Epidemiological performance and subsequent costs of different surveillance strategies to control bovine herpesvirus type 1 in dairy farms.

This study aimed at comparing the surveillance program of bovine herpesvirus type 1 (BHV1) as laid down by EU Decision 2004/558/EC and 2007/584/EC ('conventional design') with an alternative design. The alternative design was based on monthly bulk-milk testing, clinical surveillance and a risk-based component that involves testing of animals that are purchased from non-free cattle herds. Scenario-tree analyses were carried out to determine sensitivities of the surveillance system (and its components) and the monthly confidence of freedom on herd-level. Also, the expected costs per surveillance design and components thereof were calculated. Results showed that the conventional (EU) and alternative surveillance designs to obtain a BHV1-free status performed equally well in terms of sensitivity. However, total costs per cattle herd to obtain a free status were highest in the conventional design. In an endemic situation and with a within-herd design prevalence of 10%, the conventional design led to a varying probability of freedom ranging from 99.6% to 100% per month. With the alternative design, in this situation, a constant probability of freedom of >99.9% per month was found. In a disease-free situation, both designs performed equally well (probability of freedom >99.9% per month). The yearly costs per farm for monitoring the disease-free status decreased by approximately 25% in the alternative design. The alternative strategy based on monthly bulk-milk monitoring therefore was deemed most cost-effective. This study showed that the surveillance regime to attain and maintain a BHV1-free status as described by EU-legislation can be improved to reduce the monitoring costs without reduction of the system's sensitivity, given a within-herd design prevalence of 10%. The assessment of various surveillance designs could be highly useful to support decision-making towards a more risk-based approach of animal health surveillance.

Prevalence of Circulating Antibodies to Bovine Herpesvirus 1 in Yaks (Bos grunniens) on the Qinghai-Tibetan Plateau, China.

Bovine Herpesvirus 1 (BoHV-1) causes infections with many clinical signs, including rhinotracheitis, encephalitis, and genital lesions. The virus occurs worldwide in bovines, and in recent years, it has been reported in yaks (Bos grunniens) inhabiting the Tibetan Plateau in China. However, there is little epidemiologic data describing BoHV-1 infections in China's yak herds. We conducted a cross-sectional study on the Qinghai-Tibetan Plateau (QTP) in China July 2011-July 2012 to estimate the prevalence of BoHV-1 antibody in yak herds. We collected 1,840 serum samples from yaks on the QTP, in Tibet (988 yaks), Qinghai (475 yaks), and Sichuan (377 yaks) Provinces. Using an enzyme-linked immunosorbent assay, we found that 381 (38.6%) of the Tibetan samples, 212 (44.6%) of the Qinghai samples, and 105 (27.9%) of the Sichuan samples had detectable antibodies to BoHV-1. Given that this high prevalence of infection in yaks could result in heavy economic losses, we suggest that an effective management program, including vaccination and strategies for infection control, be developed.

A stochastic simulation model to determine the sample size of repeated national surveys to document freedom from bovine herpesvirus 1 (BoHV-1) infection.

BACKGROUND: International trade regulations require that countries document their livestock's sanitary status in general and freedom from specific infective agents in detail provided that import restrictions should be applied. The latter is generally achieved by large national serological surveys and risk assessments. The paper describes the basic structure and application of a generic stochastic model for risk-based sample size calculation of consecutive national surveys to document freedom from contagious disease agents in livestock. METHODS: In the model, disease spread during the time period between two consecutive surveys was considered, either from undetected infections within the domestic population or from imported infected animals. The @Risk model consists of the domestic spread in-between two national surveys; the infection of domestic herds from animals imported from countries with a sanitary status comparable to Switzerland or lower sanitary status and the summary sheet which summed up the numbers of resulting infected herds of all infection pathways to derive the pre-survey prevalence in the domestic population. Thereof the pre-survey probability of freedom from infection and required survey sample sizes were calculated. A scenario for detection of infected herds by general surveillance was included optionally. RESULTS: The model highlights the importance of residual domestic infection spread and characteristics of different import pathways. The sensitivity analysis revealed that number of infected, but undetected domestic herds and the multiplicative between-survey-spread factor were most correlated with the pre-survey probability of freedom from infection and the resulting sample size, respectively. Compared to the deterministic pre-cursor model, the stochastic model was therefore more sensitive to the previous survey's results. Undetected spread of infection in the domestic population between two surveys gained more importance than infection through animals of either import pathway. CONCLUSION: The model estimated the pre-survey probability of freedom from infection accurately as was shown in the case of infectious bovine rhinotracheitis (IBR). With this model, a generic tool becomes available which can be adapted to changing conditions related to either importing or exporting countries.

