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At least 955 records · Page 53Linked to original sources
PubMed2026

Modeling reptile virus infection in vitro using Python regius airway organoids.

Zoonoses pose substantial global health risks, highlighting the need to better understand animal-to-human transmission. Reptiles are increasingly recognized as hosts of diverse pathogens, including numerous viruses, yet the diversity and prevalence of reptile pathogens, as well as their potential risk to humans, remain poorly understood. Here, we establish and characterize airway organoids derived from Python regius, providing an in vitro model to study reptile airway infection. Through de novo assembly of a Python regius reference genome, we characterize airway organoids at single-cell resolution, which suggests the presence of diverse cell populations including ionocytes, ciliated, secretory, goblet, endocrine, tuft, and basal cells. The organoids support productive infection with Ball Python Nidovirus (BPNV) and mount a robust epithelial antiviral response through the induction of interferon-stimulated genes, cytokines, and genes involved in chemical defense. As a proof-of-concept, treating organoids with antiviral drugs during infection reduces BPNV levels, highlighting the model's utility for drug testing. By providing a reductionist system of the serpentes airway, these organoids constitute a physiologically relevant in vitro model to study reptile viruses and host-pathogen interactions in their native host.

Animals↗
PubMed2003

Advances in biotechnology: new tools in future pig production for agriculture and biomedicine.

Biotechnology in livestock comprises an arsenal of reproductive biotechniques and molecular genetics. While molecular genetics are poorly developed in swine, reproductive techniques are more advanced and applied under field conditions. This review describes three selected examples of our own research to illustrate the implication of biotechnology in future pig reproduction. Sperm sexing technology is now available and can be used to generate piglets of the desired sex by IVF and ICSI. First studies also indicate satisfactory success rates following intrauterine insemination with sexed spermatozoa. Cloning technique and production of transgenic pigs require information about the regulation and time course of gene expression during in vitro production and pre-implantation development. Information on gene expression is scare in porcine embryos. With the exception of transcripts for the oestrogen receptor gene, no mRNA's from the activated porcine genome have been identified. Recent development of cDNA arrays might help to identify a larger amount of genes in single embryos. Remarkable progress has been made in organ transplantation technology. As the demand for human organs is increasing rapidly, the pig might serve as donor of xenotranplants, provided the transmission of zoonoses from the donor animal to the human recipient is prevented, donor organ anatomy and function are compatible, and immunological rejections (HAR, VAR MAC) can be overcome. The most promising strategy is the synthesis of human complement regulatory proteins in the pig. Transgenic pigs have been generated for hDAF or hCD 46 and their hearts have been transplanted into non human primates for up to 90 days. HCD 59 driven by CMV promotor provides significant protection against HAR at least under in vitro and in vivo conditions. Current studies indicate a temporary use in patients within the next 3-5 years. As the microinjection technology to produce transgenic offspring is time consuming and very expensive, nuclear transfer technology provides a possibility for multiplication without going through the germ line with recombination effects. A functional nuclear transfer system will be crucial for xenotransplantation as it is anticipated that the expression of several transgenes will be required.

Agriculture↗
PubMedDate not supplied

Campylobacter.

Species within the genus, Campylobacter, have emerged over the last three decades as significant clinical pathogens, particularly of human public health concern, where the majority of acute bacterial enteritis in the Western world is due to these organisms. Of particular concern are the species, C. jejuni and C. coli, which are responsible for most of these gastrointestinal-related infections. Although these organisms have already emerged as causative agents of zoonoses, several aspects of their epidemiology and pathophysiology are only beginning to emerge. Trends in increasing antibiotic resistance are beginning to emerge with oral antibiotics, which may be the drug of choice for when it is necessary to intervene chemotherapeutically. This review wishes to examine (i) emerging clinical aspects of the disease, such as Guillain Barre syndrome (GBS), (ii) the association between these organisms and poultry as a natural host, (iii) environmental aspects of Campylobacter epidemiology, (iv) the emergence of atypical campylobacters (v) emerging trends in antibiotic resistance, (vi) adoption of modern methods for the detection of campylobacters.

Animals↗
PubMed2001

Which hepatocyte will it be? Hepatocyte choice for bioartificial liver support systems.

