Dr. Thomas Clark, a medical epidemiologist at the CDC. | CENTERS FOR DISEASE CONTROL AND PREVENTION
With clusters of meningitis cases appearing among gay men on two continents coupled with a significant outbreak in New York City, epidemiologists cannot explain how the bug is spreading.
“The cases in Europe similarly do not have a direct link to NYC so we can’t say that they are part of that outbreak, but no, this is not really a coincidence and again indicates there is some unusual pattern of sustained transmission going on that we need to keep trying to sort out,” wrote Dr. Thomas Clark, a medical epidemiologist at the federal Centers for Disease Control and Prevention, in an email.
Starting in 2010, New York City saw a meningitis outbreak among gay men that eventually grew to 22 cases with seven deaths. A 23rd case occurred in a man who lived outside the city, but spent significant time here.
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Los Angeles had a cluster of three related cases in December 2012 and January of 2013. The bacteria that caused those cases was the same as the bacteria found in the New York cases. A fourth Los Angeles case in April of this year was caused by a bacteria that was different from the New York cases and the other Los Angeles cases.
In August of this year, the Salt Lake County Health Department in Utah reported a meningitis death in a 20-year-old gay man who undertook “recent cross country travel” and was infected with a bacteria that was the same as the one found in Los Angeles and New York.
In a July issue, the journal Science reported on a five-case meningitis cluster in Germany this year. France reported three cases among gay men this year, and Belgium reported one case. The same bug is causing the US and European cases.
The fact that the bug is the same is unremarkable.
“Most of the serogroup C isolates in the United States are pretty related anyway,” Clark told Gay City News, referring to the bacteria. “Identical is easy because it’s identical and you can say those two bacterial isolates are the same… We always say that [the DNA] doesn’t really tell us anything that the epidemiology doesn’t tell us in the first place.”
Close to 100 percent of meningitis cases are individual occurrences, with no epidemiological evidence of subsequent secondary cases. The bacteria that cause both clusters and outbreaks (which are defined more stringently than clusters) tend to be more virulent, which explains the deaths. What remains unexplained is how the bug is moving from city to city and from one continent to another. How the bacteria is transmitted is also unknown.
The explanation could be as simple as some gay men carrying the bacteria in their noses or throats and infecting others in some setting where there is close contact or during sex. At any given time, a percentage of the population is carrying the bacteria without experiencing symptoms so gay men who travel for parties, for example, may be more likely to encounter the bug.
“The factors, the social factors, that kind of promote transmission are more favorable in the gay community,” Clark said. “It’s just going around in the gay community… It’s all about risk factors, it’s all about the likelihood of coming into contact and acquiring meningitis.”
The suggestion that meningitis is a sexually transmitted disease has recently drawn the ire of some in the gay community, who have posted online comments saying they are offended that gay sex is once again being implicated in the spread of a disease. But the bacteria requires close contact so it is possible that it is transmitted during sex.
A 1981 study published in the American Journal of Public Health isolated hundreds of samples of Neisseria meningitidis, the bacteria causing the current clusters and outbreak, from the “genitourinary tract and/ or anal canal” of dozens of men who visited a New York City “clinic treating homosexuals” over a four-year period.
“I think finding mening in the GU tract means it can be acquired there, probably by oral sex,” Clark wrote, adding that it is unknown whether transmission can occur in both directions.
“It’s not clear if it can be transmitted from there to the throat, but seems like it could,” he wrote. “In medicine we’d probably say that this is an incidental finding and no one is sure if this is a sufficient step in the disease-causing process, or if it’s just a dead end for the bugs.”
The Science article reported that New York City’s health department has begun a study to determine if the bacteria, typically transmitted from the nose or throat of one person to the nose and throat of another, has found a new transmission route.
Meningitis remains a rare infection in the US, with an estimated 1,500 cases a year. Health authorities say that they identify more than 80 percent of the cases every year so it is highly unlikely that there is a larger outbreak occurring among gay men that has gone undetected.