Immune-mediated hemolytic anemia is an uncommon finding in gorillas. ZSL has lost two male gorillas through an unidentified disease that presented as a non-specific malaise with severe hemolytic anemia and marked hemoglobinuria.
Our current male has exhibited intermittent, milder, bouts of malaise and hemoglobinuria. Extensive diagnostic tests have been performed. The more common causes of hemolytic anemia have been ruled out. Consequently, immune-mediated hemolytic anemia, triggered by an unknown pathogen, was considered most likely. As all three males had mated the same female, sexually transmitted diseases were also investigated.
During the investigation most of the gorillas were found, surprisingly as all the gorillas are captive-bred, to have circulating antibodies to dengue fever. Dengue fever is not present in the UK, a vector-free country. Cross-reaction to anti-Brucella spp. antibodies can occur. Thus, a sero-survey for Brucella antibodies was performed. All animals showed titres to Brucella spp. Using archived samples, both dead males also demonstrated very high titres (IgG>1000). PCR analysis, currently being sequenced, of tissues from one dead male and genital swabs from the current male and the female mated by all males confirms the presence of a Brucella spp. The group has been treated for brucellosis with a rifampicin/doxycycline combination. At the time of writing the new male has had no further episodes. We believe this is the first time a Brucella spp. has been diagnosed and associated with disease in apes. Given the zoonotic potential of brucellosis we urge all colleagues to consider testing their collection.