Preliminary estimates of the direct costs associated with endemic diseases of livestock in Great Britain

Seroprevalence and associated risk factors of Toxoplasma gondii and Neospora caninum infections in cattle in Central India

Toxoplasma gondii and Neospora caninum are closely related cyst-forming parasites identified as important causes of reproductive failures in ruminants. While these parasites have been reported worldwide, seroprevalence and associated risk factors for cattle infections have not been determined in India. A total of 576 serum samples of cattle were analyzed for antibodies to T. gondii and N. caninum using enzyme-linked immunosorbent assay (ELISA), modified/Neospora agglutination test (MAT/NAT), and an indirect fluorescent antibody test (IFAT-tachyzoite and bradyzoite). Additionally, general information about cattle, movement of cats and dogs, the menace of rodents, management, and reproductive disorders were assessed to identify the potential risk factors. Overall, 32.9% (190/576) serum samples reacted positively to T. gondii and 24.8% (143/576) to N. caninum. The performance of the diagnostic tests showed excellent agreement between IFAT and ELISA (kappa [κ] = 0.98) and between MAT/NAT and ELISA (κ = 0.97). Combining both infections on avidity test, 94% sera had high-IgG avidity, and 3% had low-IgG avidity antibodies, indicating chronic infection in the majority of the cases. The identified risk factors (p < 0.05) for exposure to T. gondii were: increasing age (Odds Ratio [OR]: 2.02), movement of cat (OR: 4.8) and rodents (OR: 1.57) in the farm; and for N. caninum: increasing age (OR: 1.6), movement of dogs in the farm (OR: 2.07), drinking pond water (OR: 1.64) and abortion (OR: 1.82). These findings revealed that T. gondii and N. caninum infections are widespread in the study area and suggest conducting nationwide epidemiological studies owing to their economic importance.

Stochastic Assessment of the Economic Impact of Streptococcus suis-Associated Disease in German, Dutch and Spanish Swine Farms

The economic assessment of animal diseases is essential for decision-making, including the allocation of resources for disease control. However, that assessment is usually hampered by the lack of reliable data on disease incidence, or treatment and control measures, and that is particularly true for swine production diseases, such as infections caused by Streptococcus suis. Therefore, we deployed a questionnaire survey of clinical swine veterinarians to obtain the input data needed for a stochastic model to calculate the costs caused by S. suis, which was implemented in three of the main swine producing countries in Europe: Germany, the Netherlands and Spain. S. suis-associated disease is endemic in those countries in all production phases, though nursery was the phase most severely impacted. In affected nursery units, between 3.3 and 4.0% of pigs had S. suis-associated disease and the mortalities ranged from 0.5 to 0.9%. In Germany, the average cost of S. suis per pig (summed across all production phases) was 1.30 euros (90% CI: 0.53-2.28), in the Netherlands 0.96 euros (90% CI: 0.27-1.54), and in Spain 0.60 euros (90% CI: 0.29-0.96). In Germany, that cost was essentially influenced by the expenditure in early metaphylaxis in nursery and in autogenous vaccines in sows and nursery pigs; in the Netherlands, by expenditure on autogenous vaccines in sows and nursery pigs; and in Spain, by the expenditures in early metaphylaxis and to a lesser extent by the mortality in nursery pigs. Therefore, the differences in costs between countries can be explained to a great extent by the measures to control S. suis implemented in each country. In Spain and in Germany, use of antimicrobials, predominantly beta-lactams, is still crucial for the control of the disease.

Advances in therapeutic and managemental approaches of bovine mastitis: a comprehensive review

Mastitis (intramammary inflammation) caused by infectious pathogens is still considered a devastating condition of dairy animals affecting animal welfare as well as economically incurring huge losses to the dairy industry by means of decreased production performance and increased culling rates. Bovine mastitis is the inflammation of the mammary glands/udder of bovines, caused by bacterial pathogens, in most cases. Routine diagnosis is based on clinical and subclinical forms of the disease. This underlines the significance of early and rapid identification/detection of etiological agents at the farm level, for which several diagnostic techniques have been developed. Therapeutic regimens such as antibiotics, immunotherapy, bacteriocins, bacteriophages, antimicrobial peptides, probiotics, stem cell therapy, native secretory factors, nutritional, dry cow and lactation therapy, genetic selection, herbs, and nanoparticle technology-based therapy have been evaluated for their efficacy in the treatment of mastitis. Even though several strategies have been developed over the years for the purpose of managing both clinical and subclinical forms of mastitis, all of them lacked the efficacy to eliminate the associated etiological agent when used as a monotherapy. Further, research has to be directed towards the development of new therapeutic agents/techniques that can both replace conventional techniques and also solve the problem of emerging antibiotic resistance. The objective of the present review is to describe the etiological agents, pathogenesis, and diagnosis in brief along with an extensive discussion on the advances in the treatment and management of mastitis, which would help safeguard the health of dairy animals.

Cat-dependent diseases cost Australia AU$6 billion per year through impacts on human health and livestock production

Abstract ContextCats are the definitive or primary host for pathogens that cause diseases in people and livestock. These cat-dependent diseases would not occur in Australia if cats had not been introduced, and their ongoing persistence depends on contacts with cats. Toxoplasma gondii is a protozoan parasite that cycles between cats and any other warm-blooded animals. People infected by T. gondii may appear asymptomatic, or have a mild illness, or experience severe, potentially lethal symptoms; the parasite may also affect behaviour and mental health. T. gondii is also a major contributor to spontaneous abortion in sheep and goats. Two species of Sarcocystis, another genus of protozoan parasite, cycle through cats and sheep, causing macroscopic cysts to form in sheep tissues that reduce meat saleability. Toxocara cati, the cat roundworm, causes minor illnesses in humans and livestock, and the bacterium Bartonella henselae causes cat scratch disease, an infection that can be contracted by people when scratched or bitten by cats carrying the pathogen. AimsWe estimated the economic costs of cat-dependent pathogens in Australia. MethodsWe collated national and global data on infection rates, health and production consequences. Key resultsWe estimated the costs of two cat-dependent diseases (toxoplasmosis, cat scratch disease) in people at AU$6.06 billion (plausible range AU$2.11–10.7 billion) annually, and the costs to livestock production from toxoplasmosis and sarcocystosis at AU$11.7 million (plausible range AU$7.67–18.3 million). Most of the human health costs are due to the associations between T. gondii and higher rates of traffic accidents and mental illness in people. The causality behind these associations remains uncertain, so those costs may be overestimated. Conversely, our estimates are incomplete, infections and illness are under-reported or misdiagnosed, and our understanding of disease outcomes is still imperfect, all of which make our costs underestimated. ConclusionsOur analysis suggests that substantial benefits to public health and livestock production could be realised by reducing exposure to cats and breaking parasite transmission cycles. ImplicationsReducing feral cat populations in farming and urban areas, reducing the pet cat population and increasing rates of pet cat containment could help reduce the burden of cat-dependent diseases to people and livestock.

