Vector-borne diseases account for approximately 17% of the global burden of non-communicable diseases, causing more than 700,000 deaths annually, particularly in the African Region of the World Health Organization (WHO) [1] . Among these, dengue is a rapidly expanding mosquito-borne viral disease primarily transmitted by Aedes aegypti [2] . While dengue cases are widely reported worldwide, surveillance in Africa remains limited, and outbreaks often go undocumented. However, past outbreaks in Mozambique (1984-1985), Senegal (2006), Côte d’Ivoire (2008), Cape Verde (2009) and Burkina Faso (2016-2017, 2023) highlight the growing threat of dengue in the region [2] . Currently, vector control is the only effective means to reduce dengue transmission, but traditional interventions such as insecticide spraying and larval source reduction face challenges, including insecticide resistance and inconsistent implementation. To address these limitations, innovative approaches like Wolbachia-based mosquito control are being developed [3] . Wolbachia is an intracellular endosymbiotic bacterium that naturally infects approximately 66% of insect species, including Aedes albopictus, but it is not naturally found in Aedes aegypti [4] - [6] . When introduced into Aedes aegypti, Wolbachia spreads through maternal transmission and disrupts mosquito reproduction via mechanisms such as cytoplasmic incompatibility, sex ratio distortions, and parthenogenesis [4] [7] [8] . Importantly, Wolbachia blocks dengue virus replication within mosquitoes, reducing their ability to transmit the disease [9] . Decades of research have led to the successful establishment of Wolbachia strains in Aedes aegypti populations, and field trials are now planned in Africa, including Burkina Faso, to evaluate their effectiveness in controlling dengue. As these releases would be the first of their kind in the region, ethical and biosafety committees have emphasized the need for a comprehensive risk assessment to ensure that Wolbachia-infected Aedes aegypti do not pose unintended ecological or public health risks. This study aims to systematically assess these risks by identifying potential hazards, establishing a risk assessment framework, and quantifying the likelihood and severity of adverse outcomes. Given the limited empirical data on Wolbachia releases in Africa, this research will provide critical insights to inform decision-making and guide the implementation of Wolbachia-based dengue control strategies [10] .

Our study focuses on assessing the risks inherent in releasing Ae. aegypti mosquitoes infected with Wolbachia as part of the fight against dengue. We identified and evaluated risks based on participant feedback and a Bayesian Belief Network (BBN). To achieve this, we designed a questionnaire informed by identified risks, which allowed us to collect participant opinions and conduct a superficial evaluation of the biosafety management systems of their respective departments.

Notably, 20% of study participants reported the absence of a biosafety management system in their departments. Additionally, 68% of respondents conducted their research activities without support from a biosafety team, and 12% had never participated in biosafety training. This highlights the presence of an existing biosafety management system but with significant structural deficiencies, as five out of 20 participants were unaware of its existence. Given the activities conducted at IRSS/DRO, a biosafety officer or team should accompany all experimental manipulations, and all personnel should undergo mandatory biosafety training tailored to their specific roles.

Using the questionnaire, participants assigned probability and consequence scores to hazards categorized as having “CMH” (economic, social, and cultural) effects. These scores were used to calculate the risk associated with each hazard. All calculated risks (100%) ranged between 0 and 0.261 (below 0.40), indicating that the identified hazards were either negligible, very low, or low. Specifically, 46.15% of the risks were negligible, 44.23% were very low, and 9.62% were low. These results might initially suggest a positive conclusion; however, the Bayesian Belief Network (BBN) reveals certain limitations.

The BBN is a tree-like structure that illustrates the relationships between risks, highlighting their interactions. It comprises a Directed Acyclic Graph (DAG) and a Conditional Probability Table (CPT). In the BBN, hazards (or risks) are represented as nodes, which interact in a way that the occurrence of one node can trigger or exacerbate another’s consequences. The DAG consists of nodes and links that describe relationships between variables. Here, the nodes represent identified risks, and each is connected to others by links, arcs, or edges to show conditional dependencies. A link between a parent node and a child node indicates a functional or statistical correlation. Each child node (connected to one or more parent nodes) contains a CPT that specifies the conditional probability of the node being in a particular state, given the state configurations of its parent nodes. Conditional probability reflects the likelihood of an event occurring if another event occurs, and it was used to calculate the probability of each node. The absence of a link between two nodes means no CPT can be defined.

