Oral Health in the Population Assessment of Tobacco and Health Study.

Tobacco use is a well-established risk factor for multiple adverse oral conditions. Few nationally representative oral health data sets encompass the current diversity of tobacco and nicotine products. This investigation examines the validity of oral health measures in the Population Assessment of Tobacco and Health (PATH) Study to assess relationships between tobacco use and oral health. Cross-sectional data from PATH Study wave 4 (N = 33,643 US adults, collected 2016-2018) were used to obtain estimates for 6 self-reported oral conditions (e.g., bone loss around teeth, tooth extractions) and compared with analogous estimates from the National Health and Nutrition Examination Survey (NHANES) cycle 2017-2018 (N = 5,856). Within the PATH Study, associations were calculated between tobacco use status and lifetime and past 12-mo experience of adverse oral conditions using survey-weighted multivariable logistic regression. Nationally representative estimates of oral conditions between the PATH Study and NHANES were similar (e.g., ever-experience of bone loss around teeth: PATH Study 15.2%, 95% CI, 14.4%-15.9%; NHANES 16.6%, 95% CI, 14.9%-18.4%). In the PATH Study, combustible tobacco smoking was consistently associated with lifetime and past 12-mo experience of adverse oral health (e.g., exclusive cigarette smoking vs. never tobacco use, adjusted odds ratio [AOR] for loose teeth in past 12 mo: 2.02; 95% CI, 1.52-2.69). Exclusive smokeless tobacco use was associated with greater odds of loose teeth (AOR, 1.93; 95% CI, 1.15-3.26) and lifetime precancerous lesions (AOR, 3.85; 95% CI, 1.73-8.57). Use of other noncigarette products (e.g., pipes) was inconsistently associated with oral health outcomes. PATH Study oral health measures closely align with self-reported measures from NHANES and are internally concurrent. Observed associations with tobacco use and the ability to examine emerging tobacco products support application of PATH Study data in dental research, particularly to examine potential oral health effects of novel tobacco products and longitudinal changes in tobacco use behaviors.

Second-trimester maternal distress increases the risk of small for gestational age.

BACKGROUND: The effect of prenatal distress on the risk of a small for gestational age (SGA) infant is uncertain. We have addressed the influences of prenatal stress, anxiety and depression on the risk of SGA. We also examined the effects of infant sex and timing of distress during pregnancy on any observed associations. METHOD: The study population comprised 5606 healthy nulliparous pregnant women who participated in the international prospective Screening for Obstetric and Pregnancy Endpoints (SCOPE) study. Women completed the Perceived Stress Scale (PSS), the short form of the Spielberger State-Trait Anxiety Inventory (STAI) and the Edinburgh Postnatal Depression Scale (EPDS) at 15 ± 1 and 20 ± 1 weeks' gestation. SGA was defined as birthweight below the 10th customized percentile. Logistic regression was used for data analysis, adjusting for several potential confounders such as maternal age, body mass index (BMI), smoking, socio-economic status and physical exercise. RESULTS: The risk of SGA was increased in relation to mild [adjusted odds ratio (aOR) 1.35, 95% confidence interval (CI) 1.07-1.71], moderate (aOR 1.26, 95% CI 1.06-1.49), high (aOR 1.45, 95% CI 1.08-1.95) and very high stress scores (aOR 1.56, 95% CI 1.03-2.37); very high anxiety score (aOR 1.45, 95% CI 1.13-1.86); and very high depression score (aOR 1.14, 95% CI 1.05-1.24) at 20 ± 1 weeks' gestation. Sensitivity analyses showed that very high anxiety and very high depression increases the risk of SGA in males but not in females whereas stress increases the risk of SGA in both males and females. CONCLUSIONS: These findings suggest that prenatal stress, anxiety and depression measured at 20 weeks' gestation increase the risk of SGA. The effects of maternal anxiety and depression on SGA were strongest in male infants.

Effects of milk composition, stir-out time, and pressing duration on curd moisture and yield.

