A packed-bed filtration system for collection of Myxobolus cerebralis triactinomyxons

Information on the distribution and abundance of Myxobolus cerebralis triactinomyxons in natural systems is limited because direct and accurate sampling methods for this life stage have not been developed. Existing methods are based on indirect measures of triactinomyxon densities and are therefore confounded. Direct estimation of triactinomyxon concentrations would more exactly pinpoint the ambient infection risk to wild fish and allow evaluation of management strategies designed to mitigate the effects of the disease. We developed a mobile packed-bed filtration system that quickly, accurately, and precisely collects, concentrates, and quantifies triactinomyxons. The system includes pumping, prefiltration, two rounds of packed-bed filtration, and centrifugation. Laboratory tests of the completed system using known quantities of triactinomyxons resulted in a mean recovery rate of 91% with a minimum detectable concentration of triactinomyxons of 0.04/L. We subsequently field-tested the system at a site known to be positive for the parasite and recovered triactinomyxons at densities of 0.7-1.4/L. The packed-bed filtration system has the potential to quickly determine the temporal and spatial variation in infection risk and to test the efficacy of various management strategies.     

Experimentally Induced Whirling Disease I. Dose Response of Fry and Adults of Rainbow Trout Exposed to the Triactinomyxon Stage of Myxobolus cerebralis

Abstract

The intensity and prevalence of whirling disease was tested by exposure of 2-monthold fry and 1-, 2-, and 3.5-year-old adults of rainbow trout Oncorhynchus mykiss to a known number of laboratory-produced Myxobolus cerebralis at the actinosporean triactinomyxon stage. Fry exposed to graded concentrations of infectivity (triactinomyxons) for 3 h were individually examined for spores of Myxobolus cerebralis 5 and 6 months later. Exposure of fish to the lowest doses, 1 and 10 triactinomyxons per fish, did not result in detectable myxosporean spores. Fish that became lightly infected by a dose of 100 triactinomyxons per fish experienced a decrease in the incidence of infection between 5 and 6 months after exposure. A linear relationship was found between the numbers of recovered myxosporean spores and doses of 100–10,000 triactinomyxons per fish, and the spore burden appeared to plateau at doses of 10,000–100,000 triactinomyxons per fish. Adult fish continuously exposed to the highest dose of triactinomyxons for 3.5 months were infected and asymptomatic, however, the severity of myxosporean infection decreased with increased age of fish. This information may help in controlling whirling disease in salmonids.     

Experimentally Induced Whirling Disease II. Determination of Longevity of the Infective Triactinomyxon Stage of Myxobolus cerebralis by Vital Staining

Abstract

Effects of temperature and aging on viability and infectivity of laboratory-produced actinosporean triactinomyxon spores (infective stage of the organism causing whirling disease) were studied. In vitro staining of triactinomyxon spores with vital fluorescein diacetate correlated with the ability of the spores to infect fry of rainbow trout Oncorhynchus mykiss. The experimentally produced actinosporean stage of Myxobolus cerebralis was short-lived, persisting for only 3–4 d at 12.5°C and for less time at warmer temperatures. The vital staining method has potential for screening therapeutants intended to control myxosporean infection of fish.     

Laboratory and Hatchery-Scale Evaluation of Sand Filters and Their Efficacy at Controlling Whirling Disease Infection

Abstract

In two separate tests rapid sand filtration was evaluated as a means of removing the waterborne triactinomyxon actinospores (TAMs) of Myxobolus cerebralis, the causative agent of salmonid whirling disease, from contaminated water. In the first test we independently evaluated two sizes of sandblast sands: #4010 (effective size, (ES) = 250 μm) and #4060 (ES = 300 μm). The product number relates to the sand's size composition, and each had a different effective size. Effective size is defined by that size fraction at which only 10% of smaller particles remain. Rainbow trout Oncorhynchus mykiss were stocked into two separate systems with filters containing either one or the other size of sand, and TAMs were added to each system three times per week for all but the final 2 weeks of the 16-week test. A positive control (in which fish were exposed to the same number of TAMs without filtration) and a negative control (in which fish were not exposed to TAMs) were also included. Infection quantified by the pepsin?trypsin digest method showed no infection in fish from the two filter treatments. The average myxospore load among the positive controls was over 90,000 spores per fish head. In a final test, a nonreplicated comparison of filtration systems was conducted. The three systems used were as follows: (1) a drum filter in line with a UV filter, (2) a media filter followed by an ultraviolet (UV) unit, and (3) a sand filter containing three layers of sand. Water contaminated with TAMS was run through each filtration system, as well as through a positive control system, to raceways containing rainbow trout. Both of the dual-component commercial systems were 100% effective at preventing infection; the sand filter was 92% effective.     

