Pathogenicity and pathogenesis of a recent highly pathogenic avian influenza subtype H5N8 in mule ducklings in Egypt

Research (Published online: 10-01-2023)

7. Pathogenicity and pathogenesis of a recent highly pathogenic avian influenza subtype H5N8 in mule ducklings in Egypt

Mahmoud M. Abotaleb, Ahlam Mourad, Esraa Fouad, Walied Abdo, and Samir A. Nassif

Veterinary World, 16(1): 59-67

ABSTRACT

Background and Aim: In late 2017, an H5N8 highly pathogenic avian influenza (HPAI) virus, clade 2.3.4.4, was isolated from domestic ducks in Egypt, which was associated with high morbidity and low mortality. The pathogenicity increased due to the continuous circulation of virus in ducks. Thus, this study aimed to monitor the pathogenesis and pathogenicity of new H5N8 Avian influenza (AI) virus in mule ducklings.

Materials and Methods: The lethal dose 50 (LD50) for this new local HPAI H5N8 isolate was calculated. Twenty ducklings were inoculated with 0.1 mL of dilution containing 10 LD50 HPAI per duck. The clinical signs and mortalities were recorded until 30 days post-infection (DPI) to confirm viral pathogenesis. Reverse transcription polymerase chain reaction was used to detect viral shedding from collected cloacal swabs after 3rd, 5th, 7th, 10th, 14th, 21st, and 30th DPI. The main histopathological lesions associated with the presence of HPAI virus were also recorded on the 3rd and 14th DPI.

Results: The result showed that the LD50 of the new HPAI H5N8 was 104 log10. Clinical signs were observed after 2nd DPI, but it was clinically severe on 3rd, 4th, and 5th DPI in the form of respiratory and gastric disorders, forming 90% of all diseased ducklings, whereas 30% of the infected ducks only showed nervous signs. The mortality rate peaked on 4th and 5th DPI with a cumulative mortality rate of 60% for the inoculated ducks, whereas no mortality was recorded after 6th DPI. Dead ducks showed typical postmortem lesions of AI disease. Necrosis and ecchymotic or petechial hemorrhages on the heart, pancreas, liver, and spleen were observed, whereas the lung showed pneumonia. With regard to viral shedding, infected ducklings shed the virus from its gut until 7th DPI, but the number of duck shedders gradually decreased until 14th DPI after viral shedding. The histopathological findings indicated that the spleen and thymus showed necrosis and hemorrhages, whereas the brain showed multifocal malacic foci and spread meningitis. Moreover, the lung had intrabronchial hyaline degeneration and fibrinous pneumonia on 3rd DPI. Furthermore, the liver showed multifocal necrotic foci and subcapsular hemorrhage, whereas the kidney showed remarkable tubular degeneration, mostly within the collecting tubules. Furthermore, the heart showed marked myocardiolysis of the cardiac muscle fibers. On 14th DPI, all histopathological lesions of the examined organs were restored to normal.

Conclusion: The currently circulating HPAI H5N8 virus strain has high virulence, particularly for imported mule ducks that originated from non-vaccinated breeder ducks. Therefore, vaccination and quarantine measures must be applied on imported 1-day-old mule ducklings. Moreover, the pathogenesis must be reviewed and monitored for updating circulating AI strains caused by the continuous and rapid evolution of AI viruses.

Keywords: pathogenicity, pathogenesis, vaccination.

A review of new emerging livestock-associated methicillin-resistant Staphylococcus aureus from pig farms

Review (Published online: 10-01-2023)

6. A review of new emerging livestock-associated methicillin-resistant Staphylococcus aureus from pig farms

Aswin Rafif Khairullah, Shendy Canadya Kurniawan, Mustofa Helmi Effendi, Sri Agus Sudjarwo, Sancaka Chasyer Ramandinianto, Agus Widodo, Katty Hendriana Priscilia Riwu, Otto Sahat Martua Silaen, and Saifur Rehman

