Sindrome emorragica da BVDV tipo 2 in un vitello in Italia = BVD virus type 2 : hemorrhagic syndrome in a calf in Italy

A 5-month-old female calf hospitalized for diarrhea showed petechial bleedings on the oral, conjunctival and vaginal mucosa. Pulse- and respiratory-rate were respectively 76 bpm and 44 breaths/min. The mental status of the calf was alert, although the appetite was bad. The calf was born in Italy through Ovum Pick Up and in vitro embryo production starting from a donor cow coming from Netherlands. Laboratory analysis were characterized by leucopenia, thrombocytopenia and altered coagulation times. Differential diagnosis consisted in coccidiosis, poisoning by Warfarin, septicemia and type 2 BVDV infection. Other causes of hemorrhagic diathesis such as hemophilia and bovine neonatal pancytopenia were not considered among differential diagnosis due to the age of the subject. After fluid and electrolyte therapy and antibiotic administration, the calf got better, but 5 days later the clinical status worsened. The clinical condition was characterized by mental status depressed, sternal recumbence, severe bloody diarrhea and petechial hemorrhages. The calf died few hours later. BVDV-2 was detected by means of PCR-RT; virus isolation failed due to a low-level viremia. The absence of NS 2-3 antibodies in serum (ELISA) can be explained as sign of immune tolerance or as a first stage of an acute infection; symptoms observed were consistent with a BVDV-2 acute hemorrhagic syndrome. To further confirm the diagnosis, a seroconversion test would have been useful. Data concerning the oocyte donor are not available; oocytes employed for in vitro embryo production have been demonstrated to contain BVDV when they come from infected or persistently infected animals. A few months before, in the same farm, an apparently healthy heifer was found to be positive for BVDV-2. Due to the economic loss related to BVDV infection, many european countries underwent BVDV eradication. BVDV-2 has a lower prevalence than type-1, but the detection of BVDV-2 throughout Europe is increasing. To conclude, BVDV-2 should be now considered among differential diagnosis in case not only of hemorrhagic syndrome but even in case of mild or subclinical disease.

Nell’agosto del 2015 è stata ricoverata una vitella di 5 mesi di età affetta da diarrea che presentava petecchie emorragiche a carico delle mucose esplorabili. Il paziente presentava sensorio vigile, appetito assente; la frequenza cardiaca era di 76 bpm, quella respiratoria di 44 atti/min. Gli esami ematologici evidenziavano una marcata trombocitopenia e leucopenia associate ad una grave deplezione neutrofilica. Le diagnosi differenziali comprendevano la coccidiosi intestinale, l’avvelenamento da cumarinici, la setticemia e l’infezione da BVDv tipo 2. In quinta giornata il vitello moriva per un aggravamento del quadro clinico, caratterizzato da petecchie emorragiche diffuse ed enterorragia gravissima. Gli esami diagnostici confermavano la positività del soggetto nei confronti di BVDv tipo 2 (PCR Real Time). Il tentativo di isolamento del virus su colture cellulari è risultato però negativo a causa del basso titolo virale. La ricerca su siero di anticorpi anti-NS 2-3 dava esito negativo lasciando presupporre che si trattasse di un soggetto immunotollerante o con infezione acuta in fase precoce. Per confermare questa ipotesi sarebbe stato necessario verificare la sieroconversione. Non è stato possibile risalire allo stato sanitario della madre: è stata comunque dimostrata la presenza del virus della BVD in ovociti prelevati da donatrici infette o immunotolleranti. Qualche mese prima, nello stesso allevamento, una manza apparentemente sana era risultata positiva a BVDv-2. Negli ultimi anni le segnalazioni di BVDv-2 in Europa stanno aumentando, con manifestazioni cliniche più o meno apparenti che vanno da forme cliniche evidenti, come nel presente caso, a forme subcliniche più subdole, con soggetti apparentemente asintomatici.