Bovine tuberculosis is a chronic bacterial disease primarily caused by Mycobacterium bovis, a member of the Mycobacterium tuberculosis complex (MTBC), with significant zoonotic implications. This study aimed to detect MTBC in wildlife species, specifically nilgai (Boselaphus tragocamelus) and sambar deer (Rusa unicolor), using gross pathology, histopathology, acid-fast staining, and molecular confirmation. Necropsied tissue samples were collected during post-mortem examination of a nilgai and a sambar deer from the Assam State Zoo, Guwahati, India. Macroscopically, multiple granulomatous tubercles of varying sizes were observed in the lungs and liver, with creamy white caseous material marked upon sectioning. Ziehl-Neelsen staining of the tissue smears from granulomatous lesions confirmed the presence of acid-fast bacilli. Microscopic examination of tuberculosis granulomas revealed a central necrotic mass surrounded by inflammatory cell infiltration, including Langerhans-type giant cells. Molecular confirmation of MTBC infection was achieved by amplifying hsp65 and IS1081 in tissue samples, further validated by Basic Local Alignment Search Tool for nucleotide analysis following Sanger dideoxy sequencing. In conclusion, this study confirmed the presence of tuberculosis in these wildlife species through an integrated approach combining pathology, microbiology, and molecular diagnostics, highlighting the need to understand pathogen entry into the herd and prevent potential spillover.

The Avipoxvirus infection continues to be a serious threat to the poultry production and avain biodiversity across the globe. The present study was undertaken to characterize Avipoxvirus isolates from fowl, pigeon, and duck origin from Assam, India, and to assess their genetic stability following adaptation in chicken embryo fibroblast (CEF) cell culture. The isolates were revived through chorioallantoic membrane (CAM) route in embryonated chicken eggs and confirmed by PCR of the highly conserved 4b gene. Nucleotide and amino acid differences between revived and CEF-adapted isolates were determined through sequencing and bioinformatic analysis. The comparison of the nucleotide sequences of isolates by pair wise analysis showed that there was high identity between the corresponding isolates suggesting a low variation in the cell culture adaptation process. Multiple alignment of deduced amino acid sequences revealed few substitutions with more being diverged in duck and pigeon isolates than the reference fowl pox strain (HP444). Host-associated clustering of isolates was indicated by phylogenetic analysis. The results have shown that the Avipoxvirus isolates are relatively stable in terms of genetic changes over a short period of in vitro adaptation but also host-specific differences exist. On-going genomic monitoring and prolonged passage experiments are required in order to be in a better position to comprehend the viral evolution and host adaptation.

Background: Foot and Mouth Disease (FMD) poses a significant economic threat to the cattle population in Assam, with recurrent outbreaks occurring annually. Methods: This study aimed to compare different diagnostic techniques for the molecular detection and serotyping of Foot and Mouth Disease Virus (FMDV) outbreaks in the region. Epithelial tissue samples (n=29) were collected following standard procedures. SYBR Green real-time PCR targeting the 3D gene, sandwich enzyme-linked immunosorbent assay (S-ELISA), multiplex PCR (mPCR), and reverse transcription loop-mediated isothermal amplification (RT-LAMP) were utilized for detection and serotyping. Result: All 29 tissue samples tested positive for FMDV using SYBR Green real-time PCR, mPCR and RT-LAMP, with 100% congruence in serotyping (20 serotype O, 9 serotype A). In contrast, S-ELISA detected only 86.21% of samples as positive (17 serotype O, 8 serotype A). Statistical analysis revealed significant differences between the sensitivity of S-ELISA and molecular techniques (p = 2.91x10-7). The findings underscore the superior sensitivity of SYBR Green real-time PCR, mPCR and RT-LAMP, highlighting their potential for enhancing FMDV surveillance and control efforts in Assam.

