Serological prevalence of leptospiral infection in domestic animals in West Malaysia

A cross-sectional serological survey of domestic animals in West Malaysia revealed that 25.5% of the animals examined had agglutinating antibodies to one or more antigens belonging to Leptospira interrogans. Significant prevalence of infection was observed in cattle (40.5%), buffaloes (31%) and pigs (16%). The Sejroe serogroup was shown to be the principal one involved in cattle and buffaloes, and to a lesser extent the Tarassovi and Pomona serogroups. Evidence of infection in domestic animals by strains bearing the other seven antigens appeared insignificant and was indicative of sporadic infection. A majority of the large (semi-intensive) cattle and buffalo farms demonstrated a high prevalence of leptospiral infection. In both species of domestic animals mentioned above, the prevalence of infection was significantly higher (P = 0.01) in the semi-intensive farms than in the smallholdings. Amongst cattle, the droughtmasters had the highest prevalence whilst the Kedah-Kelantan (an indigenous breed) had the lowest prevalence of leptospiral infection. In general, the temperate breeds of cattle had a significantly (P = 0.01) higher prevalence of infection than local breeds. Leptospiral infection in goats and sheep was shown to be sporadic, and the Pomona serogroup was the principal leptospiral serogroup involved in these small ruminants. The prevalence of infection in pigs was observed to decline during the study period, and it is suspected that pigs in West Malaysia are the maintenance host for serovar pomona whilst cattle are the maintenance host for serovar hardjo. Overall, it appears that domestic animals in Malaysia will play a bigger role in the epidemiology of leptospiral infection with the advent of sophisticated farming.     

Serological prevalence to six leptospiral serovars in cattle in Asturias (Northern Spain)

The prevalence of antibody to six serovars of Leptospira interrogans in cattle in Asturias (Northern Spain) was determined by the microscopic agglutination test (MAT). Using 50% agglutination or lysis at a dilution of 1:10 or more as the criteria for seropositivity, 371 of 3578 (10.36%) animals were found to react with one serovar. The most commonly detected serovars were pomona (5.59%) and grippotyphosa (2.37%), whilst serovar hardjo (0.75%), icterohaemorrhagiae (0.64%), poi (0.64%) and autumnalis (0.36%) were found at lower frequencies.     

Serological titres to Leptospira fainei serovar hurstbridge in human sera in Australia.

A set of 723 diagnostic sera from human patients, submitted for the microscopic agglutination test (MAT) for antibodies to a group of 6 leptospiral serovars, was also tested by MAT for antibodies to the recently-discovered Leptospira fainei serovar hurstbridge. MAT titres of > or = 128 to serovar hurstbridge were detected in 13.4% of these sera, and titres of > or = 512 in 7.2%. In contrast, none of 62 sera obtained from a control population of laboratory staff gave titres of > or = 128. The difference between the number of titres of > or = 128 given by the two groups of sera was highly significant (P < 0.01). The titres observed may have been due to cross-reactions with other leptospiral serovars, but this could not be demonstrated. An alternative explanation is that serovar hurstbridge is present in the human population.     

Estimation of transmission hazard of Leptospira Sp. infections in 2 groups of people

The aim of the study was to determine the possible risk of the leptospiral transmission from animals to humans. 457 humans (both men and women) were divided into 2 groups: 1) of possible high risk infection consisted of people dealing as farm workers with cattle and pigs 2) of possible low risk infection consisted of people selected randomly. The animals on the farms were previously tested and found positive. All sera were examined using micro-agglutination test (MAT) with a battery of 18 serovars. The statistical evaluation of the results was performed using chi 2 test. The infection rate in I group was 13.79% and in II group was 1.5%. (p < or = 0.001). Sera of I group reacted with 7 serovars (sejroe, bratislava, canicola, tarassovi, bataviae, celledoni, patoc) and of II with 3 (hebdomadis, sejroe, hardjo). The infection rate in the group I was over 9 times higher than in group II. Thus dealing with infected animals is a high risk factor.     

