猪链球菌2型福建分离株的主要毒力基因分析

目的为了解福建地区猪链球菌2型菌株毒力因子分布情况。方法选取谷氨酸脱氢酶(gdh)、荚膜多糖(cps)、溶菌酶释放蛋白(mrp)、胞外因子(ef)、溶血素(sly)、纤连蛋白/血纤蛋白原结合蛋白(fbps)及毒力相关序列orf2等7个猪链球菌2型主要毒力基因,分别设计了7对引物,采用PCR方法,对本室分离保存的猪链球菌2型福建分离株的毒力基因进行分析。结果从屠宰生猪体内分离的4个猪链球菌2型菌株和SS2PFJ07株基因型为gdh+/cps2J+/mrp+/ef-/sly-/fb-ps+/orf2+,另1株从生猪体内分离的分离菌株基因型为gdh+/cps2J+/mrp+/ef+/sly+/fbps+/orf2+。结论福建地区生猪中猪链球菌2型至少有两种毒力基因型。     

从正常屠宰猪扁桃体中分离到致病性猪链球菌2型

目的从江苏省某屠宰场采集的40份屠宰猪的扁桃体中分离到一株细菌,通过玻片凝集试验、培养特性、菌体形态、菌落形态、染色特性、生化试验、PCR检测试验,确定为猪链球菌2型,编码为HA0610。进一步研究发现,该菌株含有已知的8种主要毒力因子基因,动物试验显示对猪和兔均有较强的致病性。结果表明,在正常猪扁桃体中可携带对猪有高度致病性的猪链球菌2型。     

Enterobius vermicularis infection among pre-school children in Karen hilltribe villages in Chiang Mai,Thailand

We surveyed Karen hilltribe villages in the Mae Chaem District of Chiang Mai Province between April and May 2001. Two hundred and forty-nine pre-school children were selected by stratified sampling from 10 villages and were examined for Enterobius vermicularis eggs by the Scotch tape perianal examination technique. One hundred and thirteen (53 boys and 60 girls) were found to have E. vermicularis eggs, giving an overall infection rate of 45.38%. We were able to determine that E. vermicularis infection is prevalent among the children of these hilltribe villages.     

Genotype distribution of genital Chlamydia trachomatis in Chiang Mai,Thailand

Urogenital isolates (N=84) of Chlamydia trachomatis collected from high-risk STD subjects in Chiang Mai and the surrounding areas were investigated for genotype distribution. C. trachomatis genotypes were determined by the PCR-based RFLP technique and confirmed by nucleotide sequencing. By this method, the VD4 DNA of the MOMP gene was amplified and digested separately with 4 restriction endonucleases, AluI, HindIII, DdeI, and EcoRII. The nucleotide sequence was determined by dye terminator cycle sequencing. Eight different C. trachomatis genotypes were identified: genotype D (34.5%), F (21.4%), K (13.1%), H/Ia (8.3%), E (7.1%), B/Ba (7.1%), G (6.0%), and J (2.4%). Genotype D and F were the commonest, accounting for 56% of the C. trachomatis infections. When nucleotides of the VD4-MOMP gene were anlyzed, 43 samples (51.2%) had nucleotide sequences that differed from the prototypes, while 41 (48.8%) were identical. Nucleotide substitution mutation was the major mechanism in these variants; changes in nucleotide sequences usually resulted in amino acid substitution, which could lead to a modification of antigenic determinants and the consequent evasion of immune responses.     

Serotyping and evaluation of the virulence in mice of Streptococcus suis strains isolated from diseased pigs

A total of 110 strains of Streptococcus suis, isolated from diseased pigs in Brazil were serotyped and analyzed for virulence. Serotyping of the strains resulted in the following classification: 42 strains of serotype 2 (38.2%), 10 strains of serotype 14 (9.1%), seven strains of serotype 9 (6.4%), three strains each of serotype 7 and 11 (2.7%), two strains each of serotype 1 and 8 (1.8%) and one strain each of serotypes 1/2, 3, 5, 6 and 10 (0.9%). Cross reactions among serotypes 1, 14 and 7 were observed in 21 strains (19.1%). Only 41.9% of the strains were lethal for mice using the pathogenicity test.     