Whirling disease dynamics: An analysis of intervention strategies

Whirling disease (WD), a severe and widespread disease of salmonids, is caused by the myxosporean parasite Myxobolus cerebralis. It is further characterized by a unique two-host life cycle, utilizing the oligochaete Tubifex tubifex as an intermediate host. M. cerebralis is an invasive species that has been affecting populations in the United States including epidemics that killed in excess of 90% of populations in Colorado and Montana streams within the past 20 years. Currently, there is no known cure for WD, and the accepted method of control is removal of infected fish from the population. We have created a compartmental model of the WD system in order to assess more efficient means of control and management of the disease. Using data gathered from the literature, we used Bayesian model fitting to estimate model parameters and estimated that R₀ ≈ 1.51 (95% CI: 1.39, 1.72), a value which implies that WD can be controlled using available strategies. To this end, we posit several parameters that we expect to be most influential to WD propagation, namely: release of triactinomyxons by T. tubifex, release of spores by salmonids, and infectious particle loads in each respective host. Based on currently available control strategies, approaches targeting the infectious particles and the oligochaete host appear the most effective alternative strategies for management and control of WD.     

Evaluation of host and bacterial gene modulation during Lawsonia intracellularis infection in immunocompetent C57BL/6 mouse model

BackgroundProliferative enteritis caused by Lawsonia intracellularis undermines the economic stability of the swine industry worldwide. The development of cost-effective animal models to study the pathophysiology of the disease will help develop strategies to counter this bacterium.ObjectivesThis study focused on establishing a model of gastrointestinal (GI) infection of L. intracellularis in C57BL/6 mice to evaluate the disease progression and lesions of proliferative enteropathy (PE) in murine GI tissue.MethodsWe assessed the murine mucosal and cell-mediated immune responses generated in response to inoculation with L. intracellularis.ResultsThe mice developed characteristic lesions of the disease and shed L. intracellularis in the feces following oral inoculation with 5 × l0⁷ bacteria. An increase in L. intracellularis 16s rRNA and groEL copies in the intestine of infected mice indicated intestinal dissemination of the bacteria. The C57BL/6 mice appeared capable of modulating humoral and cell-mediated immune responses to L. intracellularis infection. Notably, the expression of genes for the vitamin B12 receptor and for secreted and membrane-bound mucins were downregulated in L. intracellularis -infected mice. Furthermore, L. intracellularis colonization of the mouse intestine was confirmed by the immunohistochemistry and western blot analyses.ConclusionsThis is the first study demonstrating the contributions of bacterial chaperonin and host nutrient genes to PE using an immunocompetent mouse model. This mouse infection model may serve as a platform from which to study L. intracellularis infection and develop potential vaccination and therapeutic strategies to treat PE.     

Detection of Myxobolus cerebralis in Rainbow Trout and Oligochaete Tissues by Using a Nonradioactive in Situ Hybridization (ISH) Protocol

