INTRODUCTION: Smallholder poultry production is a major contributor to food security and rural livelihoods in low-and middle-income countries. However, infectious diseases limit improvements to smallholder poultry production and performance of the sector in general. Infectious diseases of poultry, especially viral diseases, have major impacts on the health and productivity of flocks and account for significant morbidities and mortalities of birds each year. METHODS: This study utilized participatory epidemiology approaches to better understand the poultry health constraints and challenges faced by smallholder poultry producers in village poultry systems in Northern Ghana and Central Tanzania. RESULTS: The results show dominance of small-scale semi-intensive and extensive scavenging poultry production systems in the study areas. Newcastle disease ranked as the highest cause of morbidity and mortality in chickens in the two countries. The disease occurred mainly during the months coinciding with the dry season in both countries. Other health challenges among poultry flocks included worm infestation, fowl pox, coryza, and coccidiosis. Producers, especially in rural locations, had poor access to veterinary services and critical inputs necessary for poultry production. In the Northern region of Ghana, producers lacked definitive diagnoses for sick poultry due to a shortage of veterinary personnel and diagnostic laboratories. DISCUSSION: These challenges point to the need for increased investment in poultry disease control and prevention programs, particularly in rural areas. Interventions focused on expansion of veterinary and agricultural extension services and diagnostic laboratory capacity in rural areas and increased gender-sensitive training to enhance smallholder knowledge in poultry husbandry and disease prevention measures will support the development of the smallholder village poultry systems. Tapping into the diverse genetic reservoir of local chicken ecotypes with enhanced resistance to Newcastle disease through genomic selection, coupled with models for enhancing ND vaccination supply and use in the rural areas are potential future avenues for addressing ND constraints to production.

OBJECTIVE: The present study estimated the seroprevalence of avian reovirus (ARV) infections in backyard chickens of the Mymensingh district in Bangladesh. MATERIALS AND METHODS: Considering several risk factors, a total of 460 serum samples were collected from backyard chickens from eight Upazilas of the Mymensingh district in Bangladesh. Blood samples were taken from the wing vein using 3-ml sterile syringes and kept at room temperature for clotting in a slanting position and then transported to the laboratory maintaining the cool chain. Subsequently, the prepared sera were harvested and stored at -20°C until used. Finally, an indirect enzyme-linked immunosorbent assay (ELISA) was performed to detect ARVspecific antibodies using a commercial ARV antibody detection ELISA test kit. RESULTS: The results revealed high prevalence rates of ARV antibodies, with a total seroprevalence of 69.78% (321/460). Area-wise, 74.55% (82/110) seroprevalence was recorded as the highest in Mymensingh Sadar, whereas 64% (32/50) was the lowest in Gauripur Upazila. With regard to sex, female chickens showed a significantly higher (p < 0.05) seroprevalence as 90.33% (271/300) compared to male chickens 31.25% (50/160). With regard to age groups, the seroprevalence of ARV infection was 59.33% (89/150) within 2-8 weeks, 82% (205/250) within 9-16 weeks, and 45% (27/60) within 17-20 weeks, respectively. Based on hygienic conditions, the highest seroprevalence of ARV was noted in backyard chickens housed in poor conditions 80% (120/150) than good conditions 50% (40/80). Backyard chickens reared in free-ranging conditions exhibited a significantly higher seroprevalence 73.33% (220/300) of ARV antibodies compared to rearing in separate houses 63.12% (101/160). The seroprevalence of ARV was higher in crossbreeds 71.67% (43/60), brought from market 76% (38/50), and unhealthy 78.57% (55/70) backyard chickens than non-descriptive indigenous 69.5% (278/400), home-reared 69.02% (283/410), and healthy chickens 68.21% (266/390). CONCLUSION: The high prevalence of ARV antibodies revealed in the current study indicates an extensive exposure of ARV to backyard chickens in Bangladesh that may be transmitted naturally to other chickens, ultimately leading to ominous economic effects on the poultry sector.

BACKGROUND: Avian pox is a viral disease documented in a wide range of bird species. Disease-related detrimental effects can cause dyspnea and dysphagia, and birds with high metabolic requirements, such as hummingbirds, are thus especially vulnerable to the pathogen. Hummingbirds have a strong presence in California, especially in urban environments. However, little is understood regarding the impact of pox virus on hummingbird populations. Currently, diagnosing a pox infection relies on obtaining a tissue biopsy, which poses significant risks to birds and challenges in the field. Understanding the ecology of hummingbird pox viral infections could be advanced by a minimally invasive ante-mortem diagnostic method. Our aim was to address whether pox infections can be diagnosed using integumentary system samples besides tissue biopsies. To meet this goal, we tested multiple integumentary sample types using a quantitative real-time PCR assay. A secondary study goal was to determine which sample types (ranging from minimally to highly invasive sampling) were optimal for identifying infected birds. METHODOLOGY AND PRINCIPAL FINDINGS: Pox-like lesion tissue, pectoral muscle, feathers, toenail clippings, blood, and swabs (both pox-like lesion tissue and non pox-like lesion tissue) were taken from live birds and carcasses of two species of hummingbirds found in California. To maximize successful diagnosis, especially for samples with low viral load, a real-time quantitative PCR assay was developed for detecting the hummingbird-specific Avipoxvirus 4b core protein gene. Avipoxvirus DNA was successfully amplified from all sample types obtained from 27 individuals. These results were compared to those of conventional PCR and comparisons were also made among sample types, utilizing lesion tissue samples as the gold standard. CONCLUSIONS AND SIGNIFICANCE: Hummingbird avian pox can be diagnosed without relying on tissue biopsies. We identify that feather samples, of which contour feathers yielded the best results, can be used for diagnosing infected birds, thus reducing sampling risk. In sum, the real-time PCR assay detected viral DNA in various integumentary system sample types and will be useful in future studies of hummingbird disease ecology.