Evaluation of a hepatitis B vaccination program in Chiang Mai, Thailand

Chiang Mai is a province in northern Thailand that started a vaccination program for hepatitis B virus (HBV) infection in 1989. In this paper, we report the long-term efficacy of this program. Of children aged 4-9 years, 65.7% had a complete course and 3.8% had an incomplete vaccination course. Urban schoolchildren had higher percentage of HB vaccination than rural schoolchildren (89.1% vs 46.9% for the complete course, p < 0.001). The overall prevalence rate of HBsAg in Chiang Mai schoolchildren was 1.2%, with no significant differences between gender (p = 0.496) and school areas (p = 0.477). Anti-HBc antibodies were detected in 6.9% of children. Overall, 26.2% of children had protective levels of anti-HBs antibodies (> 10.0 mlU/ml), and 11.2% had low levels of these antibodies (1.0-9.9 mlU/ml). Compared to previous reports, our results show a lower percentage of anti-HBs antibodies, 33.8% of children age 4 years had protective anti-HBs antibodies, dropping to 18.4% by age 9 years. Among those anti-HBs seropositive, 9.1% were anti-HBc positive, indicating a natural infection with HBV. We found a small number of children, despite adequate immunization, developed HBV infection.     

Molecular epidemiology of Rhodococcus equi of intermediate virulence isolated from patients with and without acquired immune deficiency syndrome in Chiang Mai, Thailand

We investigated the prevalence of virulent Rhodococcus equi in clinical isolates from 69 sporadic cases (60 men, 8 women, and 1 patient of unknown sex) in Chiang Mai, Thailand, between 1993 and 2001. Fifty were human immunodeficiency virus (HIV) positive, 3 were HIV negative, and HIV status was unknown for 16. Fifty-two (75%) of 69 isolates were strains of intermediate virulence that contained the virulence-associated 20-kDa antigen, and 17 isolates (25%) were avirulent. No virulent strains with the virulence-associated 15-17-kDa antigens were identified. R. equi was isolated from HIV-positive patients' houses and those of their neighbors: avirulent strains were widespread, but only 1 strain of intermediate virulence was isolated. R. equi strains of intermediate virulence were isolated from 4 (0.8%) of 500 submaxillary lymph nodes from apparently healthy pigs in Chiang Mai. The routes of R. equi acquisition should be investigated from the viewpoint of zoonosis and public health.     

Campylobacter jejuni in hospitalized children with diarrhoea in Chiang Mai, Thailand

In this hospital based study, Campylobacter jejuni, although endemic in Northern Thailand was not found in a significantly higher percentage of diarrhoea than in control children. It was isolated from the stools of 14 of 208 diarrhoea (6.7%) and 6 of 108 (5.5%) control patients. Ten of the 14 positive diarrhoea cases were mixed infections, other pathogens isolated simultaneously were enteropathogenic E. coli 4x, Shigella spp. 3x, Salmonella spp. 4x, rotavirus 3x, Plesiomonas shigelloides 1x and parasites 3x. Infection with Campylobacter jejuni occurred mainly in the 1-2 year age group and was not found in patients over 5. It was distributed over the year without seasonal peaks. In four of the 14 positive C. jejuni cases no other pathogens were found. One of these suffered 2nd degree malnutrition with measles and one was a chronic diarrhoea case with a history of antibiotic use and past Salmonella and Shigella infections. The remaining two cases had no underlying or associated illnesses. It was concluded that Campylobacter jejuni may be important as an associated pathogen in complicated diarrhoea infections but is rare as a sole causative agent.     

