysis were carried out following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Meta-analysis was conducted to assess the efficacy of FMDV vaccination using the meta for package of R.

Results

Vaccinated animals have roughly a 69.3% lower chance of FMDV infection compared to unvaccinated animals, as indicated by the pooled results from the random-effects model, which showed a risk ratio (RR) of 0.3073. There was a statistically significant heterogeneity (p < 0.05) across all of the included articles.

Conclusion

Overall findings suggest that if properly planned and implemented, FMDV vaccination programs and strategies in Africa could help control the spread of the disease throughout the continent and beyond.

Understanding what shapes disease control: An historical analysis of foot-and-mouth disease in Kenya

Interpreting the interplay between politics, social demographics and epidemiology is essential for understanding how a disease's occurrence and control evolve over time. Foot-and-mouth disease (FMD) virus was first detected in Kenya in 1915 and serotyped in 1932. This review aims to describe and appraise initiatives to control FMD in Kenya since its independence from British rule in 1964, using information from the scientific literature. We describe the historical dynamics of FMD epidemiology in the country and determine socio-political factors that have shaped the control strategies used. PubMed, Scopus, CAB abstracts, Science Direct, Web of Science and Google Scholar were used to search and retrieve papers, using predetermined search criteria encompassing FMD, Kenya and disease control programme descriptors. In total 1234 papers were identified and screened for relevance using the World Health Organization's guidelines for rapid review. Ultimately 69 references from this search were included, and information extracted and consolidated. These papers highlight that following independence, there was a structured effort to control FMD consisting of a compulsory subsidised vaccination programme in the Rift Valley with movement controls and quarantine when outbreaks occurred. This programme led to an initial decrease in recorded FMD outbreaks. However, endemic circulation continued and this programme was discontinued due to multiple factors, including political deprioritisation and changes in the structure of veterinary services. Only low levels of active surveillance have been applied since 1964; most surveillance is passive and relies on outbreak reports. Currently control focuses on outbreak management and a mixture of public- and privately-funded vaccination. This review highlights critical drivers influencing disease control programme implementation including veterinary service structure, the active participation of stakeholders with farming systems and availability of affordable and matched FMD vaccine. Additionally, it appraises the availability of historical information and draws attention to gaps in the historical record.

Evolution of antigenic and genetic characteristics of foot-and-mouth disease virus serotype A circulating in Thailand, 2007-2019

Foot-and-mouth disease (FMD) is a persistent, major economic concern for livestock productivity, which is highly exacerbated by outbreaks in Thailand. FMD virus (FMDV) serotype A is more highly antigenic and genetically diverse than other serotypes, which has important implications for vaccine development as well as selection. Therefore, it is essential to continuously monitor antigenic and genetic changes of field isolates of FMDV serotype A. Here we used antisera against three vaccine strains (A/118/87, A/Sakolnakorn/97, and A/Lopburi/2012) to analyze the antigenicity of 133 field isolates of FMDV serotypes A in Thailand from 2007 to 2019. The majority of the isolates from 2007 to 2008 reacted only with the antiserum against strain A/118/87. In contrast, antigenic analysis revealed broad cross-reactivity and antigenic variations of the isolates from 2009 through 2019 against strains A/Sakolnakorn/97 and A/Lopburi/2012. These results indicate periodic changes in the antigenicity of field isolates of FMDV serotype A. Phylogenetic analysis of the VP1 region revealed that all isolates were of the Sea-97 lineage within the ASIA topotype. Analysis of the L-fragment genome sequences of 30 FMDV isolates collected throughout Thailand revealed highly variable amino acid sequences of VP1 and 3A, with the lowest average identity (94.56 %) and invariant (78.43 %) rates, respectively. The present findings indicate the importance of an active routine surveillance system incorporating antigenic and genetic analysis designated to continually update information about field isolates of FMDV serotype A. Such a system is essential for establishing and improving measures to control FMDV infections in Thailand and in neighboring Asian countries.

A gold nanoparticle strip for simultaneously evaluating FMDV immunized antibody level and discriminating FMDV vaccinated animals from infected animals

A gold nanoparticle strip was developed for rapidly evaluating FMDV type O antibody level and simultaneously discriminating FMDV vaccinated animals from infected animals. The strip was established depending on the colloidal gold nanoparticle labeling technique. Staphylococcal protein A colloidal gold nanoparticles were used as a probe. The epitope antigens of FMDV structural proteins and nonstructural proteins were dispensed on a nitrocellulose membrane as two test lines, respectively, and goat anti-pig antibody IgG was used as a control line. The assay was evaluated with FMDV immunized, infected sera and positive sera for another virus. The results showed the specificities of the T1 and T2 lines were 95.17% and 100% respectively. The sensitivity was in accordance with commercial ELISA kits. The coincidence rate of the new strip with 3ABC Mab-bELISA and LPB-ELISA was 95.5% and 93.13%, respectively. In summary, this experimental strip could provide a simple, inexpensive and rapid approach for onsite detection of FMDV type O antibody level and discrimination of FMDV vaccinated from infected animals without any expensive instrument.

A gold nanoparticle strip was developed for rapidly evaluating FMDV type O antibody level and simultaneously discriminating FMDV vaccinated animals from infected animals.

Characterisation of recent foot-and-mouth disease viruses from African buffalo (Syncerus caffer) and cattle in Kenya is consistent with independent virus populations

BACKGROUND

Understanding the epidemiology of foot-and-mouth disease (FMD), including roles played by different hosts, is essential for improving disease control. The African buffalo (Syncerus caffer) is a reservoir for the SAT serotypes of FMD virus (FMDV). Large buffalo populations commonly intermingle with livestock in Kenya, yet earlier studies have focused on FMD in the domestic livestock, hence the contribution of buffalo to disease in livestock is largely unknown. This study analysed 47 epithelia collected from FMD outbreaks in Kenyan cattle between 2008 and 2012, and 102 probang and serum samples collected from buffalo in three different Kenyan ecosystems; Maasai-Mara (MME) (n = 40), Tsavo (TSE) (n = 33), and Meru (ME) (n = 29).

RESULTS

Antibodies against FMDV non-structural proteins were found in 65 of 102 (64%) sera from buffalo with 44/102 and 53/102 also having neutralising antibodies directed against FMDV SAT 1 and SAT 2, respectively. FMDV RNA was detected in 42% of the buffalo probang samples by RT-qPCR (Cycle Threshold (Ct) ≤32). Two buffalo probang samples were positive by VI and were identified as FMDV SAT 1 and SAT 2 by Ag-ELISA, while the latter assay detected serotypes O (1), A (20), SAT 1 (7) and SAT 2 (19) in the 47 cattle epithelia. VP1 coding sequences were generated for two buffalo and 21 cattle samples. Phylogenetic analyses revealed SAT 1 and SAT 2 virus lineages within buffalo that were distinct from those detected in cattle.

CONCLUSIONS

We found that FMDV serotypes O, A, SAT 1 and SAT 2 were circulating among cattle in Kenya and cause disease, but only SAT 1 and SAT 2 viruses were successfully isolated from clinically normal buffalo. The buffalo isolates were genetically distinct from isolates obtained from cattle. Control efforts should focus primarily on reducing FMDV circulation among livestock and limiting interaction with buffalo. Comprehensive studies incorporating additional buffalo viruses are recommended.