Abstract

A nonradioactive in situ hybridization (ISH) protocol was developed to detect Myxobolus cerebralis, the causative organism of whirling disease, in its primary host, rainbow trout Oncorhynchus mykiss, and in its alternate oligochaete host, Tubifex tubifex. A cocktail of three oligonucleotide primers (derived from the small subunit ribosomal DNA sequence) directed at target sequences of the parasite DNA was tailed at the 3′ end with digoxigenin-labeled deoxyuridine triphosphate (DIG-dUTP). Labeled probes were hybridized to parasite DNA present in deparaffinized tissue sections from infected trout and oligochaetes. The bound probes were visualized after modifications of existing ISH protocols. By using the new ISH procedure, the parasite was found in target tissues of subclinically and clinically infected fish and tubificid oligochaetes after exposures of these hosts to triactinomyxons and mature spores, respectively. The probe did not bind with salmonid tissues infected with two other myxosporean parasites, Ceratomyxa shasta or the PKX organism, or to a Myxobolus sp. infecting the cartilage of plain sculpin Myoxocephalus jaok. These initial results indicate that ISH is an effective and specific test for detecting Myxobolus cerebralis in its fish and oligochaete hosts.     

Reduced Myxobolus cerebralis Actinospore Production in a Colorado Reservoir May Be Linked to Changes in Tubifex tubifex Population Structure

Abstract

Elucidating the dynamics of a parasitic infection requiring two hosts in a natural ecosystem can be a daunting task. Myxobolus cerebralis (Mc), the myxozoan parasite that causes whirling disease in some salmonids, was detected in the Colorado River upstream of Windy Gap Reservoir (WGR) in 1988. Subsequently, whirling disease was implicated in the decline of wild Rainbow Trout Oncorhynchus mykiss in the river when WGR was identified as a point source of Mc triactinomyxons (TAMs). Between 1997 and 2004, numerous investigations began to elucidate the etiology of Mc in WGR. During this period, Mc TAM production in WGR declined more than 90%. Explanations for the decline have included differences in stream discharge between years, changes in the thermal regime of the lake, severe drought, changes in the fish population structure in WGR, and reductions in the prevalence and severity of Mc infection in salmonids in the Colorado and Fraser rivers upstream of WGR. All of these have been discredited as explanations for the reduced TAM production. In 2005, a new study was conducted to replicate the studies completed in 1998. In this paper, the results of a new real-time polymerase chain reaction assay utilized to quantify the mitochondrial 16S rDNA specific to each of four lineages of Tubifex tubifex in pooled samples of 50 oligochaetes are presented. These results suggest that compared with 1998, the densities of aquatic oligochaetes and T. tubifex have increased, TAM production has been greatly reduced, and the decline is congruent with the dominance of lineages I, V, and VI of T. tubifex—three lineages that are refractory or highly resistant to Mc infection—in the oligochaete population. While it is possible that the resistant lineages function as biofilters that deactivate Mc myxospores, the reason for the decline in TAM production in WGR remains an enigma.

Received February 15, 2012; accepted March 17, 2013     

An epidemiological study of Fasciola hepatica in the Netherlands

Summary

Transmission of F.hepatica under natural conditions was analysed in a three year programme. The variables used were the indirect haemagglutination (IHA) technique, worm establishment in tracer lambs and the population dynamics, infection rate and shedding pattern of Lymnaea truncatula.

It is concluded that fluke eggs, infected snails and metacercariae on herbage can survive the winter in the Netherlands. Metacercarial availability was positively correlated to the amount of rainfall in the grazing period. The role of developed eggs that survive the winter is important, because this results in earlier infections in the herd.

The use of the serological diagnosis method IHA is important to detect F. hepatica infection in an early stage. Use of cellophane paper on floats is a useful method for determining the shedding pattern of cercariae from L. truncatula. It is concluded that collection of metacercariae on cellophane floats, inventarization of L. truncatula and its infection level are useful tools for the prediction of liverfluke infections.     