A study was undertaken to investigate the effects of milk composition (i.e., protein level and protein:fat ratio), stir-out time, and pressing duration on curd moisture and yield. Milks of varying protein levels and protein:fat ratios were renneted under normal commercial conditions in a pilot-scale cheese vat. During the syneresis phase of cheese making, curd was removed at differing times, and curd moisture and yield were monitored over a 22-h pressing period. Curd moisture after pressing decreased with longer stir-out time and pressing duration, and an interactive effect was observed of stir-out time and pressing duration on curd moisture and yield. Milk total solids were shown to affect curd moisture after pressing, which has implications for milk standardization; that is, it indicates a need to standardize on a milk solids basis as well as on a protein:fat basis. In this study, a decreased protein:fat ratio was associated with increased total solids in milk and resulted in decreased curd moisture and increased curd yield after pressing. The variation in total solids of the milk explains the apparent contradiction between decreased curd moisture and increased curd yield. This study points to a role for process analytic technology in minimizing variation in cheese characteristics through better control of cheesemilk composition, in-vat process monitoring (coagulation and syneresis), and post-vat moisture reduction (curd pressing). Increased control of curd composition at draining would facilitate increased control of the final cheese grade and quality.

Validation of a curd-syneresis sensor over a range of milk composition and process parameters.

An online visible-near-infrared sensor was used to monitor the course of syneresis during cheesemaking with the purpose of validating syneresis indices obtained using partial least squares, with cross-validation across a range of milk fat levels, gel firmness levels at cutting, curd cutting programs, stirring speeds, milk protein levels, and fat:protein ratio levels. Three series of trials were carried out in an 11-L cheese vat using recombined whole milk. Three factorial experimental designs were used, consisting of 1) 3 curd stirring speeds and 3 cutting programs; 2) 3 milk fat levels and 3 gel firmness levels at cutting; and 3) 2 milk protein levels and 3 fat:protein ratio levels, respectively. Milk was clotted under constant conditions in all experiments and the gel was cut according to the respective experimental design. Prediction models for production of whey and whey fat losses were developed in 2 of the experiments and validated in the other experiment. The best models gave standard error of prediction values of 6.6 g/100 g for yield of whey and 0.05 g/100 g for fat in whey, as compared with 4.4 and 0.013 g/100 g, respectively, for the calibration data sets. Robust models developed for predicting yield of whey and whey fat losses using a validation method have potential application in the cheese industry.

Effects of cutting intensity and stirring speed on syneresis and curd losses during cheese manufacture.

Recombined whole milk was renneted under constant conditions of pH, temperature, and added calcium, and the gel was cut at a constant firmness. The effects of cutting and stirring on syneresis and curd losses to whey were investigated during cheese making using a factorial design with 3 cutting modes designed to provide 3 different cutting intensity levels (i.e., total cutting revolutions), 3 levels of stirring speed, and 3 replications. These cutting intensities and stirring speeds were selected to give a wide range of curd grain sizes and curd shattering, respectively. Both factors affected curd losses, and correct selection of these factors is important in the cheesemaking industry. Decreased cutting intensity and increased stirring speed significantly increased the losses of fines and fat from the curd to the whey. Cutting intensities and stirring speeds in this study did not show significant effects on curd moisture content over the course of syneresis. Levels of total solids, fines, and fat in whey were shown to change significantly during syneresis. It is believed that larger curd particles resulting from low cutting intensities coupled with faster stirring speeds resulted in a higher degree of curd shattering during stirring, which caused significant curd losses.

Application of image texture analysis for online determination of curd moisture and whey solids in a laboratory-scale stirred cheese vat.

