Spatial distribution and incidence of bovine neonatal pancytopenia in Bavaria, Germany.

BACKGROUND: Bovine neonatal pancytopenia (BNP) is a haemorrhagic disease of neonatal calves. BNP was first described in Germany in 2009, later on also in other European countries, and in New Zealand in 2011. The disease is characterised by spontaneous bleeding, pancytopaenia in the bone marrow, and a high case fatality ratio. The causal role of a specific bovine viral diarrhoea virus (BVDV) vaccine (PregSure®BVD, then Pfizer Animal Health, now Zoetis, Berlin, Germany) has been established over the last years, causing the production of alloantibodies in some vaccinated cattle, which in the case of pregnant cattle, are transferred to the newborn calf via the colostrum. However, striking regional differences in the incidence of the disease were observed within Germany and other countries, but as the disease was not notifiable, no representative data on the spatial distribution are available. In this study, we address the spatial distribution and incidence of BNP using the results of two representative surveys amongst cattle practitioners in Bavaria, Germany. The surveys, asking about the occurrence of BNP, were conducted in 2009 and 2010. Answers were analysed spatially by testing for clusters using space-time models. Practitioners were also asked how many cows they serve in their practice and this number was used to estimate the incidence of BNP. Furthermore, in the survey of 2010, practitioners were also asked about usage of vaccine against BVDV. RESULTS: From the results of the surveys, three clusters were identified in Bavaria. These clusters also coincided with the usage of the specific BVDV vaccine as indicated by the veterinary practices. Furthermore, the representative surveys allow the estimation of the incidence of BNP to be in the order of 4 cases per 10,000 calves at risk. CONCLUSIONS: The study is the only representative survey conducted on BNP. Despite the fact that BNP is a non-infectious disease, regional clusters were identified.

Incidence of bovine neonatal pancytopenia in 243 farms in Germany.

BACKGROUND: Several research groups from different European countries have worked on the aetiopathogenesis of bovine neonatal pancytopenia (BNP) and an association between the use of the vaccine PregSure BVD (Pfizer, Germany) and the development of this haemorrhagic disease was confirmed. Because BNP is not a notifiable disease, it is difficult to obtain information on its incidence. Based on pharmacovigilance (PhV) data, which are the only officially available data at the national level, the incidence of BNP is considered low. However, voluntary reporting of the disease can lead to underreporting. To gain more insight into the incidence of BNP among the affected herds, an epidemiological study was performed, which focused on 243 farms in Germany with cases of BNP. Farmers were asked to report the occurrence of BNP, including the number of cases, which allowed calculation of incidence in the affected herds. Matching such data with the registered cases in the National PhV System (NPhVS) gave us an opportunity to assess the extent of BNP underreporting. RESULTS: On 243 farms, a total of 1195 calves younger than 4 weeks with haemorrhagic diathesis were registered. In 58 % of the reports, a diagnosis of BNP was confirmed by blood analysis and or by necropsy. The number of cases observed on individual farms ranged from 1 to 80. Based on these results, the incidence of BNP on affected farms ranged from 0.3 to 15.2 % (median 2.9 %). The maximal incidence in the year with the highest number of BNP calves ranged between 0.4 and 18.6 % (median 3.3 %). Comparing the number of cases registered in the NPhVS to the numbers found in this study revealed considerable underreporting to the national database: only 44 % of the farms and 41 % of the BNP calves included in the study were registered in the NPhVS. CONCLUSIONS: In spite of the opportunity to report BNP calves to the Paul-Ehrlich-Institut (Langen, Germany), the estimated number of undetected BNP cases is remarkably high. However, even if the revealed substantial underreporting is taken into account, the incidence of BNP is low. Nevertheless, the incidence on some affected farms is very high, resulting in considerable financial losses that should not be underestimated. Although the exact pathomechanism of BNP at the molecular level is still not known, its incidence is clearly declining following withdrawal of PregSure BVD from the market.

Ingestion of colostrum from specific cows induces Bovine Neonatal Pancytopenia (BNP) in some calves.

BACKGROUND: Since 2006, cases of haemorrhagic diathesis in young calves have been observed with a much higher incidence than previously known. The syndrome, now uniformly called Bovine Neonatal Pancytopenia (BNP), is characterized by multiple (external and internal) haemorrhages, thrombocytopenia, leukocytopenia, and bone marrow depletion. Although various infectious and toxicological causes of bleeding disorders in calves have been ruled out, the aetiology of BNP remains unknown. However, field observations have led to the hypothesis that the aetiological principle may be transmitted to calves via colostrum.The objective of the present study was to verify whether ingestion of colostrum from dams of known BNP calves can elicit signs of BNP and typical haematological findings in conveniently selected neonatal calves. Six such calves received one feeding of colostrum (or a mixture of colostrum batches) from dams of known BNP calves. As controls, another six conveniently selected calves from herds which had never had a BNP case received one feeding of colostrum from their own dams. Haematological and clinical parameters were monitored. RESULTS: One of the six experimental calves never showed any haematological, clinical or pathological evidence of BNP. In the other five calves, thrombocyte and leukocyte counts dropped within a few hours following ingestion of colostrum. Of those, three calves developed clinical signs of BNP, their post-mortem examination revealed bone marrow depletion. Of the remaining two calves, a pair of mixed twins, marked thrombocytopenia and recurrent leukocytopenia was evident in one, in which only slight changes in the bone marrow were detected, while in the other thrombocyte counts dropped, but rebounded later, and no bone marrow changes were noted. Thrombocyte counts of the experimental calves were statistically significantly lower than those of the control calves at 2 hours post ingestion of colostrum and at every sampling point between 9 hours and 8 days postcolostral. Leucocyte counts of the experimental calves were statistically significantly lower than those of control calves at 2 hours post ingestion of colostrum and 3-7 days postcolostral. CONCLUSIONS: BNP can be induced in some calves by ingestion of colostrum from cows that have given birth to BNP calves.