Susceptibility of Selected Inland Salmonids to Experimentally Induced Infections with Myxobolus cerebralis,the Causative Agent of Whirling Disease

Abstract

Laboratory exposures to the infectious stages (triactinomyxons) of Myxobolus cerebralis demonstrated a range of susceptibility to whirling disease among four species of inland salmonids. Replicate groups of each species were exposed to two concentrations of triactinomyxons, a low dose (100–200 per fish) and a high dose (1,000–2,000 per fish). Exposed fish were evaluated for clinical signs, for severity of microscopic lesions at 35 d, 2 and 5 months, and for spore concentrations in the head cartilage at 5 months. A standard strain of rainbow trout Oncorhynchus mykiss matched for age served as a susceptible species control. Rainbow trout, westslope cutthroat trout O. clarki lewisi, Yellowstone cutthroat trout O. clarki bouvieri, and bull trout Salvelinus confluentus were susceptible to M. cerebralis infections. Clinical signs, including radical swimming (“whirling”) and black tails, were observed at 7 weeks postexposure among rainbow and cutthroat trout challenged at 3 weeks of age. Clinical signs were rare among bull trout exposed at an age of 4 weeks and absent among rainbow and cutthroat trout exposed at 3 months posthatch. Most rainbow, cutthroat, and bull trout were found to be infected when examined at 5 months postexposure. The most severe microscopic lesions among infected fish at 5 months postexposure were found among rainbow trout. Cutthroat trout had less severe lesions, bull trout had mild infections, and no evidence of infection was found among Arctic grayling Thymallus arcticus. Mean spore concentrations among infected fish correlated with the severity of microscopic lesion scores. Rainbow trout had mean concentrations of spores in head cartilage reaching 10⁶, whereas more resistant species such as bull trout had 10⁴ spores; no spores were found among Arctic grayling at 5 months postexposure.     

Comparison of Susceptibility of Five Cutthroat Trout Strains to Myxobolus cerebralis Infection

Abstract

Susceptibility to infection by the myxosporean parasite Myxobolus cerebralis was compared among strains of cutthroat trout Oncorhynchus clarki in two separate exposure tests in the laboratory. In both tests, each strain was exposed to 1,000 triactinomyxons/fish for 2 h in 8.0 L of water. In the first test, three strains of 10-week-old cutthroat trout were compared: two strains of Bonneville cutthroat trout O. c. utah (Bear Lake and southern Bonneville strains) and Yellowstone cutthroat trout O. c. bouvieri. In the second test, these strains plus Snake River fine-spotted cutthroat trout O. c. subsp. and Colorado River cutthroat trout O. c. pleuriticus were exposed at either 5 or 10 weeks of age. The prevalence of the M. cerebralis infection was determined by single-round polymerase chain reaction (PCR) assay 5 weeks after exposure. In the first test, the prevalence was significantly lower in the Bear Lake strain of Bonneville cutthroat trout (78.5%) than in the Yellowstone (97.8%) or southern Bonneville (100%) strains when exposed at 10 weeks of age. In the second test, the Bear Lake strain also had significantly lower infection rates after exposure at 5 (54%) or 10 weeks (82%) of age than the other four strains, which did not differ from each other (94–100%). The severity of the infection was also significantly reduced in Bear Lake Bonneville cutthroat trout, as suggested by the strength of the product of the single-round PCR assay. These results suggest that intraspecific differences in susceptibility to M. cerebralis infection exist, further supporting the need to maintain the genetic diversity among subspecies and geographic variants of cutthroat trout.     

Leptospira interrogans at the Human–Wildlife Interface in Northern Botswana: A Newly Identified Public Health Threat

Leptospirosis is the most widespread zoonosis in the world. In northern Botswana, humans live in close proximity to a diversity of wildlife and peridomestic rodents and may be exposed to a variety of zoonotic pathogens. Little is known regarding the occurrence and epidemiology of L. interrogans in Africa despite the recognized global importance of this zoonotic disease and the threat it poses to public health. In Botswana, banded mongooses (Mungos mungo) live in close proximity to humans across protected and unprotected landscapes and may be a useful sentinel species for assessing the occurrence of zoonotic organisms, such as L. interrogans. We utilized PCR to screen banded mongoose kidneys for leptospiral DNA and identified 41.5% prevalence of renal carriage of L. interrogans (exact binomial 95% CI 27.7–56.7%, n = 41). Renal carriage was also detected in one Selous' mongoose (Paracynictis selousi). This is the first published confirmation of carriage of L. interrogans in either species. This is also the first report of L. interrogans occurrence in northern Botswana and the only report of this organism in a wildlife host in the country. Pathogenic Leptospira are usually transmitted indirectly to humans through soil or water contaminated with infected urine. Other avenues, such as direct contact between humans and wildlife, as well as consumption of mongooses and other wildlife as bushmeat, may pose additional exposure risk and must be considered in public health management of this newly identified zoonotic disease threat. There is a critical need to characterize host species involvement and pathogen transmission dynamics, including human–wildlife interactions that may increase human exposure potential and infection risk. We recommend that public health strategy be modified to include sensitization of medical practitioners to the presence of L. interrogans in the region, the potential for human infection, and implementation of clinical screening. This study illustrates the need for increased focus on neglected zoonotic diseases as they present an important threat to public health.     

