Relating the bivalve shellfish harvesting area classification criteria in the United States and European Union programmes.

Estimation of the level of risk of faecal contamination of shellfish harvesting areas is undertaken by monitoring faecal indicator bacteria in seawater samples under the United States programme and shellfish flesh samples under the European Union (EU) programme. Determining the relationship between the two approaches is important for assessing the relative level of public health protection and regulating international trade. The relationship was investigated using both statistical modelling and simple compliance assessment on large international data sets of paired seawater and shellfish samples. The two approaches yielded the same conclusions: EU class A is more stringent than the US Approved category for all species; the US Restrictive standard is more restrictive than EU class B for some bivalve species. Therefore, the classifications under the two programmes are not exactly equivalent.

Viral load of various tissues of rainbow trout challenged with viral haemorrhagic septicaemia virus at various stages of disease.

Market-sized rainbow trout Oncorhynchus mykiss were challenged by waterborne exposure to viral haemorrhagic septicaemia virus (VHSV isolate of genogroup Ia). Fish were sampled at 4 stages of infection (before onset of clinical signs, clinically affected fish, mortalities and survivors) and the viral load determined in (1) internal organs, (2) muscle tissue and (3) brain and gill tissue. Virus levels were determined by virus titration and real-time RT-PCR. VHSV was detected by either method in the majority of fish before onset of clinical signs and in the survivor group as well as in all fish in the clinically affected fish and mortality groups. Mean virus amounts per mg of tissue determined by virus titration (TCID50) or real-time RT-PCR (copy number) were > 10(4) in preclinical fish, > 10(3.8) in clinically affected fish, > 10(3.9) in mortalities and > 10(1.2) in survivors. Virus levels tended to be highest in the internal organs of subclinical and clinically affected fish and in brain and gill tissue of survivors. The results demonstrate that significant levels of VHSV can be found in tissues of rainbow trout that may be marketed for human consumption, which may have relevance for the biosecurity of VHS-free areas.

Emergence of cold water strawberry disease of rainbow trout Oncorynchus mykiss in England and Wales: outbreak investigations and transmission studies.

Cold water strawberry disease (CWSD), or red mark syndrome (RMS), is a severe dermatitis affecting the rainbow trout Oncorynchus mykiss. The condition, which presents as multifocal, raised lesions on the flanks of affected fish, was first diagnosed in Scotland in 2003 and has since spread to England and Wales. Results of field investigations indicated the condition had an infectious aetiology, with outbreaks in England linked to movements of live fish from affected sites in Scotland. Transmission trials confirmed these results, with 11 of 149 and 106 of 159 naive rainbow trout displaying CWSD-characteristic lesions 104 to 106 d after being cohabited with CWSD-affected fish from 2 farms (Farm B from England and Farm C from Wales, respectively). The condition apparently has a long latency, with the first characteristic lesions in the previously naive fish not definitively observed until 65 d (650 day-degrees) post-contact with affected fish. Affected fish from both outbreak investigations and the infection trial were examined for the presence of viruses, oomycetes, parasites and bacteria using a combination of techniques and methodologies (including culture-independent cloning of PCR-amplified bacterial 16S rRNA genes from lesions), with no potentially causative infectious agent consistently identified. The majority of the cloned phylotypes from both lesion and negative control skin samples were assigned to Acidovorax-like beta-Proteobacteria and Methylobacterium-like alpha-Proteobacteria.

Assessment of fitness for purpose of an insect bioassay using the desert locust (Schistocerca gregaria L.) for the detection of paralytic shellfish toxins in shellfish flesh.

We have developed a bioassay using 5th instar desert locusts (Schistocerca gregaria L.) for the detection of saxitoxin-the paralytic shellfish poison in shellfish flesh. The bioassay procedure is to inject 10 locusts with a shellfish extract, and assess their conditions at time points up to 2h post injection, looking for an endpoint of paralysis. From the proportion responding, the equivalent dose of pure saxitoxin could be estimated. Performance characteristics of the bioassay were assessed using shellfish samples spiked with saxitoxin, and we found the bioassay could detect and quantify toxin levels in the range of regulatory relevance. Relative toxicities of selected saxitoxin analogues differed from those reported in mammalian systems. Variation for repeatability conditions was acceptable but variation was higher under reproducibility conditions. This was related to (a) batches of insects from different suppliers, (b) different operators, and (c) different observers assessing the endpoint. We also noted adverse reactions with some shellfish species. These problems may be resolved by further refinement of the method and operator training, before formal validation. Nevertheless, we suggest the method potentially offers a simple, ethically acceptable, broad-specificity functional bioassay, which is desirable in any toxin-monitoring programme.