A noninvasive technology, which could be employed online to monitor syneresis, would facilitate the production of higher quality and more consistent cheese products. Computer vision techniques such as image texture analysis have been successfully established as rapid, consistent, and nondestructive tools for determining the quality of food products. In this study, the potential of image texture analysis to monitor syneresis of cheese curd in a stirred vat was studied. A fully randomized 2-factor (milk pH and stirring speed), 2-level factorial design was carried out in triplicate. During syneresis, images of the surface of the stirred curd-whey mixture were captured using a computer vision system. The images were subjected to 5 image texture analysis methods by which 109 image texture features were extracted. Significant correlations were observed between a number of image texture features and curd moisture and whey solids. Multiscale analysis techniques of fractal dimension and wavelet transform were demonstrated to be the most useful for predicting syneresis indices. Fractal dimension features predicted curd moisture and whey solids during syneresis with standard errors of prediction of 1.03% (w/w) and 0.58 g/kg, respectively. It was concluded that syneresis indices were most closely related to the image texture features of multiscale representation. The results of this study indicate that image texture analysis has potential for monitoring syneresis.

Application of mid-infrared spectroscopy to the prediction of maturity and sensory texture attributes of cheddar cheese.

The objective of this study was to determine the potential of mid-infrared spectroscopy in conjunction with partial least squares (PLS) regression to predict various quality parameters in cheddar cheese. Cheddar cheeses (n= 24) were manufactured and stored at 8 degrees C for 12 mo. Mid-infrared spectra (640 to 4000/cm) were recorded after 4, 6, 9, and 12 mo storage. At 4, 6, and 9 mo, the water-soluble nitrogen (WSN) content of the samples was determined and the samples were also evaluated for 11 sensory texture attributes using descriptive sensory analysis. The mid-infrared spectra were subjected to a number of pretreatments, and predictive models were developed for all parameters. Age was predicted using scatter-corrected, 1st derivative spectra with a root mean square error of cross-validation (RMSECV) of 1 mo, while WSN was predicted using 1st derivative spectra (RMSECV = 2.6%). The sensory texture attributes most successfully predicted were rubbery, crumbly, chewy, and massforming. These attributes were modeled using 2nd derivative spectra and had corresponding RMSECV values in the range of 2.5 to 4.2 on a scale of 0 to 100. It was concluded that mid-infrared spectroscopy has the potential to predict age, WSN, and several sensory texture attributes of cheddar cheese.

Computer vision and color measurement techniques for inline monitoring of cheese curd syneresis.

Optical characteristics of stirred curd were simultaneously monitored during syneresis in a 10-L cheese vat using computer vision and colorimetric measurements. Curd syneresis kinetic conditions were varied using 2 levels of milk pH (6.0 and 6.5) and 2 agitation speeds (12.1 and 27.2 rpm). Measured optical parameters were compared with gravimetric measurements of syneresis, taken simultaneously. The results showed that computer vision and colorimeter measurements have potential for monitoring syneresis. The 2 different phases, curd and whey, were distinguished by means of color differences. As syneresis progressed, the backscattered light became increasingly yellow in hue for circa 20 min for the higher stirring speed and circa 30 min for the lower stirring speed. Syneresis-related gravimetric measurements of importance to cheese making (e.g., curd moisture content, total solids in whey, and yield of whey) correlated significantly with computer vision and colorimetric measurements.

Evaluating mid-infrared spectroscopy as a new technique for predicting sensory texture attributes of processed cheese.

