Coinfection and vertical transmission of Brucella and Morbillivirus in a neonatal sperm whale (Physeter macrocephalus) in Hawaii, USA

Abstract

The viral genus Morbillivirus and the bacterial genus Brucella have emerged as important groups of pathogens that are known to affect cetacean health on a global scale, but neither pathogen has previously been reported from endangered sperm whales (Physeter macrocephalus). A female neonate sperm whale stranded alive and died near Laie on the island of Oahu, Hawaii, US, in May of 2011. Congestion of the cerebrum and enlarged lymph nodes were noted on the gross necropsy. Microscopic findings included lymphoid depletion, chronic meningitis, and pneumonia, suggesting an in utero infection. Cerebrum, lung, umbilicus, and select lymph nodes (tracheobronchial and mediastinal) were positive for Brucella by PCR. Brucella sp. was also cultured from the cerebrum and from mediastinal and tracheobronchial lymph nodes. Twelve different tissues were screened for Morbillivirus by reverse-transcriptase (RT)–PCR and select tissues by immunohistochemistry, but only the tracheobronchial lymph node and spleen were positive by RT-PCR. Pathologic findings observed were likely a result of Brucella, but Morbillivirus may have played a key role in immune suppression of themother and calf. The in utero infection in this individual strongly supports vertical transmission of both pathogens.