Weil's disease, milker's fever and other leptospiroses, 1981-1987

In The Netherlands, human leptospirosis is mainly caused by the serovars icterohaemorrhagiae and copenhageni, both of which belong to the Icterohaemorrhagiae group and originate from rats, serovars hardjo from cattle and grippotyphosa from voles. In 1981-1987, 175 cases of leptospirosis were registered. In 17 of these cases the infection was acquired outside The Netherlands. Infections caused by serovars from the Icterohaemorrhagiae group were mainly observed in the province of Zuid-Holland, hardjo infections in the province of Friesland. The number of hardjo infections increased. Hardjo also causes problems in cattle. Infections caused by serovars icterohaemorrhagiae and copenhageni were mainly associated with exposure to inland surface waters in relation with recreational or professional activities or accidents. Hardjo infections were characteristically associated with dairy farming. The incidences of all types of leptospirosis were highest in late summer and early autumn.     

Serological studies on British leptospiral isolates of the Sejroe serogroup. I. The identification of British isolates of the Sejroe serogroup by the cross agglutinin absorption test

Using the cross agglutinin absorption test 12 British leptospiral isolates of the Sejroe serogroup were identified to serovar level. Six strains isolated from cattle, two from pigs and one from a human were identified as Leptospira interrogans serovar hardjo. Two isolates from wildlife were identified as Leptospira interrogans serovar saxkoebing. One further strain isolated from wildlife closely resembled serovar saxkoebing, but specific identification was not possible. These are the first reported isolations of serovar saxkoebing in the United Kingdom. The problems associated with the cross agglutinin absorption test, and possible alternative typing procedures are discussed.     

Serological studies on British leptospiral isolates of the Sejroe serogroup. I. The identification of British isolates of the Sejroe serogroup by the cross agglutinin absorption test.

Using the cross agglutinin absorption test 12 British leptospiral isolates of the Sejroe serogroup were identified to serovar level. Six strains isolated from cattle, two from pigs and one from a human were identified as Leptospira interrogans serovar hardjo. Two isolates from wildlife were identified as Leptospira interrogans serovar saxkoebing. One further strain isolated from wildlife closely resembled serovar saxkoebing, but specific identification was not possible. These are the first reported isolations of serovar saxkoebing in the United Kingdom. The problems associated with the cross agglutinin absorption test, and possible alternative typing procedures are discussed.     

Human leptospirosis in Somalia: a serological survey

Sera from Somalis of both sexes between the ages of 16 and 60 were examined for leptospiral agglutinins. 37% of 105 apparently healthy individuals living in the arid Mogadishu area were positive, as were 64% of 107 schistosomiasis patients living in two villages on the Shabeele River (50 · 5% over-all). Pools of sera from similar subjects, as well as leprosy patients living on the Juba River and patients in Mogadishu hospitals with suspected viral hepatitis showed a similar prevalence rate of 56%. These figures are higher than prevelance rates for leptospiral antibodies generally found in other parts of the world, and in part may be related to the nomadic, cattle-droving existence common in Somalia. The titres of 11 · 2% of the positive sera examined singly indicated recent infection. Approximately twice as many subjects from the river villages as from the Mogadishu area were positive for more than one serovar, and a greater number of serovars were recorded from the villages. Antibodies to bratislava serovar, not previously recorded in Africa, were found in 57% of positive subjects, showing the highest prevalence rate among the investigated serovars. Co-antibodies to saprophytic Leptospira biflexa serovars were found in many of the sera.     

江西省钩端螺旋体分离株脉冲场凝胶电泳分型和分析

目的 采用脉冲场凝胶电泳(PFGE)技术,对江西省钩端螺旋体(钩体)患者及动物宿主中分离的钩体菌株型别进行分子流行病学调查.方法 利用核酸内切酶Not Ⅰ对提取的钩体菌株染色体DNA进行酶切,通过PFGE将DNA片段分离.获得的PFGE图像采用分析软件BioNumerics 4.0进行处理并建立数字化数据库,以相似度＞75%为标准,将获各钩体PFGE图谱与中国15群15型钩体参考标准株进行比较并进行聚类分析.结果 江西省不同地区(的139株钩体可分为46个PFGE型,优势型为LepNot Ⅰ.0071、LepNotⅠ.0072和LepNotⅠ.0043型,分别占所有钩体菌株的28.06%、15.11%和7.19%.139株钩体分离株中,84.89%(118/139)菌株的PFGE图谱与6群6型中国钩体参考标准株基本相符,其中32.37%(45/139)钩体菌株属于黄疸出血群赖型,15.83%(22/139)和15.11%(21/139)钩体菌株分别属于澳洲群澳洲型和爪哇群爪哇型.结论 PFGE是一种快速、准确、高效的钩体分型方法 .黄疸出血群赖型是江西省人群及动物中优势血清型,澳洲群澳洲型和爪哇群爪哇型位于其次.     