Veterinary World, 16(1): 46-58

ABSTRACT

Methicillin-resistant Staphylococcus aureus (MRSA) is a S. aureus strain resistant to β-lactam antibiotics and is often associated with livestock, known as livestock-associated (LA)-MRSA. Using molecular typing with multi-locus sequence typing, MRSA clones have been classified in pigs, including clonal complex 398. Livestock-associated-methicillin-resistant S. aureus was first discovered in pigs in the Netherlands in 2005. Since then, it has been widely detected in pigs in other countries. Livestock-associated-methicillin-resistant S. aureus can be transmitted from pigs to pigs, pigs to humans (zoonosis), and humans to humans. This transmission is enabled by several risk factors involved in the pig trade, including the use of antibiotics and zinc, the size and type of the herd, and the pig pen management system. Although LA-MRSA has little impact on the pigs' health, it can be transmitted from pig to pig or from pig to human. This is a serious concern as people in direct contact with pigs are highly predisposed to acquiring LA-MRSA infection. The measures to control LA-MRSA spread in pig farms include conducting periodic LA-MRSA screening tests on pigs and avoiding certain antibiotics in pigs. This study aimed to review the emerging LA-MRSA strains in pig farms.

Keywords: livestock-associated-methicillin-resistant Staphylococcus aureus, pig, zoonosis, public health.

Economic and value chain analysis to support an investigation and risk mitigation efforts on Marek's disease in layers in the southern part of Thailand

Research (Published online: 09-01-2023)

5. Economic and value chain analysis to support an investigation and risk mitigation efforts on Marek's disease in layers in the southern part of Thailand

Tosapol Dejyong, Karoon Chanachai, Tippawon Prarakamawongsa, Wandee Kongkaew, Anyarat Thiptara, Taweesak Songserm, Theera Rukkwamsuk, Damian TagoPacheco, and Waraphon Phimpraphai

Veterinary World, 16(1): 35-45

ABSTRACT

Background and Aim: Marek's disease (MD) is a common lymphoproliferative disease affecting chickens and causing economic losses in commercial poultry. The MD outbreak was noticed in the southern part of Thailand in 2019. The suspected cases were found with an abnormal number of cases of layers dying with clinical signs, for example, weakness and emaciation, with evidence of MD gross lesions. This study aimed to raise awareness of the MD outbreak through value chain analysis (VCA), identifying associated possible risk factors, and estimating the associated economic impact.

Materials and Methods: Value chain analysis, including seasonal calendar, value chain diagram, and layer movement mapping of the layer industry, was conducted. High-risk stakeholders were identified on the basis of risk practices and interactions between stakeholders. A case–control study was conducted to determine risk factors associated with the MD outbreak on layer farms, and partial budget analysis was used to estimate economic losses associated with MD.

Results: The value chain diagram showed the linkages between stakeholders, including estimation of the percentage of products moved from one stakeholder group to another and the negotiated price. Fourteen out of 35 layer farms were case farms. Farm size and source of birds were significantly associated with the MD outbreak. The MD outbreak caused total economic losses of 295,823 USD. Farms that slaughtered infected birds with additional revenues incurred losses of 140,930 USD, whereas farms that culled infected birds without additional revenue returned incurred losses of 1995 USD.

Conclusion: The VCA provided a better understanding of the layer and egg businesses in South Thailand and guided the development of questionnaires for outbreak investigation. The potential risk factor findings suggested the need for further exploration of the source of the MD outbreak.

Keywords: birds, case–control study, risk factors, Thailand.

Growth performance, meat quality, and blood characteristics of finisher crossbred pigs fed diets supplemented with different levels of green tea (Camellia sinensis) by-products

Research (Published online: 07-01-2023)

4. Growth performance, meat quality, and blood characteristics of finisher crossbred pigs fed diets supplemented with different levels of green tea (Camellia sinensis) by-products

Nguyen Cong Oanh, Cu Thi Thien Thu, Nguyen Thi Hong, Nguyen Thi Phuong Giang, Jean-Luc Hornick, and Pham Kim Dang

Veterinary World, 16(1): 27-34

ABSTRACT

Background and Aim: Dietary supplementation with green tea by-product shows special effects on animal parameters. This study aimed to assess the effects of green tea by-products (GTBP) in the diet on some blood parameters, growth performance, and carcass characteristics of finishing pigs and on meat quality, and nutritional composition of pork.

Materials and Methods: One hundred and sixty crossbred pigs with an initial body weight of 65.15 ± 0.38 kg, were distributed into four dietary treatments, with four replicates of 10 pigs each. The dietary treatments were a basal diet (control diet, CON), and three experimental diets (GTBP8, GTBP16, and GTBP24) based on the CON diet supplemented with GTBP at 8, 16, and 24 g/kg of feed. The studied parameters were examined during the experimental period of 10 weeks.

