Skip directly to site content Skip directly to page options Skip directly to A-Z link Skip directly to A-Z link Skip directly to A-Z link
Volume 14, Number 12—December 2008

Human Case of Rickettsia felis Infection, Taiwan

On This Page
Article Metrics
citations of this article
EID Journal Metrics on Scopus

Cite This Article

To the Editor: Rickettsia felis, the etiologic agent of flea-borne spotted fever, is carried by fleas worldwide (1). In the past decade, several human cases of R. felis infection have been reported (13). Clinical symptoms and biological data for R. felis infections are similar to those for murine typhus and other rickettsial diseases, which makes clinical diagnosis difficult (2). Patients with R. felis infections may have common clinical manifestations, such as fever, headache, myalgia, macular rash, and elevated levels of liver enzymes (4,5).

Reportable rickettsioses in Taiwan include scrub typhus, epidemic typhus, and murine typhus. Although there are no known human cases of infections caused by spotted fever group (SFG) rickettsiae in Taiwan, novel strains of SFG rickettsiae have been isolated as recently described (6,7). In addition, evidence for R. felis infections in cat and cat flea populations has been identified by using immunofluorescence assay (IFA), PCR, and organism isolation (K.-H.Tsai et al., unpub. data). We report an indigenous human case of R. felis infection in Taiwan.

In January 2005, a 27-year-old woman living in Fongshan City, Kaohsiung County, in southern Taiwan was admitted to Kaohsiung Medical University Hospital with a 4-day history of intermittent fever (37.8°C–38.0°C), chills, headache, and fatigue. Associated symptoms were frequent micturition and a burning sensation upon voiding. The patient was admitted with a possible urinary tract infection; urinalysis showed pyuria (leukocyte count 25–50/high-power field), compatible with the clinical diagnosis. During the 6-day hospital stay, the patient received daily intravenous first-generation cephalosporin (cefazolin); gentamicin was given only on the first 3 days. She was discharged with a prescription for oral antimicrobial drugs (cephradine 500 mg every 6 h) to be taken for 7 days. Micturition-associated symptoms subsided after treatment.

The patient also had headaches and glove-and-stocking numbness in both hands because of fever, but denied any associated rash and arthralgia. Although the patient did not recall any arthropod bites, she had noticed some stray dogs and cats nearby and rodents in the neighborhood surrounding her house. Because of acute polyneuropathy-like symptoms and exposure history, we prescribed oral doxycycline (100 mg every 12 hours) for 5 days as empirical therapy on the second day at the hospital, suspecting a zoonosis such as rickettsioses, Q fever, or leptospirosis. Headache and glove-and-stocking numbness subsided. Her blood sugar level and thyroid function were within normal limits. Chest radiograph, liver function, renal function, and levels of electrolytes were all normal.

Whole blood counts were normal, although differential counts demonstrated a left shift (polymorphonuclear leukocytes 80.7%, reference range 37%–75%). C-reactive protein level was 66.7 μg/mL, (reference <5 μg/mL) upon admission. Blood culture and urine culture were negative for bacteria.

Additionally, painful vesicles on the external genitalia appeared on the fourth day postadmission, and valacyclovir was administered for 5 days because of suspected infection with herpes simplex virus. The lesion subsided after valacyclovir treatment and the patient was discharged in good condition.

Patient whole blood specimens were collected on days 4 and 16 after the onset of fever and sent to the Taiwan Centers for Disease Control for laboratory diagnosis of rickettsial infection. For molecular diagnosis, DNA from the acute-phase blood sample (day 4) was analyzed by using the SYBR green-based real-time PCR specific for 17-kDa antigen, 60-kDa heat-shock protein (groEL) gene, and outer membrane protein B (ompB) gene for typhus group and SFG rickettsiae and primers listed in the Table. Nucleotide sequences of real-time PCR products demonstrated 100% identity with 17-kDa antigen, groEL, and ompB genes of R. felis URRWXCal2. Real-time PCR results were negative for Orientia tsutsugamushi and Coxiella burnetii (8).

For serologic diagnosis, serum samples were tested for rickettsial-specific antibodies by IFA using whole cell antigens of R. felis isolated from the cat flea. The patient’s serum (days 4 and 16) had immunoglobulin (Ig) G, IgA, and IgM titers of 160 and 2,560, respectively. The serum sample collected from R. felis–infected cat served as the positive control. Test results were negative for R. typhi, R. conorii, R. rickettsii, R. japonica, O. tsutsugamushi, and C. burnetii.

Absence of rash, eschar, and unawareness of arthropod bite may be easily overlooked in some patients with rickettsial infections. In this case, suspicion of rickettsial infection was based on exposure history and acute polyneuropathy, which responded quickly to doxycycline treatment. There are limited reports of rickettsioses with polyneuropathy, and none for cases of R. felis infection (9,10). It was hard to tell whether the urinary tract and herpes simplex virus infections were associated with an R. felis infection, but it is quite rare for 3 different infections to occur in a patient at the same time as isolated entities. The finding of a human case of infection and the existence of R. felis in cat fleas highlights the need for further studies on flea-borne rickettsioses in Taiwan.


