Behavioral and ecological factors account for variation in the mass-independent energy expenditures of endotherms.

A persistent controversy has concerned the identification of the factors that influence the quantitative variation in the physiological characters of species, an example of which is the basal rate of metabolism of endotherms. The most important factor accounting for its variation is body mass as long as the range in mass is appreciable. But mass never accounts for all of the variation and none if species have the same mass. Most of the residual variation around the mass curve is associated with behavioral characters, ecological factors, and phylogeny, i.e., history. These agents influence energy expenditure by different means and at different stages in the life history of species. Phylogeny describes the historic origin, evolution, and distribution of character states in contemporary species. However, the level of energy expenditure is quantitatively determined by the collective of realized states in combination with conditions in the environment. Therefore, two stages determine energy expenditure: (1) the evolution of character states and (2) their impact in conjunction with conditions on the environment. Behavioral characters and ecological factors, when coupled with log10 mass, usually account for >94 % of the variation in the log10 basal rates of birds and mammals, a capacity not found in phylogenetic analyses. The difficulty of determining a direct impact of phylogeny on physiological characters results from its correlation with behavioral characters. When appropriate, the passerine/non-passerine dichotomy in birds and the sub/infraclass dichotomy in mammals combine with behavioral characters, ecological factors, and log10 mass to increase r (2) to account for 96-99 % of the variation in log10 basal rate. This occurs because dichotomies incorporate factors other than those already in the analyses. The clearest demonstration of the direct impact of character states is the equality of energy expenditure in species convergent with species from other clades without any evidence of the clade to which the species belong. A multifactorial approach depends on the inclusion of life history characteristics of species, but this analysis applies only to continuous, quantitative relationships, which are often modified by discontinuous agents. Distinctive character states distinguish species and therefore must be included in any attempt to account for differences in their level of energy expenditure. No analysis that ignores life history characteristics can account for the quantitative variation in energy expenditure beyond that associated with body mass.

A review of simulation modelling approaches used for the spread of zoonotic influenza viruses in animal and human populations.

Increasing incidences of emerging and re-emerging diseases that are mostly zoonotic (e.g. severe acute respiratory syndrome, avian influenza H5N1, pandemic influenza) has led to the need for a multidisciplinary approach to tackling these threats to public and animal health. Accordingly, a global movement of 'One-Health/One-Medicine' has been launched to foster collaborative efforts amongst animal and human health officials and researchers to address these problems. Historical evidence points to the fact that pandemics caused by influenza A viruses remain a major zoonotic threat to mankind. Recently, a range of mathematical and computer simulation modelling methods and tools have increasingly been applied to improve our understanding of disease transmission dynamics, contingency planning and to support policy decisions on disease outbreak management. This review provides an overview of methods, approaches and software used for modelling the spread of zoonotic influenza viruses in animals and humans, particularly those related to the animal-human interface. Modelling parameters used in these studies are summarized to provide references for future work. This review highlights the limited application of modelling research to influenza in animals and at the animal-human interface, in marked contrast to the large volume of its research in human populations. Although swine are widely recognized as a potential host for generating novel influenza viruses, and that some of these viruses, including pandemic influenza A/H1N1 2009, have been shown to be readily transmissible between humans and swine, only one study was found related to the modelling of influenza spread at the swine-human interface. Significant gaps in the knowledge of frequency of novel viral strains evolution in pigs, farm-level natural history of influenza infection, incidences of influenza transmission between farms and between swine and humans are clearly evident. Therefore, there is a need to direct additional research to the study of influenza transmission dynamics in animals and at the animal-human interface.

A minimum data set of animal health laboratory data to allow for collation and analysis across jurisdictions for the purpose of surveillance.

A minimum data set consisting of 15 data elements originating from laboratory submissions and results was formulated by a national committee of epidemiologists in Canada for the purposes of disease reporting, disease detection and analysis. The data set consists of both data that are filled out on the submission form as well as the results of the laboratory testing. The elements in the data set are unique identifier, premises identification, date submitted, geographic location, species, farm type, group type, total population of tested species on the farm, number sick, number dead, test(s) performed, disease agent, test result, disease classification by submitter and final laboratory diagnosis. The data set was designed to be concise while allowing for domestic and international disease reporting, effective analysis, including geographic, temporal and prevalence outputs, and syndromic surveillance to enable disease detection. The selected data elements do not identify the producer as specific geographic and nominal information is not included in the data set. The data elements selected, thus, allow for voluntary collaboration and data sharing by avoiding issues associated with privacy legislation.