Results: No statistical differences in average daily feed intake, average daily gain, and feed conversion ratio were observed between the diet treatments (p > 0.05). Backfat thickness decreased (linear, p < 0.05) according to the GTBP levels but no other carcass parameters. Meat quality was not influenced by the GTBP levels (p > 0.05). However, pigs fed with GTBP had a decrease in cholesterol content and an increase in crude protein and total omega-3 content of pork compared to the CON diet (p < 0.05). Moreover, dietary supplementation with GTBP significantly decreased plasma cholesterol (p < 0.05), and trends for the decrease in low-density lipoprotein cholesterol and urea nitrogen were observed (linear, p = 0.08).

Conclusion: Up to 24 g/kg GTBP in the diet for finishing pigs does not impair animal performance and makes carcass leaner with softer meat as well as positive effects on cholesterol and fatty acid metabolism. Further experiments are needed to determine the optimal levels of GTBP addition in finishing pig diet to produce higher meat quality.

Keywords: blood parameter, finishing pigs, green tea, growth performance, meat quality.

Antifungal activity of silver nanoparticles prepared using Aloe vera extract against Candida albicans

Research (Published online: 06-01-2023)

3. Antifungal activity of silver nanoparticles prepared using Aloe vera extract against Candida albicans

Mbarga Manga Joseph Arsène, Podoprigora Irina Viktorovna, Marukhlenko Alla, Morozova Mariya, Senyagin Alexander Nikolaevitch, Anyutoulou Kitio Linda Davares, Mumrova Evgenia Yurievna, Manar Rehailia, Ada Arsene Gabin, Kulikova A. Alekseevna, Yashina Natalia Vyacheslavovna, Zhigunova Anna Vladimirovna, Orlova Svetlana, and Das Milana

Veterinary World, 16(1): 18-26

ABSTRACT

Background and Aim: Resistance to antifungal agents is a serious public health concern that has not been investigated enough because most studies on antimicrobials are dedicated to antibacterial resistance. This study aimed to synthesize silver nanoparticles (AgNPs) using Aloe vera extract, and to assess its antifungal activity against Candida albicans.

Materials and Methods: Silver nanoparticles were synthesized by reducing Ag nitrate with aqueous A. vera extracts. Physicochemical properties of synthesized AgNPs were determined by ultraviolet–visible spectrophotometry, photon cross-correlation spectroscopy, energy-dispersive X-ray fluorescence spectrometry, X-ray diffraction analysis, and Fourier-transform infrared spectroscopy. An antifungal investigation was performed against four clinical C. albicans (C1, C2, C3, and C4) and a reference strain, C. albicans ATCC 10321.

Results: Cubic AgNPs with a mean X50 hydrodynamic diameter of 80.31 ± 10.03 nm were successfully synthesized. These AgNPs exhibited maximum absorbance at 429.83 nm, and X-ray fluorescence (XRF) confirmed the presence of Ag in AgNPs solution by a characteristic peak in the spectrum at the Ag Kα line of 22.105 keV. Infrared spectra for AgNPs and A. vera extract indicated that the compounds present in the extract play an essential role in the coating/capping of synthesized AgNPs. Different concentrations (200, 100, 50, 25, 10, and 5 μg/mL) of AgNPs were tested. The antifungal activity was shown to be dose-dependent with inhibition zones ranging from 10 mm to 22 mm against C. albicans ATCC 10231, 0 mm to 15 mm against C1, 0 mm to 16 mm against C2 and C3, and 0 mm to 14 mm for C4. Minimum inhibitory concentration ranged from 16 μg/mL to 32 μg/mL against clinical C. albicans (C1, C2, C3, and C4) and was 4 μg/mL against C. albicans ATCC 10231.

Conclusion: This study showed the ability of A. vera to serve as an efficient reducing agent for the biogenic synthesis of AgNPs with excellent antifungal activity.

Keywords: Aloe vera, antifungal, antimicrobials, green synthesis, silver nanoparticles.