Pro and contra IBR-eradication.

Bovine herpesvirus type 1 (BoHV-1) is the causative agent of respiratory and genital tract infections such as infectious rhinotracheitis (IBR), infectious pustular vulvovaginitis (IPV, balanoposthitis (IBP), and abortion. Despite of a pronounced immune response, the virus is never eliminated from an infected host but establishes life-long latency and may be reactivated at intervals. Europe has a long history of fighting against BoHV-1 infections, yet, only a small number of countries has achieved IBR-eradication. Therefore, it seemed appropriate to review the reasoning pro and contra such a task. Clearly, the goal can indeed be achieved as has been demonstrated by a number of European countries. However, detection and stamping out of seemingly healthy virus carriers is inevitable in the process. Unfortunately, the use of vaccines is only of temporary and limited value. Therefore, there are numerous considerations to be put forward against such plans, including the high costs, the great risks, and the unsatisfactory quality of tools. If either control or eradication of IBR is nonetheless a goal, then better vaccines are needed as well as better companion tests. Moreover, better tools for the characterization of viral isolates are required. Collaborative actions to gather viral strains from as many countries as possible for inclusion into a newly created clustering library would be most advantageous.

Water, socioeconomic factors, and human herpesvirus 8 infection in Ugandan children and their mothers.

BACKGROUND: Human herpesvirus 8 (HHV-8) infection is common in sub-Saharan Africa, but its distribution is uneven. Transmission occurs during childhood within families by unclear routes. METHODS: We evaluated 600 Ugandan children with sickle cell disease and their mothers for factors associated with HHV-8 seropositivity in a cross-sectional study. HHV-8 serostatus was determined using an HHV-8 K8.1 glycoprotein enzyme immunoassay. Odds ratios for seropositivity were estimated using logistic regression, and factor analysis was used to identify clustering among socioeconomic variables. RESULTS: One hundred seventeen (21%) of 561 children and 166 (34%) of 485 mothers with definite HHV-8 serostatus were seropositive. For children, seropositivity was associated with age, mother's HHV-8 serostatus (especially for children aged 6 years or younger), lower maternal education level, mother's income, and low-status father's occupation (P < 0.05 for all). Using communal standpipe or using surface water sources were both associated with seropositivity (OR 2.70, 95% CI 0.80-9.06 and 4.02, 95% CI 1.18-13.7, respectively) as compared to using private tap water. These associations remained, albeit attenuated, after adjusting for maternal education and child's age (P = 0.08). In factor analysis, low scores on environmental and family factors, which captured household and parental characteristics, respectively, were positively associated with seropositivity (P(trend) < 0.05 for both). For mothers, HHV-8 seropositivity was significantly associated with water source and maternal income. CONCLUSIONS: HHV-8 infection in Ugandan children was associated with lower socioeconomic status and using surface water. Households with limited access to water may have less hygienic practices that increase risk for HHV-8 infection.

[Risk and economics of disease introduction to dairy farms]. / Risico en economie van insleep van ziekten op melkveebedrijven.

