Serologic evidence of rickettsialpox (Rickettsia akari) infection among intravenous drug users in inner-city Baltimore, Maryland.

Abstract

Abstract. We tested single serum samples from 631 intravenous (IV) drug users from inner-city Baltimore, Maryland for serologic evidence of exposure to spotted fever group rickettsiae. A total of 102 (16%) individuals had titers Ն 64 to Rickettsia rickettsii by an indirect immunofluorescence assay. Confirmation that infection was caused by R. akari was obtained by cross-adsorption studies on a subset of serum samples that consistently resulted in higher titers to R. akari than to R. rickettsii. Current IV drug use, increased frequency of injection, and shooting gallery use were significant risk factors for presence of group-specific antibodies reactive with R. rickettsii. There was a significant inverse association with the presence of antibodies reactive to R. rickettsii and antibodies reactive to the human immunodeficiency virus. This study suggests that IV drug users are at an increased risk for R. akari infections. Clinicians should be aware of rickettsialpox, as well as other zoonotic diseases of the urban environment, when treating IV drug users for any acute febrile illness of undetermined etiology.

Evidence of rodent-associated Bartonella and Rickettsia infections among intravenous drug users from Central and East Harlem, New York City.

“…In Baltimore, the presence of antibodies to R. akari in a cohort of 630 IDUs was significantly associated with shooting gallery use, and it was speculated that contact with rodents was likely to occur under such conditions. 9 However, shooting gallery use was not significantly associated with reactivity to any antigen in the cohort from Harlem. It is likely that rickettsialpox routinely occurs in disadvantaged inner-city populations in many large American cities and is being underdiagnosed for a variety of reasons.…”

“…The IFA was conducted as described, 9 except that conjugate specific for the gamma chain of human immunoglobulin G (Kirkegaard and Perry, Gaithersburg, MD) was used at a 1/150 dilution in all tests. All titers were expressed as the reciprocal of the highest dilution that was reactive to the respective agents.…”

“…In the same cohort, 16% of the IDUs had antibodies to a Rickettsia species that was shown through cross-adsorption studies to be Rickettsia akari, the agent of rickettsialpox. 9 This organism is primarily maintained by another rodent species introduced from the Old World, the house mouse (Mus musculus), which also enjoys a near-cosmopolitan distribution. Because of these reports of rickettsial and Bartonella infections in IDUs, we tested a cohort of IDUs from Central and East Harlem for further evidence of widespread infection with these agents.…”

Fever and a Solitary Papule on the Foot

“…In addition, there is a higher incidence of rickettsialpox infection among intravenous drug users, and this diagnosis should be considered in a patient with such a history. 3 A painless, erythematous, indurated 0.5-to 1.5-cm papule develops after 1 to 2 days at the site of the mite bite. It evolves into a vesicle and then an eschar, forming the characteristic tache noire.…”

Increased Detection of Rickettsialpox in a New York City Hospital Following the Anthrax Outbreak of 2001

“…1,2 Rickettsialpox has been described primarily in New York City, but it has also been reported in large cities in the eastern United States (in Massachusetts, Connecticut, Maryland, Ohio, and Pennsylvania) [2][3][4][5][6][7][8] and in rural North Carolina, 9 Utah, 8 Russia, 10 Korea, 2 and South Africa. 2,11 The disease has been reported in patients ranging in age from 6 months to 72 years.…”