Human Spotted Fever Group Rickettsioses Are Underappreciated in Southern Taiwan, Particularly for the Species Closely-Related to Rickettsia felis

Abstract

BackgroundDespite increased identification of spotted fever group rickettsioses (SFGR) in animals and arthropods, human SFGR are poorly characterized in Taiwan.MethodsPatients with suspected Q fever, scrub typhus, murine typhus, leptospirosis, and dengue fever from April 2004 to December 2009 were retrospectively investigated for SFGR antibodies (Abs). Sera were screened for Rickettsia rickettsii Abs by indirect immunofluorescence antibody assay (IFA), and those with positive results were further examined for Abs against R. rickettsii, R. typhi, R. felis, R. conorii, and R. japonica using micro-immunofluorescence (MIF) tests. Polymerase chain reaction (PCR) for detection of SFGR DNA was applied in those indicated acute infections. Case geographic distribution was made by the geographic information system software.ResultsA total of 413 cases with paired serum, including 90 cases of Q fever, 47 cases of scrub typhus, 12 cases of murine typhus, 6 cases of leptospirosis, 3 cases of dengue fever, and 255 cases of unknown febrile diseases were investigated. Using IFA tests, a total of 49 cases with 47 (11.4%) and 4 (1.0%) cases had sera potentially positive for R. rickettsii IgG and IgM, respectively. In the 49 cases screened from IFA, MIF tests revealed that there were 5 cases of acute infections (3 possible R. felis and 2 undetermined SFGR) and 13 cases of past infections (3 possible R. felis and 10 undetermined SFGR). None of the 5 cases of acute infection had detectable SFGR DNA in the blood specimen by PCR. Possible acute infection of R. felis was identified in both one case of Q fever and scrub typhus. The geographic distribution of SFGR cases is similar with that of scrub typhus.ConclusionsHuman SFGR exist and are neglected diseases in southern Taiwan, particularly for the species closely-related to R. felis.

Severe scrub typhus infection: Clinical features, diagnostic challenges and management

“…Scrub typhus is seen in several parts of South-East Asia including India [4][5][6][7][8][9][10][11] , Bangladesh [12] , China [13] , Taiwan [14] , South Korea [15] , Japan [16] and Northern Australia [17] . Although scrub typhus has been reported from isolated parts of these countries [2,5,9,13,14] , it is likely that this disease is ubiquitous.…”

“…Although scrub typhus has been reported from isolated parts of these countries [2,5,9,13,14] , it is likely that this disease is ubiquitous. The majority of cases are from the rural areas given that these mites thrive in those environments.…”

The Epidemiology and Characteristics of Q fever and Co‐infections with Scrub Typhus, Murine Typhus or Leptospirosis in Taiwan: A Nationwide Database Study

“…Clinicians usually report multiple diseases simultaneously to the Taiwan CDC and diseases in addition to QF and co‐infections of QF with other diseases were identified (Tables and ). Co‐infections of QF with ST, MT, or spotted fever group rickettsioses (Janbon et al., ; Rolain et al., ; Lai et al., , ; Prabhu et al., ; Chang et al., ) and co‐infection of LS with ST (Watt et al., ; Ellis et al., ; Lee and Liu, ; Wei et al., ) have been reported in Taiwan and in the literature. However, QF with LS co‐infection has rarely been reported, and only one prospective study from northern Tanzania mentioned that one (4.2%) of 24 QF cases had LS co‐infection (Prabhu et al., ).…”

“…In addition to QF, scrub typhus (ST), murine typhus (MT) and the spotted fever group of rickettsioses are also endemic in southern Taiwan (Lai et al, 2009b(Lai et al, , 2014b. Thus, co-infection of QF with ST (Lai et al, 2009a), MT (Chang et al, 2012), and other rickettsioses (Lai et al, 2014b) has been clinically identified by reporting suspected both these diseases and QF simultaneously to the Centers for Disease Control, Taiwan (Taiwan CDC). Although several studies have reported the epidemiology and clinical characteristics of QF in Taiwan, all of these studies were single-centre, retrospective and clinical studies (Lai et al, 2007(Lai et al, , 2009b(Lai et al, ,c, 2014a.…”

The epidemiology, characteristics and outbreaks of human leptospirosis and the association with animals in Taiwan, 2007–2014: A nationwide database study

“…When clinicians report cases of suspected diseases to the Taiwan CDC, they are required to send paired blood specimens (acute and convalescent phases) and relevant specimens for confirmatory or exclusive diagnosis by laboratory tests. In brief, LS was diagnosed either by a fourfold or greater increase in specific antibodies against leptospires using a microscopic agglutination test (MAT) or by isolation of leptospires from urine (Lai et al, ). QF, ST and MT were confirmed either by a serological fourfold or greater increase in specific antibodies against C. burnetii phase II antigens, O. tsutsugamushi and R. typhi , respectively, using an indirect immunofluorescence antibody assay (IFA) or by molecular methods of positive detection of the DNA of the causative pathogen in the blood using polymerase chain reaction (PCR).…”