The leaves of Moringa oleifera have several pharmacological properties, including antimicrobial and antioxidant activities, and are rich in vitamins and minerals that may benefit human and animal health. Hence, this study aimed to determine the effects of Moringa oleifera ethanolic leaf extract (MOELE) on the immunity level of broiler chickens. A total of 144 day-old broiler chicks (Vencobb 430) were randomly allocated to four groups, with three replicates per group and twelve birds per replicate. The treatments were: T0/control = no extract; T1 = 2 mL/L MOELE in drinking water; T2 = 4 mL/L MOELE in drinking water; and T3 = 6 mL/L MOELE in drinking water. Immune organ indices and selected blood parameters were evaluated among the four groups. The average bursa of Fabricius organ indices in groups T2 and T3 were significantly (P < 0.05) higher than those in groups T0 and T1. For the spleen and thymus, group T3 showed statistically higher values than all other groups. On day 42, heterophil values in the MOELE-treated groups were significantly (P < 0.05) lower than those in the control group, whereas lymphocyte values in the MOELE-treated groups were higher (P < 0.05) than those in the control group. The H/L ratio also improved (P < 0.05) in the MOELE-treated groups by day 42 compared with the control group. The HI titre against Newcastle disease vaccine in groups T2 and T3 was significantly higher (P < 0.05) by day 42 than in the other groups. From these results, it can be concluded that addition of moringa extract to drinking water may have beneficial effects on broiler chicken health and may improve immunity.

Newcastle disease (ND) is a highly contagious viral infection affecting poultry and wild birds, caused by the ND virus (NDV), an avian paramyxovirus serotype 1. NDV strains vary in virulence and are categorized into three pathotypes based on their pathogenicity in chickens: lentogenic (low or avirulent), mesogenic (moderate virulence), and velogenic (high virulence). Velogenic strains cause high morbidity and mortality, leading to significant production losses and substantial economic impacts due to the cost of control measures. NDV exhibits high genetic diversity, emphasizing the need for continuous surveillance, advanced diagnostics, and improved prevention strategies. With the expansion of the global poultry industry and increasing international trade, effective ND control – particularly through vaccination – remains essential. However, a comprehensive overview that incorporates recent findings is lacking. This chapter addresses that gap by discussing NDV’s molecular structure, virulence, infection routes, and current research progress in vaccine development, including thermostable, genotype-matched, recombinant, vectored, and new-generation adjuvanted vaccines. It also evaluates various vaccination strategies, their efficacy, and recent innovations aimed at improving disease control in endemic regions. The overall goal is to enhance our understanding of ND and support the development of more effective vaccines.

Avian bornaviruses are a recently described genetically diverse group consisting of 15 separate viruses within five different viral species belonging to the genus Orthobornavirus within the family Bornaviridae. Amongst the avian bornaviruses discovered, the parrot bornaviruses (PaBV) belonging to species Orthobornavirus alphapsittaciforme possess the highest veterinary relevance and is considered to be a major threat to psittacine aviculture. Since the discovery of PaBV in psittacine birds suffering from proventricular dilatation disease (PDD) in 2008, PaBV infections have been reported worldwide. In India, to assess whether avian bornaviruses circulates in parrots, 83 psittacines from 13 different species including birds with suspected PDD based on clinical examination results (n = 33), cage mates of PDD-suspected birds without any clinical signs (n = 26) and dead birds with previous clinic suspicious for PDD (n = 24) were tested for PaBV. Cloacal swabs were collected from live birds and tissues were collected from dead birds and investigated for the presence of PaBV-RNA using reverse transcription polymerase chain reaction (RT-PCR). PaBV infection was detected in 44 birds (53.01%) belonging to 9 psittaciform species. Eighteen of the group of PDD-suspected birds (54.54%), 21 dead birds (87.50%), and 5 clinically healthy cage mates (19.23%) were positive for PaBV-RNA. Sequence analysis of the matrix (M) gene revealed infection by PaBV-4, belonging to the species Orthobornavirus alphapsittaciforme. To the best of our knowledge, there is no publication describing the circulation of Orthobornavirus alphapsittaciforme, PaBV-4 in captive psittacines in India. This study highlights the major impact on conservation projects including endangered/ vulnerable/ near threatened species as these birds rely on captive breeding for their survival. Therefore, there is an urgent need to recognize and understand the factors that might play a critical role in recent expansion of emergent avian pathogens and how they continue to spread and thrive.

