Samson, an African elephant, started showing symptoms of endotheliotropic herpesvirus, a strain of herpes that is deadly to elephants, on Feb. 26, The Baltimore Sun reported.
Experts at the zoo began put Samson on around-the-clock treatment, which includes 40 times the human dose of herpes medication, gallons of diluted Gatorade and regular enemas, the newspaper said.
The virus is mostly seen in Asian elephants between the ages 1 to 4, and kills about 80 to 90 percent of infected elephants, wrote Johns Hopkins University professor Gary Hayward in a February 2012 article.
Left untreated, the infections cause internal bleeding and heart failure in elephants.
The strain infecting Samson is rare to African elephants and is not usually lethal to them, Hayward said.
"This would be the first time it has been seen at this 'primary' stage in an African elephant calf and so it is prudent to monitor the situation carefully," Hayward said.
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