Survival analysis of confirmed elephant endotheliotropic herpes virus cases in Thailand from 2006 – 2018

Abstract

The elephant endotheliotropic herpesvirus (EEHV) has been a known cause of death of young elephants in Thailand for over a decade. In this study, we report on the demography, disease characteristics and mortality of 58 elephants with confirmed EEHV hemorrhagic disease between January 2006 and August 2018 using retrospective data subjected to survival analysis. Median age of EEHV presentation was 29 months, and the mortality rate was 68.97% with a median survival time of 36 h. Most EEHV cases occurred in the north of Thailand, the region where most of the country’s captive elephants reside. The hazard ratio analysis identified application of medical procedures and antiviral medications as being significant factors correlated to the risk of death. Our results indicate a need to focus EEHV monitoring efforts on young elephants and to follow current protocols that advise starting treatments before clinical signs appear.

Use of immunostimulants in the successful treatment of a clinical EEHV1A infection in an Asian elephant (Elephas maximus)

“…The majority of reported cases of fatal EEHV‐HD associated with EEHV‐1A have progressed rapidly to death within days, often despite intensive veterinary intervention 4 7 23. Common to all is a rapid rise in viraemia prior to the development of clinical signs.…”

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

“…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 ].…”

Milk Composition of Asian Elephants (Elephas maximus) in a Natural Environment in Myanmar during Late Lactation

“…In zoos, the calf mortalities are high, especially in Asian elephants (on average 30% during the first year), and one of the most important reasons is rejection of the calf by the mother, resulting in a need for human intervention to supplementally feed the calves [14]. Many of the reasons underlying such high calf mortality are relatively well studied in elephants [9][10][11][15][16][17][18], but milk composition has gained less attention even though it may be an important factor underlying mortality. Such information, particularly from animals managed in their natural habitat, could have major potential to bring about important advances for improving calf survival and maternal well-being in diverse elephant populations.…”