Application of subjective methods to the determination of the likelihood and consequences of the entry of foot-and-mouth disease into New Zealand

New Zealand has a history of continuous freedom from foot-and-mouth disease and relies on a two-tier system of surveillance to maintain this status. The first involves border control procedures and stringent importation standards, and the second is an exotic disease and pest response programme. As part of an economic evaluation comparing the exotic disease and pest response programme against a hypothetical lower grade ;measured response programme subjective judgements of the risks involved were required. Twenty-eight selected animal health professionals, predominantly veterinarians, were posted a questionnaire that used three techniques (single point estimates, three point estimates and elicitation methods) to determine the risk components in a foot-and-mouth disease outbreak. The two key variables were the probability of an outbreak in New Zealand, and the number of secondary properties to which the disease spread during the epidemic. A Delphi conference of ten selected participants then focused mainly on the two key variables, with a second round postal extension to this group for the first variable. The individual data sets were then analysed and combined using a stochastic simulation technique. The final mean probability of an outbreak was about once in 50 years (0.0199). The mean numbers of farms to which disease would spread during an epidemic under the existing exotic disease and pest response programme, a measured response programme which allowed vaccination and a measured response programme which excluded vaccination were estimated to be 61, 478 and 2230 respectively. The policy implications arising from the quantification of these two key variables are that more expenditure on preparedness is justifiable and current resource planning is barely adequate.     

Sensitivity,specificity, and predictive values of reagent test strip estimations of blood urea nitrogen

Azostix-reagent-tests(R) strips (Ames, Miles, Inc., Diagnostic Division, Elkhart, IN) were used to measure blood urea nitrogen values in blood samples from 125 dogs and cats at the North Carolina State University, College of Veterinary Medicine. Results of the tests were compared with standard serum urea nitrogen results. Sensitivity, specificity, and negative predictive values were high (86.4, 90.3, and 96.5%, respectively). Positive predictive value was low, 65.5% of the dogs and cats with elevated blood urea nitrogen values were correctly classified as abnormal The test performs well when the prevalence of abnormal values is near 50%.     

Effect of incubation temperature on the gross pathology of turkey embryos

1. Turkey eggs were incubated at 36.5, 37.5 and 38.5°C. The age of mortality, the incidence of malpositions and the incidence of morphological abnormalities were recorded from all unhatched eggs.

2. Eggs incubated at 36.5°C hatched later than eggs incubated at 37.5°C but did not differ in age of mortality or incidence of malpositions and abnormalities.

3. Eggs incubated at 38.5°C hatched significantly less well than eggs incubated at 37.5°C and showed significant differences in time of embryo mortality. Overheated embryos had a mortality peak between 15 and 20 d of incubation and an increased mortality after 24 d of incubation.

4. Overheated eggs were characterised by a high incidence of embryos with head in small end, with excess albumen, ruptured yolk sacs, oedematous heads, eye cataracts and swollen down‐plumules.