Tick-borne ills - we're not out of the woods

PITTSBORO -- After a couple of recent news stories, some citizens are breathing a sigh of relief about Rocky Mountain spotted fever, feeling they no longer need to be so concerned.

Actually, medical providers and residents need to be more vigilant about Rocky Mountain spotted fever and related infections, not less.

North Carolina is the leading state in number of deaths caused by Rocky Mountain spotted fever. From 1979 through 2004, an average of 3.5 people per year died from the illness here. And the Centers for Disease Control estimates that these are only one-third of the actual deaths. Nor do the 842 non-fatal cases reported here last year represent the true number.

Rocky Mountain spotted fever is a serious rickettsial infection transmitted by the American dog tick. It has a mortality rate of 20 percent to 30 percent in untreated cases, and as much as 5 percent with treatment.

Rickettsias invade certain human cells, including white blood cells, where they freely multiply. Two of the newer diseases they are known to cause have fancy names -- ehrlichiosis and anaplasmosis. Other new illnesses, including that caused by Rickettsia amblyommii (which prompted a Sept. 29 news story), remain without names at this point -- nor have standard tests been developed to detect their presence. Four kinds of ticks in North Carolina bite humans and can transmit one or more human pathogens. All of the organisms previously established as human pathogens can cause death or long-term disability if not treated promptly.

Researchers who studied the apparent illness associated with the rickettsia named after the Lone Star tick cannot know with certainty if it is "mild" or "cannot kill." No one has had time to study these aspects. And the natural course of this illness cannot be known, because patients in the study were treated for tick-borne infections, since they presented with symptoms and a tick exposure history. Not to treat them would have been unethical and risky.

If 95 percent of the cases in the state that appear to be Rocky Mountain spotted fever are actually due to this "mild" Rickettsia amblyommii, that does not explain why North Carolina is the leading state for deaths from Rocky Mountain spotted fever. Either this newly recognized pathogen is not mild, or we also have a lot of the real spotted fever around.

Either way, more needs to be done, because these deaths are preventable.

Studies on the various tick-borne infections find that victims are often unaware of a tick bite. Awareness, avoiding risky environments during tick season (which is almost year-round here) and using repellents all help but will never be completely protective. Short of living on an island of concrete, we can't completely protect ourselves from tick bites.

It appears that medical providers need to consider rickettsial tick-borne infections in their list of possible diagnoses more often than they have been, when patients appear with compatible symptoms. A good rule to follow is that when suspected, treat. Tests in the acute phase are not helpful. Withholding seven days of a reasonably safe antibiotic, doxycycline, is not worth a possible death.

In addition to rickettsial diseases we have other tick-borne infections, including STARI (Southern tick-associated rash illness), Lyme disease and several others. Lyme has recently been found in two dogs in central North Carolina that never traveled outside the state. There are no tests for either STARI or the new infection from Rickettsia amblyommii.

Thousands of people get sick each year in our state from tick-borne infections. Public health officials can do more to educate the public and medical providers about ticks. Funds recently appropriated by the legislature for education, testing and prevention of tick-borne infections will help in this effort.

(Marcia E. Herman-Giddens is an adjunct professor at the UNC School of Public Health and president of the Tick-borne Infections Council of N.C.)