Two zoo gorillas likely died from E. coli in water
The two gorillas who died in April at the Milwaukee County Zoo died of gastrointestinal infections, likely E. coli from the exhibit’s water system, the zoo announced Thursday.
The zoo released test results from the necropsies of the two Western lowlands gorillas, Cassius and Naku.
The water systems for both the gorillas and the bonobos have been disinfected and the zoo has im-
plemented new protocols to disinfect produce, which can be another source of E. coli.
Water supplied to the public was not affected.
The gorillas’ water system is separated from the rest of the zoo’s water by a backflow preventer, which would stop water from the gorilla enclosure from backing up into the rest of the zoo’s water system.
There is a connection from the gorillas’ water to the bonobos’ water. One bonobo did show signs of illness around the time Naku and Cassius died. He was given antibiotics and recovered the next day.
A healthy amount of E. coli exists in the intestines of humans and gorillas. Some variants of E. coli cause intestinal damage or disease.
Cassius was the zoo’s 31-year-old dominant male lowlands gorilla. He died April 12. Naku, a 17-year-old female lowlands gorilla, died April 28. They were part of a family group at the zoo, a group that is now in a state of transition.
Two other male gorillas at the zoo are not part of the family group.
Shalia, Sulaiman and Zahra are the three remaining members of the family unit. Shalia is an adult female. She and Cassius produced male Sulaiman, who is now 3 years old. Zahra is the offspring of Cassius and Naku. She is 8 months old. Femelle, a senior female lowlands gorilla who was also part of the family group, died in December 2016. She was 54 years old.
Zahra is a baby and still needs 24hour care.
The zoo is following a Species Survival Plan that the Association of Zoos and Aquariums has for Western lowlands gorillas, especially as it considers what to do with Zahra.
What the zoo thinks happened
“We’re being very thorough with trying to put the pieces of the puzzle together,” Vickie Clyde, the zoo’s staff veterinarian, said about figuring out the cause of death for the gorillas.
The zoo sent samples to six labs across the country. The University of Wisconsin School of Veterinary Medicine performed necropsies on the animals. “The gorillas have severe and extensive lesions in both intestines,” Clyde said. “The lining on the gut was so damaged that it could not be repaired.”
It all happened in a matter of days. “Naku got sick before we got the results back from Cassius,” said Clyde. Once Naku got sick, zoo staff immediately sent her to surgery.
There was a contamination in romaine lettuce around the same time the gorillas died, but the zoo ruled out the lettuce as a source of the infection.
What Clyde believes could have happened is that someone hosed down the gorilla enclosure and that feces could have sprayed back into the hose, then bacteria from the feces could have grown in the hose and could have been reintroduced to the gorillas through their drinking water.
The City of Milwaukee tested chlorine levels throughout the zoo, including in the public areas, and everything looked good, but the water in the gorilla area may have been depleted of chlorine at the time.
“We brought in specialists to hyperchlorinate and disinfect the water,” Clyde said.
“Right now, we’re still completing repairs,” said Beth Rich, the director of animal management and health at the zoo. “(The gorillas) are not in quarantine, but we’re still finishing improvements.”
The gorillas will return to the exhibit once the zoo has disinfected the water supply and has finished deep-cleaning the exhibit.
“The plumbers are very busy,” Rich said.