Temporal dynamics of EEHV shedding and viremia in African elephants (Loxodonta africana ) in the United States

Elephant endotheliotropic herpesvirus (EEHV) can cause fatal hemorrhagic disease in Asian (Elephas maximus) and African elephants (Loxodonta africana). Most existing knowledge about EEHV is based on research and clinical experiences in Asian elephants, which may not fully reflect viral dynamics in African elephant populations. This study aimed to characterize EEHV shedding and viremia in African elephants under human care. A total of 24 elephants from four U.S. institutions were sampled weekly (N = 72 weeks) and tested for EEHV2, EEHV3/4/7 and EEHV6 via real-time quantitative polymerase chain reaction (qPCR) using four sample types (trunk wash, saliva swab, feces, and whole blood). Binomial and beta-binomial models were used to assess shedding by herd, age, and sex, and temporal cluster and time series analyses were conducted to examine temporal dynamics of shedding over time. All elephants shed EEHV intermittently, with 92% (22/24) shedding different African elephant EEHV species at different points in the study, 63% (15/24) shedding multiple EEHV species concurrently, and 25% (6/24) shedding EEHV in over 50% of the study weeks. Viremia events were infrequent compared to shedding events. Younger elephants had a higher probability of shedding than older individuals (p < 0.05). Time series analysis indicated that shedding could not be explained by seasonal patterns, though EEHV shedding events did exhibit statistically significant intermittent temporal clustering. These findings provide baseline data on EEHV epidemiology, identify host factors influencing viral shedding, and underscore the need to investigate additional factors to better understand the drivers of EEHV shedding.