Transboundary and Emerging Diseases

Macrobrachium rosenbergii holds significant importance in aquaculture within tropical and subtropical regions globally. An infection called infectious precocity virus disease (IPVD), caused by infectious precocity virus (IPV), has emerged in M. rosenbergii in China and causes significant economic losses. The diseased M. rosenbergii presents with the characteristics of sexual precocity and slow growth. Elaborating the route of transmission and host range of IPV is necessary to prevent the disease. Transmission of IPV to healthy M. rosenbergii can occur through the ingestion of IPV-infected tissue, immersion of viral filtrate, cohabitation with infected M. rosenbergii, or water-borne transmission in contaminated environment. Results showed that fertilized eggs and different growth and development stages (larvae Ⅰ–Ⅵ, postlarvae, juveniles, and adult prawns) from infected M. rosenbergii were negative for IPV, indicating that vertical transmissions did not occur. The results of artificial infection experiments showed that M. nipponense tested positive for the presence of IPV, but not in fishes Carassius auratus, Pangasius bocourti, Micropterus salmoides, and Oreochromis mossambicus, and crabs Scylla paramamosain and Eriocheir sinensis. IPV could cause slow growth in M. nipponense and mainly infected the second pereiopod, brain, eyes, and gills of M. nipponense. M. nipponense was found to be a new freshwater crustacean host for IPV. From December 2019 to March 2022, 260 M. nipponense samples in four regions were collected, including 230 M. nipponense IPV-positive samples according to nested PCR and 40 M. nipponense IPV-negative samples according to nested PCR. These findings could aid in preventing and managing IPV infections in crustaceans.

Avian influenza viruses (AIVs) are significant transboundary zoonotic pathogens that concern both animal and human. Since the first report of H5N1 AIV in Bangladesh in early 2007, it resulted in numerous outbreaks across the country, hindering the sustainable growth of the poultry industry through economic losses in different production systems (commercial and backyard). Highly pathogenic avian influenza (HPAI) virus and low pathogenic avian influenza (LPAI) virus are currently cocirculating and causing infection in poultry sectors in an endemic manner in Bangladesh as well as in wild bird species. The introduction of multiple clades of H5N1 in different poultry species and the reassortment of AIVs with different patterns of infections have complicated the epidemiological situation for control and created conditions to increase the virulence of the virus, host range, and potential zoonotic transmission. The risk of viral transmission at the human–poultry interface is increasing over time due to inadequate surveillance and early detection strategies and practices, ineffective biosecurity practices among poultry raisers, and the complex supply chains of backyard and commercial poultry and live bird market (LBM) systems. Improving AIV surveillance in poultry flocks and LBMs, vaccination, biosecurity, and awareness among poultry professionals is beneficial to controlling the disease burden in the poultry sector. However, human cases of AIV related to poultry production and marketing chain in Bangladesh suggest a One Health approach engaging various stakeholders from the public and private would be a better option for successfully controlling avian influenza outbreaks in Bangladesh. This review of literature presents the comprehensive overview of AIV infection status in Bangladesh, including a description of pathways for zoonotic transmission at different epidemiological interfaces, the genetic evolution of the virus, and the need for improvement of disease control strategies incorporated with early detection, application of effective vaccines, increases the proper biosecurity practices and improvement of awareness among the poultry raisers, traders and consumers using a One Health approach.

After 26 years of absence in Japan, a classical swine fever (CSF) outbreak occurred at a domestic pig farm in 2018. Vaccination against the CSF virus with a live attenuated vaccine at pig farms was restarted in October 2019, which was 13 years after the 2006 ban on vaccination. An individual-based simulation model for CSF antibody dynamics was developed to determine an effective CSF vaccination strategy for pig populations. In creating a simulated pig herd, the optimal vaccination age of piglets and the effect of vaccinating piglets twice were evaluated. Additionally, the herd immunity was monitored every 6 months for 4 years after the start of vaccination, and the effects of intensive sow replacement policies were assessed. The simulation results indicated that the vaccination age should be delayed relative to the age used before the 2006 ban on vaccination and shifted earlier, from 8 weeks to 6 weeks, as time elapses. The simulations indicated a tradeoff in protection between the weaning period (i.e., maternally derived antibodies) and the fattening period (i.e., by vaccine-induced antibodies). Mixing sows with high and low antibody titers, particularly sows that received the first vaccination and those born after the start of vaccination, resulted in a high variation in antibody titer among pigs on the farm. This study also clarified the positive effect of intensive sow replacement strategies on shortening the period in which sows show diverse titers. Differences in sow replacement rates among farms and/or the time lag in starting vaccination in different prefectures result in heterogeneity in herd immunity in Japan; thus, herd immunity status should be examined at every farm using this simulation model.