The objective of this study was to investigate the potential application of mid-infrared spectroscopy for determination of selected sensory attributes in a range of experimentally manufactured processed cheese samples. This study also evaluates mid-infrared spectroscopy against other recently proposed techniques for predicting sensory texture attributes. Processed cheeses (n = 32) of varying compositions were manufactured on a pilot scale. After 2 and 4 wk of storage at 4 degrees C, mid-infrared spectra (640 to 4,000 cm(-1)) were recorded and samples were scored on a scale of 0 to 100 for 9 attributes using descriptive sensory analysis. Models were developed by partial least squares regression using raw and pretreated spectra. The mouth-coating and mass-forming models were improved by using a reduced spectral range (930 to 1,767 cm(-1)). The remaining attributes were most successfully modeled using a combined range (930 to 1,767 cm(-1) and 2,839 to 4,000 cm(-1)). The root mean square errors of cross-validation for the models were 7.4 (firmness; range 65.3), 4.6 (rubbery; range 41.7), 7.1 (creamy; range 60.9), 5.1 (chewy; range 43.3), 5.2 (mouth-coating; range 37.4), 5.3 (fragmentable; range 51.0), 7.4 (melting; range 69.3), and 3.1 (mass-forming; range 23.6). These models had a good practical utility. Model accuracy ranged from approximate quantitative predictions to excellent predictions (range error ratio = 9.6). In general, the models compared favorably with previously reported instrumental texture models and near-infrared models, although the creamy, chewy, and melting models were slightly weaker than the previously reported near-infrared models. We concluded that mid-infrared spectroscopy could be successfully used for the nondestructive and objective assessment of processed cheese sensory quality.

Persistence of anti-leptospiral IgM, IgG and agglutinating antibodies in patients presenting with acute febrile illness in Barbados 1979-1989.

The persistence of anti-leptospiral IgM and IgG antibodies and agglutinating antibodies was studied in serologically confirmed cases of severe leptospirosis during the acute illness and over periods of several years after recovery. The antibody response in non-leptospirosis patients presenting to hospital with similar symptoms over the same period of time was used to estimate the background antibody level to leptospirosis in the community. All patients enrolled in the study had blood samples collected twice in the acute stage of illness, once during convalescence and then annually from the time of initial hospitalisation until the end of the study period. Six hundred and thirty-eight patients presented to hospital with acute febrile illness, of whom 321 were diagnosed with leptospirosis. Patients who had severe leptospirosis commonly remained seropositive, with IgM, IgG and agglutinating antibodies detectable for several years after infection. A significant proportion of cases had high titres of agglutinating antibody detectable by the microscopic agglutination test (> or = 800). There were marked differences in the magnitude and duration of persistence of agglutinating antibodies directed against different serogroups. More than 20% of cases with evidence of infection with serogroup Autumnalis retained titres of >800, 4 years after the acute illness. In one case a titre of 800 was detected 11 years after infection. Persistence of agglutinating antibody titres can create problems in interpretation of serological results and make it impossible to estimate the time of infection, given a specific titre. This study demonstrates that in endemic areas where seroprevalence is high, use of a single elevated titre is not reliable to define a current infection.

Assessment of the efficacy of an IgM-elisa and microscopic agglutination test (MAT) in the diagnosis of acute leptospirosis.

In a prospective study in Barbados between 1979 and 1989, 321 cases were diagnosed in 638 patients presenting at a hospital with symptoms of leptospirosis. Initial diagnosis was based on patient history and characteristic signs and symptoms. In 92 cases (29%), diagnosis was confirmed by isolation of organisms from the blood, urine, or dialysate fluid; in the remaining 229 cases (71%) diagnosis was confirmed by serology alone. Results of an IgM-ELISA and microscopic agglutination test (MAT) in cases with isolates and in non-leptospirosis cases were used to assess the sensitivity and specificity of the tests. The sensitivity of IgM detection by ELISA was 52% in the first acute-phase specimen, increasing to 89% and 93% in the second acute-phase and convalescent specimens, respectively. The specificity of the IgM-ELISA was high (> or = 94%) in all specimens. The sensitivity of the MAT was low (30%) in the first acute-phase specimen, increasing to 63% in the second acute-phase specimen and 76% in the convalescent specimen. The specificity of the MAT was > or = 97% in all specimens.

Surveillance of leptospiral carriage by feral rats in Barbados.