Applications of the Soil, Plant and Rumen Microbiomes in Pastoral Agriculture

The production of dairy, meat, and fiber by ruminant animals relies on the biological processes occurring in soils, forage plants, and the animals' rumens. Each of these components has an associated microbiome, and these have traditionally been viewed as distinct ecosystems. However, these microbiomes operate under similar ecological principles and are connected via water, energy flows, and the carbon and nitrogen nutrient cycles. Here, we summarize the microbiome research that has been done in each of these three environments (soils, forage plants, animals' rumen) and investigate what additional benefits may be possible through understanding the interactions between the various microbiomes. The challenge for future research is to enhance microbiome function by appropriate matching of plant and animal genotypes with the environment to improve the output and environmental sustainability of pastoral agriculture.

Toxoplasma gondii infection and toxoplasmosis in farm animals: Risk factors and economic impact

The protozoan parasite Toxoplasma gondii is a zoonotic parasite that can be transmitted from animals to humans. Felids, including domestic cats, are definitive hosts that can shed oocysts with their feces. In addition to infections that occur by accidental oral uptake of food or water contaminated with oocysts, it is assumed that a large proportion of affected humans may have become infected by consuming meat or other animal products that contained infective parasitic stages of T. gondii. Since farm animals represent a direct source of infection for humans, but also a possible reservoir for the parasite, it is important to control T. gondii infections in livestock. Moreover, T. gondii may also be pathogenic to livestock where it could be responsible for considerable economic losses in some regions and particular farming systems, e.g. in areas where the small ruminant industry is relevant. This review aims to summarize actual knowledge on the prevalence and effects of infections with T. gondii in the most important livestock species and on the effects of toxoplasmosis on livestock. It also provides an overview on potential risk factors favoring infections of livestock with T. gondii. Knowledge on potential risk factors is prerequisite to implement effective biosecurity measures on farms to prevent T. gondii infections. Risk factors identified by many studies are cat-related, but also those associated with a potential contamination of fodder or water, and with access to a potentially contaminated environment. Published information on the costs T. gondii infections cause in livestock production, is scarce. The most recent peer reviewed reports from Great Britain and Uruguay suggest annual cost of about 5-15 million US $ per country. Since these estimates are outdated, future studies are needed to estimate the present costs due to toxoplasmosis in livestock. Further, the fact that T. gondii infections in livestock may affect human health needs to be considered and the respective costs should also be estimated, but this is beyond the scope of this article.

Syndromic surveillance by veterinary practitioners: a pilot study in the pig sector

Traditional indicator-based livestock surveillance has been focused on case definitions, definitive diagnoses and laboratory confirmation. The use of syndromic disease surveillance would increase the population base from which animal health data are captured and facilitate earlier detection of new and re-emerging threats to animal health. Veterinary practitioners could potentially play a vital role in such activities. In a pilot study, specialist private veterinary practitioners (PVP) working in the English pig industry were asked to collect and transfer background data and disease incident reports for pig farms visited during the study period. Baseline data from 110 pig farms were received, along with 68 disease incident reports. Reports took an average of approximately 25 minutes to complete. Feedback from the PVPs indicated that they saw value in syndromic surveillance. Maintenance of anonymity in the outputs would be essential, as would timely access for the PVPs to relevant information on syndromic trends. Further guidance and standardisation would also be required. Syndromic surveillance by PVPs is possible for the pig industry. It has potential to fill current gaps in the collection of animal health data, as long as the engagement and participation of data providers can be obtained and maintained.

A framework for reviewing livestock disease reporting systems in high-risk areas: assessing performance and perceptions towards foot and mouth disease reporting in the Thrace region of Greece, Bulgaria and Turkey

Disease reporting is an essential frontline component of surveillance systems, particularly for detecting incursions of new and emerging diseases. It has the advantages of being comprehensive and continuous, with the potential to reduce the time of disease detection and the extent of consequent spread. A number of exotic diseases, including sheep and goat pox, lumpy skin disease, peste des petits ruminants and foot and mouth disease have historically entered into south-eastern Europe through the Thrace region, which extends across neighbouring areas of Greece, Bulgaria and Turkey. In this high-risk area, multiple factors can reduce the sensitivity of disease reporting across the diverse production systems and animal health services need robust and effective disease reporting systems. While describing a training exercise designed to provide animal health services of the three countries with the knowledge and skills for conducting comprehensive in-country assessments, we provide an initial evaluation of the sensitivity of foot and mouth disease reporting and identify gaps and constraints in the Thrace region. An expert elicitation approach was used to consult official veterinarians from central and local animal health authorities of the three countries, and scenario trees modelling was applied to analyse the collected data. The reported sensitivity of disease reporting often varied between the central and local veterinary authorities within the three countries. Awareness of clinical disease, of reporting procedures and of biosecurity measures affected the early stages of disease reporting, particularly in the production systems identified at lower reporting sensitivity such as small ruminant's herds, mixed bovine herds and backyard herds. Despite its limitations this training exercise provided an effective framework (a) to develop capacities of the veterinary services in the region and (b) to supply initial evidence for guiding further interventions targeting those sectors and stakeholders at lower reporting sensitivity to reduce risks of disease introduction.

