Babesiosis

TORONTO -- Patients with moderate to severe Lyme disease could be coinfected by the agent that causes babesiosis, Dr. Charles Thompson reported in a poster at the annual Interscience Conference on Antimicrobial Agents and Chemotherapy sponsored by the American Society for Microbiology.

Babesiosis coinfection can exacerbate the symptoms of Lyme disease. It is important to diagnose babesiosis because treatments for the two infections are completely different, Dr. Paul Krause, who collaborated on the study, said in an interview with this newspaper.

The first-line treatment for Lyme disease in adults is 100 mg doxycycline b.i.d. The first-line treatment for babesiosis is 600 mg clindamycin t.i.d. and 650 mg quinine t.i.d. An alternative treatment for babesiosis in adults is azithromycin plus atovaquone, said Dr. Krause, an infectious diseases physician at Connecticut Children's Medical Center, Hartford.

Patients with Lyme disease who are coinfected with another tick-borne pathogen, the agent that causes human granulocytic ehrlichiosis (HGE), also develop more severe symptoms. But in these cases standard treatment for HGE is the same as it is for Lyme disease, Dr. Krause said.

The clinical consequences of coinfection were examined in a series of 185 adults who were diagnosed with Lyme disease, babesiosis, or HGE during May-Sept. of 1997-2000. The cases were culled from three regions of New England: Block Island, Nantucket, and southeastern Connecticut.

Lyme disease alone occurred in 91 patients, who had a mean of 5.3 symptoms and a disease duration of 3.5 weeks. In contrast, the 65 patients with Lyme disease and babesiosis had a mean of 7.4 symptoms and a mean disease duration of 5.4 weeks, reported Dr. Thompson, a pediatrician at the medical center.

Seven patients had Lyme disease and HGE. They had a mean of 7.4 symptoms, and their infections persisted for a mean of 4.5 weeks. The three patients with babesiosis and HGE simultaneously had a mean of 10 symptoms for a mean of 8 weeks. Four patients had all three diseases at once. They had a mean of 8.3 symptoms for a mean of 5 weeks.

The series was rounded out with 14 patients with babesiosis only, with a mean of 8.4 symptoms for a mean of 7.4 weeks. One patient had HGE only. This patient had five symptoms, but the duration of illness was not known. Coinfection with the agents that cause either babesiosis or HGE worsens symptoms in patients with Lyme disease. In contrast, coinfection with the Lyme disease pathogen does not worsen the course of babesiosis or HGE.

One of the easiest ways to identify patients who have Lyme disease is by the presence of erythema migrans, a bull's-eye rash. In this series, 86% of the patients with Lyme disease had erythema migrans, but the rash did not appear in any of the patients in this series who did not have Lyme disease, Dr. Thompson reported.

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