Lungworm outbreaks in adult dairy cows: estimating economic losses and lessons to be learned.

Two lungworm outbreaks in dairy herds were investigated in order to estimate the resulting economic costs. On the two farms, with 110 and 95 cows, total costs were estimated at €159 and €167 per cow, respectively. Overall, milk production reduced by 15 to 20 per cent during the outbreaks. Five cows died on one farm, while on the other farm seven cows died as a result of the lungworm outbreak. On one farm, 51.7 per cent of the total costs was due to reduced milk production and 33.1 per cent was due to disposal of dead animals. On the other farm, it was 36.3 and 50.9 per cent, respectively. The remaining 13 to 15 per cent of the total costs were due to extra inseminations, laboratory diagnosis and treatments. The history and development of the outbreaks are described. One lesson from these outbreaks is that recognising that potentially lungworm-naïve animals are to be introduced into the adult herd allows for timely measures (for example, vaccination) to prevent a lungworm outbreak.

[Outbreak of bovine virus diarrhea on Dutch dairy farms induced by a bovine herpesvirus 1 marker vaccine contaminated with bovine virus diarrhea virus type 2]. / Uitbraak van bovine virus diarree op Nederlandse rundveebedrijven na vaccinatie met een met BVDV type 2 gecontamineerd BHV1 markervaccin.

On 23 February 1999, the Dutch Animal Health Service advised all Dutch veterinary practices to postpone vaccination against bovine herpesvirus 1 (BHV1) immediately. The day before severe disease problems were diagnosed on four dairy farms after vaccination with the same batch of BHV1 marker vaccine. Using monoclonal antibodies, bovine virus diarrhoea virus (BVDV) type 2 was found in the vaccine batch. This paper describes an outbreak of BVDV type 2 infection caused by the use of a batch of modified live BHV1 marker vaccine contaminated with BDVD. Sources of information used were reports of farm visits, minutes of meetings, laboratory results, and oral communications from the people involved. The first symptoms of disease were observed on average six days after vaccination. Morbidity was high on 11 of the 12 farms. On five farms more than 70% of the animals became ill, while on one farm no symptoms could be detected. During the first week after vaccination, feed intake and milk production decreased. During the second week, some animals became clinically diseased having nasal discharge, fever, and diarrhoea. At the end of the second week and at the start of the third week, the number of diseased animals increased rapidly, the symptoms became more severe, and some animals died. Mortality varied among herds. Necropsy most often revealed erosions and ulcers of the mucosa of the digestive tract. In addition, degeneration of the liver, hyperaemia of the abomasum, and swollen mesenterial lymph nodes and swollen spleen were found. On 11 of the 12 farms all animals were culled between 32 and 68 days after vaccination after an agreement was reached with the manufacturer of the vaccine. This was the third outbreak of BVD in cattle after administration of a contaminated vaccine in the Netherlands. The possibilities to prevent contamination of a vaccine as a consequence of infection of fetal calf serum with BVDV are discussed. Improvement of controls to prevent contamination before and during vaccine production, and improvement of the monitoring of side-effects is necessary.