| Spotted fever group Rickettsia (SFGR) ,the causative agent of spotted fever, is the most complex group among Rickettsia genus. Eight rickettsiae have been included in the "Bergey's Manual of Systematic Bacteriology (9th)" Five rickettsiae were found to cause human spotted fever. SFG Rickettsia widely distributed throughout the world. Ticks or mites serve as the vector and reservoir hosts. In recent years, as the increasing activity in life, economic and tourism, the incident of spotted fever is risen, new agents are found and the distribution of the disease is changing. 10 more pathogenic or nonpathogenic SFG rickettsial species were isolated one after another all over the world, including Heilongjiang rickettsia and inner Mongolia rickettsia isolated from China. They were recognized as new species of SFGR. In China, since the first SFGR strain (HL-84) was isolated from oriental field mouse in Heilongjiang in 1962, several SFGR strains were isolated from ticks, rodents and patients with spotted fever in different areas. These cases were all observed in the northern part of China. Spotted fever had been thought to be prevalent only in the northern but not southern part of China. In 1986,the causative agent of a newly recognized illness was isolated and then identified as a new species of the SFG, R.japonica by Uchida in shikoku, Japan. The existence of R.japonica or other SFG rickettsial infection was suspected in Hainan Island because the climate is similar with Shikoku. In order to investigate the infection of Rickettsia,4especial for SFGR, and find out the new Rickettsia in Hainan Island of China, serosurvey and etiologic investigation of Rickettsiosis were performed in Hainan Island in 1990 and 1993,respecterly. We obtained 642 Serum specimens from outpatients without rickettsiosis and 37 serum specimens from suspected rickettsiosis or fever unknown organism patients at hospital located at southern-east, center-southern and northern of the Island. IgG and 1gM antibodies to R.japonica and R.typhi were determined by micro-immunofluorescence (mIFA). Among these specimens, only two contained antibodies react with R.japonica at a high dilution(≥1: 160). Suggesting that R.japonica is rare in Hainan Island. On the other hand,of the positive specimens with IgG antibodies to R.typhi from the southern-east and center-southern area, there are 40% specimens contained 1gM antibodies (dilution ≥1: 160). Among 37 serum specimens suspected cases of rickettsiosis, almost half specimens contained 1gM and IgG antibodies to R.Typhi(dilution ≥1: 160). It indicated that there is a high incidence of murine typhus in southern Hainan Island. There will be some missing cases of typhus rickettsiosis in clinic.Another Serosurvey for antibodies to SFG Rickettsia, R. prowazeki, R.tsutsugamushi by mIFA were performed in 1993. Serum specimens were collected from 561 outpatients without rickettsiosis at hospital in the east, southern, west, nor- thern and center of hainan Island. The result was that 30.83%(1641532) sera were reacted with SFG Rickettsia, 18.77%(101/538) were reacted with R.prowazeki and 13.55%(761561) were reacted with R.tsutsugamushi. It proved that there are spotted fever, Typhus and tsutsugamushi disease in Hainan Island. They spread widely in Hainan Island, especial at mountain and hilly areas (Dafeng farm of Qiongzhong country, Danzhou city, Tongza city, Baoting country and other areas around Wuzhi Mountain). The areas near seaside (Haikou city, Sanya city) is lesser. This serosurvey result showed that There are SFG rickettsiosis in Hainan Island. It was first report that the SFG rickettsiosis is existence were found in5Hainan Island, the southen part of China. It contradict the conclusion that there are no SFGR in southern part of China. Like the other Rickettsia, spotted fever group rickettsia are obligate intracellular microorganism. In general, SFGR were isolated and cultured using animal(guinea pigs) and embryonated hen's eggs. Accoding to the methods abroad, we isolated ricke... |
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