For instance, the “Economic and Sociocultural Change” component of “CMH,” which contains four of the five highest-calculated risks, has four parent nodes (healthcare, tourism, reduced income, increased expenses) leading to the child node “economic change.” It also has six other parent nodes (scapegoating, migration, unfavorable media, social conflicts, legal actions, social fear) leading to the child node “social behavior change.” These two child nodes then converge on the aforementioned subcomponent. Given these interdependencies, it is crucial to consider all risks and implement precautionary measures across all subcomponents to mitigate the identified “CMH” effects.

Beyond the limitations of the BBN, additional uncertainties must be considered. During interviews, participants revealed that the classification of “CMH” risks was predominantly based on theoretical knowledge, such as reading articles and making deductions. For example, the endosymbiotic nature of the Wolbachia bacterium led them to assert that the genetic or behavioral modification of Ae. aegypti would have no “CMH” effects. Furthermore, the lack of a well-structured biosafety management system and insufficient biosafety training among personnel are uncertainties that must be addressed for an objective and effective risk assessment. The lack of empirical data on Ae. aegypti infected with Wolbachia limits the ability to conduct a more in-depth risk analysis.

Nonetheless, as observed in Yogyakarta, Indonesia [13] , and Australia [11] , the results are promising, with risks ranging from negligible to very low. Moreover, 80% of the highest risks are social rather than biological. The “sociocultural change” parameter had the most significant influence, driven by the perception that the population might poorly receive the dissemination project. This parameter alone accounted for 80% of the most significant risks. For instance, the hazard RA 49, “negative messages on social media,” was classified as the highest individual risk (albeit low), with a probability of 0.548, a consequence of 0.476, and a calculated risk of 0.261. These hazards can be mitigated with tailored communication strategies and the involvement of social science professionals.

In contrast, in Yogyakarta, the parameter “mosquito management effectiveness” had the greatest impact, stemming from the perception that dengue had been eradicated, which could lead to reduce mosquito control efforts in households [13] . These differences highlight the importance of considering the specific ecological and socio-cultural contexts when implementing Wolbachia-based interventions. Burkina Faso differs significantly from Indonesia and Australia in terms of mosquito ecology, disease burden, public perception, and regulatory frameworks. For example, Burkina Faso has a high malaria burden, and mosquito control strategies often focus on malaria vectors rather than dengue-transmitting mosquitoes. Additionally, socio-cultural attitudes toward genetic or biological interventions in vector control may vary, influencing community acceptance. Unlike Indonesia, where community engagement played a crucial role in the project’s success, Burkina Faso may require different outreach approaches tailored to local beliefs and concerns. Understanding these distinctions can help refine risk mitigation strategies, ensuring that potential socio-economic and cultural concerns are adequately addressed.

Ultimately, the importance of risk assessment cannot be overstated. It reassures stakeholders about the safety of the study for both humans and the environment. Additionally, it protects research teams and institutions from potential legal proceedings. At the conclusion of our assessment, the results are encouraging, showing that the dissemination of Ae. aegypti mosquitoes infected with Wolbachia poses little to no danger. The parameter “sociocultural change” had the most significant influence, accounting for 80% of the most impactful risks. This explains why hazard RA 49, “negative messages on social media,” was identified as the highest individual risk, with a calculated risk of 0.261. However, in general, the identified hazards were either negligible, low, or very low. The calculated risks, as presented, are manageable, provided that an appropriate management plan is implemented. Furthermore, the Bayesian network allows for the identification of parent or source nodes, enabling proactive risk prevention at its root. That said, the limitations of the method, particularly the Bayesian Belief Network (BBN), must be considered. It is also important to acknowledge that the risks identified were based on studies conducted in Yogyakarta, Indonesia, and not under the specific conditions of Burkina Faso. Comparing Burkina Faso’s ecological and socio-cultural landscape with prior Wolbachia release sites provides valuable insights into tailoring mitigation strategies to local needs, ensuring both the effectiveness and acceptability of the intervention.

We express our gratitude to the heads of CIRDES, INSTech, IRSS, and UND. We are also sincerely thankful to all the laboratory participants for taking the time to complete the questionnaires.

This work was supported by the ARISE grant PP-FA-143 funded by the European Union and implemented by the African Academy of Sciences in partnership with the African Union Commission and the European Commission.

Conceptualization, E.M.D.B. and A.D.; Methodology, A.S., M.B.B. and E.M.D.B.; Data collection, A.S. and E.M.D.B.; data curation, A.S., E.M.D.B. and R.W.S; writing-original draft preparation, E.M.D.B., Funding acquisition, E.M.D.B. All authors have read and agreed to the published version of the manuscript.