Evaluation of 238 antigens of Leptospira borgpetersenii serovar Hardjo for protection against kidney colonisation

Leptospirosis is a zoonotic disease affecting animals and humans worldwide. Leptospiral infection in cattle can cause reproductive failure and reduced weight gain, and importantly, infection represents a significant disease risk for farmers. Current bacterin vaccines offer protection that is short-lived and restricted at best to related serovars. The development of protective vaccines that stimulate immunity across multiple leptospiral serovars would therefore be advantageous. This study used a reverse vaccinology approach to evaluate a set of Leptospira borgpetersenii proteins in the hamster infection model. The L. borgpetersenii serovar Hardjo strain L550 genome sequence was analysed and genes encoding 262 predicted outer membrane or secreted proteins were selected. From this list, 238 proteins or protein fragments were successfully expressed and purified; 28 proteins (12%) were soluble, while the remaining 210 proteins (88%) were insoluble and purified under denaturing conditions. Proteins were mixed into 48 pools of up to five each and tested for protection against infection as assessed by renal colonisation in the hamster model of infection. None of the pools of antigens protected the hamsters against infection, despite a detectable antibody response being mounted against the majority of proteins (71%). This study is the first large scale evaluation of individual leptospiral proteins for ability to induce a protective immune response in the hamster infection model. It thus constitutes an important reference of protein immunogenicity and non-protective antigens that should be consulted before embarking on any future subunit vaccine experiments.     

Ecological aspects of the epidemiology of infection with leptospires of the Ballum serogroup in the black rat (Rattus rattus) and the brown rat (Rattus norvegicus) in New Zealand.

Epidemiological aspects of infection with leptospires of the Ballum serogroup in black rats (Rattus rattus) and brown rats (Rattus norvegicus) are described. Rats inhabiting a variety of habitats were investigated and isolates identifed as belonging to the Ballum serogroup were obtained from 21 of 61 black rats (34%) and 63 of 243 brown rats (26%). The high level of endemic ballum serogroup infection in these species reported here has not been described in other countries. A statistical relationship was shown between the prevalence of infection in brown rat populations and population density but this was not evident for black rats. Epidemiological data indicates that the black rat is a maintenance host for leptospires of the Ballum serogroup in New Zealand. The brown rat does not appear to be an efficient maintenance host for these leptospires, however endemic infection can be maintained in high-density populations inhabiting synanthropic foci. An hypothesis of ''competitive exclusion'' (preferential maintenance of a particular serovar by a host species) is introduced with regard to leptospiral infection in brown rats. It is concluded that the establishment and maintenance of an endemic focus of leptospirosis is dependant on: introduction of a particular serovar; a suitable host; and a suitable host habitat. Within a maintenance population direct transmission appears to be more important than indirect transmission via the environment.     

Sero surveillance of leptospirosis among sewer workers in Pune

Leptospirosis is an important occupational disease affecting people coming in contact with animals and their discharges. The occurrence of infection in ones workplaces is linked to the environment to which the worker is exposed and the adaptability of the organism in that working environment. Rodents usually abound in underground sewers and are carriers of leptospira. The urine of rodents and other animals present in that area is likely to contaminate these sewers. Leptospira are excreted in the urine of infected animals. Thus sewer workers are at a potential risk of leptospirosis. The prevalence of leptospirosis in these workers could thus indirectly predict the presence of the disease in animals in a particular geographical niche. Total seventy-eight sewer workers from 5 different municipal wards in Pune were examined to find out the evidence of past infection with leptospira using microagglutination test (MAT). The prevalence rate was found to be 16.6%. The serovars to which antibodies were detected include autumnalis (38.4%), pyrogenes (23.0%), canicola (15.3%) and pomona (15.3%). Evidence of leptospiral infection was found to be maximum in sewer workers in the areas of the city that were infested with rodents and stray animals.     

