First detection and molecular characterization of porcine reproductive and respiratory syndrome virus in Namibia, Africa

Umberto Molini; Lauren M Coetzee; Maria Y Hemberger; Bernard Chiwome; Siegfried Khaiseb; William G Dundon; Giovanni Franzo

doi:10.3389/fvets.2023.1323974

First detection and molecular characterization of porcine reproductive and respiratory syndrome virus in Namibia, Africa

Front Vet Sci. 2024 Jan 15:10:1323974. doi: 10.3389/fvets.2023.1323974. eCollection 2023.

Authors

Umberto Molini^{1

2}, Lauren M Coetzee^{2

3}, Maria Y Hemberger¹, Bernard Chiwome¹, Siegfried Khaiseb², William G Dundon⁴, Giovanni Franzo⁵

Affiliations

¹ School of Veterinary Medicine, Faculty of Health Sciences and Veterinary Medicine, University of Namibia, Windhoek, Namibia.
² Central Veterinary Laboratory (CVL), Windhoek, Namibia.
³ Faculty of Veterinary Medicine, University of Teramo, Teramo, Italy.
⁴ Animal Production and Health Laboratory, Animal Production and Health Section, Department of Nuclear Sciences and Applications, Joint FAO/IAEA Division, International Atomic Energy Agency, Vienna, Austria.
⁵ Department of Animal Medicine, Production and Health, University of Padova, Legnaro, Legnaro, Italy.

Abstract

Introduction: The swine sector in Africa plays an important role in local economies, contributing to poverty alleviation and community subsistence. In addition, intensive farming is progressively becoming more important in the region. Therefore, any disease affecting swine populations can have detrimental effects on local communities. Porcine Reproductive and Respiratory Syndrome (PRRS) is among the most important infectious diseases affecting swine worldwide, but information on its epidemiology in Africa is extremely limited.

Material and methods: In the present study, 147 healthy butchered pigs, originating from 15 Namibian intensive and rural farms were tested by RT-PCR and the ORF7 genes of positive samples were sequenced for further genetic characterization and phylogenetic analysis. Additionally, 55 warthogs were also evaluated using the same approach.

Results: Overall, 7 out of 147 pigs (4.76%) tested positive, all originating from 3 rural farms (with a within-herd detection frequency higher than 14%) characterized by strong epidemiological links. All industrial pig and warthog samples were negative. Sequence analysis revealed that all strains belonged to the Betaarterivirus suid1 species, previously known as PRRSV type I, and were likely imported from Europe at least 6 years ago, evolving independently thereafter. When and how the first introduction occurred could not be determined due to the absence of other African sequences for comparison.

Discussion: The present work provides the first detection and characterization of PRRSV molecular epidemiology in Namibia. Based on the present findings, the presence of the PPRSV appears marginal and limited to backyard farms. While biosecurity measures applied in industrial farms appear to be effective in preventing viral introduction, PRRSV circulation in rural settings still represents a potential threat, and considering the socio-economical implication of livestock diseases decreasing animal performances in rural areas, active monitoring should be encouraged to promptly act against emerging menaces and guarantee the welfare of local pig populations.

Keywords: Africa; Namibia; PRRSV; molecular epidemiology; phylogenetics; virus.

Grants and funding

The author(s) declare financial support was received for the research, authorship, and/or publication of this article. This work was supported by the Department of Animal Medicine, Production and Health, University of Padua [grant number BIRD225455/22] and by the IAEA Peaceful Uses Initiative (PUI) VETLAB Network. The sequences were generated through the Sequencing Services of the Animal Production and Health sub-programme of the Joint Food and Agricultural Organization of the United Nations/International Atomic Energy Agency (IAEA) Division.