Newcastle disease (ND) is a devastating viral disease affecting poultry and has a substantial economic impact associated with high morbidity and mortality rates. Effective control measures rely on biosecurity measures and vaccination. However, use of phylogenetically divergent, thermolabile vaccines remains a major constraint for controlling ND outbreaks despite vaccination. To address the gap, the present study was undertaken to assess the thermostability profile of mesogenic (Genotype XIII) Newcastle disease virus (NDV) isolates with the aim of identifying heat-stable strains circulating in Assam, India. Five NDV isolates were assessed for thermostability by subjecting them to a range of temperatures at different time intervals. Among the isolates, AS/KM/18/32 exhibited the highest thermal stability, retaining HA (log2) titer and infectivity (log EID50) at 56 °C for 30 min, with a half-life of 19.99 min and an inactivation rate constant of -0.0348 min-1. In conclusion, mesogenic NDV (Genotype XIII) isolates circulating in Assam exhibit variable thermostability, warranting further studies on their biological pathogenicity and immunogenicity with a view to developing genotype-matched thermostable vaccine candidates.

Background: This study aimed to investigate the persistence of Foot-and-Mouth Disease Virus (FMDV) in clinically recovered cattle following an outbreak, focusing on both local indigenous breeds (Lakhimi) and crossbred cattle (Holstein Friesian-cross) in Assam. Methods: A total of 129 cattle (36 local and 93 crossbred), clinically recovered from FMD, were included in the study. Oropharyngeal fluid (OPF) samples (n=178) were collected at various intervals post-recovery. FMDV detection was carried out using three molecular diagnostic techniques: Multiplex PCR, reverse transcription loop-mediated isothermal amplification (RT-LAMP) and SYBR Green real-time PCR, all targeting the FMDV 3D gene. Result: FMDV was detected in 38 samples (21.35%) by multiplex PCR, 47 samples (26.40%) by RT-LAMP and 49 samples (27.53%) by SYBR Green real-time PCR. While all three methods showed comparable diagnostic accuracy, real-time PCR proved to be the most sensitive, rapid, reliable and cost-effective technique. FMDV persistence was observed in 24.81% (32/129) of cattle up to the 1st month post-recovery, 11.63% (15/129) up to the 3rd month and 1.55% (2/129) up to the 6th month. Local non-vaccinated Lakhimi cattle exhibited higher rates of viral persistence for serotype O, with 33.33% (12/36), 22.22% (8/36) and 5.55% (2/36) showing persistence at the 1st, 3rd and 6th months post-recovery, respectively. In contrast, vaccinated Holstein Friesian-cross cattle, demonstrated lower persistence rates, with 19.23% for Serotype A and 22.39% for Serotype O at the 1st month and 10.45% for Serotype O at the 3rd month post-recovery. Importantly, no transmission of the virus to healthy in-contact animals was detected during the study period. Statistical analysis (P=0.23, Chi-square=5.57) revealed no significant difference in viral persistence between local and crossbred cattle, suggesting that factors beyond vaccination status might influence FMDV persistence. However, the findings underscore the critical role of vaccination in reducing viral persistence in recovered cattle.

Background: Swinepox is an economically important, classical pox disease of piglets. The present study was undertaken with a view to develop rapid serological tests to diagnose the disease. Methods: During the study period, 25 suspected swinepox outbreaks in Assam were confirmed by polymerase chain reaction with sequencing and phylogenetic analysis, further the outbreaks were confirmed by transmission electron microscopy (TEM) for identification of swinepox positive samples. The positive samples were used to isolate the virus in PK-15 cell line and develop indirect and sandwich ELISA. Result: The cell culture-based indirect ELISA was developed that demonstrated an accuracy of 88.8% compare to VNT and 100% sensitivity with 66.67% specificity, could identify 61.71% seroprevalence of swinepox in random pig serum samples. A sandwich ELISA was also developed with polyclonal sera raised in rabbits as coating antibody and swinepox positive pig serum as tracing antibody. The sandwich ELISA detected 77.78% positive cases compared to PCR. Swinepox is an emerging disease in North-eastern region with high sero-positivity observed during random sampling. This is the first report of using immune sorbent assays to detect swinepox.

