[Study on spotted fever group Rickettsiae in Guangdong province].
OBJECTIVE
To explore the existence of spotted fever group Rickettsiae (SFGR) in Guangdong province.


METHODS
Sera were tested to find the SFGR in population and host animals. The target samples were screened by polymerase chain reaction (PCR), and Rickettsiae was isolated with embryonated hen eggs and identified by serological tests.


RESULTS
Eight hundred and sixty people in natural condition and 321 of mice were determined. The mean positive rate of healthy population was 3.84%. To compare results among elected places, Fisher's exact test was applied. The difference was suggestive (P < 0.01), and there was no significant difference between mountain and plain areas. There was also no significant difference between mountain and plain areas (P > 0.05). Positive rate of mice was 4.67%, with Rattus fulvescens, Rattus edwardsi, Bandicota indica 11.59%, 12.90%, 3.13% respectively. It was the first time that SFGR antibodies in Rattus fulvescens, Rattus edwardsi, Bandicota indica were reported. A total number of 321 mice spleens and 394 ticks from the surface of mice body were collected. Two strains of SFGR, GDFK58-2000 and GDFK59-2000, were isolated in the ticks from the body surface of 2 Rattus fulvescens. They were identified as Rickettsia sibirica by serological tests. Five hundred thirty-three bp OmpA gene fragments of the two strains were cloned and sequenced. Compared with other relevant strains in Genbank, the rates of homology of nucleotide sequences of GDFK58-2000 and GDFK59-2000 and other Rickettsia sibirica strains were from 99.6% to 100%, and the homology of amino acid speculated was 100%.


CONCLUSIONS
It has been proved that epidemic areas of north Asia tick-transmitted SFGR, did exist in Guangdong province confirmed by hostanimals, transmission vectors and aetiology.
He
Jian-feng
JF
Center for Disease Control and Prevention of Guandong Province, Guangzhou 510300, China.
Zheng
Kui
K
Li
Wei
W
Luo
Hui-ming
HM
Li
Ling-hui
LH
Bi
De-zeng
DZ
Zhang
Yuan-fu
YF
Chang
Bing-gong
BG
D000293:Adolescent; D000328:Adult; D000368:Aged; D000818:Animals; D002648:Child; D002681:China / Q000453:epidemiology; D004197:Disease Reservoirs; D005260:Female; D006801:Humans; D008297:Male; D051379:Mice; D008875:Middle Aged; D051381:Rats; D012284:Rickettsia rickettsii / Q000145:classification / Q000235:genetics / Q000302:isolation & purification*; D012373:Rocky Mountain Spotted Fever / Q000453:epidemiology* / Q000382:microbiology; D012377:Rodentia / Q000382:microbiology*; D017386:Sequence Homology, Amino Acid; D013987:Ticks / Q000382:microbiology