Serologic investigation on the prevalence of Leptospira spp infection in occupationally exposed subjects

BACKGROUND: Leptospirosis is a worldwide zoonotic infection with a high in tropical regions. OBJECTIVE: The aim of the present survey was to verify the occurrence of diffusion of leptospirosis infections in Eastern Sicily, in some groups (6 veterinarians, 34 farmers and 28 abattoir workers), who were considered at high occupational risk. METHODS: Serologic investigation were performed using the immunological method (Martin Petit test); the Leptospira serovars considered were: ictero-haemorrhagiae (Bianchi 1); canicola (Alarik); pomona (Mezzano 1); grippo-typhosa (Moskva V); bratislava (Riccio 2); sejroe (Topino 1); hardjo (Hardjoprajitno); saxkoebing (Mus 24). RESULTS: Contagion was observed in 16 subjects out of 68 (23.5%), and the anti-leptospira antibodies detected were canicola, hardjo, sejroe grippo-typhosa e ictero-haemorrhagiae. CONCLUSIONS: The authors stress the importance carrying out periodic health surveillance in subjects working in wet and contaminated environments or who are continuously in contact with animals receptive to infections. The present study also confirms the need to adopt preventive measures such as vaccines, and control programs for activities at high risk.     

Epidemiology of leptospirosis in a livestock production area of the Andes]

A cross-sectional study was conducted to estimate the prevalence of Leptospira infection in populations of workers, cattle, and pigs in livestock operations and to explore some environmental and production system variables associated with seropositivity. The research was done between November 1997 and February 1998 in the municipality of Don Matías, in the northern part of the department of Antioquia, Colombia. The area has a cold climate, and there is a "pigs-grasses-milk" production system that utilizes pig dung to fertilize grazing pastures. A total of 23 farms were studied, and blood samples were obtained from 67 dairy and pig-raising workers, 174 dairy cows, 68 pigs for fattening, and 214 pigs for breeding. The microagglutination test (MAT) was used for six Leptospira serotypes. The seropositivity prevalence was 22.4% among the workers (95% confidence interval: 13.1% to 34.2%), 60.9% among the dairy cows (95% CI: 53.2% to 68.2%), 10.3% in the fattening pigs, and 25.7% in the breeding pigs. Four logistic regression models were constructed to identify the variables that predicted infection in the workers and in the dairy cows. A high prevalence of infection with Leptospira (serotypes pomona, bratislava, and hardjo) was found in this production system, where conditions are favorable for transmitting this microorganism to the different animal species and to humans.     

Immunogenicity of boiled compared with formalized leptospiral vaccines in rabbits, hamsters and humans.

Leptospires (Leptospira interrogans serovar pomona) grown in chemically defined medium were immunogenic when given intradermally in humans if the leptospires were killed with formalin but not if they were boiled. Boiled leptospires were immunogenic for rabbits and hamsters and protected hamsters from challenge infection. On the other hand, boiled leptospires of the biflexa complex, serovar patoc, did retain some immunogenicity in humans, but the antisera did not protect hamsters against challenge with serovar pomona.     