Avian bornaviruses are a recently described genetically diverse group consisting of 15 separate viruses within five different viral species belonging to the genus Orthobornavirus within the family Bornaviridae. Amongst the avian bornaviruses discovered, the parrot bornaviruses (PaBV) belonging to species Orthobornavirus alphapsittaciforme possess the highest veterinary relevance and is considered to be a major threat to psittacine aviculture. Since the discovery of PaBV in psittacine birds suffering from proventricular dilatation disease (PDD) in 2008, PaBV infections have been reported worldwide. In India, to assess whether avian bornaviruses circulates in parrots, 83 psittacines from 13 different species including birds with suspected PDD based on clinical examination results (n=33), cage mates of PDD-suspected birds without any clinical signs (n=26) and dead birds with previous clinic suspicious for PDD (n=24) were tested for PaBV. Cloacal swabs were collected from live birds and tissues were collected from dead birds and investigated for the presence of PaBV-RNA using reverse transcription polymerase chain reaction (RT-PCR). PaBV infection was detected in 44 birds (53.01%) belonging to 9 psittaciform species. Eighteen of the group of PDD-suspected birds (54.54%), 21 dead birds (87.50%), and 5 clinically healthy cage mates (19.23%) were positive for PaBV-RNA. Sequence analysis of the matrix (M) gene revealed infection by PaBV-4, belonging to the species Orthobornavirus alphapsittaciforme. To the best of our knowledge, there is no publication describing the circulation of Orthobornavirus alphapsittaciforme, PaBv-4 in captive psittacines in India. This study highlights the major impact on conservation projects including endangered/ vulnerable/ near threatened species as these birds rely on captive breeding for their survival. Therefore, there is an urgent need to recognize and understand the factors that might play a critical role in recent expansion of emergent avian pathogens and how they continue to spread and thrive.

Myocarditis is considered a fatal form of foot-and-mouth disease (FMD) in suckling calves. In the present study, a total of 17 calves under 4 months of age and suspected clinically for FMD were examined for clinical lesions, respiratory rate, heart rate, and heart rhythm. Lesion samples, saliva, nasal swabs, and whole blood were collected from suspected calves and subjected to Sandwich ELISA and reverse transcription multiplex polymerase chain reaction (RT-mPCR) for detection and serotyping of FMD virus (FMDV). The samples were found to be positive for FMDV serotype “O”. Myocarditis was suspected in 6 calves based on tachypnoea, tachycardia, and gallop rhythm. Serum aspartate aminotransferase (AST), creatinine kinase myocardial band (CK-MB) and lactate dehydrogenase (LDH), and cardiac troponins (cTnI) were measured. Mean serum AST, cTn-I and LDH were significantly higher (P < 0.001) in < 2 months old FMD-infected calves showing clinical signs suggestive of myocarditis (264.833 ± 4.16; 11.650 ± 0.34 and 1213.33 ± 29.06) than those without myocarditis (< 2 months old: 110.00 ± 0.00, 0.06 ± 0.00, 1050.00 ± 0.00; > 2 months < 4 months: 83.00 ± 3.00, 0.05 ± 0.02, 1159.00 ± 27.63) and healthy control groups (< 2 months old: 67.50 ± 3.10, 0.047 ± 0.01, 1120.00 ± 31.62; > 2 months < 4 months: 72.83 ± 2.09, 0.47 ± 0.00, 1160.00 ± 18.44). However, mean serum CK-MB did not differ significantly amongst the groups. Four calves under 2 months old died and a necropsy revealed the presence of a pathognomic gross lesion of the myocardial form of FMD known as “tigroid heart”. Histopathology confirmed myocarditis. This study also reports the relevance of clinical and histopathological findings and biochemical markers in diagnosing FMD-related myocarditis in suckling calves.

The Newcastle disease virus (NDV) affects wild and domesticated bird species, including commercial poultry. Although the diversity of NDV in domestic chickens is well documented, limited information is available about Newcastle disease (ND) outbreaks in other bird species. We report an annotated sequence of NDV/Vulture/Borjuri/01/22, an avirulent strain of NDV reported from Borjuri, Northeast India, in Himalayan Griffon vulture. The complete genome is 15,186 bases long with a fusion protein (F) cleavage site 112GRQGR↓L117. The phylogenetic analysis based on the F protein gene and the whole genome sequence revealed that the isolate from the vulture belongs to genotype II, sharing significant homology with vaccine strain LaSota. The study highlights the possible spillover of the virus from domestic to wild species through the food chain.