Rodents, particularly rats, are widely held to be the source of most human cases of leptospirosis. Feral rats were trapped at sites throughout Barbados during two six month surveys: from October to March 1986/87 and from October to March 1994/95. During the first survey, 63 rats were trapped, of which 26 (41%) were identified as Rattus rattus and 37 (59%) as Rattus norvegicus. In the second study, 100 rats were trapped, of which R. rattus comprised 24% (24) and R. norvegicus 76% (76). Cultures of blood, urine and kidney were made in EMJH medium. Leptospires were isolated from 12/63 (19%) and from 16/100 (16%) of the rats during 1986/87 and 1994/95, respectively; 27/28 isolates were recovered from the kidneys or urine or both, while only one isolate was recovered from the blood. During the first study, isolates were identified as serovars copenhageni (11) and arborea (1), while in the second study, serovars copenhageni (9), arborea (5) and bim (1) were identified; one isolate was lost before it could be identified. In the first study, antibodies were detected by microscopic agglutination at a titre of > or = 100 in 26/62 (42%) of rats tested, while in the second survey, 5/100 (5%) of rats had similar titres. In two surveys, conducted eight years apart, we confirmed that rats in Barbados are commonly infected with leptospires, and that viable organisms are found in the kidneys and urine, evidence of chronic infection and thus excretion of leptospires in rodent urine. Moreover, the predominant serovar isolated was copenhageni, of which Rattus spp. are the worldwide reservoir. There was little evidence that rats act as a reservoir for the serovar bim, the most common cause of human leptospirosis in Barbados.

Surveillance of leptospiral carriage by feral rats in Barbados

Rodents, particularly rats, are widely held to be the source of most human cases of leptospirosis. Feral rats were trapped at sites throughout Barbados during two six month surveys: from October to March 1986/87 and from October to March 1994/95. During the first survey, 63 rats were trapped, of which 26 (41) were identified as Rattus rattus and 37 (59) as Rattus norvegicus. In the second study, 100 rats were trapped, of which R. rattus comprised 24(24) and R. norvegicus 76(76). Cultures of blood, urine and kidney were made in EMJH medium. Leptospires were isolated from 12/63 (19) and from 16/100 (16) of the rats during 1986/87 and 1994/95, respectively; 27/28 isolates were recovered from the kidneys or urine or both, while only one isolate was recovered from the blood. During the first study, isolates were identified as serovars copenhageni (11) and arborea (1), while in the second study, serovars copenhageni (9), arborea (5) and bim (1) were identified; one isolate was lost before it could be identified. In the first study, antibodies were detected by microscopic agglutination at a titre of > or = 100 in 26/62 (42) of rats tested, while in the second survey, 5/100 (5) of rats had similar titres. In two surveys, conducted eight years apart, we confirmed that rats in Barbados are commonly infected with leptospires, and that viable organisms are found in the kidneys and urine, evidence of chronic infection and thus excretion of leptospires in rodent urine. Moreover, the predominant serovar isolated was copenhageni, of which Rattus spp. are the worldwide reservoir. There was little evidence that rats act as a reservoir for the serovar bim, the most common cause of human leptospirosis in Barbados.

Seroepidemiology of canine leptospirosis on the island of Barbados.

Previous surveillance in Barbados documented the absence of infection with Leptospira serogroup Canicola in dogs. The aim of this study was to survey the current state of canine leptospirosis in Barbados, 10 years after the last survey. Sera from 78 unwanted dogs scheduled for euthanasia and 61 dogs suspected of having acute leptospirosis were tested by microscopic agglutination (MAT) and by an ELISA method adapted for canine IgM and IgG antibodies. The seroprevalence in unwanted dogs was 62% (48/78), at an MAT titre of > or = 100. The majority of animals had low titres, suggestive of previous infection. Serogroup Autumnalis was the most common reactor (45%), followed by serogroups Icterohaemorrhagiae and Australis (each 16%) and Pomona (13%). Serogroup Ballum was uncommon in this group. The seroprevalence determined by MAT in acutely-ill dogs was 75% (46/61). The most common predominant serogroup was Icterohaemorrhagiae (36%) followed by serogroup Australis (13%), while serogroups Autumnalis and Ballum were also of little significance. Paired specimens were available from eight acutely-ill dogs. One animal was seronegative while five dogs showed evidence of seroconversion. An IgM-ELISA titre of > or = 320 was used to confirm current infection in eight of these nine animals. Previous studies in Barbados showed a higher prevalence of serogroup Icterohaemorrhagiae than of Autumnalis, but the relative frequency of these two serogroups may be changing. The high seroprevalence in dogs is of public health concern because the close contact between dogs and man may provide the link between a reservoir in the environment and susceptible humans.