Genetic diversity and phylogenetic relationships between Leishmania infantum from dogs,humans and wildlife in south‐east Spain

Leishmania infantum causes human and canine leishmaniosis. The parasite, transmitted by phlebotomine sand flies, infects species other than dogs and people, including wildlife, although their role as reservoirs of infection remains unknown for most species. Molecular typing of parasites to investigate genetic variability and evolutionary proximity can help understand transmission cycles and designing control strategies. We investigated Leishmania DNA variability in kinetoplast (kDNA) and internal transcribed spacer 2 (ITS2) sequences in asymptomatically infected wildlife (n = 58) and symptomatically and asymptomatically infected humans (n = 38) and dogs (n = 15) from south‐east Spain, using single nucleotide polymorphisms (SNPs) and in silico restriction fragment length polymorphism (RFLP) analyses. All ITS2 sequences (n = 76) displayed a 99%–100% nucleotide identity with a L. infantum reference sequence, except one with a 98% identity to a reference Leishmania panamensis sequence, from an Ecuadorian patient. No heterogeneity was recorded in the 73 L. infantum ITS2 sequences except for one SNP in a human parasite sequence. In contrast, kDNA analysis of 44 L. infantum sequences revealed 11 SNP genotypes (nucleotide variability up to 4.3%) and four RFLP genotypes including B, F and newly described S and T genotypes. Genotype frequency was significantly greater in symptomatic compared to asymptomatic individuals. Both methods similarly grouped parasites as predominantly or exclusively found in humans, in dogs, in wildlife or in all three of them. Accordingly, the phylogenetic analysis of kDNA sequences revealed three main clusters, two as a paraphyletic human parasites clade and a third including dogs, people and wildlife parasites. Results suggest that Leishmania infantum genetics is complex even in small geographical areas and that, probably, several independent transmission cycles take place simultaneously including some connecting animals and humans. Investigating these transmission networks may be useful in understanding the transmission dynamics, infection risk and therefore in planning L. infantum control strategies.     

Detection of Myxobolus (Myxosoma) cerebralis in Salmonid Fishes in Oregon

Abstract

Myxobolus (Myxosoma) cerebralis, the etiological agent of whirling disease, was detected in salmonid fish populations in northeastern Oregon. This is the first record of M. cerebralis in the Pacific Northwest of the USA. During an epizootiological survey for the parasite, two methods for spore detection were compared, and an efficient procedure for determining M. cerebralis infection in adult fish was developed. The enzyme digest method was more efficient than the plankton centrifuge procedure for examination of numerous individual lots of fish processed during the survey. Sampling only the area around the otoliths was at least as effective as sampling entire heads for detection of spores in infected fish.     

Inferring source attribution from a multiyear multisource data set of Salmonella in Minnesota