A systematic review on modelling approaches for economic losses studies caused by parasites and their associated diseases in cattle

Parasites reside inside or outside their hosts and get host nutrition and blood. Here, we have emphasized economic losses in cattle caused by parasitic diseases due to ecto- and endo- parasites (flies, ticks, mites and helminths). We have outlined different methods/models including economic evaluation techniques and dynamic analysis as a major class, used for the calculation of economic losses caused by parasites in cattle. According to already conducted studies, a decrease in production is mentioned in quantity and percentage while financial losses are expressed in the form of account with respect to per head, herd or for the specific study area. The parasites cause the reduced production and financial losses due to control, treatment and mortality costs. We calculated the average decrease in milk production and organ condemnation as 1.16 L animal-1 day-1 and 12.95%, respectively, from overall cattle parasitic infections. Moreover, the average calculated financial and percentage losses were US$ 50.67 animal-1 year-1 and 17.94%, respectively. Economically important parasitic diseases mentioned here are caused by specific spp. of protozoans and helminths according to data collected from the literature. Protozoan diseases include tick-borne diseases, coccidiosis, neosporosis, trypanosomiasis and cryptosporidiosis. Losses due to tick-borne infections were encountered for decreased milk production, mortality, treatment and control. Losses from coccidiosis were due to decreased weight gain, treatment costs and mortality. While abortion losses were encountered in neosporosis. Trypanosomiasis caused losses due to a decrease in milk yield. Moreover, only diagnostic (conventional or molecular techniques) cost was taken into account for cryptosporidiosis. Economically important nematode parasites are Oesophagostomum spp., Cooperia spp., Trichostrongylus spp., Strongyloides spp., Ostertagia spp. and Haemonchus placei. Due to the zoonotic importance of echinococcosis, Echinococcus granulosus is the most economically important cestode parasite. Losses caused by echinococcosis were due to organ condemnation, carcass weight loss and decreases hide value, milk production and fecundity. While, fascioliasis is one of the most economically important trematodal disease, which causes cirrhosis of the liver due to parasite migration, and thus, the organ becomes inedible. So, it would be helpful for farmers and researchers to approach these methods/models for calculation of parasitic losses and should adopt suitable measures to avoid long-term economic losses.

A framework for estimating society's economic welfare following the introduction of an animal disease: The case of Johne's disease

Animal diseases are global issues affecting the productivity and financial profitability of affected farms. Johne’s disease is distributed on farms worldwide and is an endemic contagious bacterial infection in ruminants caused by Mycobacterium avium subspecies paratuberculosis. In cattle, the clinical disease manifests itself as chronic enteritis resulting in reduced production, weight loss, and eventually death. Johne’s disease is prevalent in the UK, including Scotland. Direct costs and losses associated with Johne’s disease have been estimated in previous research, confirming an important economic impact of the disease in UK herds. Despite this, the distributional impact of Johne’s disease among milk consumers and producers in Scotland has not been estimated. In this paper, we evaluate the change in society’s economic welfare, namely to dairy producers (i.e. infected and uninfected herds) and milk consumers in Scotland induced by the introduction of Johne’s disease in the national Scottish dairy herd. At the national-level, we conclude that the economic burden falls mainly on producers of infected herds and, to a lesser extent, milk consumers, while producers of uninfected herds benefit from the presence of Johne’s. An infected producer’s loss per cow is approximately two times larger in magnitude than that of an uninfected producer’s gain. Such economic welfare estimates are an important comparison of the relative costs of national herd prevalence and the wider economic welfare implications for both producers and consumers. This is particularly important from a policy, public good, cost sharing, and human health perspective. The economic welfare framework presented in this paper can be applied to other diseases to examine the relative burden of society’s economic welfare of alternative livestock disease scenarios. In addition, the sensitivity analysis evaluates uncertainty in economic welfare given limited data and uncertainty in the national herd prevalence, and other input parameters, associated with Johne’s disease in Scotland. Therefore, until the prevalence of Johne’s is better understood, the full economic cost to Scottish dairy herds remains uncertain but in the meantime the sensitivity analysis evaluates the robustness of economic welfare to such uncertainties.

Domestic water buffaloes: Access to surface water, disease prevalence and associated economic losses

Given the shortage and non-availability of freshwater in Pakistan, wastewater is being used for bathing water buffaloes; however, this has a negative impact on animal welfare. Although there is a vast literature on indirect linkages between wastewater and animal productivity, studies focusing on the direct impacts of water buffaloes bathing in wastewater on animal productivity and economic losses are rare. Therefore, using 360 domestic water buffalo farms, this study examines the expenditure and production losses associated with bathing (in wastewater and freshwater) and non-bathing water buffaloes by employing partial budgeting and resource adjustment component techniques. Furthermore, it investigates the prevalence of animal diseases and associated economic effects using correlation analysis and propensity score matching techniques, respectively. The findings reveal that compared to their counterparts (freshwater bathing and non-bathing water buffaloes), buffaloes bathing in wastewater are at increased risk of clinical mastitis, foot and mouth disease (FMD) and tick infestation. Moreover, the use of wastewater for bathing buffaloes also leads to higher economic and production losses by affecting milk productivity, causing premature culling, and reducing slaughter value. The findings of the double-log model show that economic losses are higher if buffaloes bathe in wastewater within 30 min after milking, as there are more chances that those buffaloes would be exposed to bacterial penetration in the teat ducts, which may result in intramammary infection. According to the propensity score matching method, the higher economic damages per month are associated with buffaloes bathing in wastewater and freshwater, 155 and 110 USD per farm, respectively. The study findings reference the need for policies to restrict wastewater access by water buffaloes, and a regular check of and access to cool clean water wallows for bathing during hot summer days, to reduce excess heat and economic losses, and thus improve animal welfare.

Protective effect of a polyvalent influenza DNA vaccine in pigs

BACKGROUND

Influenza A virus in swine herds represents a major problem for the swine industry and poses a constant threat for the emergence of novel pandemic viruses and the development of more effective influenza vaccines for pigs is desired. By optimizing the vector backbone and using a needle-free delivery method, we have recently demonstrated a polyvalent influenza DNA vaccine that induces a broad immune response, including both humoral and cellular immunity.