Evaluation of the polymerase chain reaction for early diagnosis of leptospirosis.

Early diagnosis of leptospirosis is important because severe leptospiral infection can run a fulminant course. The polymerase chain reaction (PCR) was evaluated for the detection of leptospires in clinical samples from patients with acute leptospiral infection. Blood and urine samples from 71 patients with leptospirosis were examined by PCR, culture or serology. Samples from 44 (62%) patients with the diagnosis of leptospirosis were positive by PCR as compared to 34 (48%) by culture. The presence of leptospires was demonstrated by PCR in 13 patients before the development of antibodies, as well as in two patients who were seronegative during their illness and at autopsy. Samples from 16 patients without leptospirosis were seronegative and culture negative, and also negative by PCR. We conclude that PCR is a rapid, sensitive and specific means of diagnosing leptospiral infection, especially during the first few days of the disease.

Leptospirosis in Madras--a clinical and serological study.

Leptospirosis was confirmed by Microscopic Agglutination Test (MAT) and/or ELISA in 57 patients admitted to the Government General Hospital, Madras, India, during November and December of 1990 and 1991 with symptomatology suggestive of the disease. Fifty (88%) of the 57 cases were males; the mean age of all the cases was 39.6 years (range 17-72). The main clinical features were: fever 100% jaundice 84%, Myalgia 82%, acute renal failure 72% and conjunctival suffusion 58%. Non-azotemic jaundice occurred in 19% of cases. Renal failure was non-oliguric in 24% of cases. 3.5% of patients died. 23 patients underwent peritoneal and/or hemodialysis. ELISA IgM titres ranged from 1:80 to 1:10240 (geometric mean tire 911). MAT titres > or = 1:1600 and > or = 1:800 occurred in 39 of 54 and 51 of 54 cases respectively. Autumnalis was the serogroup most commonly recorded serologically, and Leptospira interrogans serovar autumnalis was isolated from one patient. This study shows that leptospirosis is a significant health problem in Madras, though normally grossly underestimated due to the absence of routine laboratory diagnostic facilities for the disease. Gross under-reporting is also likely in other high rainfall third world areas.

A twelve-year study of leptospirosis on Barbados.

Between November 1979 and December 1991, 398 cases of severe leptospirosis were confirmed on Barbados (range for 1980-1991 23-56; mean 32.7; incidence 13.3/100,000/year). For the six-year periods 1980-1985 and 1986-1991 there was no significant change in incidence with time. Incidence is unlikely to change significantly in the next decade. Monthly average case numbers ranged from 1.4 (July) to 4.3 (November). The average (2.8) for June to December (the 7 wetter months) was not significantly higher than that (2.5) for January to May (the 5 drier months). The age range was 7-86. There were three times as many male cases (302) as female (96), and nearly 10 times as many in those < 35. Although the highest number of cases (69) was in males aged 15-24, the highest incidence was in the older age groups, particularly the male 65-74 year-olds, and the female 55-64 year-olds. Leptospirosis was the proven cause of death in 55 (13.8%) hospital patients (annual range 0-13, mean 4.5). Some of a further 39 fatalities might have been cases. Death from leptospirosis was nearly twice as common among the women as among the men. Only one patient under 20 years of age died. Leptospira were isolated and identified from 117 (29.4%) of the 398 sick patients. The infecting organisms were bim (serogroup Autumnalis--75), copenhageni (Icterohaemorrhagiae-26), arborea (Ballum-14) and bajan (Australis-2). These infecting serovars could not be distinguished clinically, but infection was milder in children than in adults. Despite its predominance in surveyed children, serogroup Panama was virtually absent in this study. Rainfall is the major factor affecting the distribution of cases; not surprisingly, sanitation workers and agricultural workers appear to be the groups at highest risk. The general lack of clear-cut risk factors reflects the ubiquity of leptospires in the environment and the fact that the disease is not entirely occupational.

