Characteristics of pediatric scrub typhus in a new endemic region of northern China.

BACKGROUND: Scrub typhus emerged in northern China in 1986. Our objective was to document epidemiologic, clinical and laboratory features of pediatric scrub typhus in this new endemic area. METHODS: The pediatric patients diagnosed with scrub typhus during the 12-year period from 1995 through 2006 in Feixian County, Shandong province were enrolled in the study. The cases were diagnosed based on either specific antibody detection using the indirect immunofluorescent assay or detection of partial Orientia tsutsugamushi gene by polymerase chain reaction. RESULTS: Seventy pediatric scrub typhus cases were included in the study. The cases occurred from September through November. The common clinical manifestations included headache (100%), skin rash (91%), eschar (84%), lymphadenopathy (61%), and gastrointestinal signs (56%). None of the patients had neurologic involvement or thrombocytopenia. All children responded well to treatment with chloramphenicol. The patients who presented with abnormal chest radiography took significantly longer time to defervescence (Z[r] = 2.528, P = 0.011). Three strains of O. tsutsugamushi were isolated and all were identified as Kawasaki type. CONCLUSIONS: The manifestations of pediatric scrub typhus cases in the novel endemic region of northern China may be less severe than in other regions. Careful examination of skin eschars is helpful for the clinical diagnosis.

Clinical characteristics of the autumn-winter type scrub typhus cases in south of Shandong province, northern China.

BACKGROUND: Before 1986, scrub typhus was only found endemic in southern China. Because human infections typically occur in the summer, it is called "summer type". During the autumn-winter period of 1986, a new type of scrub typhus was identified in Shandong and northern Jiangsu province of northern China. This newly recognized scrub typhus was subsequently reported in many areas of northern China and was then called "autumn-winter type". However, clinical characteristics of associated cases have not been reported. METHODS: From 1995 to 2006, all suspected scrub typhus cases in five township hospitals of Feixian county, Shandong province were enrolled. Indirect immunofluorescent assay (IFA) was used as confirmatory serodiagnosis test. Polymerase chain reaction (PCR) connected with restriction fragment length polymorphism (RFLP) and sequence analyses were used for genotyping of O. tsutsugamushi DNAs. Clinical symptoms and demography of confirmed cases were analyzed. RESULTS: A total of 480 scrub typhus cases were confirmed. The cases occurred every year exclusively between September and December with a peak occurrence in October. The case numbers were relatively higher in 1995, 1996, 1997, and 2000 than in other years. 57.9% of cases were in the group aged 21-50. More cases occurred in male (56%) than in female (44%). The predominant occupational group of the cases was farmers (85.0%). Farm work was reported the primary exposure to infection in 67.7% of cases. Fever, rash, and eschar were observed in 100.0%, 90.4%, and 88.5% of cases, respectively. Eschars formed frequently on or around umbilicus, abdomen areas, and front and back of waist (34.1%) in both genders. Normal results were observed in 88.7% (WBC counts), 84.5% (PLT counts), and 89.7% (RBC counts) of cases, respectively. Observations from the five hospitals were compared and no significant differences were found. CONCLUSION: The autumn-winter type scrub typhus in northern China occurred exclusively from September to December with a peak occurrence in October, which was different from the summer type in southern China. In comparison with the summer type, complications associated with autumn-winter type scrub typhus were less severe, and abnormalities of routine hematological parameters were less obvious.

[Clinical manifestations and epidemic factors of autumn-winter type scrub typhus in children from northern new endemic area].

OBJECTIVE: Scrub typhus is an infectious disease due to Orientia tsutsugamushi transmitted by infected chigger mites. Scrub typhus has long been recognized to occur in southern areas of China, but has recently been increasingly often reported from the north since the first case was reported in Mengyin County, Shandong Province in 1986. The key objectives of the present study were to investigate the clinical manifestations and epidemic factors of scrub typhus in children from the northern new natural foci. METHODS: The case records of 56 children with scrub typhus who were admitted to the 5 hospitals of Fei County from September 1993 to January 2004 were reviewed. Orientia tsutsugamushi (Ot) was isolated from the cases. Based on ecological observations on the composition, seasonal fluctuation of animal hosts and chigger mites, Ot was isolated from rodents and chiggers. IgG antibodies to Ot was detected by IFA. Genotypes of the Ot isolates were also identified by nested PCR. RESULTS: Among 56 children scrub typhus cases, 46 were male, 10 were female; 96% exhibited typical eschars or ulcers, 100% cases had high fever, skin rashes were observed in 55 cases (98%), and regional lymphadenopathy occurred in 48 cases (86%). All cases came from countryside, and all had histories of exposure to the crop field. fifty-one serum samples of suspected patients with scrub typhus were collected, 48 were positive for antibodies to Ot. The serotypes were Gilliam types. The cases only appeared in September to December with the peak at mid and late October. Leptotrombidium (L.) scutellare was the most important vector causing scrub typhus in the foci. Apodemus (A.) agrarius was the main host animals of Ot in the crop field. Totally 26 strains were isolated from patients, rodents, and chigger mites. The serotypes of 24 out of the 26 isolates were Gilliam types, while the genotypes of these isolates were Kawasaki types. The serotypes of the other 2 isolates were identical and both were Karp types. CONCLUSION: Children scrub typhus patients were frequently seen in the new natural foci of Shandong province. Exposure history, typical eschars or ulcers, and presence of IgG antibody were the important indexes to diagnose the disease.

Key differentiating features between scrub typhus and hemorrhagic fever with renal syndrome in northern China.

Both scrub typhus and hemorrhagic fever with renal syndrome (HFRS) are severely epidemic in northern China and often present with acute undifferentiated fever. To correctly distinguish the two diseases at an early stage, we collected and compared clinical and routine laboratory data of 46 patients with confirmed scrub typhus and 49 patients with confirmed HFRS presenting to the outpatient departments of three town hospitals in northern China. Most patients with HFRS but none of the patients with scrub typhus had hemorrhagic manifestations. Retro-orbital pain, lumbar back pain, flank tenderness, proteinuria, and occult blood in urine often occurred in patients with HFRS. However, skin eschar, regional lymphadenopathy, and maculopapular rash were more commonly found in patients with scrub typhus. In addition, platelet counts in patients with HFRS were significantly lower than in patients with scrub typhus. These findings will be useful for physicians to distinguish scrub typhus from HFRS.