Behavioral responses to baited enclosure method that activates habituation in stray dogs

Research (Published online: 04-01-2023)

2. Behavioral responses to baited enclosure method that activates habituation in stray dogs

Sumpun Thammacharoen, Sapon Semsirmboon, Visara Chit-Opas, Phak-Anong Tangcharoensin, Kran Nilkachatarn, and Narongsak Chaiyabutr

Veterinary World, 16(1): 12-17

ABSTRACT

Background and Aim: The behavioral mechanism of stray dog occurrence is associated with domestication process. This study aimed to investigate the population and demographic relationship of stray dogs from our ecological habitat. We tested whether baited enclosure method could be used as an operant conditioning treatment to activate habituation behavior in stray dogs.

Materials and Methods: The first investigation determined the population and demographic characteristics of stray dogs in the metropolitan city of Bangkok using the mark and recapture procedure. In the second investigation, a large cage equipped with a digital camera was used as the feeding and habituation area. Food was provided at four corners for 2 h. The approach behaviors and eating patterns were recorded during this period for 7 days.

Results: The average number of stray dogs calculated within each cluster was 24 ± 6 dogs. For the natural small habitat, the density of stray dogs was 662 dogs per km2. This indicated that the number of dogs is underestimated using the mark and recapture procedure because of undetected puppies and shifts in the sex ratio in adult dogs. In the second investigation, we demonstrated that food was a potent positive reinforcer for stray dogs. The average onset of cage entry after offering the food was 17 min. The onset of cage entry and the reduction in the first meal duration suggested that the habituation process could be achieved within 1 week.

Conclusion: The results revealed the possibility of using a large cage as a novel enclosure for food offered as the positive reinforcer for TNR program trapping procedures. We suggest that this humane trapping procedure could be used to activate habituation behavior in stray dogs.

Keywords: food intake, operant conditioning, population, stray dog, trap, neuter, and release.

Distribution pattern of antibiotic resistance genes in Escherichia coli isolated from colibacillosis cases in broiler farms of Egypt

Research (Published online: 03-01-2023)

1. Distribution pattern of antibiotic resistance genes in Escherichia coli isolated from colibacillosis cases in broiler farms of Egypt

Mona A. A. Abdel-Rahman, Engy A. Hamed, May F. Abdelaty, Hend K. Sorour, Heba Badr, Wafaa M. Hassan, Azhar G. Shalaby, Ahmed Abd-Elhalem Mohamed, Mohamed A. Soliman, and Heba Roshdy

Veterinary World, 16(1): 1-11

ABSTRACT

Background and Aim: Multidrug resistance (MDR) of Escherichia coli has become an increasing concern in poultry farming worldwide. However, E. coli can accumulate resistance genes through gene transfer. The most problematic resistance mechanism in E. coli is the acquisition of genes encoding broad-spectrum β-lactamases, known as extended-spectrum β-lactamases, that confer resistance to broad-spectrum cephalosporins. Plasmid-mediated quinolone resistance genes (conferring resistance to quinolones) and mcr-1 genes (conferring resistance to colistin) also contribute to antimicrobial resistance. This study aimed to investigate the prevalence of antimicrobial susceptibility and to detect β-lactamase and colistin resistance genes of E. coli isolated from broiler farms in Egypt.

Materials and Methods: Samples from 938 broiler farms were bacteriologically examined for E. coli isolation. The antimicrobial resistance profile was evaluated using disk diffusion, and several resistance genes were investigated through polymerase chain reaction amplification.

Results: Escherichia coli was isolated and identified from 675/938 farms (72%) from the pooled internal organs (liver, heart, lung, spleen, and yolk) of broilers. Escherichia coli isolates from the most recent 3 years (2018–2020) were serotyped into 13 serotypes; the most prevalent serotype was O125 (n = 8). The highest phenotypic antibiotic resistance profiles during this period were against ampicillin, penicillin, tetracycline, and nalidixic acid. Escherichia coli was sensitive to clinically relevant antibiotics. Twenty-eight selected isolates from the most recent 3 years (2018–2020) were found to have MDR, where the prevalence of the antibiotic resistance genes ctx, tem, and shv was 46% and that of mcr-1 was 64%. Integrons were found in 93% of the isolates.

Conclusion: The study showed a high prevalence of E. coli infection in broiler farms associated with MDR, which has a high public health significance because of its zoonotic relevance. These results strengthen the application of continuous surveillance programs.

Keywords: antibiotic resistance, Egypt, Escherichia coli, integron, mcr-1, poultry.