OBJECTIVES

To investigate the protection of our polyvalent influenza DNA vaccine approach in a pig challenge study.

METHODS

By intradermal needle-free delivery to the skin, we immunized pigs with two different doses (500μg and 800μg) of an influenza DNA vaccine based on six genes of pandemic origin, including internally expressed matrix and nucleoprotein and externally expressed hemagglutinin and neuraminidase as previously demonstrated. Two weeks following immunization, the pigs were challenged with the 2009 pandemic H1N1 virus.

RESULTS

When challenged with 2009 pandemic H1N1, 0/5 vaccinated pigs (800μg DNA) became infected whereas 5/5 unvaccinated control pigs were infected. The pigs vaccinated with the low dose (500μg DNA) were only partially protected. The DNA vaccine elicited binding-, hemagglutination inhibitory (HI) - as well as cross-reactive neutralizing antibody activity and neuraminidase inhibiting antibodies in the immunized pigs, in a dose-dependent manner.

CONCLUSION

The present data, together with the previously demonstrated immunogenicity of our influenza DNA vaccine, indicate that naked DNA vaccine technology provides a strong approach for the development of improved pig vaccines, applying realistic low doses of DNA and a convenient delivery method for mass vaccination.

Engaging veterinarians and farmers in eradicating bovine viral diarrhoea: a systematic review of economic impact

Bovine viral diarrhoea (BVD) is a significant drain on efficient and successful cattle production in both dairy and beef systems around the world. Several countries have achieved eradication of this disease, but always through the motivation of stakeholders who accept the benefits of eradication. These include increased cattle welfare and fitness of cattle to withstand other diseases, and decreased costs of production, the latter resulting from both decreased costs spent on managing the disease and decreased losses. This paper provides a systematic review of 31 papers, published between 1991 and 2015, that address the economic impact of BVD. Each paper takes a different approach, in either beef or dairy production or both. However with the breadth of work collated, a stakeholder engaged in BVD eradication should find an economic figure of most relevance to them. The reported economic impact ranges from £0 to £552 per cow per year (£2370 including outliers). This range represents endemic or subclinical disease situations seen in herds with stable BVD virus infection, and epidemic or severe acute situations, most often seen in naïve herds. The outcome of infection is therefore dependent on the immune status of the animal and severity of the strain. The variations in figures for the economic impact of BVD relate to these immune and pathogenicity factors, along with the variety of impacts monitored.

Human-livestock contacts and their relationship to transmission of zoonotic pathogens, a systematic review of literature

BACKGROUND

Micro-organisms transmitted from vertebrate animals - including livestock - to humans account for an estimated 60% of human pathogens. Micro-organisms can be transmitted through inhalation, ingestion, via conjunctiva or physical contact. Close contact with animals is crucial for transmission. The role of intensity and type of contact patterns between livestock and humans for disease transmission is poorly understood. In this systematic review we aimed to summarise current knowledge regarding patterns of human-livestock contacts and their role in micro-organism transmission.

METHODS

We included peer-reviewed publications published between 1996 and 2014 in our systematic review if they reported on human-livestock contacts, human cases of livestock-related zoonotic diseases or serological epidemiology of zoonotic diseases in human samples. We extracted any information pertaining the type and intensity of human-livestock contacts and associated zoonoses.

RESULTS

1522 papers were identified, 75 were included: 7 reported on incidental zoonoses after brief animal-human contacts (e.g. farm visits), 10 on environmental exposures and 15 on zoonoses in developing countries where backyard livestock keeping is still customary. 43 studies reported zoonotic risks in different occupations. Occupations at risk included veterinarians, culling personnel, slaughterhouse workers and farmers. For culling personnel, more hours exposed to livestock resulted in more frequent occurrence of transmission. Slaughterhouse workers in contact with live animals were more often positive for zoonotic micro-organisms compared to co-workers only exposed to carcasses. Overall, little information was available about the actual mode of micro-organism transmission.

CONCLUSIONS

Little is known about the intensity and type of contact patterns between livestock and humans that result in micro-organism transmission. Studies performed in occupational settings provide some, but limited evidence of exposure response-like relationships for livestock-human contact and micro-organism transmission. Better understanding of contact patterns driving micro-organism transmission from animals to humans is needed to provide options for prevention and thus deserves more attention.

An economic evaluation of intervention strategies for Porcine Epidemic Diarrhea (PED)

The economic losses of Porcine Epidemic Diarrhea (PED) and the net benefits of strategies to control the virus are calculated for individual farrow-to-finish herds. A production simulation model that estimates the number of pigs by population cohorts on a weekly basis for a farrow-to-finish farm depending on production parameters is simulated under normal operating conditions and then with an outbreak of PED. The estimated annual costs of a PED outbreak with the closure of the breeding herd as the only intervention is approximately $300,000 for a 700-sow farrow-to-finishing herd. The net returns per sow (hog) fall from $255 ($11.54) to a loss of $174 ($10.68). These losses can be significantly reduced with any of the 16 intervention strategies considered in this study. The most profitable strategy involving front loading of gilts with average feedback of infected material to improve herd immunity, intensive biosecurity protocols and no vaccination costs $27,000 to implement but reduces losses by 10 times this amount. Even the implementation of the least comprehensive strategy, which involves back-loading gilts after the herd reopens and an average feedback practice at a cost of $1000 reduces the losses caused by a PED outbreak by $130,000. Front-loading gilts in combination with herd closure is more cost-effective than back-loading. Despite the extra spending on intensive biosecurity protocols, the overall loss reductions achieved by the intensive biosecurity effort can be significant. Vaccination is the least cost-effective of the intervention practices considered. Even with significant increases in cost or effectiveness in the practices, intervention is justified across all strategies. The spreadsheet model of a farrow-finish hog farm developed in this study can be used to examine changes to the production parameters or to consider other swine disease outbreaks.

