WATERLOO -- In the last decade, outbreaks in Iowa of meningitis, mumps, E. coli and staph all centered in one place -- Black Hawk County.

The Black Hawk County Health Department often asked itself: Why us?

A report released Friday commissioned by the department sought to find answers. No easy ones surfaced.

Rather, researchers discovered a variety of factors combined to make Black Hawk County susceptible to all kinds of nasty bugs. Among the explanations:

A unique mix of multiple high-risk populations: Low-income whites, college students, African-Americans, migrant Latinos, a corrections system and several pockets of high-risk immigrants like Africans from Liberia and Congo.

The department's emphasis and expertise in communicable disease prevention means it uncovers cases that may go unnoticed elsewhere.

"It's the combination of these high-risk populations and their numbers which have given us very serious concerns from an infectious disease standpoint," said Michele Devlin, a University of Northern Iowa professor who co-authored the study.

Devlin also serves on the health board. She was not paid for her work.

Co-author Mark Grey, also a UNI professor, recommended the health department find a way to roll back cuts to its sexually transmitted disease clinics and expand hours and locations.

That's because STDs are an increasing cause for concern, the study found.

In 2008, they accounted for 81 percent of communicable diseases in the county, up from 66 percent in 2006.

The county also has the highest STD rate in the state, with 776 cases of syphilis, chlamydia or gonorrhea per 100,000 people.

"STDs are taking over as the dominant communicable disease," Grey said.

However, Grey cautioned the county may also suffer from inflated numbers when compared to the rest of the state because of its robust detection efforts.

Matt Hobson, a public health veteran who has worked with counties across Iowa, said Black Hawk County possesses one of the state's top STD and communicable disease programs.

"While the rate is high in other places, in many other places people aren't looking," said Hobson, who serves on the health board.

Health department director Tom O'Rourke said many of the results did not surprise him.

However, he said a few findings debunked common assumptions that one group is responsible for the county's diseases.

"What usually happens is one ethnic group, whether its blacks or Hispanics, take the hit, and this tells you it's not just one. (STDs) are an equal opportunity disease and impact all kinds of people," O'Rourke said.

The study found whites visiting the clinics were more likely than blacks to use drugs and engage in high-risk sexual behaviors, which the health department defines as 10 or more partners in a lifetime.

The study also found more people from the 50613 zip code, which makes up all of Cedar Falls and is largely white, visit clinics than those in Waterloo's 50701 zip code.

In 2006, more people living in the Cedar Falls zip code visited an STD clinic than anywhere in the county, including Waterloo's 50703 zip code, which contains most of the area's black residents.

Waterloo has the largest African American population in the state.

Contact Jens Manuel Krogstad at (319) 291-1580 or jens.krogstad@wcfcourier.com.