Liver failure, notwithstanding advances in medical management, remains a cause of considerable morbidity and mortality in the developed world. Although bioartificial liver (BAL) support systems offer the potential of significant therapeutic benefit for such patients, many issues relating to their use are still to be resolved. In this review, these issues are examined in terms of the functions required, the cells of choice in such a system, and the most appropriate environment to optimize the function of such cells. The major functions identified to date for a BAL are ammonia detoxification and biotransformation of toxic compounds, although this somewhat belies the complexity of the functions required. Two practical choices for cell type within such a system are xenogenic hepatocytes and immortalized human hepatocyte lines. Both these choices have drawbacks, such as the transmission of zoonoses and malignant infiltration, respectively. Finally, improvements in culture conditions, such as supplemented media, biodegradable scaffolds, and coculture, offer the possibility of prolonging the differentiated function of hepatocytes in a BAL.

Animals↗
PubMed1995

Ehrlichiosis in a golf-oriented retirement community.

BACKGROUND: Ehrlichiosis due to Ehrlichia chaffeensis usually occurs sporadically or in small clusters, with an annual incidence estimated at 3 to 5 cases per 100,000 population in areas of endemic disease. The putative principal vector is the Lone Star tick (Amblyomma americanum). We investigated an outbreak of ehrlichiosis that occurred in June 1993 among members of a golf-oriented retirement community (community A) in Tennessee. The community is densely wooded and borders a wildlife-management area where deer are numerous. METHODS: We conducted a case-control study, using medical-history reviews, serologic testing, and testing with the polymerase chain reaction for E. chaffeensis infection. We also surveyed a sample of 10 percent of the households in community A and in another golf-oriented community (community B) more than 20 miles (32 km) from the wildlife-management area. Survey participants completed a questionnaire and provided specimens for serologic testing. In both communities, searches for ticks were undertaken. RESULTS: Eleven cases of symptomatic ehrlichiosis were identified in the case-control study, 10 of which were in community A (attack rate, 330 per 100,000). Of 311 surveyed residents of community A, 12.5 percent had serologic evidence of past E. chaffeensis infection, as compared with 3.3 percent of 92 in community B (relative risk in community A as compared with community B, 3.9; 95 percent confidence interval, 1.2 to 12.2). The risk of infection was associated with tick bites, exposure to wildlife, golfing, and among golfers, retrieving lost golf balls from the rough. Persons who never used insect repellent were more likely to have had infection than persons who did. In community A, thousands of Lone Star ticks were found; in community B, only three ticks were found. CONCLUSIONS: The high rate of E. chaffeensis infection in community A resulted from its proximity to a wildlife reserve. When outdoor recreational activities are common and concentrations of ticks are high, outbreaks of arthropod-borne zoonoses can be anticipated.

Adolescent↗
PubMed1989

Occasional parasitic infections of man in Papua New Guinea and Irian Jaya (New Guinea).

Most parasites of man in New Guinea are cosmopolitan species, widely distributed and highly prevalent in the island. Reports of other parasite infections are reviewed. This impoverished fauna includes anthroponotic species normally occurring at low prevalences, e.g. Isospora belli, Dientamoeba fragilis, Trichomonas hominis and a few zoonotic forms with pigs as reservoir hosts, notably Balantidium coli and Entamoeba polecki. Other zoonoses are very few and extremely rare. This may be due to the reduced placental mammal fauna. The potential for the spread of Taenia solium infection is highlighted, as is the unique zoogeographical distribution of the Strongloides species resembling S. fuelleborni. Enterobius gregorii is recorded for the first time from Papua New Guinea.

Adolescent↗
PubMed1987

Modern trends in veterinary public health.

The veterinary profession and its contribution to public health should expand in breadth, depth and flexibility to respond to the changing needs of community and society. This longstanding issue is still the subject of controversy between on the one hand those whose scientific activities contribute to our knowledge of food and environmental hygiene, enteric infections, food-borne diseases and zoonoses in general, and on the other the all too numerous traditionalists (even within the profession) who resist the venture of veterinarians into new territories and resent involvement in public health. Veterinarians are ideally suited to function in public health because of their orientation to populations, disease prevention, and the economic implications of disease.

Animals↗
PubMed2004

ProMED-mail: an early warning system for emerging diseases.

The Program for Monitoring Emerging Diseases (ProMED-mail) reports on outbreaks of diseases of infectious or toxic etiology, whether natural or intentionally released, that affect humans. Open to all sources, free of political constraints, and available to users free of charge, ProMED-mail exploits the speed and ubiquity of the Internet to serve as an early warning system for the detection of emerging disease outbreaks. ProMED-mail monitors diseases of plants and animals of agricultural importance in addition to zoonoses because of their key role in disease emergence. Reports are carefully screened for validity and are placed in an appropriate context by commentary and references from a panel of expert moderators. Reports are then posted to the Web and sent by e-mail to >32,000 subscribers in >150 countries.