Biochemical and hematological manifestations of HIV/AIDS in Chiang Mai, Thailand

HIV/AIDS is a multifactorial and multi-step disease. No single treatment against AIDS can save a patient. Our last report showed that vitamin A, vitamin E and beta-carotene were decreased while malondialdehyde (MDA) was increased. This report aims to evaluate biochemical and hematological parameters in HIV/AIDS patients in Chiang Mai, Thailand by holistic approaches. Sera from HIV/AIDS patients were examined for sugar, cholesterol, uric acid, total protein, albumin, urea, creatinine, AST, ALT, ALP, total/direct bilirubin, vitamin E, MDA, total antioxidant capacity (TAC), beta-carotene, complete blood cell counts, platelet count, CD4 count, prothrombin time, partial prothrombin time and soluble Fas (sFas). The results found that sFas levels in sera prior to holistic approach was not different from reference values and not significantly correlate with CD4 and absolute lymphocyte count. sFas could not serve as putative marker for CD4 destruction. After 3 months CD4 count, MDA, vitamin E and TAC did not change statistically. This approach had no effect on liver and kidney functions, red blood cell, white blood cell, platelet counts, and blood clotting factors. This presentation may be some alternative approaches to combat HIV infections and AIDS, leading to stabilize or extend survival time which should further be elucidated.     

Genotypes of hepatitis B virus among children in Chiang Mai, Thailand

In sub-Saharan Africa, the Pacific, and particularly Asia, hepatitis B virus (HBV) infection is highly endemic, the most common route of transmission is perinatal. To minimize the number of horizontal transmissions, we determined the prevalence of HBV genotypes among children in northern Thailand. From a survey of 1,231 schoolchildren in Chiang Mai during 1998 to 2000, 55 (4.5%) were found positive for HBsAg. Fifty-three HBsAg-positive samples were available for this study. These came from 28 girls (52.8%) and 25 boys (47.2%), age 5-16 years, with a mean age of 12.8 (+/-2.6) years. The laboratory method was based on a multiplex-PCR for the detection of 6 HBV genotypes (A-F). Among 53 HBsAg positive cases, 48 (90.6%) were genotype C, followed by 4 cases of genotype B (7.5%), and 1 case (1.9%) with mixed infection with genotypes B and C. The high prevalence of HBV genotype C follow by genotype B is similar to that found among blood donors in northern Thailand and the nationwide epidemiological survey conducted in 2004. Perinatal transmission may play an important role in the spread of the virus in this area, as in other Asian countries, where genotypes C and B are highly prevalent.     

High prevalence of Haplorchis taichui metacercariae in cyprinoid fish from Chiang Mai Province, Thailand

This study aimed to investigate Haplorchis taichui metacercarial infection in fish collected from the Chom Thong and Mae Taeng districts, Chiang Mai Province during November 2001 to October 2002. A total 617 cyprinoid fish of 15 species were randomly collected and examined for H. taichui metacercariae. All the species of fish were found to be infected with H. taichui. The infection rates were 91.4% (266/290) and 83.8% (274/327), with mean intensities of 242.9 and 107.4 in the Chom Thong and Mae Taeng districts, respectively. The portion of the fish body with the highest metacercarial density was the muscles, and second, the head, in both districts. In addition, the fish had mixed-infection with other species of trematodes, namely: Centrocestus caninus, Haplorchoides sp, and Haplorchis pumilio.     

Seroprevalence of melioidosis in dairy cattle in Chiang Mai Province,northern Thailand

The seroprevalence of melioidosis in dairy cattle in Chiang Mai Province was investigated using of the indirect hemagglutination antibody (IHA) method. Two hundred and fifty-three samples were tested for serum antibodies to Burkholderia pseudomallei. The samples were from a total population of 8,688 dairy cattle in the province; random sampling, stratified by the location of cattle, was used. The seroprevalence was determined as 2% at 1:40 cut-off value, which was estimated to equate to 0.3% to 3.7% (95% CI). This report of relatively low disease prevalence in the animal population corresponds to other prevalence studies of the agent in the environment and the human population in the region. The prevalence is markedly different to that reported from northeastern Thailand, where the disease is highly endemic.     