Paradoxical effects of coupling infectious livestock populations and imposing transport restrictions

Spatial heterogeneity of a host population of mobile agents has been shown to be a crucial determinant of many aspects of disease dynamics, ranging from the proliferation of diseases to their persistence and to vaccination strategies. In addition, the importance of regional and structural differences grows in our modern world. Little is known, though, about the consequences when traits of a disease vary regionally. In this paper, we study the effect of a spatially varying per capita infection rate on the behaviour of livestock diseases. We show that the prevalence of an infectious livestock disease in a community of animals can paradoxically decrease owing to transport connections to other communities in which the risk of infection is higher. We study the consequences for the design of livestock transportation restriction measures and establish exact criteria to discriminate those connections that increase the level of infection in the community from those that decrease it.

Development of an improved Streptococcus uberis experimental mastitis challenge model using different doses and strains in lactating dairy cows

Developing a reliable mastitis challenge infection model is required to test new intramammary antimicrobial preparations, other novel bovine mastitis treatments, and study mastitis pathogenesis. Three treatment groups of Holstein Friesian cows in active lactation were administered two doses (104 and 106 cfu/quarter) on a single occasion with one of the three Streptococcus uberis strains (BFR6019, MFF1283 and SA002) suspended in 5 ml of sterile PBS, administered via intramammary inoculation immediately after milking. All quarters that were challenged with S. uberis strains MLF1283 and BFR6019 showed clinical signs of mastitis on day 1 and 2 after the challenge. Strain SA002 had a lower rate of inducing clinical mastitis which was detected later than day 3 after the challenge. We successfully developed a rapid and reliable model for inducing experimental S. uberis mastitis with 100% success rate in cows in active lactation. On the basis of the correlation results between strains, RAPD fingerprinting results, clinical findings, and a 100% success rate of mastitis induction for low and high doses S. uberis strains MLF1283 and BFR6019, strain virulence seems to be a more important effect than challenge dose in induction of clinical mastitis following experimental challenge.

Not all cows are epidemiologically equal: quantifying the risks of bovine viral diarrhoea virus (BVDV) transmission through cattle movements

Many economically important cattle diseases spread between herds through livestock movements. Traditionally, most transmission models have assumed that all purchased cattle carry the same risk of generating outbreaks in the destination herd. Using data on bovine viral diarrhoea virus (BVDV) in Scotland as a case example, this study provides empirical and theoretical evidence that the risk of disease transmission varies substantially based on the animal and herd demographic characteristics at the time of purchase. Multivariable logistic regression analysis revealed that purchasing pregnant heifers and open cows sold with a calf at foot were associated with an increased risk of beef herds being seropositive for BVDV. Based on the results from a dynamic within-herd simulation model, these findings may be partly explained by the age-related probability of animals being persistently infected with BVDV as well as the herd demographic structure at the time of animal introductions. There was also evidence that an epidemiologically important network statistic, "betweenness centrality" (a measure frequently associated with the potential for herds to acquire and transmit disease), was significantly higher for herds that supplied these particular types of replacement beef cattle. The trends for dairy herds were not as clear, although there was some evidence that open heifers and open lactating cows were associated with an increased risk of BVDV. Overall, these findings have important implications for developing simulation models that more accurately reflect the industry-level transmission dynamics of infectious cattle diseases.

The heritability of abortion in pedigree Charollais flocks

Foetal death, or abortion at term, in sheep is of major significance to the livestock industry, accounting for more than £24million lost per annum. We have investigated whether there is a genetic component to abortion within two flocks of pedigree Charollais sheep, one followed from 1989 to 2006, the other from 1992 to 2006. Abortion occurred at a rate of 5.74-8.78% per annum against a total mortality rate of 14-24%. By model covariate analysis we have shown that 15.5% aborting ewes went on to have one or more abortions and that this risk increased with parity (p=0.006). Heritability estimates were approximately 0.08 as calculated by SOLAR, pedigreemm and ASReml3, with sire and dam components of 0.046 and 0.048, respectively. Where the lamb was aborted, heritability estimates were highly variable according to the method employed, 0.046-0.378, with sex of the lamb being a significant covariate. This variability indicated one or more underlying, significant factors that were not measured in these analyses, potentially including infectious agents that may be involved. Nevertheless, the ASReml3 estimate (0.179) resolved to 0.074 variance attributable to the sire and 0.092 attributable to the dam, which, while not significant, was suggestive that genetic variants passed by the dam to the lamb may be of more weight than that from the sire in determining whether a lamb will abort.

Codon optimisation to improve expression of a Mycobacterium avium ssp. paratuberculosis-specific membrane-associated antigen by Lactobacillus salivarius

Subunit and DNA-based vaccines against Mycobacterium avium ssp. paratuberculosis (MAP) attempt to overcome inherent issues associated with whole-cell formulations. However, these vaccines can be hampered by poor expression of recombinant antigens from a number of disparate hosts. The high G+C content of MAP invariably leads to a codon bias throughout gene expression. To investigate if the codon bias affects recombinant MAP antigen expression, the open reading frame of a MAP-specific antigen MptD (MAP3733c) was codon optimised for expression against a Lactobacillus salivarius host. Of the total 209 codons which constitute MAP3733c, 172 were modified resulting in a reduced G+C content from 61% for the native gene to 32.7% for the modified form. Both genes were placed under the transcriptional control of the PnisA promoter; allowing controlled heterologous expression in L. salivarius. Expression was monitored using fluorescence microscopy and microplate fluorometry via GFP tags translationally fused to the C-termini of the two MptD genes. A > 37-fold increase in expression was observed for the codon-optimised MAP3733synth variant over the native gene. Due to the low cost and improved expression achieved, codon optimisation significantly improves the potential of L. salivarius as an oral vaccine stratagem against Johne's disease.

