Since the appearance in the late of December 2019, SARS-CoV-2 is rapidly evolving and mutating continuously, giving rise to various variants with variable degrees of infectivity and lethality. The virus that initially appeared in China later mutated several times, wreaking havoc and claiming many lives worldwide amid the ongoing COVID-19 pandemic. After Alpha, Beta, Gamma, and Delta variants, the most recently emerged variant of concern (VOC) is the Omicron (B.1.1.529) that has evolved due to the accumulation of high numbers of mutations especially in the spike protein, raising concerns for its ability to evade from pre-existing immunity acquired through vaccination or natural infection as well as overpowering antibodies-based therapies. Several theories are on the surface to explain how the Omicron has gathered such a high number of mutations within less time. Few of them are higher mutation rates within a subgroup of population and then its introduction to a larger population, long term persistence and evolution of the virus in immune-compromised patients, and epizootic infection in animals from humans, where under different immune pressures the virus mutated and then got reintroduced to humans. Multifaceted approach including rapid diagnosis, genome analysis of emerging variants, ramping up of vaccination drives and receiving booster doses, efficacy testing of vaccines and immunotherapies against newly emerged variants, updating the available vaccines, designing of multivalent vaccines able to generate hybrid immunity, up-gradation of medical facilities and strict implementation of adequate prevention and control measures need to be given high priority to handle the on-going SARS-CoV-2 pandemic successfully.
Avian coccidiosis is a major parasitic disorder in chickens resulting from the intracellular apicomplexan protozoa Eimeria that target the intestinal tract leading to a devastating disease. Eimeria life cycle is complex and consists of intra- and extracellular stages inducing a potent inflammatory response that results in tissue damage associated with oxidative stress and lipid peroxidation, diarrheal hemorrhage, poor growth, increased susceptibility to other disease agents, and in severe cases, mortality. Various anticoccidial drugs and vaccines have been used to prevent and control this disorder; however, many drawbacks have been reported. Drug residues concerning the consumers have directed research toward natural, safe, and effective alternative compounds. Phytochemical/herbal medicine is one of these natural alternatives to anticoccidial drugs, which is considered an attractive way to combat coccidiosis in compliance with the “anticoccidial chemical-free” regulations. The anticoccidial properties of several natural herbal products (or their extracts) have been reported. The effect of herbal additives on avian coccidiosis is based on diminishing the oocyst output through inhibition or impairment of the invasion, replication, and development of Eimeria species in the gut tissues of chickens; lowering oocyst counts due to the presence of phenolic compounds in herbal extracts which reacts with cytoplasmic membranes causing coccidial cell death; ameliorating the degree of intestinal lipid peroxidation; facilitating the repair of epithelial injuries; and decreasing the intestinal permeability induced by Eimeria species through the upregulation of epithelial turnover. This current review highlights the anticoccidial activity of several herbal products, and their other beneficial effects.
In line with the substantial increase in the broiler industry worldwide, Clostridium perfringens -induced necrotic enteritis ( NE ) became a continuous challenge leading to high economic losses, especially after banning antimicrobial growth promoters in feeds by many countries. The disease is distributed worldwide in either clinical or subclinical form, causing a reduction in body weight or body weight gain and the feed conversion ratio, impairing the European Broiler Index or European Production Efficiency Factor. There are several predisposing factors in the development of NE. Clinical signs varied from inapparent signs in case of subclinical infection (clostridiosis) to obvious enteric signs (morbidity), followed by an increase in mortality level (clostridiosis or clinical infection). Clinical and laboratory diagnoses are based on case history, clinical signs, gross and histopathological lesions, pathogenic agent identification, serological testing, and molecular identification. Drinking water treatment is the most common route for the administration of several antibiotics, such as penicillin, bacitracin, and lincomycin. Strict hygienic management practices in the farm, careful selection of feed ingredients for ration formulation, and use of alternative antibiotic feed additives are all important in maintaining broiler efficiency and help increase the profitability of broiler production. The current review highlights NE caused by C. perfringens and explains the advances in the understanding of C. perfringens virulence factors involved in the pathogenesis of NE with special emphasis on the use of available antibiotic alternatives such as herbal extracts and essential oils as well as vaccines for the control and prevention of NE in broiler chickens.
Salmonellosis is one of the most important bacterial diseases in poultry, causing heavy economic losses, increased mortality and reduced production. The aim of this study was the comparative efficacy of a commercial probiotic and/or prebiotic with a live attenuated Salmonella Enteritidis (SE) vaccine on the protection of broiler chickens from SE challenge. The efficacy of probiotic or prebiotic products, as well as a live Salmonella Enteritidis (SE) vaccine at the 7th day of age, administered via drinking water, were evaluated for clinical protection and effects on growth performance of broiler chickens experimentally challenged with SE at the 28th day of age. The use of probiotic or prebiotic simultaneously with the live Salmonella vaccine can diminish the negative effect of live vaccine growth performance, reducing mortality rate, fecal shedding, and re-isolation of SE from liver, spleen, heart and cecum. The use of probiotic or prebiotic simultaneously with the application of the live Salmonella vaccine is a good practice to diminish the negative effect of the harmful bacteria and improve the growth performance of broilers. Thus, further studies may be carried out with layers and breeders.
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