Salmonella enterica is a global health concern because of its widespread association with foodborne illness. Bayesian models have been developed to attribute the burden of human salmonellosis to specific sources with the ultimate objective of prioritizing intervention strategies. Important considerations of source attribution models include the evaluation of the quality of input data, assessment of whether attribution results logically reflect the data trends and identification of patterns within the data that might explain the detailed contribution of different sources to the disease burden. Here, more than 12,000 non‐typhoidal Salmonella isolates from human, bovine, porcine, chicken and turkey sources that originated in Minnesota were analysed. A modified Bayesian source attribution model (available in a dedicated R package), accounting for non‐sampled sources of infection, attributed 4,672 human cases to sources assessed here. Most (60%) cases were attributed to chicken, although there was a spike in cases attributed to a non‐sampled source in the second half of the study period. Molecular epidemiological analysis methods were used to supplement risk modelling, and a visual attribution application was developed to facilitate data exploration and comprehension of the large multiyear data set assessed here. A large amount of within‐source diversity and low similarity between sources was observed, and visual exploration of data provided clues into variations driving the attribution modelling results. Results from this pillared approach provided first attribution estimates for Salmonella in Minnesota and offer an understanding of current data gaps as well as key pathogen population features, such as serotype frequency, similarity and diversity across the sources. Results here will be used to inform policy and management strategies ultimately intended to prevent and control Salmonella infection in the state.     

Feline immunodeficiency. ABCD guidelines on prevention and management

OverviewFeline immunodeficiency virus (FIV) is a retrovirus closely related to human immunodeficiency virus. Most felids are susceptible to FIV, but humans are not. Feline immunodeficiency virus is endemic in domestic cat populations worldwide. The virus loses infectivity quickly outside the host and is susceptible to all disinfectants.InfectionFeline immunodeficiency virus is transmitted via bites. The risk of transmission is low in households with socially well-adapted cats. Transmission from mother to kittens may occur, especially if the queen is undergoing an acute infection. Cats with FIV are persistently infected in spite of their ability to mount antibody and cell-mediated immune responses.Disease signsInfected cats generally remain free of clinical signs for several years, and some cats never develop disease, depending on the infecting isolate. Most clinical signs are the consequence of immunodeficiency and secondary infection. Typical manifestations are chronic gingivostomatitis, chronic rhinitis, lymphadenopathy, weight loss and immune-mediated glomerulonephritis.DiagnosisPositive in-practice ELISA results obtained in a low-prevalence or low-risk population should always be confirmed by a laboratory. Western blot is the ‘gold standard’ laboratory test for FIV serology. PCR-based assays vary in performance.Disease managementCats should never be euthanased solely on the basis of an FIV-positive test result. Cats infected with FIV may live as long as uninfected cats, with appropriate management. Asymptomatic FIV-infected cats should be neutered to avoid fighting and virus transmission. Infected cats should receive regular veterinary health checks. They can be housed in the same ward as other patients, but should be kept in individual cages.Vaccination recommendationsAt present, there is no FIV vaccine commercially available in Europe. Potential benefits and risks of vaccinating FIV-infected cats should be assessed on an individual cat basis. Needles and surgical instruments used on FIV-positive cats may transmit the virus to other cats, so strict hygiene is essential.     

Comparison of a commercial ELISA with an indirect fluorescent antibody test to detect antibodies to Lawsonia intracellularis in experimentally challenged pigs

Objective The ability of a new commercial ELISA to detect pigs with subclinical proliferative enteropathy (PE) was compared with the traditional indirect fluorescent antibody test (IFAT). Methods Serum samples were selected from pigs with known Lawsonia intracellularis infection status and clinical signs of PE, but the sample population consisted predominantly of pigs subclinically affected by PE. Results Significant association and agreement were shown between the ELISA and IFAT assays. ELISA results correlated well with the duration of L. intracellularis shedding as detected by polymerase chain reaction. Conclusion ELISA can be successfully used to monitor L. intracellularis infection in pigs.     

First report of Angiostrongylus vasorum (French heartworm) in red foxes (Vulpes vulpes) on Prince Edward Island

