Epidemics and control strategies for diseases of farmed salmonids: a parameter study.

The susceptibility of the English and Welsh fish farming and fisheries industry to emergent diseases is assessed using a stochastic simulation model. The model dynamics operate on a network comprising directed transport and river contacts, as well as undirected local and fomite transmissions. The directed connections cause outward transmission risk to be geographically more confined than inward risk. We consider reactive, proactive, and hybrid methods of control which correspond to a mixture of policy and the ease of disease detection. An explicit investigation of the impact of laboratory capacity is made. General quantified guidelines are derived to mitigate future epidemics.

Preventable H5N1 avian influenza epidemics in the British poultry industry network exhibit characteristic scales.

Epidemics are frequently simulated on redundantly wired contact networks, which have many more links between sites than are minimally required to connect all. Consequently, the modelled pathogen can travel numerous alternative routes, complicating effective containment strategies. These networks have moreover been found to exhibit 'scale-free' properties and percolation, suggesting resilience to damage. However, realistic H5N1 avian influenza transmission probabilities and containment strategies, here modelled on the British poultry industry network, show that infection dynamics can additionally express characteristic scales. These system-preferred scales constitute small areas within an observed power law distribution that exhibit a lesser slope than the power law itself, indicating a slightly increased relative likelihood. These characteristic scales are here produced by a network-pervading intranet of so-called hotspot sites that propagate large epidemics below the percolation threshold. This intranet is, however, extremely vulnerable; targeted inoculation of a mere 3-6% (depending on incorporated biosecurity measures) of the British poultry industry network prevents large and moderate H5N1 outbreaks completely, offering an order of magnitude improvement over previously advocated strategies affecting the most highly connected 'hub' sites. In other words, hotspots and hubs are separate functional entities that do not necessarily coincide, and hotspots can make more effective inoculation targets. Given the ubiquity and relevance of networks (epidemics, Internet, power grids, protein interaction), recognition of this spreading regime elsewhere would suggest a similar disproportionate sensitivity to such surgical interventions.

Evaluation of two cowside tests for the detection of subclinical ketosis in dairy cows.

The goal of this study was to evaluate the sensitivity and specificity of two cowside tests for subclinical ketosis in dairy cows. The tests utilize milk and urine samples, respectively. One hundred and eighty-five cows, one to sixty days postpartum, were sampled for milk, urine, and blood. Subclinical ketosis was defined with serum beta-hydroxybutyrate measurements. The sensitivity and the specificity of both tests at different beta-hydroxybutyrate levels were estimated. When subclinical ketosis was defined at beta-hydroxybutyrate levels of 1.4 mmol/L and higher, the milk test had sensitivity of 90% and specificity of 96%. The urine test lacked specificity (values < 67%), but sensitivity was 100% at beta-hydroxybutyrate levels of 1.4 mmol/L upward. Both the milk and urine test can be used to monitor subclinical ketosis in a herd. Milk testing is preferred, because of the easy obtainability of milk combined with the overall better test characteristics.

Colon-interposition as replacement for the esophagus. A follow-up study.

The longterm results of the use of colon-interposition as a substitution for the esophagus have been studied. Colon-interposition was carried out in eleven patients. There was one operative death. A second child died of an unknown cause nine years and eight months after operation. Nine patients could be studied from sixteen years and nine months to thirteen months after the operation. In six patients a satisfactory result has been achieved. One child is staying in a psychiatric infirmary. Feeding problems due to recurrent fistulae have led to growth retardation in another patient, while a third patient has regurgitation symptoms. A study of the case histories gives insight into the many early and late complications which occur in this operative procedure. The colon-interposition is a complicated procedure and should only be carried out in centers for pediatric surgery, because of its specific indication, its technique and the occurrence of complications afterwards. The development of alternative, less complicated, methods leaves a restricted indication for colon-interposition.

A method for calculating acetabular anteversion, femur anteversion and the instability index of the hip joint.

A method of calculating the degree of anteversion of the acetabular fossa and femoral neck with computed tomography is described. The instability index of the hip joint can be measured directly with this method.