Journal of Biosafety and Biosecurity最新文献

This study investigated the usefulness of a two-serotype dengue mathematical model to gain insights into the effects of antibody-dependent enhancement and temperature on dengue transmission dynamics in the presence of vaccination and Wolbachia-carrying mosquitoes. In particular, the effects of temperature on the mosquito death and maturation rates in secondary infections were examined. A deterministic mathematical model was formulated and analysed to address this problem. The results suggest that controlling the population of aquatic mosquitoes is appropriate for reducing the incidence of secondary infections. Furthermore, the wAu Wolbachia strain was more effective in reducing secondary infections.

Disease dynamics are influenced by changes in the environment. In this study, unreported cases (U), environmental perturbations, and exogenous events are included in the epidemic Susceptible–Exposed–Infectious–Unreported–Removed model with time delays. We examine the process of switching from one regime to another at random. Ergodicity and stationary distribution criteria are discussed. A Lyapunov function is used to determine several conditions for disease extinction. The spread of a disease is affected when transitioning from one random regime to another via sudden external events, such as hurricanes. The model and theoretical results are validated using numerical simulations.

Typhoid fever is an important health issue in developing countries, and the pathogenicity of Salmonella enterica serovar Typhi (S. ser. Typhi) depends on the presence of different virulence factors. Therefore, this study aimed to investigate the spread of virulence genes among S. Typhi isolates from patients with typhoid fever in Baghdad, Iraq. Sixty S. Typhi isolates were collected from several hospitals in Baghdad and identified using VITEK-II and confirmed by polymerase chain reaction (PCR) to detect the 16S rRNA gene. After testing their susceptibility to different antimicrobials (via the disk diffusion method), we found the highest resistance rates (100 %) were to ampicillin, piperacillin, cefotaxime, and ceftriaxone. The highest sensitivity rates (100 %) were to ertapenem, imipenem, meropenem, and sulfamethoxazole/trimethoprim. The presence of genes encoding for virulence in S. Typhi isolates was tested by conventional PCR. The results showed that out of 60 isolates, 59 (98.3 %), 59 (98.3 %), 58 (96.7 %), and 60 (100 %) were positive for viaB, staA, cdtB, and orfL genes, respectively. The sequencing of PCR products (viaB, staA, cdtB, and orfL genes) was carried out at the Macrogen Company (Seoul, Korea). The sequences were compared with nucleotide sequences in the BLAST GenBank database, and data obtained from the sequencing of these virulence genes were submitted to GenBank under different accession numbers. A phylogenetic analysis of the 16S rRNA gene sequence found a high similarity between local sequences and the closely related sequences of genes in GenBank. The presence of the viaB, staA, cdtB, and orfL virulence genes in nearly all of the isolates under examination suggests that they play an important role in the pathogenicity of local isolates.

This study aims to investigate the potential impact of inhibitors targeting the papain-like protease (PLpro) of SARS-CoV-2 on viral replication and the host immune response. A mathematical model was developed to simulate the interaction among susceptible cells, infected cells, PLpro, and immune cells, incorporating data on PLpro inhibition. Through numerical simulations using MATLAB, the model parameters were estimated based on available statistical data. The results indicate that strategically positioned inhibitors could impede the virus’s access to host cellular machinery, thereby enhancing the immune response and gradually reducing susceptible and infected cells over time. The dynamics of the viral enzyme PLpro showed reduced activity with the introduction of the inhibitor, leading to a decline in viral replication. Moreover, the immune cell population exhibited functional recovery as the inhibitor suppressed PLpro activity. These findings suggest that inhibitors targeting PLpro may serve as therapeutic interventions against SARS-CoV-2 by inhibiting viral replication and bolstering the immune response.

This research aims to understand the effect of human awareness and the use of bed nets on malaria control programs. A deterministic host-vector mathematical model was utilized and simplified using the Quasi-Steady State Approximation, assuming the mosquito population is at equilibrium due to its fast, dynamic behavior. The model reveals two equilibrium states: the malaria-free equilibrium and the endemic equilibrium. The malaria-free equilibrium is locally asymptotically stable when the basic reproduction number is less than one and unstable if it is larger than one. Conversely, the malaria-endemic equilibrium is unique and stable if the reproduction number exceeds one and does not exist otherwise. Based on incidence data from Papua, parameter estimation and sensitivity analyses indicate that human awareness and the use of bed nets significantly reduce the reproduction number. To address budget constraints for interventions, the model was reformulated as an optimal control problem, characterized using the Pontryagin Maximum Principle, and solved with the forward–backward sweep method. Numerical experiments were conducted to assess the impact of various scenarios on the malaria control program. Cost-effectiveness analyses employing ACER, ICER, and IAR metrics suggest that while the combined implementation of awareness campaigns and bed nets effectively reduces infections, it incurs high costs. In contrast, implementing human awareness campaigns alone emerges as the best strategy based on ACER, ICER, and IAR standards. This study demonstrates that enhancing human awareness and promoting the use of bed nets are effective strategies for controlling malaria. However, due to budget constraints, focusing solely on awareness campaigns proves to be the most cost-effective intervention. This approach not only reduces malaria transmission but also optimizes resource allocation, highlighting the importance of targeted educational programs in public health initiatives for malaria control.

This paper presents and examines a COVID-19 model that takes comorbidities and up to three vaccine doses into account. We analyze the stability of the equilibria, examine herd immunity, and conduct a sensitivity analysis validated by data on COVID-19 in Indonesia. The disease-free equilibrium is locally and globally asymptotically stable whenever the basic reproduction number is less than one, while an endemic equilibrium exists and is globally asymptotically stable when the number is greater than one. Subsequently, the model incorporates two effective measures, namely public education and enhanced medical care, to determine the most advantageous approach for mitigating the transmission of the disease. The optimal control model is then determined using Pontryagin’s maximum principle. The integrated control strategy is the best method for reliably safeguarding the general population against COVID-19 infection. Cost evaluations and numerical simulations corroborate this conclusion.

The emergence and zoonotic transmission of poxviruses in the Middle East have been recognized as complex public health issues. Poxviruses, a vast family of DNA viruses, can infect many hosts, including animals and humans. The Middle East has had multiple epidemics of poxvirus infections (e.g., Monkeypox, Smallpox, and Camelpox) that have raised concerns owing to their detrimental effects on livestock, wildlife, and sporadic human cases. This review aims to thoroughly examine the complexity of the epidemiological patterns, intricate genetic diversity, and several contributing factors that support the emergence and zoonotic transmission of poxviruses in the Middle East. Several aspects of poxviruses contribute to the emergence of endemics and zoonotic breakouts, such as the complex nature of human-animal interactions, environmental changes, and their subtle capacity for viral adaptability. This review was compiled in the hopes of contributing to the current understanding of poxvirus biology and its implications for human and animal health in the Middle East. We provide a comprehensive overview of the most common poxviruses in the Middle East, including their classification, structure, replication cycle, pathogenesis, route of transmissions, and of how the Middle East has developed ways to mitigate these biological threats.