The multiple burdens of zoonotic disease and an Ecohealth approach to their assessment

Zoonoses occur at the interface of human and animal disease and partly because their impact and management fall across two sectors they are often neglected. The Global Burden of Disease captures the impact of zoonoses on human health in terms of disability-adjusted life years (DALYs). Based on this, we estimate that in low income countries, zoonoses and diseases which recently emerged from animals make up 26 % of the DALYs lost to infectious disease and 10 % of the total DALYs lost. In contrast, in high income countries, zoonoses and diseases recently which emerged from animals represent less than 1 % of DALYs lost to infectious disease and only 0.02 % of the total disease burden. We present a framework that captures the costs of zoonoses and emerging disease to human, animal and ecosystem health in terms of cost of treatment, cost of prevention, health burden and intangible and opportunity costs. We also discuss how ecohealth concepts of transdisciplinarity, participation and equity can help in assessing the importance of zoonoses in developing countries and illustrate these with an example of assessing milk-borne disease.

Novel polymorphisms in ovine immune response genes and their association with abortion

The sheep has worldwide agricultural importance, yet the genetic control of the immune responses underlying susceptibility or resistance to ovine disease is little understood. Here, we identify six novel polymorphisms in the ovine immune response genes interferon-γ (IFNG), tumour necrosis factor-α (TNF), interleukin-1β (IL1B) and interleukin-4 (IL4) in pedigree Charollais flocks. We confirm the presence of previously reported polymorphisms in IFNG and IL1B in Charollais. Restriction fragment length polymorphism (RFLP) genotyping assays have been developed for four polymorphisms, IFNGg.168C>T, IFNGg.285A>G, IL1Bg.689C>T and TNFg.3UTRA>G, and a Taqman genotyping assay has been developed for IL4g.485C>T. The previously described IL2g.647C>T polymorphism is adapted for RFLP analysis. Allele frequencies are described in Charollais, Lleyn and Suffolk cross sheep. Polymorphisms are typed in both Charollais ewes and lambs and analysed against abortion phenotypes. A subset of animals have also been analysed for the presence of Toxoplasma gondii, an abortion-causing protozoan. The IFNGg.168T allele is shown to be associated with increased risk of a ewe having an abortion, while the IFNGg.285G allele is associated with increased risk of a lamb being aborted. These assays provide tools for the investigation of the genetic basis of other phenotypes in sheep, including infectious disease susceptibility.

Toxoplasma gondii: the effects of infection at different stages of pregnancy on the offspring of mice

Congenital toxoplasmosis can cause fetal damage in humans and domestic animals. This study was focused on the effects of Toxoplasma gondii (Prugniaud strain) infection at different stages of pregnancy on the offspring of mice. Results showed that newborn mice from all infected groups were significantly lower in weight than those from the control group but significant difference was not found among these groups at day 60 after birth. The survival rate of the offspring from the group of mice infected at the earlier stage of pregnancy was significantly lower than those of infected and control groups. The positive offspring (with cysts found in their brain tissues) born from the mice infected at the earlier and intermediate stages of pregnancy showed a shorter latency and greater number of errors in the step-through passive avoidance test than those born from the mice infected at the late stage of pregnancy, the control group and the negative offspring from the infected groups. The number of cysts in the brain tissue was significantly higher in the offspring born from the groups of mice infected at the earlier and intermediate stages of pregnancy than those from the group of mice infected at the late stage of pregnancy. In addition, our results indicated that a high congenital transmission rate (90%) occurred in this NIH mouse model. In conclusion, the earlier and intermediate maternal infection of T. gondii can result in severe congenital toxoplasmosis, exhibiting conditions such as stillbirth or non-viability, and learning or memory capability damage in this mouse model. These results not only provide useful data for better understanding the effects of T. gondii infection on the offspring of mice infected at different stages of pregnancy but also for better consideration of the effect of this infection on other mammalian hosts including humans.

Loss of income from cows shedding Mycobacterium avium subspecies paratuberculosis prior to calving compared with cows not shedding the organism on two Minnesota dairy farms

Quantification of the financial effect of Mycobacterium paratuberculosis infection on lactation performance is essential to encourage participation of dairy cattle producers in Johne's disease (JD) control programs. The objective of this study was to evaluate the differences in net income per lactation of cows shedding Mycobacterium paratuberculosis before calving compared with test-negative cows. Two Minnesota dairies were enrolled in the study and fecal samples were collected from 1,048 cows during the close-up period. Milk production, clinical diseases (other than clinical JD), and reproductive performance data were recorded for each cow. Overall, fecal-culture-positive (FCP) cows produced 1,355 kg less than fecal-culture-negative (FCN) cows. Fecal-culture-positive cows that survived their current lactation produced $276 less in milk income than cows that were FCN ($1,956 vs. $1,680; SD $526, $570). Fecal-culture-positive cows were 3.0 (95% confidence interval: 1.6-5.8) times more likely to be culled than FCN cows. The mean days open (number of days from calving to conception) was not statistically significant and the cost differences for clinical disease other than JD were small and neither statistically nor economically significant between FCP and FCN cows. Among all FCP cows, income over feed costs losses were $366 per cow per lactation compared with FCN cows. Among FCP nonculled cows, income over feed costs losses were $276 more compared with FCN cows and this difference was statistically significant. There was a total loss of $155 per lactation for nonculled FCP cows retained in the herd compared with FCN cows retained in the herd. Among culled cows, FCP cow losses were $50 less because of age at culling and $120 for reduced beef value. This totaled a loss of $441 for culled FCP cows compared with culled FCN cows. The losses as a result of lower lactation performance and early culling from the herd should alarm dairy producers and motivate them to implement the appropriate control measures for the disease.

Efficacy of a teat dip containing the bacteriocin lacticin 3147 to eliminate Gram-positive pathogens associated with bovine mastitis

On most dairy farms teat dips are applied to the teats of cows either before or after milking in order to prevent pathogens from gaining access to the mammary gland via the teat canal. In the present experiments, a natural teat dip was developed using a fermentate containing the live bacterium Lactococcus lactis DPC 3251. This bacterium produces lacticin 3147, a two-component lantibiotic which was previously shown to effectively kill Gram-positive mastitis pathogens. Lacticin 3147 activity in the fermentate was retained at 53% of its original level following storage for 3 weeks at 4 degrees C. In the initial experiments in vitro, 105 colony-forming units/ml (cfu/ml) of either Staphylococcus aureus, Streptococcus dysgalactiae or Streptococcus uberis were introduced into the lacticin-containing fermentate. Neither Staph. aureus nor Str. dysgalactiae could be detected after 30 min or 15 min, respectively, while Str. uberis was reduced approximately 100-fold after 15 min. Following these trials, preliminary experiments were performed in vivo on teats of lactating dairy cows. In these experiments, teats were coated with each of the challenge organisms and then dipped with the lacticin-containing fermented teat dip. Following a dip contact time of 10 min, staphylococci were reduced by 80% when compared with the undipped control teat. Streptococcal challenges were reduced by 97% for Str. dysgalactiae and by 90% for Str. uberis. These trials showed that the teat dip is able to reduce mastitis pathogens on the teats of lactating cows.