Animals↗
PubMed2001

Issues in public health entomology.

Public health entomology focuses on the population biology of vector-borne infections, seeking to understand how such pathogens perpetuate over time and attempting to devise methods for reducing the burden that they impose on human health. As public health entomology passes its centennial, a series of pervasive research themes and spirited debates characterize the discipline, many reflecting a tension between field and laboratory research. In particular, institutional support for population-based research and training programs has fallen behind that for those using modern lab-based approaches. Discussion of modes of intervention against vector-borne infections (such as deployment of genetically modified vectors, the role of DDT in malaria control, host-targeted acaricides for Lyme disease risk reduction, and truck-mounted aerosol spraying against West Nile virus transmission) illustrates the discipline's need for strengthening population-based research programs. Even with the advent of molecular methods for describing population structure, the basis for anophelism without malaria (or its eastern North American counterpart, ixodism without borreliosis) remains elusive. Such methods have not yet been extensively used to examine the phylogeography and geographical origins of zoonoses such as Lyme disease. Basic ecological questions remain poorly explored: What regulates vector populations? How may mixtures of pathogens be maintained by a single vector? What factors might limit the invasion of Asian mosquitoes into North American sites? Putative effects of "global warming" remain speculative given our relative inability to answer such questions. Finally, policy and administrative issues such as the "no-nits" dictum in American schools, the Roll Back Malaria program, and legal liability for risk due to vector-borne infections serve to demonstrate further the nature of the crossroads that the discipline of public health entomology faces at the start of the 21st Century.

Animals↗
PubMed1996

Analysis of west African hunters for foamy virus infections.

Foamy viruses are a genus of complex retroviruses that infect a wide variety of mammals. However, a clear association with any disease process has yet to be proven for these viruses. A higher human seroprevalence was reported in African populations, perhaps due to exposure to simian foamy viruses (SFV) endemic in primates. However, the earlier serologic surveys were not confirmed by studies employing nucleic acid amplification. Foamy virus infections of humans clearly do occur as rare zoonoses among primate center or laboratory workers exposed to captive primates or their blood. We sought to detect foamy virus infections in a cohort of humans also presumed to be exposed to SFV, i.e., West African hunters. We constructed recombinant vaccinia viruses that expressed human foamy virus (HFV) Gag or Env polyproteins in mammalian cells. The sera from 17 monkey hunters or several controls were tested in radioimmunoprecipitation assays (RIPAs) against the recombinant HFV proteins. Chimpanzee sera or HFV-positive human sera immunoprecipitated gp130, the HFV Env precursor, as well as p74, the HFV Gag polyprotein. None of the hunters' sera recognized both of these recombinant proteins. We then employed a nested polymerase chain reaction (PCR) analysis of the hunters' DNA but also failed to detect foamy virus infections. Therefore, by utilizing a recombinant RIPA and a nested PCR assay, we have not identified foamy virus infections occurring naturally in hunters exposed to wild monkeys in West Africa.

Africa, Western↗
PubMed2004

Derivation and comparative assessment of retinal pigment epithelium from human embryonic stem cells using transcriptomics.

Human stem-cell derivatives are likely to play an important role in the future of regenerative medicine. Evaluation and comparison to their in vivo counterparts is critical for assessment of their therapeutic potential. Transcriptomics was used to compare a new differentiation derivative of human embryonic stem (hES) cells--retinal pigment epithelium (RPE)--to human fetal RPE. Several hES cell lines were differentiated into putative RPE, which expressed RPEspecific molecular markers and was capable of phagocytosis, an important RPE function. Isolated hES cell-derived RPE was able to transdifferentiate into cells of neuronal lineage and redifferentiate into RPE-like cells through multiple passages (>30 Population doublings). Gene expression profiling demonstrated their higher similarity to primary RPE tissue than of existing human RPE cell lines D407 and ARPE-19, which has been shown to attenuate loss of visual function in animals. This is the first report of the isolation and characterization of putative RPE cells from hES cells, as well as the first application of transcriptomics to assess embryonic stem-cell derivatives and their in vivo counterparts--a "differentiomics" outlook. We describe for the first time, a differentiation system that does not require coculture with animal cells or factors, thus allowing the production of zoonoses-free RPE cells suitable for subretinal transplantation in patients with retinal degenerative diseases. With the further development of therapeutic cloning, or the creation of the banks of homozygous human leucocyte antigen (HLA) hES cells using parthenogenesis, RPE lines could be generated to overcome the problem of immune rejection and could be one of the nearest term applications of stem-cell technology.