Infectious bronchitis is an acute, extremely contagious viral disease affecting chickens of all ages, leading to devastating economic losses in the poultry industry worldwide. Affected chickens show respiratory distress and/or nephritis, in addition to decrease of egg production and quality in layers. The avian coronavirus, infectious bronchitis virus (IBV), is a rapidly evolving virus due to the high frequency of mutations and recombination events that are common in coronaviruses. This leads to the continual emergence of novel genotypes that show variable or poor crossprotection. The immune response against IBV is complex. Passive, innate and adaptive humoral and cellular immunity play distinct roles in protection against IBV. Despite intensive vaccination using the currently available live-attenuated and inactivated IBV vaccines, IBV continues to circulate, evolve, and trigger outbreaks worldwide, indicating the urgent need to update the current vaccines to control the emerging variants. Different approaches for preparation of IBV vaccines, including DNA, subunit, peptides, virus-like particles, vectored and recombinant vaccines, have been tested in many studies to combat the disease. This review focuses on several key aspects related to IBV, including its clinical significance, the functional structure of the virus, the factors that contribute to its evolution and diversity, the types of immune responses against IBV, and the characteristics of both current and emerging IBV vaccines. The goal is to provide a comprehensive understanding of IBV and explore the emergence of variants, their dissemination around the world, and the challenges to define the efficient vaccination strategies.

Duck Tembusu virus (DTMUV), an emerging avian pathogenic flavivirus, causes severe neurological disorders and acute egg drop syndrome in ducks. Currently, several clusters of DTMUV, including clusters 1, 2, and 3, have been identified and caused outbreaks in Asia. However, most of the DTMUV pathogenesis evaluation has mainly focused on cluster 2, while limited information is available on the pathogenesis of other DTMUV clusters, particularly cluster 1. In this study, the pathogenesis of a cluster 1 DTMUV was investigated in Cherry Valley ducks and compared to our previously reported cluster 2.1 DTMUV. Our results demonstrated that cluster 1 DTMUV was generally less pathogenic than cluster 2.1 DTMUV in ducks as evidenced by slower body weight loss, lower morbidity and mortality rates, and milder pathological changes. Concordantly, delayed viremia, reduced viral loads in blood and tissues, and shorter shedding period with lower viral loads were also observed in cluster 1 DTMUV inoculated ducks compared with those reported in cluster 2.1 DTMUV. In addition, we also found that cluster 1 DTMUV exhibited significant antigenic difference compared to cluster 2.1 DTMUV. Altogether, our findings suggest distinct pathogenicity and antigenicity between cluster 1 and 2.1 DTMUVs in ducks, highlighting the potential association between DTMUV genotype and pathogenicity/disease severity. This study enhances our understanding of DTMUV pathogenesis in ducks and provides useful information for the design and development of effective DTMUV vaccines.

The phenomenon of antibiotic resistance stands as a paramount health challenge in the contemporary era. Within a One Health approach, it becomes crucial to effectively track the dissemination of antibiotic resistance, not only within humans and animals but also within the environment. To investigate the environment, the honey bee (Apis mellifera) has emerged as a prominent environmental bioindicator due to its social, behavioral, and morphological features. The objective of this study was to describe the antimicrobial resistance (AMR) patterns of bacterial isolates from the body surface and the gut of honey bees sampled from 33 colonies throughout the Emilia-Romagna region (Italy). A total of 608 strains were examined for 19 distinct antimicrobial compounds from various classes, and the results showed that more than 50% of the isolates for eight out of nine provinces showed characteristics of nonsusceptibility toward amoxicillin and penicillin, and, generally, 98.19% of isolated strains were considered AMR and 74.67% exhibited multidrug resistance (MDR) characteristics, more frequent in Gram-negative strains (87.74%) than in Gram-positive ones (60.34%). Additionally, a significant correlation with a lower prevalence of MDR bacteria was demonstrated for one province (Ferrara, odds ratio (OR) = 3.33, (1.67; 6.64), ). In conclusion, this study provides evidence for the utility of A. mellifera colonies as bioindicators for MDR bacteria, enabling their characterization and distribution at a geographical level. Additional investigations are required to further explore the potential role of honey bees as bioindicators for antimicrobial-resistant bacteria, particularly in terms of their association with environmental characteristics.