Introduction to network analysis and its implications for animal disease modelling.

Social networks analysis (SNA) has recently been used in veterinary epidemiology to study livestock movements. A network is obtained by considering livestock holdings as nodes in a network and movements among holdings as links among nodes. Social networks analysis enables the study of the network as a whole, exploring all the relationships among pairs of farms. Highly connected livestock holdings in the network can be identified, which can help surveillance and disease prevention activities. Observed livestock movement networks in various countries have shown an important level of contact heterogeneity and clustering (topological, not necessarily geographical or spatial) and understanding the architecture of these networks has provided a better understanding of how infections may spread. The findings of SNA studies of livestock movement should be used to build and parameterise epidemiological models of infection spread in order to improve the reliability of the outputs from these models.

Using simplified models to communicate the importance of prevention, detection and preparedness before a disease outbreak.

Frontline farm workers and veterinary-policy-makers are arguably in the best positions to influence prevention, detection, and preparedness-for-control of farm animal diseases. It is important that such individuals make biologically sound decisions concerning the daily management and regulation of the health of animals. Such decisions should be based on a good understanding of key principles of disease spread and control. This paper summarises these principles, as described in previous publications, into simple models. These models may be used to communicate concepts to readers who may not have time to study more complex models. These models illustrate the relationship between the development of new disease cases (from existing cases, i.e., the reproductive ratio R) and (i) the duration of the period during which existing cases are available as infectious, (ii) contact rates, (iii) transmission rates and (iv) susceptibility. Understanding these concepts through models has great utility, facilitating better decisions for disease prevention, detection and preparedness-for-control, before an outbreak becomes unmanageable. These basic concepts apply to all animal species, including humans.

Estimating potential epidemic size following introduction of a long-incubation disease in scale-free connected networks of milking-cow movements in Ontario, Canada.

We used the movements of adult milking cows among farms enrolled in the Dairy Herd Improvement (DHI) program in Ontario to explore the size of an epidemic that might result from farm-to-farm movements of cows in the Province if a reportable long-incubation infection like tuberculosis (TB) were introduced and not detected for 1-3 years after introduction. A directed network was created for each year (2004-2006) using all pairs of individual shipments, defined as the movement of one or more cows on a single day, from a single source DHI farm to a single recipient DHI farm. A 3-year network was also developed that included all cow shipments that took place during these 3 years. The lower and upper bounds of potential maximal epidemic size were estimated using four network-analysis measures: (1) the farm out-degree, (2) the size of the largest strong and weak components, (3) the bow-tie approach, classifying farms into six different areas of a directed network and (4) the infection chain of a farm. All four of the DHI movement networks were found to be small-world, indicating that infection could spread over considerable distances by shipments that linked potentially distant clusters of farms. The networks were also scale-free, indicating most farms had relatively few connections to other farms, while there were a few highly connected farms. Characterization of the yearly networks showed that 41-47% of DHI farms were not involved in any cow shipments and were therefore not at risk of infection from this movement network; furthermore, if infection were introduced into a DHI farm that shipped animals that year, the infection would have stopped at that farm (or at least, not been passed on by shipment of adult milking cows) >50% of the time, and 75% of the time only one more DHI farm would have become infected through animal movements. Compared to the infection chain, which accounted for both the direction and the time sequence of shipments in the movement network, the other network-analysis measures provided biased estimates of potential epidemic size. The bow-tie approach provided a schematic representation of the level of risk of each farm in the network in spreading an infection, but overestimated the lower- and upper-bound measures of potential epidemic size because it did not account for the time sequence of shipments. Our infection-chain results suggest that introducing a long-incubation disease into the network of farms enrolled in the DHI program in Ontario that was not identified until 12 months after the incursion would, in a worst-case scenario, have resulted in 168 farms (representing 5% of all Ontario DHI herds) being infected as a consequence of adult cow movements among DHI farms. This estimate increased to 850 farms (26% of all DHI herds) if the infection were not identified for 36 months.

A review of network analysis terminology and its application to foot-and-mouth disease modelling and policy development.