Cell Differentiation↗
PubMedDate not supplied

Epidemiology of hemorrhagic fever viruses.

Twelve distinct viruses associated with hemorrhagic fever in humans are classified among four families: Arenaviridae, which includes Lassa, Junin, and Machupo viruses; Bunyaviridae, which includes Rift Valley fever, Crimean-Congo hemorrhagic fever, and Hantaan viruses; Filoviridae, which includes Marburg and Ebola viruses; and Flaviviridae, which includes yellow fever, dengue, Kyasanur Forest disease, and Omsk viruses. Most hemorrhagic fever viruses are zoonoses, with the possible exception of the four dengue viruses, which may continually circulate among humans. Hemorrhagic fever viruses are found in both temperate and tropical habitats and generally infect both sexes and all ages, although the age and sex of those infected are frequently influenced by the possibility of occupational exposure. Transmission to humans is frequently by bite of an infected tick or mosquito or via aerosol from infected rodent hosts. Aerosol and nosocomial transmission are especially important with Lassa, Junin, Machupo, Crimean-Congo hemorrhagic fever, Marburg, and Ebola viruses. Seasonality of hemorrhagic fever among humans is influenced for the most part by the dynamics of infected arthropod or vertebrate hosts. Mammals, especially rodents, appear to be important natural hosts for many hemorrhagic fever viruses. The transmission cycle for each hemorrhagic fever virus is distinct and is dependent upon the characteristics of the primary vector species and the possibility for its contact with humans.

Animals↗
PubMedDate not supplied

Epidemiology of Clostridium difficile-induced intestinal disease.

The epidemiology of Clostridium difficile-induced intestinal disease is an intriguing subject about which there are few answers but many remaining questions. Although it is accepted that altered intestinal microecology (usually the result of antimicrobial therapy) is a major predisposition to disease, the details of microbial interactions are not yet known and clearly involve more than simple overgrowth of a resistant member of the resident flora. A variety of reservoirs of C. difficile are recognized. These include endogenous carriage, environmental contamination, and zoonoses, but the relative epidemiologic importance of these varied sources is yet to be determined. Because minor variations in methods for cultivation of C. difficile can markedly affect the ability to detect the organism, even the prevalence of endogenous carriage by various populations is not fully defined. There is good evidence for nosocomial acquisition of disease, but the frequency of this event and the usefulness of preventive measures need to be determined. The development of a typing system would provide a valuable tool for investigating many of the remaining questions. Finally, in addition to the recognized risk factors, which include the apparently predisposing alteration in intestinal microecology and exposure to C. difficile, there appear to be other, as yet undefined, variables that help to determine whether disease will occur. Perhaps the elucidation of the details of the pertinent microbial interactions as well as an understanding of the relevant host-pathogen relationships will provide important insights into the epidemiology of C. difficile-induced disease.

Anti-Bacterial Agents↗
PubMed1982

Pre-exposure rabies immunization of man with suckling mouse brain vaccine.

A case series study is reported which included serologic results obtained in 195 persons recruited from personnel and trainees of the Pan American Zoonoses Center in Buenos Aires, Argentina, and workers from other institutions. The individuals were vaccinated with three doses of suckling mouse brain vaccine administered on alternate days, and some of them were given a booster dose 30 or 365 days after the primary immunization. The sizeable percentage of reactors with a high neutralizing antibody response in a short period of time, the small number of persons requiring a booster dose 30 days after the first vaccine dose, the rapid and intense secondary immune response and the absence of serious post-vaccinal reactions justify encouraging the use of this abbreviated prophylactic course of suckling mouse brain vaccine.

Antibody Formation↗
PubMed1995

Eosinophilic enteritis in northeastern Australia. Pathology, association with Ancylostoma caninum, and implications.