A more closed farming system will enhance the success of disease eradication programmes, because the introduction or re-introduction of infectious diseases is less likely. The objective of the study was to obtain input for the development of an on-farm decision support model to calculate the economic consequences of a more closed farming system. The input was based on bovine herpesvirus 1 (BHV1), since there were numerous data on this disease, but a more closed farming system will prevent introduction of other diseases as well (i.e. bovine virus diarrhoea virus (BVDV), L. hardjo, and S. dublin). Direct animal contacts, such as purchase of cattle, participation in cattle shows, and cattle that escape and mingle with other cattle, were found to be important risk factors for the introduction of BHV1. Furthermore, the use of protective farm clothing was found to be an important preventive factor. The effect of an IBR outbreak at an IBR-free farm on milk production caused limited losses of on average 0.9 kg per cow per day during 9 weeks, but the variability was high (95% CI 0-2 kg). Nine percent of Dutch IBR-free dairy farms that were also at risk for BVDV, L. hardjo or S. dublin had one introduction per year of one of these four diseases. All these results were incorporated in the economic model. Management measures to reduce the probability of introduction of BHV1, the costs of these measures, and the risk reduction after these measures were obtained from other sources. The calculations showed that the implementation of a more closed system will be profitable for most farms. The profitability will increase when a farm is at risk for more diseases, but will decrease when farms are limited in their facilities to rear replacement heifers or when a large proportion of pasture adjoins pasture of other cattle farms.

Evaluating control strategies for outbreaks in BHV1-free areas using stochastic and spatial simulation.

Several countries within the EU have successfully eradicated bovine herpesvirus type I (BHV1), while others are still making efforts to eradicate the virus. Reintroduction of the virus into BHV1-free areas can lead to major outbreaks - thereby causing severe economic losses. To give decision-makers more insight into the risk and economic consequences of BHV1 reintroduction and into the effectiveness of various control strategies, we developed the simulation model InterIBR. InterIBR is a dynamic model that takes into account risk and uncertainty and the geographic location of individual farms. Simulation of a BHV1-outbreak in the Netherlands starts with introduction of the virus on a predefined farm type, after which both within-farm and between-farm transmission are simulated. Monitoring and control measures are implemented to simulate detection of the infection and subsequent control. Economic consequences included in this study are related to losses due to infection and costs of control. In the simulated basic control strategy, dairy farms are monitored by monthly bulk-milk tests and miscellaneous farms are monitored by half-yearly serological tests. After detection, movement-control measures apply, animal contacts are traced and neighbour farms are put on surveillance. Given current assumptions on transmission dynamics, we conclude that a strategy with either rapid removal or vaccination of infected cattle does not reduce the number of infected farms compared to this basic strategy - but will cost more to control. Farm type with first introduction of BHV1 has a considerable impact on the expected number of secondarily infected farms and total costs. To limit the number of infected farms and total costs due to outbreaks, we suggest intensifying the monitoring program on farms with a high frequency of cattle trade, and monthly bulk-milk testing on dairy farms.

Assessing the economic benefits of antiherpes therapy.

Increasing pressures on health-care budgets mean that health-care treatments and programmes need not only to demonstrate that they are efficacious, but also that they deliver good value for money. In the context of pharmaceuticals it is likely that both in Australia and Ontario (Canada) evidence of cost effectiveness will become a mandatory requirement prior to reimbursement (government subsidy) of drugs. However, in most jurisdictions economic data will be one of a number of factors taken into account by decision makers, be they policy makers, members of formulary committees, or individual prescribers. Methods of economic evaluation have been developed for the assessment of healthcare treatments, but these have not been extensively applied to antiherpes therapy. However, this paper, based on a literature review of the clinical trials of acyclovir, shows that there are many indicators of potential economic benefit, depending on the clinical indication, in length or quality of life, savings in other health-care resources, or wider benefits (e.g., reductions in lost work time). If appropriate economic data are to be gathered in future for new antiherpes therapy, a more systematic approach is required, conducting economic evaluation alongside, or as an integral part of, clinical trials. This raises important logistical and methodological challenges. It is important that researchers acknowledge these challenges early so that they can be adequately addressed.

The impact of physician denial upon patient autonomy and well-being.

It is now widely accepted that a patient's ability to engage in autonomous decision-making can be seriously threatened when she denies significant aspects of her medical condition. In this paper I use a true case to reveal the harmful effects of physician denial upon patient autonomy and well-being. I suggest further that such physician denial may be more common than is generally acknowledged, since aspects of the contemporary medical ethos likely serve to reinforce rather than to undercut such denial.