This study investigates the epidemiology of subclinical mastitis, focusing on prevalence, risk factors, bacterial pathogens, virulence factors, antimicrobial sensitivity, and detection of methicillinresistant Staphylococcus aureus (MRSA) bacterial isolates in organized and unorganized dairy farms of Kamrup and adjoining districts of Assam. The overall prevalence of bovine subclinical mastitis was found to be 43.81% using the California Mastitis Test (CMT). Risk factor analysis revealed that age-wise, the highest prevalence was noted in the 4-6 years age group (51.95%) and at 4th lactation (60.40%). Significant associations were found between mastitis prevalence and various factors including age, breed, lactation number, stage of lactation, quarter-wise distribution, farm type, management system, and season. A total of 185 bacterial isolates were obtained, predominantly Staphylococcus spp. (143), with notable occurrences of Streptococcus spp. (22), Escherichia coli (14), and Enterococcus faecalis (6). Staphylococcus aureus emerged as the primary etiological agent, with 81.82% of isolates producing coagulase and 45.45% producing hemolysin, while 54.0% of Staphylococcus aureus isolates tested positive for the protein A (spa) gene. Antimicrobial sensitivity testing revealed enrofloxacin, gentamicin, and ceftriaxone as the most effective antibiotics, with penicillin-G demonstrating the least efficacy. Methicillin resistance was detected in 11.96% of Staphylococcus aureus isolates phenotypically and in 2.56% genotypically (mecA) revealing the emergence of MRSA which is important from a public health point of view. These findings highlight the prevalence of subclinical mastitis, the predominance of Staphylococcus aureus as the causative agent, and the emergence of antimicrobial resistance, which warrants effective control measures and antimicrobial management in dairy farming practices.

Newcastle disease (ND) is a critical viral disease in poultry, affecting various avian species worldwide and causing substantial economic losses annually in commercial and backyard poultry operations. Despite its global prevalence, ND can be controlled through proper vaccination and biosecurity management. Over the past 60-65 years, both live attenuated and inactivated ND virus vaccines have been extensively used to mitigate the economic impact of ND. Although live vaccines demonstrate high efficacy against the disease, achieving comprehensive control of ND outbreaks and their financial consequences remains challenging. The primary limitation of most commercially available live vaccines is their heat sensitivity, necessitating a cold chain for quality maintenance, which poses difficulties in village conditions or remote areas of developing tropical countries. This review discusses various methods of ND vaccine administration, their efficacy, and immunogenicity, focusing on the efficacy and stability of thermostable ND vaccines. A thorough understanding of these factors is essential for the long-term control and eradication of ND.

OBJECTIVE:Considering the paucity of information about food-associated Clostridioides difficile from India, a study was undertaken to establish the prevalence of C. difficile in a variety of foods of animal origin, together with molecular strain characterization and antimicrobial resistance. METHODS:A total of 235 samples comprising raw meat and meat products, fish products, and milk and milk products were screened for C. difficile. Toxin genes and other parts of PaLoc were amplified in isolated strains. The resistance pattern towards commonly used antimicrobial agents was studied by the Epsilometric test. RESULTS:C. difficile was isolated from 17(7.23%) different food samples of animal origin, including toxigenic (6) and non-toxigenic (11) isolates. In four toxigenic strains, the tcdA gene could not be detected under used conditions (tcdA-tcdB+). However, all strains had binary toxin-associated genes (cdtA and cdtB). The antimicrobial resistance was highest in non-toxigenic C. difficile isolates in food of animal origin. CONCLUSION:Meat, meat products and dry fish, but not milk and milk products were contaminated with C. difficile. Contamination rates were low with diverse toxin profiles and antibiotic resistance patterns among the C. difficile strains.