Objective To identify first-stage nematode larvae (L1) recovered from a red fox scat sample and adult female worms recovered from 2 red fox lungs at necropsy, using published molecular methods to confirm a morphological diagnosis of Angiostrongylus vasorum (French heartworm).Animal Red fox (Vulpes vulpes).Procedure Nematode larvae recovered from a Baermann examination survey of wild canid scats (n = 101) conducted from January 2017 to August 2020, were identified by size and morphology and subjected to PCR and DNA sequencing of the small subunit (SSU) rRNA gene, the large subunit (LSU) rRNA gene, or the second internal transcribed spacer (ITS2). In addition, these techniques were applied to adult female worms recovered from the heart/lungs of 2 red foxes (obtained from PEI trappers and stored frozen at −20°C since December of 2018 and 2020).Results Size and morphology of L1 recovered by Baermann examination from a wild canid scat sample (presumed to be red fox) collected near Montague, PEI and adult female worms recovered at necropsy from 2 red fox carcasses were identified as A. vasorum. Molecular analysis confirmed the larvae and adult worms were A. vasorum.Conclusion These findings indicated that A. vasorum has become endemic in the red fox population on PEI.Clinical relevance Angiostrongylus vasorum infection is potentially fatal in dogs. Veterinarians and regional diagnostic laboratories in the Maritime provinces should consider the possibility of A. vasorum infection in dogs with clinical signs of cardiopulmonary and/or central nervous system disease or bleeding disorders.     

Prevalence and risk factors associated with intestinal parasites in pigs in Chongqing, China

From 2007 to 2009, the prevalence of intestinal parasites was investigated in intensive and extensive pig farms in Chongqing, China. A total of 2971 samples from both sexes and five age categories (breeding boars, breeding sows, fatteners, growers and weaners) were evaluated by standard methods for the presence of helminth ova and protozoan oocysts, cysts and/or trophozoites. Of the 2971 pigs sampled, 362(12.18%) were infected with Ascaris suum, 301(10.13%) with Trichuris suis, 301(10.13%) with Oesophagostomum spp., 491(16.53%) with Eimeria spp., 149(5.02%) with Isopora suis, 677(22.79%) with Balantidium coli and 196(6.60%) with Cryptosporidium spp. Growers had the highest infection rate while breeding boars had the lowest among the five age categories. B. coli was the most common protozoan in all pig age groups. Pigs infected with multiple parasites were common. Risk factors such as management methods, seasons, ages, etc. can influence the infection rate to a certain degree. This investigation provides relevant data about risk factors for pig farmers, thus allowing them to make more appropriate antiparasitic treatments according to farm conditions and local climate in Chongqing.     

Evaluation of a minimally invasive non-calibrated pulse contour cardiac output monitor (FloTrac/Vigileo) in anaesthetized dogs

ObjectiveTo evaluate the accuracy of a new cardiac output monitor (FloTrac/Vigileo), originally designed for humans, in dogs. This pulse contour cardiac output monitoring system cannot be calibrated and measures cardiac output (

t) from a standard arterial catheter.Study designProspective experimental trial.AnimalsEight adult Beagle dogs weighing 13.1 (9.8–17.1) kg [median (range)].MethodsAnaesthesia in the dogs was maintained using isoflurane. A pulmonary artery catheter and a metatarsal arterial catheter (22 gauge) were placed. Cardiac output was measured simultaneously 331 times by thermodilution and FloTrac technique. A broad spectrum of

t measurements was achieved through alterations of isoflurane concentration, administration of propofol boluses and dobutamine infusions. Agreement between the methods was quantified with Bland Altman analysis and disagreement was assessed with linear mixed models.ResultsMedian (10th and 90th percentile) cardiac output as measured with thermodilution was 2.54 (1.47 and 5.15) L minute^?1 and as measured with FloTrac 8.6 (3.9 and 17.3) L minute^?1. FloTrac measurements were consistently higher with a mean bias of 7 L minute^?1 and limits of agreement of ?3.15 to 17.17 L minute^?1. Difference between the methods was most pronounced in high

t measurements. Linear mixed models showed an estimated difference between the two methods of 8.05 (standard error 1.18) L minute^?1 and a significant interaction between mean arterial pressure and method. Standard deviation (4.45 higher) with the FloTrac method compared to thermodilution was increased.ConclusionCompared to thermodilution measurements, the FloTrac system was influenced to a higher degree by arterial blood pressure, resulting in consistent overestimation of cardiac output.Clinical RelevanceThe FloTrac monitor, whose algorithms were developed based on human data, cannot be used as an alternative for thermodilution in dogs.