The epidemiology of Dirofilaria immitis infection in outpatient dogs at Chiang Mai University Small Animal Hospital, Thailand

Five hundred eighty-nine dog blood samples from the small animal hospital of Chiang Mai University were examined for Dirofilaria immitis prevalence using a microhematocrit tube technique for microfilaria detection. In parallel, a once a month follow-up study on 36 D. immitis negative dogs was conducted to detect the time of acquiring infection in each animal. The diagnostic criteria for the incidence study was based on microfilaria detection or on positive findings against D. immitis antigen using the Witness commercial kit. The estimated prevalence was 18.2% (15-21%; 95% CI). There was no statistical difference between male and female infection rates. The age-specific prevalence of dogs under 2 years old was 6.4%, which was lower than the 2-4 year old group and all the other age groups at a 95% confidence level. In older dogs the prevalence reached 41.5%. Most of the dogs housed outdoors had a statistically higher infection rate than the dogs housed indoors (chi-square = 9.662, 1 df, p = 0.002). Only 109 dogs received chemoprophylaxis resulting in a significantly lower infection rate than in the non-heartworm prevention dogs (chi-square =14.424, 1 df, p = 0.000). The overall incidence density and the incidence during the rainy, cool and hot seasons were 5.2, 6.9, 3.5, and 2.7 animals per 100 animal-months, respectively. The incidence rate ratio between wet/dry, rainy/cool, rainy/summer, and cool/hot seasons were 2.18, 1.98, 2.59 and 1.30, respectively. The 95% confidence interval revealed no difference among seasons. In conclusion, dogs in D. immitis endemic northern Thailand contract infection in about 2 years.     

Parasitic and bacterial contamination in collards using effluent from treated domestic wastewater in Chiang Mai,Thailand

Thailand often has inadequate water supply for agriculture during the dry season. The reuse of treated wastewater treatment plants could solve this problem. Treatment of domestic wastewater of Chiang Mai municipality by the aerated lagoon system (AL) releases more than 25,000 m3 of treated water everyday. The reuse of wastewater in agriculture is an efficient use of water, especially in tropical countries or in drought zones. The objective of this study is to demonstrate the possibility of using treated wastewater in growing edible vegetables, ie collards (kale), without pathogenic parasite and bacterial contamination. Collards (Brassica oleracea var acephala) were grown using either the treated wastewater from the aerated lagoon system (AL) or ground water (GW). Three cropping times were scheduled in February, May and July, 2000. Samples of water from AL system and GW were taken two times per month (the consecutive weeks) from February to July and examined for bacteria and parasites. Irrigation water (IW) that was normally used in agriculture was also collected, at the same time of the AL and GW collection, for bacteria and parasite investigation. A soil sample was taken before and after each crop for parasite examination. Collards were also collected at the end of the crop for parasite investigation. The results showed that GW seems to be a clean water since no pathogenic bacteria were found although small amount of Escherichia coli was noted in May. For AL and IW, similar number and types of bacteria were found. They were Aeromonas sobria, A. hydrophila, E. coli, Citrobacter freundii, Pseudomonas aeruginosa, non-pathogenic type of Vibrio cholerae. The small number of Salmonella enteritidis gr E was found in AL in April. After investigating 12 samples in 6 months of each kind of water, ie GW, Al, and IW, no parasite was found. Only unidentified free living nematodes were found in IW but those parasites are non pathogenic. A small number of unidentified free living nematodes (UFLN), a natural parasite, were found in soil after cropping. After each cropping time, similar number of hookworm was found in the plots which used either GW or AL. Collards grown by using either GW or AL showed no harmful parasite contamination. We conclude that the effluent from wastewater treatment, using aerated lagoon system, of Chiang Mai municipality could be safely used for growing collards.     

Studies on the Japanese encephalitis vectors in Amphoe Muang, Chiang Mai, Northern Thailand

From February 1987 to January 1988, biological and ecological studies were made to obtain the basic knowledge of Japanese encephalitis vectors, Culex tritaeniorhynchus, Cx. gelidus, and Cx. fuscocephala, in Amphoe Muang, Chiang Mai, northern Thailand. The following results were found. Peaks in the population densities of the vectors as measured four times a month, by UV-light trap and human-baited trap collections, occurred during rainy season. The JE vectors in rural areas showed a sharp rise in the population in July when most of the rice fields were ploughed and a marked decline in mosquito population densities occurred after transplanting in August when the fields were flooded. The average number of larvae plus pupae per m2 in rice fields was highest in July when the fields were ploughed, but in the period from transplanting to harvesting (August to November), the densities were very low. Daily survival rates of the adult females, as estimated from parous rates, were mostly as high as 0.7 throughout the year.