The cost of medical care and lost productively from Zika infections in six southern U.S. states could exceed $2 billion, and that’s if only 2 percent of the region’s population becomes infected, according to economic modeling done recently at Johns Hopkins Bloomberg School of Public Health.

The financial — and human toll — would be far higher if more people were infected in those states or beyond, a scenario public health officials described as inevitable Monday during a panel of close to three dozen experts.

The panel, held at Johns Hopkins Hospital, was convened as a fact finding effort by U.S. Sen. Ben Cardin, a Maryland Democrat.

Cardin sought the information as Congress debates an Obama Adminsitration request for $1.9 billion in emergency funding for domestic and international response to the mosquito-borne virus already causing grave harm largely in Central and South America. Pregnant women infected with the virus are giving birth to babies with microcephaly, a disorder that stunts the growth of their brains and heads.

“This should not be viewed as a cost but as an investment,” said Dr. Bruce Y. Lee, and associate professor of international health who modeled the lifetime costs of a Zika epidemic that ends within a year. Lee called the estimate “conservative.”

So far there have been 544 confirmed U.S. cases of Zika, 17 of them in Maryland, and all are travel-related, according to the U.S. Centers for Disease Control and Prevention. Pregnant women, who are more likely to seek testing, accounted for 157 of the cases, including one from Maryland.

Other panel members from government, private and academic posts around Maryland said funding so far for short and long-term Zika response has been diverted largely from state and federal budgets earmarked for other purposes.

As a result, the resources of local health departments are being stretched, as they try to disseminate the latest information to women who are pregnant or want to become pregnant and provide safety kits including bug repellent, larvicide and condoms, since Zika also can be sexually transmitted.

Dr. Howard Haft, deputy secretary of public health at the Maryland Department of Health and Mental Hygiene, stressed the importance of preparing the public to defend itself since there are more than 70,000 births in the state annually.

“Women need to be aware of the risks,” he said. “Family planning is key.”

State agriculture officials also are straining their budgets to spray for adult mosquitoes and target larvae. Several communities contract with the Maryland Department of Agriculture for vector control, though officials say any community where Zika is confirmed will be treated without charge.

Delayed federal funding also hurts efforts by university and government researchers to develop an accurate rapid test that could be done using a drop of blood in doctors’ offices to quickly determine who is infected and at risk for complications. For now, Americans who have traveled to an affected country, with or without symptoms, must be tested in a state-run or CDC lab.

Because of trouble distinguishing Zika from similar viruses such as dengue, many women must be tested multiple times, increasing costs and “causing a great deal of anxiety,” said Dr. Christopher Harman, chair of the department of obstetrics, gynecology and reproductive sciences at the University of Maryland School of Medicine.

Vaccine experts from both Johns Hopkins University and the University of Maryland, as well as others around the country in public and private labs, are working on a vaccine that could prevent the disease in pregnant women and those of child-bearing years.

Safety trials of vaccine candidates could begin by fall, said Dr. Anna P. Durbin, associate professor in the Hopkins Bloomberg School’s Center for Immunization Research. Funding for larger trials testing the efficacy of any vaccine could be at risk without more dollars, she said.

Cardin said he would go back to Congress and fight for the full request from the president, a prospect he acknowledged might be unlikely for this first funding request. The Senate already has approved about $1.1 billion but the House has approved only $622 million. The two chambers need to hammer out a compromise.

An initial infusion of money, which Cardin said was likely, could aid local educational campaigns, mosquito control and development of the rapid test in the short term, as well as sustain vaccine development efforts for the long term, he said.

“We can’t shortchange these efforts,” Cardin said. “We need funding at the level the experts tell us is needed. As we learned, the financial costs will add up, and more importantly, so will the human costs.”