Washington: A new CDC study has found that an epidemic of Rocky Mountain spotted fever among several American Indian tribes on two reservations in Arizona has caused over $13 million in societal costs in around nine years.

The amount includes treatment, time off work, and loss of lifetime productivity due to early death. The researchers from the U.S. Centers for Disease Control and Prevention, Indian Health Services and the affected tribes say that it is likely that the actual cost of the epidemic was underestimated by the study because it doesn't include long-term losses from disability and expensive medical procedures.

Rocky Mountain spotted fever is caused by Rickettsia rickettsii bacteria and spread through the bite of an infected tick. The researchers claim that the disease has only recently become a serious problem among American Indians in Arizona. The brown dog tick which transmits the bacteria in Arizona can be carried into homes by untreated dogs and other pets.

For the study, 205 cases of Rocky Mountain spotted fever were reviewed by the researchers. These cases occurred between 2002 and 2011. More than 80 percent of the cases required emergency room visits, the study found. About 14 percent of patients were admitted to the intensive care unit, and 7 percent of patients died.

"Rocky Mountain spotted fever is completely preventable," Naomi Drexler, a CDC epidemiologist and one of the study authors, said in an agency news release.

"State, federal and tribal health authorities have been working together since the start of the epidemic to build effective community-based tick control programs, and these efforts have produced remarkable reductions in human cases," she added. "These programs are costly, but medical expenses and lives lost cost four times more than Rocky Mountain spotted fever prevention efforts. Increasing access to these prevention efforts is critical to save lives and protect communities."

The findings of the study were published recently in The American Journal of Tropical Medicine and Hygiene.