Livestock movements are important in spreading infectious diseases and many countries have developed regulations that require farmers to report livestock movements to authorities. This has led to the availability of large amounts of data for analysis and inclusion in computer simulation models developed to support policy formulation. Social network analysis has become increasingly popular to study and characterize the networks resulting from the movement of livestock from farm-to-farm and through other types of livestock operations. Network analysis is a powerful tool that allows one to study the relationships created among these operations, providing information on the role that they play in acquiring and spreading infectious diseases, information that is not readily available from more traditional livestock movement studies. Recent advances in the study of real-world complex networks are now being applied to veterinary epidemiology and infectious disease modelling and control. A review of the principles of network analysis and of the relevance of various complex network theories to infectious disease modelling and control is presented in this paper.

Comparing network analysis measures to determine potential epidemic size of highly contagious exotic diseases in fragmented monthly networks of dairy cattle movements in Ontario, Canada.

Adult milking cow movements occurring in monthly periods in 2004-2006 were analysed to compare three network analysis measures to determine the lower and upper bounds of potential maximal epidemic size in an unrestrained epidemic: the out-degree, the infection chain or output domain of a farm, and the size of the strong and weak components. The directed networks generated by the movements of adult milking cows were highly fragmented. When all the farms that were not involved in shipments were included in the analysis, the risk of infection transmission through movements of adult cows was very low. To determine the size of an epidemic when an infected farm shipped cows in such a fragmented network, farm out-degree and infection chain provided similar and more reasonable estimates of potential maximal epidemic size than the size of the strong and weak components. Component analysis always provided estimates that were two to three times larger than the out-degree of infection chain approaches. For example, the upper bound was estimated to be 12-13 farms using out-degree and 16-17 farms using the infection chain, the components approach showed a range of 39-51 potentially exposed farms. Strong components provided an inflated measure of the lower bound of potential maximal epidemic size at first diagnosis because the time sequence of shipments was not considered. Weak components provided an inflated measure of the upper bound because both the time sequence and directionality of shipments between farms were ignored. Farm degree and infection chain measures should now be tested to determine their usefulness for estimating maximum epidemic size in large connected networks.

Antibiotic resistance of Campylobacter jejuni and Campylobacter coli isolated from hog, beef, and chicken carcass samples from provincially inspected abattoirs in Ontario.

Campylobacterjejuni is one of the most common causes of bacterial foodborne infection in the United States, and there are reports of resistance of Campylobacter spp. to antimicrobial agents used for the treatment of gastroenteritis. The purpose of this study was to determine the antimicrobial resistance patterns of Campylobacter spp. isolated from hog, beef, and chicken carcasses from provincially inspected abattoirs in Ontario. The agar dilution method was performed to measure antimicrobial resistance of the isolates. Antimicrobial resistance of Campylobacter isolates from hogs (n = 401), beef (n = 21), and chicken (n = 435) to ampicillin, azithromycin, chloramphenicol, ciprofloxacin, clindamycin, erythromycin, gentamicin, nalidixic acid, streptomycin, and tetracycline was determined. Resistance of chicken, hog, and beef isolates was 14.3, 18.2, and 9.5% to ampicillin; 17.9, 67.3, and 38.1% to azithromycin; 0, 0.5, and 0% to chloramphenicol; 3.7, 1.2, and 0% to ciprofloxacin; 2.3, 46.6, and 4.8% to clindamycin; 6.7, 43.6, and 4.8% to erythromycin; 0.2, 0, and 0% to gentamicin; 5.1, 10.7, and 0% to nalidixic acid; 13.6, 57.4, and 4.8% to streptomycin; and 52.6, 44.1, 42.9% to tetracycline, respectively. The hog isolates had the greatest resistance to seven of the ten antimicrobials tested. Results of this study confirm the existence of antimicrobial resistance of Campylobacter to various antimicrobial agents,especially ciprofloxacin and erythromycin, commonly used for treatment of campylobacteriosis in humans.

Antibiotic resistance of Salmonella isolated from hog, beef, and chicken carcass samples from provincially inspected abattoirs in Ontario.

