New Bartonella Species Uncovered

Bartonella

N Engl J Med.

An American woman who had signs, symptoms, and a travel history typical of Oroya fever was found to be infected with a heretofore unrecognized species ( 2007;356: 2381-2387).

Bartonella bacilliformis

The 43-year-old woman presented with fever, splenomegaly, and anemia a few weeks after returning to the United States from a visit to a region in Peru where is endemic. (The other countries where the disease is common are Ecuador and Colombia.) She recalled being bitten by insects on numerous occasions while hiking in Peru.

B quintana

Human body lice, vector of .

B bacilliformis

Bartonella

Bartonella clarridgeiae

was isolated from a blood specimen, but molecular characterization determined that the organism was a new species of that was closely associated with, but distinct from, , a species that had previously been found only in domestic cats in the United States and elsewhere.

B bacilliformis

Bartonella quintana

Bartonella

Bartonella henselae

and —the other species for which humans are the sole reservoir host—are transmitted to humans by arthropods. has been isolated in the occasional immunocompromised human, but domestic cats are its primary reservoir. Although this suggests that the insect bites when in Peru may well have been the source of this patient's infection (she had no contact with cats), the exact route of infection and the associated burden of disease in humans of this new species remain unknown.

The risk factors for acquiring the 3 species known to infect humans are:

• Homelessness and exposure to human body lice (B quintana)
• Scratches from flea-infested kittens (B henselae)
• Visiting or living in a region of the Andes where the sand-fly vector is found (B bacilliformis).

Bartonella

The patient described here was successfully treated with a 5-day course of oral levofloxacin (Levaquin) as empiric treatment for enteric fever. This case underscores the need for careful evaluation of patients suspected of having a -related illness, including culture and molecular characterization of isolates, along with vigilance for new species.