Leptospirosis serodiagnosis by ELISA based on recombinant outer membrane protein

The outer membrane protein LipL21, LipL32, LipL41 and Loa22 of Leptospira interrogans serovar Copenhageni were previously revealed by immunoproteomic analysis, using sera from acute phase infection in a guinea pig. The full-length DNA of each protein was then cloned from the same serovar and expressed in pRSET vector. The obtained molecular weight (MW) of recombinant proteins rLipL21, rLipL32 and rLoa22 were slightly higher than the MW predicted from nucleotide sequences of each inserted gene, while only the N-terminal half of rLipL41 was obtained. Mice antiserum raised against each purified recombinant protein could react with the whole cell lysate of leptospiral serovars, implying that leptospiral native proteins shared a common epitope with recombinant protein. Serodiagnosis using recombinant protein antigen based on indirect ELISA procedure was developed in this study. The optimization of the ELISA components lead to determination of optical density (OD) from a single serum-dilution of 1:1000 in the leptospirosis patients group and normal healthy control group. The cut off OD values for both IgG and IgM class were investigated, and based on this fixed dilution only the IgG class could be used for differential diagnosis of patients and normal individuals. Compared with the MAT assay, ELISA assay utilizing both rLipL32 and rLoa22 as antigen, gave high accuracy and could thus be useful as a confirmative serology test.     

钩端螺旋体毒力相关基因的分布特点分析

目的 探讨钩端螺旋体(钩体)毒力相关基因的分布特点。方法 根据钩体赖型赖株全基因组序列的生物信息学分析资料，选择了12个可能与钩体毒力相关的基因，采用聚合酶链反应(PCR)方法，对中国问号钩体38株参考菌株和81株分离的野生菌株，以及12株非致病性的双曲钩体共131株菌株进行了检测。结果 问号钩体中各毒力相关基因分布广泛，双曲钩体中仅检测到个别毒力相关基因。lipL32基因存在于所有检测的问号钩体，lipL36基因在问号钩体不同菌株中的变异较大，阳性检测率为0％～90．91％；lal608基因在问号钩体黄疸出血群菌株中阳性检测率为87．50％，而在其他血清群菌株间阳性检测率为0％～25．00％，sphA基因仅在问号钩体少数菌株中能检测到，阳性检测率为17．65％，且在中国赛罗群哈焦型参考菌株中未检测到。结论 这些基因可能是问号钩体重要的毒力相关基因。其中lipL32可能是问号钩体各血清群菌株共同抗原的编码基因；lipL36基因可能和问号钩体血清群特异性和多样性有关；lal608基因可能是黄疸出血群菌株特有的基因；哈焦型菌株与问号钩体菌株在基因结构具有较大的差异。     

Recombinant LipL32 and LigA from Leptospira are unable to stimulate protective immunity against leptospirosis in the hamster model

The major antigenic component of pathogenic Leptospira spp. is lipopolysaccharide (LPS). However, due to the specificity of the immune response generated towards LPS and the diversity in leptospiral LPS carbohydrate structure, current commercial vaccines stimulate protection only against homologous or closely related serovars. Vaccines that confer heterologous protection would enhance protection in vaccinated animals and reduce transmission to humans. Several studies have investigated the potential of various leptospiral outer membrane proteins to stimulate protective immunity against pathogenic Leptospira species. These include the surface-exposed lipoproteins LipL32 and LigA. However, consistent protection from infection has proved difficult to reproduce. In this study we assessed the protective capacity of recombinant LipL32, the six carboxy-terminal unique Ig-like repeat domains of LigA (LigANI) and a LipL32-LigANI fusion protein in hamsters against infection with Leptospira interrogans serovar Manilae. Despite all of the proteins eliciting antibody responses, none of the hamsters was protected against infection.     

Seroprevalence of leptospirosis in a rural flood prone district of Bangladesh.

Leptospirosis is a worldwide zoonotic disease. In the present investigation, a total of 89 human sera from a flood prone district of Bangladesh was screened by a one-point microscapsule agglutination test (MCAT). MCAT-positive and -doubtful sera were further tested by microscopic agglutination test (MAT) against 16 reference serovars of Leptospira interrogans, and the antibody titres determined. In MCAT, 34 sera were positive and 22 were doubtful. Among those positive and doubtful sera, 33 and 20, respectively were tested by MAT. Thirty-four out of 53 MCAT-screened samples were MAT-positive. The titres ranged from 20 to 1600 with antibodies to serovars copenhageni, australis, cynopteri and icterohaemorrhagiae being the most prevalent. Eleven MCAT-positive samples failed to react with any strains used by MAT, suggesting the presence of new or untested serovars. Among the MAT-positive samples, the presence of antibody against two or more serovars was more common than that of a single serovar. The present study suggests that rural people in Bangladesh are at high risk to leptospiral infection.