To the Editor: Urban trench fever caused by Bartonella quintana has been reported in persons who abuse alcohol and in homeless persons in large cities worldwide. Symptoms vary from asymptomatic intermittent bacteremia to serious complications (1). Pediculus humanus lice, the known vector of the infection, are not always identified, which raises the possibility that other vectors might also be involved (2). We report on an outbreak of B. quintana infection among a young family of high socioeconomic status and their visiting relatives.

The family resides in a regional city (population 104,000) in northern Czech Republic in an old, renovated apartment located on the top floor, just under the roof. In the summer of 2007, hundreds of ectoparasitic mites migrated from a hole in the roof and settled on the inner side of a permanently open window before infesting family members. Two weeks later (day 1 of symptom onset), a papular rash and pruritic vesicular lesions were noted by the parents on the body and legs of their 2 children, a 1-year-old girl and a 3-year-old boy. On day 3, the girl’s body temperature rose to 38.0°C, and the boy’s temperature rose to 39.5°C. The rash resolved in ≈10 days in both children. Vesicular lesions on the girl’s buccal mucosal membrane resolved in 5 days. Excoriated areas resulting from spontaneous rupture of lesions or scratching were still visible on day 14.

On day 4, a fever (temperature, 38.5°C) and intense tibialgia, which persisted for 5 days, developed in the 33-year-old father of the infected children. On day 5, a vesicular rash, which resolved in 10 days, developed in the 33-year-old mother. The children’s grandfather and both grandmothers also showed symptoms of infection within ≈14 days after having spent >1 days or nights in the infected family’s household (Table). In addition, the regional epidemiologist who was involved in the investigation showed development of a severe infection 16 days after exposure to implicated mites that escaped from a collection tube (Table). Recurrent fevers of decreasing intensity, followed by remissions at 1-week intervals, were observed in all patients for up to 3 months.

Seven mites, which were collected by the father on day 6 after symptom onset, were identified as engorged and nonengorged members of the genus Dermanyssus. After treatment with ethanol, the mites were investigated by culture and DNA analysis. DNA fragments specific for Bartonella spp. (i.e., a 185-bp [3] and a 397-bp [4,5] fragment of the 16S rRNA gene) were amplified; the sequence of the 397-bp fragment was 100% similar to the htrA sequence of the B. quintana strain Toulouse (Table). Results were negative for PCRs with primers for 16S rDNA of Anaplasma phagocytophilum (6) and primers for ospA of Borrelia burgdorferi (7). Only Staphylococcus cohnii subsp. urealyticus, as part of human or animal commensal flora, was detected on blood agar plates that were cultured for 30 days in a microaerophilic atmosphere.

Patient samples were analyzed by using the specific 16S rRNA primers; the Bartonella-specific amplicon was found only in a sample that was collected on day 4 from the father. Amplification of the htrA gene fragment of identical size and with identical sequences also confirmed the presence of DNA specific for B. quintana in the father’s sample. Hemocultures were not performed at symptom onset, but results for patient serum samples cultured under the same conditions as the homogenized parasites remained negative. Significant titers of IgG against B. quintana and B. henselae or IgG seroconversion in paired serum samples were observed for all patients except the grandfather (Table).

Oral clarithromycin and doxycycline were administered to the children and adults, respectively, for 10 days. The apartment was repeatedly treated with insecticide, and the hole in the roof was repaired, leading to eradication of the mites. The few dead and dry mites that were available for additional parasitologic analysis were mounted in Swan mounting medium (information about the medium is available from the authors), but no characteristics allowing differentiation between species of the genus Dermanyssus were recognized during examination by light microscopy. Failed attempts were made to trap pigeons that had lived on the roof of the apartment or in the same city; however, samples from trapped synanthropic pigeons from the north (n = 20) and central (n = 33) part of the country were negative for Bartonella spp. by the culture and amplification methods described above. Recurrent fever reported by adult patients resolved in 3 months, and all patients made a full clinical recovery. Laboratory findings for the patients were followed for 6 months after symptom onset (Table).

The fact that the suspected vector was a hematophagous mite (Dermanyssus sp.), a parasite of synanthropic pigeons and a suspected vector of other bacterial pathogens (8,9), and that the 16S rRNA Bartonella spp. gene was detected in mites (Steatonyssus sp. from the superfamily Dermanyssoidea) (10) remains a challenge for additional study. Pigeons probably played the role of accidental host in this outbreak, but the source of the infection remains unclear.