A new species of Bartonella, Candidatus Bartonella melophagi, that has only recently been identified in sheep has now also been isolated in two women, which adds to the increasing number of Bartonella species that have been found in people in the past 10 years. One of the women had a two-year history of cyclical clinical symptoms, including fatigue, muscle pain, chills, chest pain, and weakness. Bartonella henselae was also isolated in this woman, and treatment with rifampin, azithromycin, and cefuroxime resolved her symptoms. The other woman had a six-month history of fatigue and weakness that was initially thought to be pericarditis.

Although both women had histories of exposure to many arthropod and animal species, including sheep in the case of the second woman, a definitive transmission route could not be established. The vector in sheep is thought to be sheep keds. The clinical relevance of Candidatus B. melophagi infection in these patients remains to be established. But nonspecific abnormalities, including muscle weakness and joint pain, have been associated with isolation of Bartonella henselae and Bartonella vinsonii subspecies berkhoffi. Pericardial effusion is an infrequent complication of B. henselae infection in cases of classic cat-scratch disease. Dr. Edward Breitschwerdt, a veterinary internist from North Carolina State University, helped in the isolation of this species.

Maggi RG, Kosoy M, Mintzer M, et al. Isolation of Candidatus Bartonella melophagi from human blood. Emerg Infect Dis [serial on the Internet]. 2009 Jan [01/15/1009].