December 20, 2011: This study assessed the feasibility of identifying asymptomatic viral shedders using a novel TaqMan real-time PCR on trunk washes and swabs from the conjunctiva, palate and vulva of elephants. Six elephants from a UK collection were sampled weekly over a period of 11 weeks for this study. The herd prevalence of elephant endotheliotropic herpesvirus-1 (EEHV-1) was 100 per cent by PCR.
The virus DNA was detected in all the sampling sites; however, the prevalence of virus DNA in the conjunctiva swabs was higher. In addition, Asian elephants from two continental European collections were sampled once and one animal tested positive on a trunk wash. The virus from this animal was phylogenetically typed as EEHV-1A based on 231 nucleotides of the terminase gene.
ELEPHANT endotheliotropic herpesvirus (EEHV) poses one of the biggest threats to the captive Asian elephant (Elephas maximus) breeding programmes worldwide (Richman and others 1999, Zong and others 2008, Latimer and others 2011). EEHV was first diagnosed in 1995 (Richman and others 1999). To date, over 60 cases have been reported worldwide, with a mortality of 85 per cent (Latimer and others 2011). EEHV has now been attributed to be the cause of death of both wild and captive Asian elephants in India, Thailand and Cambodia (Reid and others 2006, Hayward and others 2009).
Elephant herpesviruses appear to be far less pathogenic in the African elephant (Loxodonta africana) compared with the Asian elephant. The first herpesvirus from the African elephant was described by Mccully and others (1971). It was associated with pulmonary nodules that were commonly found in otherwise healthy elephants. The virus was also isolated from cutaneous papillomas in African elephants in the Kruger National Park (Jacobson and others 1986). Further genetic analysis identified these herpesviruses as being identical to a strain fatal to Asian elephants (EEHV-1) (Richman and others 1999). Download the complete report in pdf format here.