While eosinophilic gastroenteritis is considered a rare condition, eosinophilic enteritis without gastric involvement is quite common in northeastern Australia. We present 79 patients with biopsy-proven eosinophilic enteritis, 70 seen since 1987. In 10 patients, eosinophilic enteritis was associated with infection by single, sexually immature, adult hookworms, most positively identified as the common dog hookworm Ancylostoma caninum. An additional 22 patients (of 34 tested) had serological evidence of A. caninum exposure. The essential pathology, i.e., edema and eosinophilic infiltration of the gut wall, ascites, and regional lymphadenopathy, was identical to that seen in eosinophilic gastroenteritis. Additional, more specific features included pathological reactions centered on attached worms, mucosal alterations and ulcers considered to be hookworm bite sites, and submucosal and lymph node granulomas with central eosinophil degranulation and degradation products. Since A. caninum has an almost worldwide distribution, it is probable that A. caninum-induced eosinophilic enteritis occurs outside Australia. We show that the worm is easily overlooked in pathological specimens and that care is required to preserve worms intact for specific parasitological identification. The clinical and pathological features were similar to those seen in another human enteric helminthic zoonosis, anisakiasis. The possibility that there are yet other undiscovered intestinal zoonoses remains.

Adolescent↗
PubMed1999

Artificial liver support in acute liver failure.

The concept that a bioartificial device could compensate for the loss of hepatic function and thus improve the outcome of acute liver failure (ALF) was first suggested more than three decades ago. Currently, and reflecting renewed interest in this possibility, three such devices are undergoing clinical evaluation. Each has been shown to perform metabolic functions normally performed by the liver, thus affecting the serum biochemistry of patients with ALF. However, despite potential merit, these devices have not yet been shown to improve the outcome of patients with ALF. Also, some major safety issues remain to be resolved, in particular the risk of transmission of unknown zoonoses to man.

Animals↗
PubMed2005

Newer respiratory virus infections: human metapneumovirus, avian influenza virus, and human coronaviruses.

PURPOSE OF REVIEW: Recently, several previously unrecognized respiratory viral pathogens have been identified and several influenza A virus subtypes, previously known to infect poultry and wild birds, were transmitted to humans. Here we review the recent literature on these respiratory viruses. RECENT FINDINGS: Human metapneumovirus has now been detected worldwide, causing severe respiratory tract illnesses primarily in very young, elderly and immunocompromised individuals. Animal models and reverse genetic techniques were designed for human metapneumovirus, and the first vaccine candidates have been developed. Considerable genetic and antigenic diversity was observed for human metapneumovirus, but the implication of this diversity for vaccine development and virus epidemiology requires further study. Two previously unrecognized human coronaviruses were discovered in 2004 in The Netherlands and Hong Kong. Their clinical impact and epidemiology are largely unknown and warrant further investigation. Several influenza A virus subtypes were transmitted from birds to humans, and these viruses continue to constitute a pandemic threat. The clinical symptoms associated with these zoonotic transmissions range from mild respiratory illnesses and conjunctivitis to pneumonia and acute respiratory distress syndrome, sometimes resulting in death. More basic research into virus ecology and evolution and development of effective vaccines and antiviral strategies are required to limit the impact of influenza A virus zoonoses and the threat of an influenza pandemic. SUMMARY: Previously unknown and emerging respiratory viruses are an important threat to human health. Development of virus diagnostic tests, antiviral strategies, and vaccines for each of these pathogens is crucial to limit their impact.

Communicable Diseases, Emerging↗
PubMed2001

Monitoring and surveillance for rare health-related events: a review from the veterinary perspective.

Disease monitoring and surveillance systems (MOSSs) have become one of the major components of veterinary activity. Such systems are used to assess the existing levels of prevalence, the effectiveness of control programmes and, after disease eradication, to document the continued absence of disease from a given region or zone. With decreasing disease or infection prevalence, traditional approaches become less reliable and increasingly costly. The objective of this work was to summarize and discuss methodological issues related to veterinary (animal health) MOSSs. There are considerable inconsistencies in the use of the terms 'monitoring' and 'surveillance'. Passive as well as active MOSS have their disadvantages when used for rare health-related events such as emerging and re-emerging diseases. There is a need for evaluation and improvement of these approaches. Integrated systems that call for the use of several parallel surveillance activities seem to be the favoured approach, and analytical methods to combine MOSS data from various sources into a population prevalence, or probability of disease freedom, are under development. The health and safety of the animal and human generations depends on our continuous ability to detect, monitor and control newly emerging or re-emerging livestock diseases and zoonoses rapidly. Uniform surveillance definitions, sound scientifically based approaches that use the resources and data available, and a pool of researchers and veterinary public health officials with sufficient training in epidemiology, are critically important to handle this challenging task.

Animals↗