HYPODERMA BOVIS - SEQUENTIAL SAMPLING OF HERDS FOR SURVEILLANCE OF OUTBREAKS IN ERADICATED ZONES

A quasi-sequential sampling plan for observing cattle was undertaken i n the framework of Hypoderma bovis epidemiological surveillance. This plan enabled us to test whether or not the prevalence of Hypoderma bov is is within a threshold p(0) chosen for an eradication scheme or for qualifying a zone. The sampling cost was reduced but the estimation pr ecision remained acceptable. The sensitivity of monthly controls with respect to the reference period (April, May, June, July) was studied f rom data observed over 6 consecutive years in Cotes d'Armor, France. T he best ratio sensitivity/sampling cost was obtained with a unique cou nting plan in June where 48% (36 to 60%) of the herds found to be infe sted during the reference period were detected. The test procedure con cerning the prevalence level was then adapted to take into account the sensitivity of the observation method. This is tantamount to reducing the threshold p(0).