No abstract

Expert opinion was elicited to undertake a qualitative risk assessment to estimate the current and future risks to the European Union (EU) from five vector-borne viruses listed by the World Organization for Animal Health. It was predicted that climate change will increase the risk of incursions of African horse sickness virus (AHSV), Crimean-Congo haemorrhagic fever virus (CCHFV) and Rift Valley fever virus (RVFV) into the EU from other parts of the world, with African swine fever virus (ASFV) and West Nile virus (WNV) being less affected. Currently the predicted risks of incursion were lowest for RVFV and highest for ASFV. Risks of incursion were considered for six routes of entry (namely vectors, livestock, meat products, wildlife, pets and people). Climate change was predicted to increase the risk of incursion from entry of vectors for all five viruses to some degree, the strongest effects being predicted for AHSV, CCHFV and WNV. This work will facilitate identification of appropriate risk management options in relation to adaptations to climate change.

Sea lice are a persistent problem for farmed and wild salmonid populations. Control can be achieved through the use of veterinary medicines. A model was developed to describe the patterns of sea lice infection on salmon farms in Scotland and to predict the likely effect of various treatment strategies. This model takes into account development rates and mortality using compartments representing life history stages and external infection pressure. The national sea lice infection pattern was described using parameters representing stage survival, background infection levels and egg viability rates. The patterns observed across farms varied greatly and the model gave broad agreement to observed trends with different parameters being required in the model for sites using hydrogen peroxide and cypermethrin treatments. The parameter estimates suggest that the background infection pressure on sites where cypermethrin was administered was higher than for those using hydrogen peroxide. Both models had comparable magnitudes of sensitivity with survival from one stage to another being the most sensitive parameter, followed by feedback rates at which gravid females produce eggs, with background infection levels the least sensitive. The effect of different cypermethrin treatment strategies was assessed using the model. Increasing treatments in a production cycle gave more effective control. However, the model showed that timing of treatments is most important if sea lice are to be effectively controlled.

Summary Q fever is a zoonotic disease caused by the bacterium Coxiella burnetii which is endemic in cattle, sheep and goats in much of the world, including the United Kingdom (UK). There is some epidemiological evidence that a small proportion of cases in the developed world may arise from consumption of unpasteurised milk with less evidence for milk products such as cheese. Long maturation at low pH may give some inactivation in hard cheese, and viable C. burnetii are rarely detected in unpasteurised cheese compared to unpasteurised milk. Simulations presented here predict that the probability of exposure per person to one or more C. burnetii through the daily cumulative consumption of raw milk in the UK is 0·4203. For those positive exposures, the average level of exposure predicted is high at 1266 guinea pig intraperitoneal infectious dose 50% units (GP_IP_ID50) per person per day. However, in the absence of human dose–response data, the case is made that the GP_IP_ID50 unit represents a very low risk through the oral route. The available evidence suggests that the risks from C. burnetii through consumption of unpasteurised milk and milk products (including cheese) are not negligible but they are lower in comparison to transmission via inhalation of aerosols from parturient products and livestock contact.

Great Britain has been rabies-free since 1922, which is often considered to be in part due to the strict laws requiring that imported cats and dogs be vaccinated and quarantined for 6 months immediately on entry into the country. Except for two isolated incidents, this quarantine policy has contributed to ensuring that Great Britain has remained free of rabies. In 2000, amendments to the UK quarantine laws were made and the Pet Travel Scheme (PETS) was launched for companion animals traveling from European Union countries and rabies-free islands. Since its introduction, it has been proposed that other countries including North America should be included within the UK scheme. A quantitative risk assessment was developed to assist in the policy decision to amend the long-standing quarantine laws for dogs and cats from North America. It was determined that the risk of rabies entry is very low and is dependent on the level of compliance (i.e., legally conforming to all of the required regulations) with PETS and the number of pets imported. Assuming 100% compliance with PETS and the current level of importation of cats and dogs from North America, the annual probability of importing rabies is lower for animals traveling via PETS (7.22 x 10(-6), 95th percentile) than quarantine (1.01 x 10(-5), 95th percentile). These results, and other scientific evidence, directly informed the decision to expand the PETS scheme to North America as of December 2002.