The emergence of antimicrobial-resistant Salmonella organisms, especially Salmonella Typhimurium DT104, has been reported in many countries, including the United States and Canada. The purposes of this study were to determine the antimicrobial resistance patterns of Salmonella isolated from hog, beef, and chicken carcasses from provincially inspected abattoirs in Ontario and to determine the agreement between the agar dilution method and the microbroth dilution method for measurement of antimicrobial resistance of the isolates. Antimicrobial resistance of Salmonella isolates from hogs (n = 71), beef (n = 24), and chicken (n = 295) to amikacin, ampicillin, cephalothin, chloramphenicol, ciprofloxacin, gentamicin, streptomycin, sulfamethoxazole, and tetracycline was determined using the two methods. None of the 390 isolates were resistant to ciprofloxacin at levels of 0.125 microg/ml. All chicken and hog isolates were sensitive to amikacin, whereas all beef isolates were sensitive to both amikacin and gentamicin. Multiple antimicrobial resistance (resistance to more than one antimicrobial) was found in 29% of bovine isolates and 42% of porcine isolates using both methods for testing and in 42% by the agar dilution and 33% by the microbroth dilution methods in the chicken isolates. Overall, there was good agreement between the two test methods for resistance to most of the antimicrobials, with disagreement found in the results in 1.3% of the isolates for ampicillin and sulfamethoxazole, 8.2% for streptomycin, 5.6% for cephalothin, and 1.0% of the isolates for tetracycline. The lack of agreement between the two test methods was found mostly among the chicken isolates.

Standard energetics of leaf-nosed bats (Hipposideridae): its relationship to intermittent- and protracted-foraging tactics in bats and birds.

Basal rates of metabolism within the insectivorous genera Hipposideros and Ascelliscus, Old World leaf-nosed bats (Hipposideridae), ranged from 58% to 77% of the mammalian standard. The larger species, Hipposideros diadema and Hipposideros maggietaylori, effectively thermoregulated at ambient temperatures down to 9 degrees C, whereas two smaller species, Hipposideros galeritus and Hipposideros cervinus, occasionally permitted body temperatures to fall below 32 degrees C. The low basal rates of metabolism in hipposiderids correlated with a predatory life-style characterized by intermittent flight from a perch to capture insects, a correlation similar to that found in nonpasserine birds. Intermittent-foraging bats and nonpasserines collectively had basal rates of metabolism that averaged 75% of those that pursue insects during protracted flight. However, no difference in basal rate was found between protracted- and intermittent-foraging passerines, which had basal rates 1.8- and 2.4-times those of protracted-foraging and intermittent-foraging bats and nonpasserines, respectively. Bats, swifts, and caprimulgids that enter torpor have basal rates that are 85% of those of similar species that do not enter torpor. Body mass, order affiliation, foraging mode, and propensity to enter into torpor collectively account for 97% of the variation in basal rate of metabolism in insectivorous bats and birds. Foraging style therefore appears to be a factor contributing to the diversity in endotherm energetics. Minimal thermal conductance in the genus Hipposideros ranged from 75% to 102% of the mammalian standard. Birds have minimal thermal conductances that are 75% of mammals and intermittent foragers have minimal conductances that are 78% of protracted foragers.

Methacholine challenge: test-shortening procedures.

STUDY OBJECTIVES: Validation of test-shortening procedures for the 2-min tidal breathing methacholine challenge method. DESIGN: Retrospective chart review. SETTING: Tertiary-care university clinical pulmonary function laboratory. PATIENTS: One thousand subjects aged 10 to 85 years (mean +/- SD, 44.5 +/- 16.0 years), 44.5% male, referred for methacholine challenge. INTERVENTION: Two-minute tidal breathing methacholine challenge was performed, with both physician and technician access to published test-shortening procedures. MEASUREMENTS AND RESULTS: There were 315 positive test results (provocative concentration of methacholine causing a 20% fall in FEV(1) [PC(20)] < or = 8 mg/mL) and 685 negative test results. The subjects with positive test results were less likely to be male (39.1 vs 47.5%; p < 0.02) and had lower FEV(1) (91.8 +/- 14.9% predicted vs 97.2 +/- 13.9% predicted; p < 0.001). The average starting PC(20) was between 0.5 mg/mL and 1.0 mg/mL; the most common PC(20) was 1 mg/mL (67%). There were 431 skipped concentrations in 380 subjects. The mean number of methacholine inhalations was 3.7 +/- 1.1 (3.9 +/- 0.1 for negative test results vs 3.3 +/- 1.2 for positive test results; p < 0.001). Eighteen subjects had a > or = 20% FEV(1) fall on the first inhalation, and 11 subjects had a > or = 20% FEV(1) fall after a skipped concentration. In only one case (0.1%) an FEV(1) fall > or = 40% on the first concentration was reported, compared with no cases after a skipped concentration and seven cases with a > or = 40% FEV(1) fall after a routine doubling dose step-up. CONCLUSIONS: The 2-min tidal breathing methacholine test in clinical practice can be safely shortened to an average of less than four inhalations using starting concentrations based on FEV(1), asthma medication, and clinical features, and by occasionally omitting concentrations.

