Zimbabwe hosts WOAH workshop on AMR in Aquaculture for english-speaking Africa

The theory of change underlying the progressive training on antimicrobial resistance (AMR) in aquaculture anticipates that participants will disseminate the knowledge acquired to national experts, extension workers and local communities, thereby extending the impact of the training beyond the initial attendees. Additionally, the training facilitated the formation of professional networks that will continue to collaborate after the conclusion of the program.

This training was attended by national AMR focal persons and fisheries veterinarians from English-speaking African countries. It provided a valuable platform for exchanging best practices and fostering a shared understanding aimed at developing effective mitigation strategies on AMR in aquaculture.

Hydrodynamic flows as vectors of AMR in aquatic ecosystem

Despite the significant impact of AMR in aquatic environments aquaculture this issue receives inadequate attention within the country AMR national action plan of the country. Participants emphasized the complex dynamics of AMR in aquatic settings, which are largely driven by contributions from multiple sectors. The problem is exacerbated by the absence of registered antibiotics for use in aquaculture within these countries, resulting in the utilization of unauthorized antibiotics and increased risks associated with AMR.

Additionally, hydrodynamic flows of such as water currents, tides, and river flows play a critical role in disseminating resistant bacteria and resistance genes originating from aquaculture and other activities involving effluents, thereby complicating efforts to control AMR. Unlike terrestrial ecosystems, aquatic environments provide continuous connectivity among farms, rivers, lakes, and oceans. Consequently, resistant bacteria and resistant genes can spread rapidly across various farms as well as wild aquatic animal populations, heightening the risk of AMR proliferation within these ecosystems.

One Health approach is imperative to address AMR in aquaculture 

The participants noted that integrated surveillance of AMR within the aquaculture sector is presently in its nascent stages. Monitoring AMR in aquatic ecosystems could be enhanced through the incorporation of hydrodynamic modelling to identify AMR hotspots. Resistant bacteria and resistance genes possess the potential to be transmitted between aquatic environments, humans, terrestrial animals, and broader ecosystems reciprocally.

Fish, shrimp, and molluscs are frequently consumed with minimal preparation, occasionally served only lightly cooked, thereby increasing the risk of zoonotic transmission and dissemination of resistant genes to humans. AMR transcends geographical boundaries and jurisdictions; consequently, managing AMR in aquaculture necessitates an integrated approach grounded in a One Health perspective.

Risk of AMR in aquaculture is beyond conventional resistance concerns

The appropriate administration of antibiotics has become a critical subject of concern due to the lack of adequate guidelines in numerous countries. Antimicrobial agents utilized in aquaculture are introduced into aquatic ecosystems via the water column ending up in the sediments, where they may persist and facilitate the emergence of resistance among indigenous aquatic microorganisms. Consequently, this leads to the continuous presence of resistance genes within environmental bacterial populations, which have the potential to be transferred to pathogens that affect both humans and animals.

Dilution and concentration efficacy of antibiotics in the aquatic ecosystem.

Participants highlighted the challenges in attaining therapeutic antibiotic concentrations in farmed aquatic animals when administered through medicated feed. A key issue with this method in aquaculture is that treatment is applied to entire populations, resulting in inconsistent intake among individual animals. Additionally, sick animals often consume less feed, causing antibiotic levels to drop below therapeutic thresholds in these individuals.

Such sub-therapeutic concentrations pose significant risks by promoting the selection of resistant pathogens instead of effectively eradicating infections. In stagnant or low-flow environments such as ponds, lagoons, and sediments, antimicrobials and resistant microorganisms tend to accumulate within biofilms, creating hotspots for resistance selection.

WOAH standards on Antimicrobial Use and AMR in aquatic animals not optional

WOAH’s standards on Antimicrobial Use (AMU) and AMR in aquatic animals are not optional recommendations or merely advisory guidelines, they are essential international benchmarks for Members to integrate into national regulations and operational practices. Their adoption and implementation are critical to ensuring prudent antimicrobial use and safeguarding animal, human, and ecosystem health.

Sub-sequent actions required from WOAH by the participants

The pre-assessment evaluation of the needs of participating Members in the workshop indicated a continued need for training on One Health coordination related to aquaculture, the application of alternative therapies, and national surveillance systems concerning AMU and AMR.