Background

Avian pox is a viral disease documented in a wide range of bird species. Disease-related detrimental effects can cause dyspnea and dysphagia, and birds with high metabolic requirements, such as hummingbirds, are thus especially vulnerable to the pathogen. Hummingbirds have a strong presence in California, especially in urban environments. However, little is understood regarding the impact of pox virus on hummingbird populations. Currently, diagnosing a pox infection relies on obtaining a tissue biopsy, which poses significant risks to birds and challenges in the field. Understanding the ecology of hummingbird pox viral infections could be advanced by a minimally invasive ante-mortem diagnostic method. Our aim was to address whether pox infections can be diagnosed using integumentary system samples besides tissue biopsies. To meet this goal, we tested multiple integumentary sample types using a quantitative real-time PCR assay. A secondary study goal was to determine which sample types (ranging from minimally to highly invasive sampling) were optimal for identifying infected birds.

Methodology and principal findings

Pox-like lesion tissue, pectoral muscle, feathers, toenail clippings, blood, and swabs (both pox-like lesion tissue and non pox-like lesion tissue) were taken from live birds and carcasses of two species of hummingbirds found in California. To maximize successful diagnosis, especially for samples with low viral load, a real-time quantitative PCR assay was developed for detecting the hummingbird-specific Avipoxvirus 4b core protein gene. Avipoxvirus DNA was successfully amplified from all sample types obtained from 27 individuals. These results were compared to those of conventional PCR and comparisons were also made among sample types, utilizing lesion tissue samples as the gold standard.

Conclusions and significance

Hummingbird avian pox can be diagnosed without relying on tissue biopsies. We identify that feather samples, of which contour feathers yielded the best results, can be used for diagnosing infected birds, thus reducing sampling risk. In sum, the real-time PCR assay detected viral DNA in various integumentary system sample types and will be useful in future studies of hummingbird disease ecology.

The chicken immune system has provided an immense contribution to basic immunology knowledge by establishing major landmarks and discoveries that defined concepts widely used today. One of many special features on chickens is the presence of a compact and simple major histocompatibility complex (MHC). Despite its simplicity, the chicken MHC maintains the essential counterpart genes of the mammalian MHC, allowing for a strong association to be detected between the MHC and resistance or susceptibility to infectious diseases. This association has been widely studied for several poultry infectious diseases, including infectious bronchitis. In addition to the MHC and its linked genes, other non-MHC loci may play a role in the mechanisms underlying such resistance. It has been reported that innate immune responses, such as macrophage function and inflammation, might be some of the factors driving resistance or susceptibility, consequently influencing the disease outcome in an individual or a population. Information about innate immunity and genetic resistance can be helpful in developing effective preventative measures for diseases such as infectious bronchitis, to which a systemic antibody response is often not associated with disease protection. In this review, we summarize the importance of the chicken MHC in poultry disease resistance, particularly to infectious bronchitis virus (IBV) infections and the role played by innate immunity and inflammation on disease outcome. We highlight how future studies focusing on the MHC and non-MHC genes can potentially bring clarity to observed resistance in some chicken B haplotype lines.

Infectious laryngotracheitis (ILT) can cause severe losses in backyard flocks (BYFs) and commercial poultry. The prevalence of ILT, the circulating strains of ILT virus (ILTV) in BYFs, and the correlation of disease in BYF and commercial operations, is largely unknown. Of 8,656 BYF submissions, 88 cases of ILT were diagnosed at the California Animal Health and Food Safety Laboratory System in 2007-2017. ILT diagnosis by year varied from 0.19% to 1.7% of the total BYF submissions, with the highest number of cases submitted from Amador and Riverside counties. Moderate tracheitis, conjunctivitis, and occluded tracheal lumen were commonly reported gross anatomic lesions. Microscopically, inflammation and edema were observed in the trachea, lung, and conjunctiva; 62 (70%) cases had intranuclear inclusion bodies (INIBs), with 10 cases containing INIBs only in conjunctival sections. To analyze the circulating ILTV strains and to differentiate between field and vaccine strains of ILTV, real-time PCR and sequencing of 996 base pairs of the infected-cell polypeptide 4 ( ICP4) gene was performed on 15 ILTV-positive tracheal samples and compared to reference field and vaccine ILTV ICP4 sequences in GenBank. Fourteen strains were identical or closely related to the chicken embryo origin live virus vaccine strains, and one strain was closely related to a Chinese isolate, the USDA reference strain, and a vaccine strain. The presence of ILT in BYFs in counties with high commercial poultry concentrations demonstrates a risk for disease transmission and emphasizes the importance of continued surveillance and improved biosecurity in BYFs.

Herpes zoster, commonly referred to as shingles, is caused by the varicella zoster virus (VZV). VZV initially manifests as chicken pox, most commonly in childhood, can remain asymptomatically latent in nerve tissues for many years and often re-emerges as shingles. Although reactivation may be related to immune suppression, aging and female sex, most inter-individual variability in re-emergence risk has not been explained to date. We performed a genome-wide association analyses in 22,981 participants (2280 shingles cases) from the electronic Medical Records and Genomics Network. Using Cox survival and logistic regression, we identified a genomic region in the combined and European ancestry groups that has an age of onset effect reaching genome-wide significance (P>1.0 × 10(-8)). This region tags the non-coding gene HCP5 (HLA Complex P5) in the major histocompatibility complex. This gene is an endogenous retrovirus and likely influences viral activity through regulatory functions. Variants in this genetic region are known to be associated with delay in development of AIDS in people infected by HIV. Our study provides further suggestion that this region may have a critical role in viral suppression and could potentially harbor a clinically actionable variant for the shingles vaccine.