The comparative energetics of 'caviomorph' rodents.

The energetics of 11 species of New World hystricognath ('caviomorph') rodents are presented and compared with data from the literature on 19 additional species. Log(10) body mass alone accounts for 94% of the variation in the log(10) basal rate of metabolism in caviomorphs. The residual variation in basal rate is correlated with the stratum on which species live: arboreal species have low basal rates; terrestrial and fossorial species have intermediate basal rates; and aquatic species have high basal rates. When stratum is not included in the analysis, folivores, especially those that are arboreal, have lower basal rates than species with other food habits when combined with log(10) body mass. Small island endemics, all of which are folivores, have basal rates that are 61% of continental species. Log(10) basal rate correlates with family affiliation when combined with log(10) mass, but only if no other factor is included. Therefore, caviomorphs with low basal rates are arboreal, folivorous, live on small islands and belong to the Capromyidae, whereas other character combinations are associated with higher basal rates. These observations demonstrate that the basal rates of caviomorphs reflect many factor interactions. No differences in basal rate were found to reflect climate. Log(10) mass, the only factor to correlate with conductance, accounts for 82% of the variation in log(10) minimal thermal conductance. Mean interspecific body temperature was 36.9 degrees C; it was lowest in aquatic and fossorial species.

The metabolism of New Guinean pteropodid bats.

Rate of metabolism and body temperature were measured in eight species of pteropodid bats that live in Papua New Guinea. These data and those from 13 other species available in the literature are examined to determine the factors with which the energetics of pteropodids are correlated. Lowland populations of species that weigh < 35 g generally have low basal rates and often become torpid, whereas their highland populations had standard or high basal rates and were precise thermoregulators, as were all adult pteropodids that weighed more than 60 g. In large pteropodids belonging to the genera Dobsonia and Pteropus, females are smaller and consequently have lower total basal rates than males. Compared to species found on continents and large islands, species limited in distribution to small islands have lower basal rates, both because of a smaller mass and a reduction of metabolism independent of body mass. These trends are most marked in females that belong to small-island species, adjustments that may facilitate reproduction and survival on small oceanic islands with a limited resource base. Minimal thermal conductances are usually low in species that roost exposed in trees, whereas large species that roost in caves have either standard or high conductances.

The influence of body mass, climate, and distribution on the energetics of South Pacific pigeons.

Rate of metabolism and temperature regulation were studied in 16 species of South Pacific pigeons, which constitute 13 fruit-eaters, 1 seed-eater, 1 fruit/nut-eater, and 1 fruit/leaf-eater; 14 tropical and two temperate species; and ten mainland and six intermediate- or small-island species. The data presented here and those from 11 additional columbids indicate in an analysis of covariance that log(10) basal rate of metabolism is correlated with log(10) body mass (P< or =0.0001), distribution (P=0.0023), and climate (P=0.0016). These factors account for 94.3% of the variation in log(10) basal rate of metabolism. In this analysis the lowest basal rates, corrected for body mass, are found in tropical pigeons living on small oceanic islands, whereas the highest basal rates are found in temperate species living on continents. The reduction of basal rate in large columbids facilitates their long-term persistence on small islands characterized by a limited resource base and unstable weather. Some small-island specialists have a smaller mass than their continental relatives, which further reduces resource requirements. The question whether a reduction in basal rate occurs in small columbids on small islands is unresolved. Log(10) minimal thermal conductance is apparently correlated only with log(10) body mass (P< or =0.0001); r(2)=89.4%. The mean nocturnal body temperature of columbids is 39.7 degrees C.

