Comments from Website author: This article, a letter to the Editor of the New England Journal of Medicine, is a clear documentation of other-than-tick transmission of lyme. While I believe it's rare, this does finally medically document (refuting what some have said) that lyme can be transmitted by "other-than-tick".
Comments from Physicians at this article's end: None


Lyme Disease Transmitted by a Biting Fly

N Engl J Med 1990 Jun 14;322(24):1752

To the Editor:

    Lyme disese, first described by Steere et al. in 1977,1 was identified as a disease transmitted by the bite of ixodes ticks.2 Burgdorfer, Barbour, and colleagues then isolated the infectious agent, a spirochete now known as Borrelia burgdorferi.3 the spirochete has been shown to be transmitted by a variety of ixodes ticks, including Ixodes dammini, I. ricinus, I. pacificus, and I. persulcatus.4 B. burgdorferi has been identified in biting flies, and there has been anecdotal mention of possible transmission of B. burgdorferi by such flies. 5,6 This repost describes a case of Lyme disease transmitted by a fly bite.

    On July 10, 1989, while jogging with no shirt on, a 42-year-old man from Old Lyme, Connecticut, an area in which Lyme disease is endemic, was bothered by a large fly that he believed to be either a deerfly or a horsefly. After swatting at it unsuccessfully, he was bitten by the fly several times on the right side of the chest. The bites were acutely painful. The area around the bites was swollen for one to two days; the swelling then subsided. The patient was not aware of any tick bites in teh previous three months. On July 23, he presented with classic erythema migrans surrounding the bite area, headache, chills, fever, myalgias, arthralgias, and fatigue.

    The patient had a temperature of 37.2C and a pulse of 76 per minute. Examination disclosed a 16-cm by 11-cm rash (erythema migrans) on the right side of the chest, with several small papular areas in it's center consistent with fly bites No regional adenopathy was present, and no cardiac, joint, or neurologic abnormalities were found. A diagnosis of Lyme disease was made, and treatment was initiated with amoxicillin (500 mg three times a day) and probenecid (500 mg three times a day) for 10 days. On the first night after treatment the patient had a Jarisch-Herxheimer reaction, with a fever and worsening of his headache and myalgias. At his 10- and 30- day follow-up visits he was asymptomatic, and has remained well since.

    Antibody titres to B. burgdorferi were determined by enzyme-linked immunosorbent assays in the acute phase and at the 10- and 30- day follow-up visits. These analyses confirmed a more than four-fold rise in antibodies to B. burgdorferi (Table 1). Results of other laboratory tests were within normal limits.

Table 1. Antibody Response to B. burgdorferi in the Patient and According to Diagnostic Criteria.




  Negative Indeterminate Positive
  Day 1 Day 10 Day 30      
IgM <1:100 1:25,600 >1:6400 <1:100 1:1001:200 >1:200
IgG <1:400 1:400 >1:400 <1:400 1:400 >1:400

    The patient was bitten by a biting fly (an act he both saw and felt) and subsequently presented with Lyme disease, with erthema migrans at the site of the bite. Serologic testing confirmed a more than fourfold rise in antibodies to B. burgdorferi. In contrast to the painless bite of I. dammini, the bite of flies is painful and not likely to be overlooked by the patient as a means of transmission of Lyme disease. I conclude that although in most cases Lyme disease is transmitted by the bite of ixodes ticks, it may rarely be transmitted by biting flies.

Steven W. Luger, M.D.
8 Davis Rd

Old Lyme, CT  06333


  1. Steere AC, Malawista SE, Snydman DR, et al. Lyme arthritis: en epidemic of oligoarticular arthritis in children and adults in three Connecticut communities, Arthritis Rheum 1977; 20:7-17

  2. Steere AC, Malawista SE. Cases of Lyme disease in the United States: locations correlated with distribution of Ixodes dammini. Ann Intern Med 1979:91:730-3.

  3. Burgdorfer W, Barbour AG, Hayes SF, Benach JL, Brunwaldt E, Davis JP. Lyme disease -- a tick borne spirochetosis? Science 1982; 216:1317-9.

  4. Steere AC, Lyme disease. N Engl J Med 1989; 321:586-96

  5. Magnarelli LA, Anderson JF, Barbour AG. The etiologic agent of lyme disease in deer flies horse flies, and mosquitoes. J Infect Dis 1986; 154:355-8

  6. Magnarelli LA, Anderson JF. Ticks and biting insects infected with the etiologic agent of Lyme disease, Borrelia burgdorferi. J Clin Microbiol 1988; 26:1482-6