Epizootic, Endemic and Pandemic Zoonotic Viral Infections

More than 60% human infectious diseases have zoonotic origin. Cross species transmission of pathogens is a continuous, dynamic process that occurs throughout the world, giving rise to epizootic (temporary, limited infection), endemic (on-going infection limited to a defined geographic region) and pandemic viral infections (infection spreading to every part of the world) like the current COVID-19 pandemic, which depends on the existing conditions on the ground. In Nov 2021, sudden mortality of numerous migrating demoiselle cranes was reported from their resting site near Jodhpur, Rajasthan. The symptomatic cranes became gradually weak and were unable to fly. They eventually fell dead which caused concern locally, given the current prevailing SARS-CoV-2 pandemic situation the world over. By the end of Dec 2021, the number of cranes with mortality and morbidity reduced, making it a temporary “epizootic infection”. Molecular diagnosis carried out at a specialized laboratory identified the etiological agent to be the highly pathogenic Avian Influenza Virus H5N1 (HPAIV), which has been responsible for morbidity of avian species from different parts of the world. There was no report of spreading the H5N1 AIV infection from the infected migratory cranes to nearby chicken farms or pig farms for now. In the absence of vaccines against the highly pathogenic H5N1 AIVs, and the inherent ability of influenza viruses, both avian AIV and human IAVs to constantly mutate its envelope gene or the surface antigens, resulting from the error-prone nature of the viral RNA Polymerase enzyme are the roadblocks for development of a universal, broad-spectrum influenza vaccine. Even when such a universal vaccine against H5N1 is available, vaccinating a large number of wild migratory cranes would be difficult. However, it is possible and indeed necessary to vaccinate chickens in poultry farms and pigs in farms that raise pigs for human consumption.

Nipah Virus Unveiled: A Review Article

Nipah virus (NiV) is a highly infectious zoonotic pathogen that poses a significant threat to human and animal health. First identified in Malaysia in 1998, NiV has since caused several outbreaks in Southeast Asia, with sporadic cases reported in Bangladesh and India. The virus is primarily transmitted to humans through direct contact with infected animals, primarily fruit bats, or through the consumption of contaminated fruits and their juices. NiV infection presents a wide spectrum of clinical features, ranging from mild respiratory illness to severe encephalitis, with a high case fatality rate. The incubation period typically ranges from 4 to 14 days, during which patients develop fever, headache, myalgia, and respiratory symptoms such as cough and sore throat. As the disease progresses, neurological signs become prominent, including altered consciousness, seizures, and focal deficits. Severe cases may exhibit acute respiratory distress syndrome and multi organ failure. Laboratory findings often include lymphocytopenia, thrombocytopenia, and elevated liver enzymes. Diagnosis of NiV infection requires specialized laboratory testing, including reverse transcription-polymerase chain reaction (RT-PCR) and serological assays. Currently, no specific antiviral treatment exists for NiV infection, and management primarily focuses on supportive care. Prevention and control strategies encompass public health interventions, surveillance, and raising awareness among healthcare providers and the general population. The emergence and re-emergence of NiV highlight the urgent need for continued research, improved diagnostic capabilities, and the development of effective vaccines and therapeutics to mitigate the impact of this deadly virus.

Microbial Assessment and Antibiotic Susceptibility Profile of Bacterial Fish Isolates in an Aquaculture Production Site in Mefou Afamba Division of Cameroon