Economical impact of tropical theileriosis in the Cappadocia region of Turkey

This study was initiated to investigate the economical impact of vaccination against tropical theileriosis in cattle in Cappadocia in Turkey. A total of 554 vaccinated and non-vaccinated animals were monitored for Theileria annulata infection using microscopic examination serology by measuring the antibody response of the animals by the indirect immunofluorescence antibody test (IFAT). The prevalence of T. annulata infection, morbidity and mortality were significantly higher in unvaccinated than in vaccinated cattle, whereas the seropositivity was significantly lower in the unvaccinated group. Acute tropical theileriosis cases were diagnosed in 156 of 554 (27.61%) cattle, and 86 of 156 (56.21%) died from the disease. The total economic losses because of tropical theileriosis were estimated at US $598,133 for 2 years.

Economic effects of bovine mastitis and mastitis management: a review

Several studies have been published since 1990 on the economics of mastitis and mastitis management. However, hardly any of these studies has discussed the consistency of results with other studies. In the present paper, the economic factors associated with mastitis are explained, providing a framework for economic analysis. As a second step calculations of the costs of mastitis and the costs in relation to the benefits of mastitis management published since 1990 in peer-reviewed journals are extensively reviewed and analysed. The result shows a large variation in the calculated costs and benefits of mastitis and mastitis management between the different studies. Moreover, it is clear that important factors were ignored in some of the studies. The framework provided in this paper can provide a basis for analysis for future studies on the economics of mastitis and mastitis management.

The association between Mycobacterium avium subsp. paratuberculosis fecal shedding or clinical Johne's disease and lactation performance on two Minnesota, USA dairy farms

Lactation performance of cows infected with Mycobacterium avium subsp. paratuberculosis (Map) was previously studied using only serum ELISA as a diagnostic method. This study evaluated on two dairy farms in Minnesota, USA the lactation performance (measures of health, production, reproduction, and survival) of cows shedding Map in feces before calving and of cows culled with clinical signs consistent with Johne's disease (JD) during the subsequent lactation. Fecal samples were collected from 1052 cows within 21 day before calving and tested for Map with bacterial culture. Producers' observed signs of clinical disease (milk fever, retained placenta, metritis, ketosis, displaced abomasum, lameness, mastitis, pneumonia, and JD) and production and reproduction data were recorded for each cow. The association between fecal shedding or clinical JD and lactation performance was evaluated. Logistic regression was used to evaluate the association with any clinical and subclinical diseases as the outcome. General linear model was used to evaluate the association with milk production, and survival analysis techniques were used to evaluate the association with days in the study before culling and days from calving to conception. In 84 cows (8% of 1052 cows) fecal samples were positive for Map (46% light, 26% moderate, and 28% heavy shedders). In multivariable analysis, light, moderate, and heavy fecal shedding cows produced on average 537, 1403, and 1534 kg, respectively, less milk per lactation and 1.4, 5.2, and 7.5 kg, respectively, less milk per day than fecal negative cows. Fecal culture positive cows were less likely to be bred and conceive. In the multivariable analysis the 56 cows culled with presumed JD produced approximately 1500 kg/lactation or 5 kg/day less than all other cows. The negative economic impact implied by decreased lactation performance in cows shedding Map or with clinical JD may motivate producers to implement programs to control Map infection and subsequent JD.

Financial analysis of various strategies for the control of Neospora caninum in dairy cattle in Switzerland

The present study was conducted to estimate the direct losses due to Neospora caninum in Swiss dairy cattle and to assess the costs and benefits of different potential control strategies. A Monte Carlo simulation spreadsheet module was developed to estimate the direct costs caused by N. caninum, with and without control strategies, and to estimate the costs of these control strategies in a financial analysis. The control strategies considered were "testing and culling of seropositive female cattle", "discontinued breeding with offspring from seropositive cows", "chemotherapeutical treatment of female offspring" and "vaccination of all female cattle". Each parameter in the module that was considered to be uncertain, was described using probability distributions. The simulations were run with 20,000 iterations over a time period of 25 years. The median annual losses due to N. caninum in the Swiss dairy cow population were estimated to be euro 9.7 million euros. All control strategies that required yearly serological testing of all cattle in the population produced high costs and thus were not financially profitable. Among the other control strategies, two showed benefit-cost ratios (BCR) >1 and positive net present values (NPV): "Discontinued breeding with offspring from seropositive cows" (BCR=1.29, NPV=25 million euros ) and "chemotherapeutical treatment of all female offspring" (BCR=2.95, NPV=59 million euros). In economic terms, the best control strategy currently available would therefore be "discontinued breeding with offspring from seropositive cows".

Estimated direct economic costs associated with tick-borne diseases on cattle in Tanzania

Tick-borne diseases, namely, anaplasmosis, babesiosis, cowdriosis and theileriosis, constrain cattle production and improvement in Tanzania, leading to considerable economic losses. A simple spreadsheet model was used to estimate the economic losses resulting from production losses, treatment and control costs associated with tick-borne diseases (TBD) in Tanzania. Model parameters included the national cattle population, reported TBD morbidity, fatality risk, and chemotherapy and control measures used. The total annual national loss due TBD was estimated to be 364 million USD, including an estimated mortality of 1.3 million cattle. Theileriosis accounted for 68% of the total loss, while anaplasmosis and babesiosis each accounted for 13% and cowdriosis accounted for 6% of the total loss. Costs associated with mortality, chemotherapy and acaricide application accounted for 49%, 21% and 14% of the total estimated annual TBD losses, respectively, infection and treatment method milk loss and weight loss accounted for 1%, 6% and 9% of the total annual loss, respectively. Despite the inadequacies of the data used, the results give evidence that tick-borne diseases inflict substantial economic losses on cattle production and resource use in Tanzania.

