Two consecutive cases of hemorrhagic purpura characterized by severe subcutaneous bruising and extensive hemorrhages in the visceral organs of the affected suckling piglets occurred in a pig farm. A total of forty 2- to 3-day-old neonates were affected in the first case and there were eight 8- to 9-day-old piglets in the second case which occurred 3 months later. The hematological study of one affected piglet showed marked thrombocytopenia with macrocytic hypochromic anemia without coagulation factor impairment in the second case. Based on the presence of severe thrombocytopenia, extensive hemorrhagic lesions and restricted occurrence in particular suckling pigs, isoimmune thrombocytopenic purpura was suspected in both cases. This is the first such case reported in Taiwan.

Porcine reproductive and respiratory syndrome (PRRS) is one of the most common diseases in the global swine industry. PRRSV is characterized by rapid mutation rates and extensive genetic divergences. It is divided into two genotypes, which are composed of several distinct sub-lineages. The purpose of the present study was to evaluate the cross-protective efficacy of Fostera PRRS MLV, an attenuated lineage 8 strain, against the heterologous challenge of a lineage 3 isolate. Eighteen pigs were randomly divided into mock, MLV and unvaccinated (UnV) groups. The pigs in the MLV group were administered Fostera PRRS vaccine at 3 weeks of age and both the MLV and UnV groups were inoculated with a virulent PRRSV isolate at 7 weeks. Clinically, the MLV group showed a shorter duration and a lower magnitude of respiratory distress than the UnV group. The average days of fever in the MLV group was 3.0 ± 0.5, which was significantly lower than the 6.2 ± 0.5 days of the UnV group (P < 0.001). The average daily weight gains of the mock, MLV and UnV groups were 781 ± 31, 550 ± 44 and 405 ± 26 g/day, respectively, during the post-challenge phase. The pathological examinations revealed that the severity of interstitial pneumonia in the MLV group was milder compared to the UnV group. Furthermore, PRRSV viremia titers in the MLV pigs were consistently lower (101−101.5 genomic copies) than those of the UnV pigs from 4 to 14 DPC. In conclusion, vaccination with Fostera PRRS MLV confers partial cross-protection against heterologous challenge of a virulent lineage 3 PRRSV isolate.

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