Abstract Newcastle disease virus (NDV), also known as orthoavulavirus 1, is an avian pathogen that was originally identified in 1926 [10, 16]. NDV infection has been reported in a wide range of birds with varied degrees of susceptibility [14]. Several countries worldwide, including Korea, India, Sri Lanka, Japan, Australia, and the Philippines, reported successive ND outbreaks [1, 6, 23, 27]. According to National Animal Disease Referral Expert System (NADRES) data, NDV outbreaks have been reported recently from different states in India including Andaman and Nicobar Islands, Pondicherry, West Bengal, Tripura, Manipur, Meghalaya, Haryana, Nagaland, Assam, Arunachal Pradesh. Many isolates have been reported from wild avian species apart from poultry in India [11, 12, 22]. On the basis of virulence, NDV strains are broadly categorized as lentogenic (least), mesogenic (moderately), and velogenic (highly) pathotypes [2].

Newcastle disease (ND) is a highly contagious viral disease of poultry causing significant economic losses worldwide. Vaccination is considered the most reliable approach to curb the economic menace that is ND, but the thermolabile nature of Newcastle disease virus (NDV) vaccination poses a significant threat to its protective efficacy. This study aimed to profile the thermostability of NDV isolates from duck (As/Km/19/44) and parrot (As/WB/19/91) and evaluate their immunogenic potential in chicks. Fusion protein cleavage site (FPCS) and phylogenetic analysis demonstrated the lentogenic nature of both the isolates/strains and classified them as class II genotype II NDV. The characterized NDV isolates were adapted in specific-pathogen-free (SPF) chicks by serially passaging. Biological pathogenicity assessment of chicken-adapted As/Km/19/44 (PSD44C) and As/WB/19/91 (PSP91C) revealed both the isolates to be avirulent with a mean death time (MDT) of more than 90 h and an intracerebral pathogenicity index (ICPI) ranging from 0.2 to 0.4. Both of the NDV isolates displayed varied thermostability profiles. PSD44C was the most thermostable strain as compared to PSP91C and the commercially available LaSota vaccine strain. The immunogenicity of PSD44C and LaSota was significantly higher than PSP91C. Based on these results, it is concluded that NDV isolate PSD44C is more thermostable and immunogenic when administered intraocularly without any adverse effects. Therefore, PSD44C is suitable for further research and vaccine development.

The present study was carried out to detect the circulating Newcastle disease virus (NDV) from various field outbreaks in Assam during 2018-2021. Nine hundred ninety-two clinical and post mortem samples were collected from the backyard and commercial poultry and subjected to molecular detection by Reverse Transcriptase-Polymerase Chain Reaction (RT-PCR). NDV could be detected in 445 (n=757, 58.78%) tissue samples and 53 (n=235, 22.55%) cloacal swabs collected from suspected poultry cases by RT-PCR. The findings of our study suggests that the sample of choice for detection of NDV from tissue samples was trachea (n=85, 92.94%), followed by spleen (n=96, 90.62%), lung (n=92, 86.95%), caecal tonsils (n=96, 77.08%), proventriculus (n=74, 60.81%), brain (n=92, 48.91%), intestines (n=73, 31.50%), kidney (n=52, 23.07%), and cloacal swab (n=235, 22.55%) by RT-PCR. Hence, the collection of specific tissue samples from field outbreaks for the detection of NDV is of paramount importance. In addition, RT-PCR can be considered a highly sensitive detection method for rapid and confirmative diagnosis of Newcastle disease virus.

The continuous emergence of Newcastle disease virus (NDV) poses a persistent threat to the poultry industry. Recent increasing outbreaks of NDV in the North East region of India have highlighted the need to closely monitor and analyze the potential risk factors for Newcastle disease (ND) outbreaks. In the present study, an attempt was made to genotype the circulating Newcastle disease virus (NDV) in the backyard and commercial poultry flocks in Assam, India. Sera samples from unvaccinated backyard poultry flocks and tissue samples of ND suspected cases were collected and tested for the presence of NDV antibodies using the Haemagglutination inhibition (HI) test. A total of seven NDV isolates were analyzed from different districts of Assam, India, both genotypically and pathotypically. All isolates were characterized as virulent, carrying 112RRKQRF117 amino acid residues at the cleavage site. As determined by phylogenetic analysis, the isolates clustered with members of genotype XIII of class II NDV. Further analysis of risk factors of ND occurrence was conducted through a questionnaire survey. All the results indicated an occurrence of genotype XIII of NDV in the farms with inadequate biosecurity and farming practices.