[Study on the dynamic prevalence of serum antibody against severe acute respiratory syndrome coronavirus in employees from wild animal market in Guangzhou].

OBJECTIVE: To investigate the dynamic trend of specific antibody against severe acute respiratory syndrome (SARS)-CoV in serum collected at various periods among employees in Guangzhou Xinyuan animal market. METHODS: Volunteers from employees of the animal market were recruited and their serum specific antibody against SARS-CoV were determined by enzyme linked immunesorbent assay (ELISA) method. RESULTS: Positive SARS-CoV specific IgG antibody was found 25.61% (n = 328), 13.03% (n = 238), 12.59% (n = 135), 5.04% (n = 139) and 9.43% (n = 53) among volunteers, which were sampled in May 2003, Dec. 2003, Jan. 2004, July 2004 and June 2005 respectively. No specific IgM antibody was found in all of those samples. Among 129 samples which were tested twice or more, 97 were all negative, 18 all positive, 13 changed from positive to negative but only one sample from negative to positive. When the volunteers were divided by the duration of their working experiences as short-term or long-term, those who had worked at animal market for less than or more then 6 months when being tested, the positive rate for long-term employees were relatively constant, however, all of the persons employed after January 2004, when the palm civets and raccoon dogs were culled from the market, were tested negative. CONCLUSION: The prevalence of specific antibody against SARS-CoV in employees of the animal market were somehow related with the presence or absence of palm civet. No serum was tested positive for persons who were employed after palm civets and raccoon dogs were culled from market. This data indicated that the SARS-CoV might have been from the palm civets and raccoon dog, and the animal market seemed to serve as one of the sources of infection.

Molecular evolution analysis and geographic investigation of severe acute respiratory syndrome coronavirus-like virus in palm civets at an animal market and on farms.

Massive numbers of palm civets were culled to remove sources for the reemergence of severe acute respiratory syndrome (SARS) in Guangdong Province, China, in January 2004, following SARS coronavirus detection in market animals. The virus was identified in all 91 palm civets and 15 raccoon dogs of animal market origin sampled prior to culling, but not in 1,107 palm civets later sampled at 25 farms, spread over 12 provinces, which were claimed to be the source of traded animals. Twenty-seven novel signature variation residues (SNVs) were identified on the spike gene and were analyzed for their phylogenetic relationships, based on 17 sequences obtained from animals in our study and from other published studies. Analysis indicated that the virus in palm civets at the live-animal market had evolved to infect humans. The evolutionary starting point was a prototype group consisting of three viral sequences of animal origin. Initially, seven SNV sites caused six amino acid changes, at positions 147, 228, 240, 479, 821, and 1080 of the spike protein, to generate low-pathogenicity viruses. One of these was linked to the first SARS patient in the 2003-2004 period. A further 14 SNVs caused 11 amino acid residue changes, at positions 360, 462, 472, 480, 487, 609, 613, 665, 743, 765, and 1163. The resulting high-pathogenicity groups were responsible for infections during the so-called early-phase epidemic of 2003. Finally, the remaining six SNVs caused four amino acid changes, at positions 227, 244, 344, and 778, which resulted in the group of viruses responsible for the global epidemic.

[Analysis on the risk factors of severe acute respiratory syndromes coronavirus infection in workers from animal markets].

OBJECTIVE: To investigate the possible risk factors of severe acute respiratory syndromes coronavirus (SARS-CoV) infection in workers from animal markets. METHODS: Self-designed questionnaires were used and serum samples were tested. Logistic regression analysis was used to analyze the data. RESULTS: Results from simple factor logistic regression analysis showed that jobs which dealing with domestic livestock, wild livestock, wild animals, aquatics were related to risk factors of SARS-CoV infection. Results from multifactor logistic regression analysis showed that jobs that dealing with wild livestock and poultry were important risk factors with OR 12.28 and 0.41. CONCLUSION: Job that dealing with palm civets was the main risk factor of SARS-CoV infection in animal market workers.

[An epidemiologic investigation on infection with severe acute respiratory syndrome coronavirus in wild animals traders in Guangzhou].

OBJECTIVE: To investigate status of infection with severe acute respiratory syndrome coronovirus (SARS-CoV) in traders of wild animals wholesale markets in Guangzhou. METHODS: Serum antibody against SARS-CoV IgG was determined cross-sectionally and symptoms of respiratory infection were investigated retrospectively for part of traders of three wholesale markets for wild animals in Guangzhou. RESULTS: Overall rate of infection with SARS-CoV in 635 traders was 16.69%, varying in three different markets. Infection rate in market A mainly engaging in wild animals ranked the highest of 25.61%, significantly higher than that in markets B and C engaging in domestic fowls and snakes. Infection rate in traders only engaging in civet cats was 58.54%, significantly higher than that in traders engaging in snakes only (9.46%). In market A, infection rate varied in different persons, 59.34%, 20.59%, 16.00%, 15.22%, 10.40% and 9.68% in traders engaging in wild animals, managers, children of the traders, traders engaging in domestic fowls, traders engaging in snakes, and traders engaging in frozen food, respectively, in a decreasing pattern as their contact opportunities. During the period of SARS epidemic, detection rate of SARS-CoV antibody in people with symptoms of acute respiratory infection was higher (30.70%) than that in those without such symptoms (20.08%). Prevalence of symptoms of acute upper respiratory infection in people with positive antibody against SARS-CoV was higher (49.28%) than that in those with negative antibody (30.35%). CONCLUSIONS: Infection with SARS-CoV in traders of animal markets possibly related to their direct exposure to wild animals, particularly to civet cats. During the period of SARS epidemic, some of the traders did infect with SARS-CoV, but they were neglected due to clinically inapparent manifestations.

[Analysis on the characteristics of blood serum Ab-IgG detective result of severe acute respiratory syndrome patients in Guangzhou, China].

OBJECTIVE: To probe blood serum Ab-IgG characteristics of severe acute respiratory syndrome (SARS) patients in Guangzhou and investigate the related factors. METHODS: The serum of such population diagnosed as SARS convalescent patients, non-SARS patients, family consanguineous contraction persons, wild animal and vegetable salesman and community common people was collected. The lab detective method of ELISA was adopted for these serum samples. And the epidemic investigations for the SARS patients were also carried out. RESULTS: Of these populations, the detective rate of Ab-IgG for the clinic diagnosed SARS patients, which was 53.7%; That for the wild animal salesman and community common people were 16.7% and 0.9%, respectively. Among the clinic diagnosed SARS patients, the positive antibody detective rate was 90.4% for those which had specific contact history or infectivity, which was higher than that for other population. Among the specific contact history or infectivity cases, the antibody positive rate for the young and the old was lower than that for the adult. Meanwhile the difference did not exist among other cases. The antibody positive rate was identical between the male and the female. And the antibody detective rate was decreased by the month. CONCLUSION: As a whole SARS-CoV Ab-IgG detective rate for the clinic diagnosed SARS patients was 53.7% only. The reasons for that mainly lie in the wrong clinic diagnosis besides these factors such as age, hormone use and reagent and so on. The combination of lab detection results and epidemic investigation was propitious to the diagnosis veracity. It was impossible for the sub-clinic infection of SARS-CoV virus. The importance in the virus transmitting course need to be further studied.