Fana E, Shikongo B, Banda F, Qua M, Knowles N J, Shilongo A, Khaiseb S, Kapapero J K, Shoombe K K, Wadsworth J, Zaire G, Mokopasetso M, Kabajani J, Kabilika S, Di Nardo A, Hikufe E H, King D P (2022)

The first detection of a serotype O foot-and-mouth disease virus in Namibia

Transboundary and Emerging Diseases early view
Publisher’s version: https://doi.org/10.1111/tbed.14561

Abstract

This report describes the molecular characterization of a serotype O foot-and-mouth disease virus (FMDV) recovered from a field outbreak in the Zambezi region, Namibia during July 2021. Sequence analysis demonstrates that this FMDV belongs to the O/EA-2 topotype sharing closest nucleotide identity (99.5%) to FMD viruses collected since 2018 in Zambia. This is the first detection of serotype O in Namibia, and together with the cases that have been recently detected in southern Zambia, represent the first time that this serotype has been detected in the Southern African FMD endemic pool since 2000, when a virus of Asian origin (O/ME-SA/PanAsia) caused an outbreak in South Africa. This incursion poses a new threat for the region and the potential onward spread of O/EA-2 will now need to be closely monitored since serotype O vaccines are not widely used in Namibia, nor in neighbouring countries.

Abstract

Animal diseases such as peste des petits ruminants (PPR) and foot and mouth disease (FMD) cause significant economic losses in endemic countries and fast, accurate in-field diagnostics would assist with surveillance and outbreak control. The detection of these pathogens is usually performed at reference laboratories, tested using assays that are recommended by The World Organisation for Animal Health (OIE), leading to delays in pathogen detection. This study seeks to demonstrate a proof-of-concept approach for a molecular diagnostic assay that is compatible with material direct from nasal swab sampling, without the need for a prior nucleic acid extraction step, that could potentially be applied at pen-side for both PPR and FMD. The use of such a rapid, low-cost assay without the need for a cold chain could permit testing capacity to be established in remote, resource limited areas and support the surveillance activities necessary to meet the goal of eradication of PPR by 2030. Two individual assays were developed that detect > 99% of PPR and FMD sequences available in GenBank, demonstrating pan-serotype FMD and pan-lineage PPR assays. The ability for the BioGene XF reagent that was used in this study to lyse FMD and PPR viruses and amplify their nucleic acids in the presence of unprocessed nasal swab eluate was evaluated. The reagent was shown to be capable of detecting the viral RNA present in nasal swabs collected from naïve and infected target animals. A study was performed comparing the relative specificity and sensitivity of the new assays to the reference assays. The study used nasal swabs collected from animals before and after infection (12 cattle infected with FMDV and 5 goats infected with PPRV) and both PPR and FMD viral RNA were successfully detected two to four days post-infection in all animals using either the XF or reference assay reagents. These data suggest that the assays are at least as sensitive as the reference assays and support the need for further studies in a field setting.

Abstract

Foot-and-mouth disease (FMD) has large economic consequences in livestock systems, which must be robustly assessed to support disease control policy. This study described and assessed methods used within economic analyses of FMD and its control in endemic contexts. A systematic literature search was conducted in six academic search engines. Studies were included if they applied an economic analysis to a context with endemic FMD, producing a result articulated as a monetary figure. Data collected from each article included country of study, animal population, geographical level of analysis, time horizon and type of economic analysis. Each paper was scored using a quality assessment tool containing a checklist of 42 reporting criteria. Sixty-four articles were included, from 12,087 identified in the searches, describing results for 26 countries. Over half of the articles (56%) described economic impact of FMD retrospectively, often only accounting for a selection of direct costs at farm or household level. Median quality score calculated was 41% (range 8%-86%). Methods were generally poorly reported, confirming previously described difficulties in using published data to evaluate economic impact of endemic FMD. Few papers included disaggregation of public and private costs, or benefits, of FMD control, or accounted for economic or social influences of scale in vaccination programmes. Many of the studies included had gaps in both premise and methodology. This risks inefficient resource allocation if these analyses are used when planning and budgeting FMD control programmes in endemic contexts.

Pages

Trim content

® The Pirbright Institute 2024 | A company limited by guarantee, registered in England no. 559784. The Institute is also a registered charity.