Animal Disease Import Risk Analysis--a Review of Current Methods and Practice.

The application of risk analysis to the spread of disease with international trade in animals and their products, that is, import risk analysis (IRA), has been largely driven by the Sanitary and Phytosanitary (SPS) agreement of the World Trade Organization (WTO). The degree to which the IRA standard established by the World Organization for Animal Health (OIE), and associated guidance, meets the needs of the SPS agreement is discussed. The use of scenario trees is the core modelling approach used to represent the steps necessary for the hazard to occur. There is scope to elaborate scenario trees for commodity IRA so that the quantity of hazard at each step is assessed, which is crucial to the likelihood of establishment. The dependence between exposure and establishment suggests that they should fall within the same subcomponent. IRA undertaken for trade reasons must include an assessment of consequences to meet SPS criteria, but guidance is sparse. The integration of epidemiological and economic modelling may open a path for better methods. Matrices have been used in qualitative IRA to combine estimates of entry and exposure, and consequences with likelihood, but this approach has flaws and better methods are needed. OIE IRA standards and guidance indicate that the volume of trade should be taken into account, but offer no detail. Some published qualitative IRAs have assumed current levels and patterns of trade without specifying the volume of trade, which constrains the use of IRA to determine mitigation measures (to reduce risk to an acceptable level) and whether the principle of equivalence, fundamental to the SPS agreement, has been observed. It is questionable whether qualitative IRA can meet all the criteria set out in the SPS agreement. Nevertheless, scope exists to elaborate the current standards and guidance, so they better serve the principle of science-based decision-making.

Risks associated with commodity trade: transmission of viral haemorrhagic septicaemia virus (VHSV) to rainbow trout fry from VHSV-carrying tissue-homogenates.

Movements of commodity fish present a potential risk of transferring pathogens. Within a study to estimate the risk from imported rainbow trout Oncorhynchus mykiss carcases, fry were exposed to tissue homogenates from market size rainbow trout infected experimentally with viral haemorrhagic septicaemia (VHS) by waterborne exposure to VHS virus (VHSV, isolate of genotype Ia). Tissues were collected from fish that showed clinical signs and from recent mortalities. Homogenates of (i) internal organs, (ii) brain/gills and (iii) muscle tissue were prepared and added to tanks holding the fry. Virus transmission occurred from all tissues tested, causing high mortality of the fry. The results underline the potential risk of introduction of VHSV through the trade of fish products.

Clinical, ultrasound and hormonal markers of androgenicity in acne vulgaris.

Androgenic stimulation of sebaceous glands is an important factor in the development of acne. We examined 36 females (aged 14-34 years), selected because none had received oral contraceptives, anti-androgen therapy, or systemic antibiotics during the previous year, or isotretinoin therapy, prior to their participation in the study. Subjects were divided into groups on the basis of acne severity, as follows: physiological, mild and moderate. Only two patients had polycystic ovaries on ultrasound examination. Seven patients had irregular menses; none had evidence of hirsutism. We found that the severity of acne, based on the acne grade, was highly correlated with the inflammatory lesion count, and less correlated with the sebum excretion rate. Either acne grade or inflammatory lesion count could be related to some of the five androgenic hormone determinants; free testosterone (TESTOS), delta 4 androstenedione (DELTA 4), sex hormone binding globulin (SHBG), dehydroepiandrostenedione sulphate (DHEAS) and dihydrotestosterone (DHT). Multiple linear regression analysis determined the best model for predicting ACNE scores as involving DELTA 4 and DHEAS (positive effects), and SHBG (negative effect), P < 0.005, R2 = 0.36). In none of the patients were the levels of DHEAS or SHBG outside the normal range. The findings in the two patients with polycystic ovaries did not differ significantly from those in the remainder of the patients.