Meningitis cases share genetic similarities

The bacteria isolated from the campus' fourth reported case of meningitis is "genetically similar" to the bacteria that infected three students last month. All four cases are part of the same outbreak, a City health official said.

Despite this, Student Health Service director Evelyn Wiener said the fourth case, reported during spring break, is distinct from the first three and that there is no common source linking the two groups of incidents.

In other words, neither Penn nor City health officials have been able to connect the fourth case with the first three students infected in February, who attended the same one or two Greek parties between Feb. 2 and Feb. 13, said Esther Chernak, director of the City's Acute Communicable Disease Control Program.

Chernak explained that there is probably a small percentage of the Penn population who carry the Neisseria meningitidis, the bacteria that has caused the outbreak at Penn, in the back of their throats. Though they will not get sick themselves, they can infect others and "represent a reservoir" of bacteria .

It is impossible to know whether the fourth student was infected by the same carrier who introduced the bacteria into the Greek parties or whether the two groups were infected by different carriers.

There is also little SHS can do to eliminate the strain among the Penn community because about 10 percent of the general population carries the bacteria.

"You can't sterilize the world," Chernak said, though she did add that the Centers for Disease Control is examining the bacteria from all four cases to determine whether they are particularly virulent.

The CDC did not respond to a request for information on the results of those tests as of press time, though CDC spokesman Tom Skinner said strain B, which infected the students, is less common in outbreaks than other strains.

Though Chernak is not sure when the City will declare Penn's outbreak officially over, the fourth case could not have come at a better time, she said.

Spring break causes students to scatter, making it more difficult to transmit the infection. Chernak also said spring will drive more students outdoors and make further infection less likely.

Wiener also said it is impossible to know how this particular strain entered the Penn student population.

Though certain types of meningococcal bacteria are concentrated in certain geographic areas, college students coming from all over the country will bring their native strains with them to campus, said Peter Axelrod, a professor of infectious diseases at Temple University Hospital who is not involved in containing the outbreak.

This means that there is a higher chance of a meningococcal infection on a college campus, as students may not have developed immunity to strains found in other parts of the country.

Axelrod also said the first three cases are typical of what normally happens in an outbreak -- a cluster of cases that occur within a relatively short period of time.

Though it is unusual for a fourth case to occur a month after such a cluster, it probably does not presage a new round of infections, he said.

Still, Chernak advised students to be more vigilant than usual and to go to SHS if they have a fever and stiff neck. She also said students should refrain from sharing food or drinks to lessen their risk of infection.

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