EPIDEMIOLOGIC EVALUATION OF ELEPHANT ENDOTHELIOTROPIC HERPESVIRUS 3B INFECTION IN AN AFRICAN ELEPHANT (LOXODONTA AFRICANA)

Abstract

This epidemiologic study follows a 5-yr-old male African elephant ( Loxodonta africana ) during an episode of hemorrhagic disease (HD) due to elephant endotheliotropic herpesvirus 3B (EEHV3B) utilizing data from complete blood counts, electrophoresis and acute phase protein analysis, and polymerase chain reaction (PCR) of multiple body fluids during and after the clinical episode. The elephant presented with sudden onset of marked lethargy and inappetence followed by hypersalivation, hyperemia of the conjunctivae and focally on the tongue, and swellings on the head and ventrum. A moderate leukocytopenia with band neutrophilia, lymphopenia, monocytopenia, and thrombocytophilia was followed by a rise in all three cell types by day 10. Moderate increases in serum amyloid A and C-reactive protein were noted in the first weeks of illness. Conventional PCR of whole blood yielded a strong positive result for EEHV3B. Quantitative PCR revealed moderate viremia, which slowly returned to undetectable levels by day 35 of treatment. EEHV3B was shed in trunk wash samples starting at day 22 for 10 days at moderate levels, and then at low levels for up to 8.5 mo. All three female herd mates shed low levels of EEHV3B in trunk washes intermittently starting from day 28 of the calf's illness until over 7 mo afterward. The majority of saliva samples from the calf over the 8.5-mo period were also positive for EEHV3B. A subfraction of saliva samples from a female herdmate was positive from days 127-190 following disease onset in the calf. Four elephant gammaherpesviruses were detected sporadically from the calf and female herdmates during this same time period. Treatment was started at the onset of clinical signs and consisted of rectal and oral fluids and oral famciclovir. This is the first case of EEHV3B HD in an elephant species and the first thorough epidemiologic evaluation of EEHV HD in an African elephant.

Zoo elephant research: contributions to conservation of captive and free‐ranging species

“…Importantly, zoo elephant research has repeatedly identified differences between African and Asian elephants. Different drugdosage requirements (Bechert et al, 2008), reproductive pathologies Brown et al, 2016), digestive physiologies (Dierenfeld, 2006;van Sonsbeek et al, 2013), pheromones (Rasmussen & Schulte, 1998) and susceptibility to EEHV (Bronson, E., et al, 2017) are a few such examples. Nonetheless, African and Asian elephants have typically been viewed and managed collectively as 'elephants' in captive settings.…”

“…Provisionally, EEHV types 1A, 1B, 4 and 5 appear to be endemic within Asian elephants, with EEHV1A and 1B being associated with the majority of lethal cases, and the other EEHV types within African elephants (Long et al ., ). At the time of writing, EEHV‐HD has been recognized most often in Asian elephants, but a few cases have also been observed in African elephants (Richman et al ., , ; Latimer et al ., ; Bronson, E., et al ., ).…”

Serum Health Biomarkers in African and Asian Elephants: Value Ranges and Clinical Values Indicative of the Immune Response

“…Furthermore, the relatively rapid response of the acute-phase response makes measuring APP concentrations useful for identifying sub-clinical disease before clinical signs are manifested [ 12 ]. APPs have been measured in a variety of wildlife species in recent years, including Asian [ 14 , 15 , 16 ] and a single African elephant [ 17 ] to assess the response to pathologies such as elephant endotheliotropic herpesvirus (EEHV), pododermatitis, trauma, and infection. In elephants, serum amyloid A (SAA) is considered to be a major APP, increasing rapidly in response to acute inflammation, whereas haptoglobin (HP) responds more moderately and may be reflective of more chronic inflammation [ 15 ].…”

“…Several health problems affect elephants both in situ and ex situ that could benefit from a better understanding of underlying disease processes and improved tools for detection and monitoring. Elephant endotheliotropic herpesvirus hemorrhagic disease (EEHV HD) affects almost one in four Asian elephant calves born in zoos globally [ 28 ], as well as African elephants [ 17 , 29 , 30 ], and in captive and wild populations in Asia [ 31 , 32 , 33 , 34 , 35 , 36 , 37 ]. One proposed hypothesis for the severity of EEHV HD could be that immunologically naïve calves fail to mount an effective immune response to keep up with viral replication [ 38 ].…”

Lethal Hemorrhagic Disease and Clinical Illness Associated with Elephant Endotheliotropic Herpesvirus 1 Are Caused by Primary Infection: Implications for the Detection of Diagnostic Proteins

“…EEHV2, -3, -6, and -7 are recognized as endemic in African elephants (1), but to date, hemorrhagic disease caused by these viruses has not been documented to the same extent as for EEHVs in Asian elephants. Recently, however, lethal (J. Proudfoot and M. Fayette, unpublished data) and nonlethal (5) cases of EEHV3 infection have been observed, raising increased concern over EEHV-HD in these elephants, as well. Among Asian elephants, juveniles between the ages of 2 and 8 years appear to be most vulnerable to EEHV-HD (1).…”