A stochastic model simulating pathogen-specific mastitis control in a dairy herd

The objective of this study was to develop a model simulating mastitis control in dairy herds and to investigate how sensitive the model is when varying the effect parameters according to the uncertainty. The model simulates 9 pathogen-specific mastitis types, each of which can be subclinical or clinical. The clinical cases can be 1 of 4 severities defined according to the effect of the mastitis case: mild, moderate, severe, and permanent effect. The risk factors include lactation stage, parity, yield level, previous diseases, season, and contagious spread of the infection from herd mates. Occurrence of mastitis is modeled to have direct effects on feed intake, body weight, milk yield, somatic cell count in the milk, subsequent mastitis cases within the cow and in herd mates, voluntary and involuntary culling, mortality, and milk withdrawal. Thirty-five scenarios were simulated to study model behavior and model sensitivity. The consequences per cow/yr of mastitis in the default simulated herd included 0.42 clinical mastitis occurrences, 0.56 subclinical mastitis occurrences, loss of 385-kg milk yield, a 1.3% reduced feed intake, 61-kg milk withdrawal and 146 in reduced economic net return. Based on scenarios demonstrating model behavior and sensitivity analysis, the model appears to produce valid consequences of mastitis control strategies. Representation of the effect of subclinical mastitis and of variation in mastitis severity was concluded in this study to be important when modeling mastitis economics in a dairy herd. The model offers the opportunity to study the long-term herd specific effects of a wide range of control strategies against mastitis.

Ten years of bovine virus diarrhoea virus (BVDV) control in Norway: a cost-benefit analysis

A retrospective cost-benefit analysis was carried out on the Norwegian bovine virus diarrhoea (BVD) control and eradication strategy, for the years 1993-2003. Information regarding the control cost input parameters was gathered from the cattle industry (TINE Norwegian Dairies, GENO Breeding and AI association, and GILDE Norwegian Meat), The National Animal Health Authorities and The Veterinary Institute. We accounted for variable costs (both direct costs associated with the control, and those costs carried by the farmers as a consequence of the control program). The benefit was estimated as the difference between the assumed losses without control - represented overall as 10% increase of the observed 1993 BVD virus infection level - and the observed losses during the control period. An estimate of the financial losses associated with the BVD virus (BVDV) infection was based on studies of the herd level effects on health, reproduction, and production in dairy herds with evidence of recent BVDV infection. We used a stochastic simulation model to account for the total uncertainty in both the control cost and financial loss estimates. The annual net benefits over the 10 years of BVD control were discounted to a 1993 net present value (NPV). The median NPV of the BVD control, nationally, was estimated at 130 million NOK with a distribution of the NPV ranging from +51 to +201 million NOK (5th and 95th percentiles, respectively). Out of the total control costs the farmers and the farmer-owned industries (the co-operatives) had carried about 62% of these costs; however, the farmers were also the main beneficiaries. The Norwegian experience shows a robust cost-efficiency for a BVDV eradication strategy; this stands in sharp contrast to earlier studies where the results were not supportive. Even though every cattle population and country is unique, the Norwegian findings and experiences should have wider implications.

Epidemiological aspects and economic impact of bovine theileriosis (East Coast fever) and its control: a preliminary assessment with special reference to Kibaha district, Tanzania

A cross-sectional study based on clinical examination, inspection of herd health records and a questionnaire was designed to determine the epidemiology, economics and potential impact of immunisation against theileriosis in Tanzania. The results showed annual theileriosis costs to be US$ 205.40 per head, whereas the introduction of immunisation reduced this by 40-68% depending on the post immunisation dipping strategy adopted. Morbidity risk due to theileriosis was 0.048 in immunised and 0.235 in non-immunised cattle, and the difference was significant (chi(2)=66.7; P=0.000). The questionnaire results indicated that immunised cattle had a significantly (chi(2)=6; P=0.015) higher risk of anaplasmosis compared with non-immunised cattle, whereas the risk of bovine babesiosis did not differ significantly (chi(2)=0.06; P=0.807) between the two groups. Mortality risk due to anaplasmosis was 0.046 in immunised and 0.018 in non-immunised cattle and this difference was statistically significant (chi(2)=4.48; P=0.043). The theileriosis mortality risk was 0.203 in the non-immunised cattle, while the risk was 0.009 in the immunised cattle and these differences were also significant (chi(2)=103; P=0.000). It was concluded that farmers who have immunised their cattle may cautiously cut down acaricide application by 50% for extensively grazed herds and by 75% for zero grazed animals depending on the level of tick challenge at the herd level.

Direct production losses and treatment costs from bovine viral diarrhoea virus, bovine leukosis virus, Mycobacterium avium subspecies paratuberculosis, and Neospora caninum

Our purpose was to determine direct production losses (milk loss, premature voluntary culling and reduced slaughter value, mortaliy loss, and abortion and reproductive loss) and treatmetn costs (veterinary services, medication cost, and extra farm labour cost) due to four infectious diseases in the maritime provinces of Canada: bovine viral diarrhoea (BVD), enzootic bovine leukosis (EBL), Johne's Disease (JD), and neosporosis. We used a partial-budget model, and incorporated risk and sensitivity analyses to identify the effects of uncertainty on costs. Total annual costs for an average, infected, 50 cow herd were: JD$ 2472; BVD$ 2421; neosporosis $ 2304; EBL$ 806. The stochastic nature of the proportion of infected herds and prevalence of infection within a herd were used to estimate probability distributions for these ex post costs. For all diseases, these distributions were right skewed. A sensitivity analysis showed the largest effect on costs was due to milk yield effects. For example, changing milk production loss from 0 to 5% for BVD increased the costs for the disease by 266%.