Although the occasional small, fuzzy visitor to Yale dorm rooms may seem innocuous, a recent case of meningitis in Morse College indicates that mice living in residence halls could pose serious health risks.
A Morse College sophomore who lives in Entryway A contracted LCMV — a form of viral meningitis that is transmitted through rodents — while she was at Yale over spring break. The student, who blames mice living in the college for her illness, was hospitalized at Yale-New Haven Hospital for six days. Yale administrators confirmed their knowledge of the student’s condition but said they cannot be certain that she had gotten the virus from a mouse in her Morse room.
The student — who wished to remain anonymous to protect personal medical information — said her doctors grew cultures that confirmed that the virus was transmitted through infected rodents, and she said she is confident that the rodent in question is one of the mice that frequented her suite.
“I haven’t seen any other rodents,” she said.
The student said she first reported seeing a mouse in January and that she saw mice about every week after that.
Health experts said LCMV is common in mice but is rarely transmitted to humans. Yale University Health Services Medical Director Michael Rigsby said as much as 40 to 50 percent of mouse populations in some areas have been found to carry LCMV.
“LCMV is a virus that’s fairly common in rodent populations, including common house mice and also in some cases in pet rodent populations,” Rigsby said. “But it is not transmitted to humans very easily.”
Rigsby said medical experts have not yet worked out exactly how LCMV is transmitted to humans but that it can be transmitted through exposure to, inhalation of or ingestion of mouse droppings.
“There’s potential for it to be spread in many different ways by close contact with rodents,” Rigsby said. “The closer and more prolonged the exposure, the more likely the infection is.”
Robert Baltimore, a professor in the Epidemiology and Public Health Department at the Yale School of Medicine, said most people who contract the virus often display flu-like symptoms and are not seriously affected.
“Generally people get over it and do pretty well,” Baltimore said. “It’s not as serious as bacterial meningitis on average.”
Rigsby said all Yale students are required to be vaccinated against bacterial meningitis but that this vaccine does not protect against LCMV. The virus can develop anywhere from one to three weeks after exposure to an infected rodent, Rigsby said, and it is not known to be transmissable from an infected person to other humans, except in cases of transmission from a pregnant woman to her fetus.
The Morse student’s mother said she was at first very upset about her daughter’s illness but that she thinks the administration is now handling mouse sightings in an appropriate manner.
“It’s a very serious illness, and my main concern is [her] health,” the student’s mother said. “My second concern was not having anyone else having to go through this same ordeal, because it was very frightening, and I wanted to make everyone understand how serious this was.”
Morse College Master Frank Keil confirmed that the Morse student had contracted LCMV but said he is not sure how it was transmitted to her. He said that as far as he can tell, mice have been a problem “in all parts of campus,” but since reports of this infection the University has taken steps to protect Morse students.
“We never want to be complacent about any sort of vermin problem,” Keil said.
The ill student’s roommate said she felt “very paranoid and very jumpy” when she first saw the mouse in their suite, but that she now does not feel unsafe in her room, even after hearing about her roommate’s case of LCMV.
Morse and Ezra Stiles Building Manager Jerry Irizarry said the mouse problem began around the beginning of spring semester, and about six or seven rooms in Morse have reported seeing mice since then. The sightings have been concentrated in entryways A through D on the fourth floor, Irizarry said.
Irizarry said the Office of Facilities forwards all complaints to the University’s control center, which then contacts Yale’s pest control contractor, Ecolab, to set up visits to students’ suites. He said Ecolab representatives often install baits and traps and that building attendants have recently gone to Morse rooms to stop gaps around the heating system and to install “door sweeps” along the bottom of doors, which prevent mice from running through cracks under doors.
“We’re taking every step necessary to cover all of the bases and eliminate all entry points and exit points,” Irizarry said. “We’re doing the best we can to get it done in a timely fashion.”
Irizarry said students should be proactive in addressing a mouse problem and that they must keep their rooms clean and free of open food containers in order to avoid attracting the rodents.
“It’s hard to really fight this battle if we’re creating the habitat for them to flourish,” he said.
Yale spokesman Tom Conroy said the University’s Office of Environmental Health and Safety has been consulting with the New Haven Health Department and University Health Services to gather as much information about the Morse meningitis case as possible.
“The city health department has been on campus, and it did not find that Yale had any serious or unusual problem with mice,” Conroy said.
Conroy said the University has not yet determined how the student contracted the illness and that it may not be possible to make such a determination.
In addition to Morse, current or past residents of Farnam, Lanman-Wright, McClellan, Vanderbilt and Welch halls and Davenport and Branford colleges have said they have seen mice in their dorm rooms.