Boy in Texas presents with erythema after camping
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A 10-year-old male from the northern Texas Panhandle discovered a lesion on his right thigh. He thought it was an insect bite — perhaps a spider — acquired during a recent camping trip with some friends.
Four days later, he noticed that a ring of erythema had developed, and a week after that, the ring continued to expand (Figure 1), and he was taken to his primary care physician. Additional history revealed that he saw many insects on the camping trip, now about 2 weeks ago, and recalled the area about the lesion was itching during the trip, causing him to scratch through his jeans. Some of the boys had embedded ticks, but the patient did not see any on his body, except one was crawling around in his hair. Otherwise, he received only numerous mosquito bites and was exposed to poison ivy. His past medical history is normal, and his immunizations are up to date. He has no other complaints and never traveled out of the north Texas area.
Examination results reveal normal vital signs and the lesion shown in Figure 1 but otherwise that of a healthy 10-year-old male.
What’s your diagnosis?
A. Borrelia burgdorferi
B. Rickettsia rickettsia
C. Rhus dermatitis
D. Southern tick-associated rash illness, or STARI
Answer and discussion:
The answer is STARI (choice D). As summer is here, and ticks are active, this seems like a good time to review this topic. STARI is a rash-producing infection of unknown etiology that is spread by the lone star tick (Amblyomma americanum), which may be otherwise asymptomatic, or accompanied by some flu-like symptoms. It results in an expanding, annular rash lesion very similar to the erythema migrans of Lyme disease. In fact, I used this same case in the June 2007 issue of IDC, thinking it was Lyme disease. Shortly thereafter, I was corrected by the leading expert of Lyme disease and other tick-born infections, Eugene Shapiro, MD, of Yale University, who stated that we do not see endemic Lyme disease in Texas because we do not have the proper vector. So, for the first time, I had to publish a correction. Dr. Shapiro and I touched base again recently, and we both agree that the only Lyme disease seen in Texas is predominantly imported by travelers or mistaken for STARI or something else with a false-positive Lyme titer. Therefore, the cases that are reported to the local health departments in Texas (which apparently do not have to be documented by serology) and ultimately to the state and CDC are likely STARI cases but get reported as Lyme. Even if there have been cases of endemic Lyme disease reported in Texas, the map showing counties in Texas where cases have been “seen” include virtually none in the Texas Panhandle, where Amarillo is located. After practicing in Texas for a total of 34 years, I have never had a documented case of Lyme disease come through my clinic. The only documented cases I have ever seen was when I was in the Army, stationed at Walter Reed Army Medical Center in Washington, D.C., and at West Point, New York.
STARI was first described in the 1980s. Apparently, it did not catch much traction until the late 1990s and early 2000s. At the time of this Lyme disease “fake out” case (2006), I had not seen a case of STARI (and still have not), and we have an abundance of A. americanum ticks in Texas. The time from tick bite to rash is about 2 weeks, and diagnosis is clinical. The recommended treatment is usually doxycycline, especially if there is doubt about Lyme disease.
Lyme disease, which is caused by Borrelia burgdorferi, is transmitted by the very small Ixodes scapularis tick, which is about the size of the head of a pin. So, it could go unnoticed, and even unknowingly scratched off sometime after it had embedded and transmitted the organism. The same could be said for the larger A. americanum, especially when dealing with an active 10-year-old boy. Studies have shown that attachment must occur for at least 36 to 48 hours before the vector can transmit the organism for Lyme disease. The characteristic spreading annular lesion (Figure 2) of Lyme disease can look identical to that of STARI and can get fairly large (Figure 3).
Rocky Mountain spotted fever, the disease caused by Rickettsia rickettsia, is also a tick-born disease that typically begins with fever, headache, myalgias and gastrointestinal symptoms, and the “spotted” rash. It is also very uncommon in Texas — and in the Rocky Mountain states as well. The rash ranges from maculopapular to petechial, beginning on the wrists, hands, ankles and feet, then spreading toward the trunk. Diagnosis can be rapidly made with PCR of biopsy tissue from the rash, but this may not be readily available. Culture of the organism is hazardous and not recommended. Therefore, diagnosis is usually confirmed serologically with paired sera, but because of the high lethal potential, one cannot wait for confirmation to treat. The treatment of choice is doxycycline, regardless of the patient’s age. Our old friend chloramphenicol is an alternate treatment if you can find it.
Rhus dermatitis, usually caused by contact with the Toxicodendron radicans (poison ivy) plant but may also include poison sumac. The allergen, urushiol, contained in the sap of the plant can provoke an intense inflammatory reaction to those who are sensitive. There are no systemic symptoms, and the rash is usually limited to the area of skin in contact with the plant (Figure 4). It would be highly unlikely for a patient wearing jeans to get poison ivy on the upper thigh but could happen when “nature calls in the woods.”
Columnist comments
In pursuit of truth, one may occasionally need to admit the mistake and, as in golf, do a mulligan, or a “re-do”. Such is the case here. As if diagnosing Lyme disease wasn’t complicated enough already, we have to consider this “lookalike.”
Please keep in touch, and please send along any good case you might like to see in this column. I can be reached at jhbrien@aol.com.
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Brien is a member of the Healio Pediatrics and Infectious Disease News Editorial Boards, and an adjunct professor of pediatric infectious diseases at McLane Children's Hospital, Baylor Scott & White Health, in Temple, Texas.