The practice of integrated fish farming and the use of local fish meal and manure for fish feeding in Cameroon constitute potential sources of resistant pathogenic bacteria in the fish pond environment.Therefore,a periodical and constant monitoring of the microbiological quality of fish pond is imperative.This study was to assess the microbial contamination of Mfou aquaculture production site and evaluate the antibiotic resistance profile of bacterial fish isolates.Samples of pond water(n=36),sediment(n=36),fishmeal(n=12)and African catfish(Clarias gariepinus),kanga(Heterotis niloticus)and Nile Tilapia(Oreochromis niloticus)(n=36,each)were collected to determine TVAC(Total Viable Aerobic Bacterial Count),FC(Fungal Count),SAC(Staphylococcus aureus count),TCC(Total Coliform Count)and FCC(Feacal Coliform Count).The fish skin isolates of S.aureus,Enterobacter sakazakii,Citrobacter freundii,Serratia fonticola,Klebsiella oxytoca,Proteus spp.,Aeromonas hydrophila,Kluyvera spp.,Moraxella spp.,Pasteurella multocida and Pseudomonas fluorescens were tested against penicillin G(10μg),chloramphenicol(30μg),sulfamethoxazole/trimethoprim(25μg),erythromycin(15μg),tetracycline(30μg),using the disk diffusion method.Results reveal a heavy contamination of fish farms with microbial load above the recommended limits.Our study indicates that fish ponds are sources of zoonotic pathogens underlining their epidemiological and clinical relevance.All bacterial isolates were multiresistant with a multiple antibiotic resistance index above 0.2.These data raise concern about the microbial contamination of aquaculture and associated public health risks in Cameroon.

Verification of Bacteroidales 16S rRNA markers as a complementary tool for detecting swine fecal pollution in the Yangtze Delta

To correctly assess and properly manage the public health risks associated with exposure to contaminated water,it is necessary to identify the source of fecal pollution in a watershed.In this study,we evaluated the efficacy of our two previously developed real time-quantitative PCR(qPCR)assays for the detection of swine-associated Bacteroidales genetic markers(gene 1-38,gene 3-53)in the Yangtze Delta watershed of southeastern China.The results indicated that the gene 1-38 and 3-53 markers exhibited high accuracy(92.5%,91.7%conditional probability,respectively)in detecting Bacteroidales spp.in water samples.According to binary logistic regression(BLR),these two swine-associated markers were well correlated(P<0.05)with fecal indicators(Escherichia coli and Enterococci spp.)and zoonotic pathogens(E.coli O157:H7,Salmonella spp.and Campylobacter spp.)in water samples.In contrast,concentrations of conventional fecal indicator bacteria(FIB)were not correlated with zoonotic pathogens,suggesting that they are noneffective at detecting fecal pollution events.Collectively,the results obtained in this study demonstrated that a swinetargeted qPCR assay based on two Bacteroidales genes markers(gene 1-38,gene 3-53)could be a useful tool in determining the swine-associated impacts of fecal contamination in a watershed.

Dynamic interaction of neutrophils and RFP-labelled Vibrio parahaemolyticus in zebrafish(Danio rerio)

Vibrio parahaemolyticus(Vp)is an aquatic zoonotic pathogen that causes vibriosis in marine animals as well as sepsis,gastroenteritis and wound infection in human.In vertebrates,the innate immune system plays a critical defense mechanism against Vp infection including transmigration of neutrophils.In this study,we have examined the genetic recombination and infectious process of Vp in the zebrafish(Danio rerio),a vertebrate model system extensively used for studying host-pathogen interactions.A pathogenic Vp strain,Vp57,tagged with red fluorescent protein(RFP)(Vp57^(RFP))was introduced into larval zebrafish at 3 days post fertilization(dpf),in which the innate immunity is present whereas the adaptive immunity has not yet developed.Vp57 and Vp57^(RFP)showed similar LD50 and induced similar symptoms and pathological changes in the hosts.We microinjected 579 colony-forming units(CFU)Vp57^(RFP)into the zebrafish caudal vein,and observed that neutrophils were recruited to the injection site and within 3 h post infection(hpi)Vp57^(RFP)were mainly distributed in the tail,eyes,heart and optic vesicle.After 3 hpi,the fish died with slight spine bending.Several Vp57^(RFP)were also detected in somites,the phagocytosis of neutrophils was activated through the progress of bacterial infections.We found that chemotaxis and phagocytosis of neutrophils occurs when zebrafish is infected by Vp57^(RFP),whereas Vp57^(RFP)can escape from neutrophils and colonize other remote regions using the blood circulation system.