Kun-Hsien Tsai, Hsiu-Ying Lu, Jih-Jin Tsai, Sheng-Kai Yu, Jyh-Hsiung Huang, and Pei-Yun ShuComments to Author 
Author affiliations: Centers for Disease Control, Taipei, Taiwan, Republic of China (K.-H. Tsai, H.-Y. Lu, S.-K. Yu, J.-H. Huang, P.-Y. Shu); Kaohsiung Medical University, Kaohsiung, Taiwan, Republic of China (J.-J. Tsai)



  1. Pérez-Osorio  CE, Zavala-Velázquez  JE, Aris León  JJ, Zavala-Castro  JE. Rickettsia felis as emergent global threat for humans. Emerg Infect Dis. 2008;14:101923. DOIPubMedGoogle Scholar
  2. Pérez-Arellano  JL, Fenollar  F, Angel-Moreno  A, Bolaños  M, Hernández  M, Santana  E, Human Rickettsia felis infection, Canary Islands, Spain. Emerg Infect Dis. 2005;11:19614.PubMedGoogle Scholar
  3. Parola  P, Miller  RS, McDaniel  P, Telford  SR, Rolain  JM, Wongsrichanalai  C, Emerging rickettsioses of the Thai-Myanmar border. Emerg Infect Dis. 2003;9:5925.PubMedGoogle Scholar
  4. Schriefer  ME, Sacci  JB, Dumler  JS, Bullen  MG, Azad  AF. Identification of a novel rickettsial infection in a patient diagnosed with murine typhus. J Clin Microbiol. 1994;32:94954.PubMedGoogle Scholar
  5. Zavala-Velázquez  JE, Ruiz-Sosa  JA, Sánchez-Elias  RA, Becerra-Carmona  G, Walker  DH. Rickettsia felis rickettsiosis in Yucatán. Lancet. 2000;356:107980. DOIPubMedGoogle Scholar
  6. Tsai  KH, Wang  HC, Chen  CH, Huang  JH, Lu  HY, Su  CL, Isolation and identification of a novel spotted fever rickettsiae, strain IG-1, from Ixodes granulatus ticks collected on Orchid Island (Lanyu), Taiwan. Am J Trop Med Hyg. 2008;79:25661.PubMedGoogle Scholar
  7. Tsui  PY, Tsai  KH, Weng  MH, Hung  YW, Liu  YT, Hu  KY, Molecular detection and characterization of spotted fever group rickettsiae in Taiwan. Am J Trop Med Hyg. 2007;77:88390.PubMedGoogle Scholar
  8. Zhang  GQ, Hotta  A, Mizutani  M, Ho  T, Yamaguchi  T, Fukushi  H, Direct identification of Coxiella burnetii plasmids in human sera by nested PCR. J Clin Microbiol. 1998;36:22103.PubMedGoogle Scholar
  9. Raoult  D, Weiller  JP, Chagnon  A, Chaudet  H, Gallais  H, Casanova  P. Mediterranean spotted fever: clinical, laboratory and epidemiological features of 199 cases. Am J Trop Med Hyg. 1986;35:84550.PubMedGoogle Scholar
  10. Font-Creus  B, Bella-Cueto  F, Espejo-Arenas  E, Vidal-Sanahuja  R, Muñoz-Espin  T, Nolla-Salas  M, Mediterranean spotted fever: a cooperative study of 227 cases. Rev Infect Dis. 1985;7:63542.PubMedGoogle Scholar




Cite This Article

DOI: 10.3201/eid1412.080515

Related Links


Table of Contents – Volume 14, Number 12—December 2008

EID Search Options
presentation_01 Advanced Article Search – Search articles by author and/or keyword.
presentation_01 Articles by Country Search – Search articles by the topic country.
presentation_01 Article Type Search – Search articles by article type and issue.



Please use the form below to submit correspondence to the authors or contact them at the following address:

Pei-Yun Shu, Vector-Borne Viral and Rickettsial Diseases Laboratory, Research and Diagnostic Center, Centers for Disease Control, Department of Health, Taipei 11561, Taiwan, Republic of China

Send To

10000 character(s) remaining.


Page created: July 22, 2010
Page updated: July 22, 2010
Page reviewed: July 22, 2010
The conclusions, findings, and opinions expressed by authors contributing to this journal do not necessarily reflect the official position of the U.S. Department of Health and Human Services, the Public Health Service, the Centers for Disease Control and Prevention, or the authors' affiliated institutions. Use of trade names is for identification only and does not imply endorsement by any of the groups named above.