Reduction in mortality from sudden infant death syndrome in New Zealand: 1986-92.

Mortality from sudden infant death syndrome (SIDS, or cot death) in New Zealand has been high by international standards (4/1000 live births). Within New Zealand the rate is higher in Maori than in non-Maori (predominantly European infants) and higher in South Island than in North Island. The National Cot Death Prevention Programme aims to reduce the prevalence of four modifiable risk factors for SIDS, namely infants sleeping prone, maternal smoking, lack of breast feeding, and infants sharing a bed with another person. The aim of this study is to describe the total postneonatal and total SIDS mortality in New Zealand from 1986 to 1992. Official publications from 1986 to 1990 and preliminary death notifications for 1991 and 1992 were examined. Deaths from all causes in the postneonatal age group (28 days to 1 year) and the total number of deaths from SIDS irrespective of age decreased markedly in 1990 and has continued to decrease. This decrease occurred particularly in non-Maori groups, in South Island, and in the winter months. The proportion of infants sleeping in a prone position has decreased from 43% to less than 5%. This suggests that the prone position is causally related to SIDS. The mechanism appears to be related directly or indirectly to environmental temperature.

Detection of seven species of pathogenic leptospires by PCR using two sets of primers.

Two sets of primers derived from genomic DNA libraries of Leptospira serovars icterohaemorrhagiae (strain RGA) and bim (strain 1051) enabled the amplification by PCR of target DNA fragments from leptospiral reference strains belonging to all presently described pathogenic Leptospira species. The icterohaemorrhagiae-derived primers (G1/G2) enabled amplification of DNA from L. interrogans, L. borgpetersenii, L. weilii, L. noguchii, L. santarosai and L. meyeri, whereas the bim-derived primers (B64-I/B64-II) enabled the amplification of L. kirschneri. Southern blot and DNA sequence analysis revealed inter-species DNA polymorphism within the region spanned by primers G1 and G2 between L. interrogans and various other Leptospira species. Using a mixture of primer sets G1/G2 and B64-I/B64-II, leptospires of serovars icterohaemorrhagiae, copenhageni, hardjo, pomona, grippotyphosa and bim were detected in serum samples collected from patients during the first 10 days after the onset of illness.

Prevalence of leptospiral agglutinins among conservancy workers in Madras City, India.

In a study of 584 Corporation conservancy (sanitation) workers who lived mostly in slums, and who worked in four Corporation Circles of Madras City, India, 192 (32.9%) were found to be positive for agglutinins to Leptospira interrogans. Seropositivity prevalence increased with age, but was similar in males and females except in the youngest age group, where males predominated. Prevalence in the four study areas ranged between 17.8 and 40.5% (P < 0.01). Among 152 sera in which one serogroup predominated, Autumnalis was the most commonly recorded (33.6%), followed by Icterohaemorrhagiae (15.1%), Panama (15.1%), Sejroe (14.5%) and others (21.7%). Forty sera reacted to two or more serogroups at the same (highest) titre, most frequently to the first three serogroups above. The titre range was 1:50-1:3200 (geometric mean titre 149). Among a group of 46 male automobile industry workers who lived in middle-class housing, seropositivity prevalence (17.4%) was approximately half that of the sanitation workers (P < 0.05), and the titre range was lower (1:50-1:200, GMT 84). The predominating serogroups were those found in the sanitation workers. Bearing in mind that sanitation workers are the urban group probably at highest risk of leptospiral infection, the prevalence rate (< 33%) found in our study is not considered to be particularly high.