The article says to that:
Together with experts from the Leibniz Institute for Zoo and Wildlife Research (VIC) and the Freie Universität Berlin is seeking since Tayos death for a cause, the zoo said on Tuesday. "The pathological changes varied among the deceased Gerenuks of pneumonia on indigestion, liver damage and kidney damage," said zoo and zoo director Andreas Knieriem. From Priscilla Blood samples were regularly taken, you hope for a result of this long-term study. A spokeswoman added that they have also the drinking water of the animals, the food and the soil analyzed. So far without success.
Nevertheless, I hope, the Us-Zoos do not will send again gerenuks to middle-european zoos. It is not okay to keep gerenuks for six months a year in the barn without any acccess to outdoor exhibits, if it is too cold for that. If kept in europe, than defenitely only in southern europe, where the species can be kept outdoors yearround and feed with fresh leafs also yearround.Could be better for the welfare and husbandry of these sensitive gazelles. A shame, five gerenuks had to die unnecessarily.