Twice weekly isoniazid and rifampin treatment of latent tuberculosis infection in Canadian plains Aborigines.

Six months of twice weekly directly observed isoniazid and rifam-picin treatment of latent tuberculosis (TB) infection was implemented to improve the outcome of treatment. A total of 591 infected aborigines without previous tuberculosis or treatment of latent TB infection received twice weekly isoniazid and rifampicin for 6 mo from 1992 to 1995. The outcome was compared with 403 infected aborigines without previous tuberculosis or treatment of latent TB infection who received self-administered isoniazid daily for 1 yr from 1986 to 1989. Of patients, 487 (82%) completed the twice weekly 6-mo regimen compared with 77 (19%) who completed the daily 12-mo regimen. The main reason for incomplete treatment was default. Both groups were followed over a 6-yr period. The rate of tuberculosis in the twice-weekly isoniazid and rifampicin-treated patients was 0.9/1,000 patient-years compared with 9/1,000 patient-years in the daily isoniazid-treated patients. The rate of side effects was higher for directly observed treatment patients, 136/1,000 patient-years of drugs, compared with 39/ 1,000 patient-years for self-administered treatment patients. Life-threatening side effects such as skin allergic reactions and hepatitis were the same in both groups. A regimen of 52 doses of directly observed twice weekly isoniazid and rifampicin is an effective and well-tolerated regimen to improve the outcome of the treatment of latent tuberculosis infection in a population with a high rate of default with daily self-administered isoniazid.

Detection of pulmonary tuberculosis in patients with a normal chest radiograph.

OBJECTIVES: To describe the early symptoms of pulmonary tuberculosis (TB) when the chest radiograph (CXR) is normal. SETTING: Centralized, provincial TB control program. SUBJECTS: Twenty-five patients with culture-positive pulmonary TB and a normal CXR were identified from a review of 518 consecutive patients with culture-positive pulmonary TB in the province of Saskatchewan from January 1, 1988 to March 31, 1997. Patients with abnormal CXRs at the time of diagnosis were excluded from the analysis. RESULTS: Twenty-three of the 25 patients (92%) were symptomatic at the time of diagnosis, with cough/sputum (76%) being reported most commonly. Eleven patients were identified because of contact tracing from cases of infectious pulmonary TB, while the other 14 patients were identified because of an investigation of symptoms. Twenty-four patients (96%) exhibited one or more symptoms of cough for > 1 month, fever for > 1 week, or skin-test conversion after contact with infectious TB. The sputum smear of only one patient was positive. Two patients were pregnant at the time of diagnosis, one patient was HIV-positive, and one patient demonstrated isoniazid-resistant organisms on sensitivity testing. Five patients were diagnosed as having primary TB associated with Mantoux skin-test conversion. The incidence of culture-positive pulmonary TB with a normal chest radiograph was < 1% in the period from 1988 to 1989 and steadily increased to 10% in the period from 1996 to 1997. CONCLUSIONS: Culture-positive pulmonary TB with a normal CXR is not uncommon, and the incidence of this presentation is increasing. Patients with this presentation of TB are typically symptomatic and/or are detected by contact tracing to infectious cases of pulmonary TB. The results suggest that patients presenting with a cough for > 1 month, with a fever for > 1 week, or with documented skin-test conversion < 2 years after known exposure to infectious TB should have sputum submitted for a Mycobacterium tuberculosis smear and culture despite a normal CXR.

Epidemiological typing of Campylobacter isolates from meat processing plants by pulsed-field gel electrophoresis, fatty acid profile typing, serotyping, and biotyping.

Campylobacter spp. are a leading cause of bacterial gastroenteritis. Foods of animal origin, particularly under-cooked poultry, are common sources of Campylobacter species associated with disease in humans. A collection of 110 Campylobacter jejuni and 31 C. coli human and environmental isolates from different Ontario, Canada, abattoirs were analyzed by pulsed-field gel electrophoresis, fatty acid profile typing, and biotyping. Previously collected serotyping data for the same isolates were also analyzed in this study. Pulsed-field gel electrophoresis was found to be the most discriminatory of the typing methods, followed by serotyping, fatty acid profile typing, and biotyping. A wide variety of typing profiles were observed within the isolates, suggesting that several different Campylobacter sp. strains were present within the abattoirs.