Epidemic and endemic seroprevalence of antibodies to Cryptosporidium and Giardia in residents of three communities with different drinking water supplies.

This study was carried out to compare cryptosporidiosis and giardiasis seroprevalence rates in residents of three communities. Community (Com 1) uses drinking water from deep wells, community 2 (Com 2) uses surface water from a protected watershed, and community 3 (Com 3) uses surface water frequently containing Cryptosporidium oocysts and Giardia cysts. Unfiltered drinking water from each community was collected at the tap and tested for Cryptosporidium oocysts and Giardia cysts during the 12 months in which sera were collected for testing. No oocysts or cysts were detected in the water from the Com 1 deep wells; oocysts and cysts were detected intermittently in the drinking water from the other two communities. A waterborne outbreak of cryptosporidiosis occurred in a municipality adjacent to Com 3 six months into this 12-month study. Sera from residents of each of the communities were collected proportionately by month and by population size. Coded sera were tested for IgG to Cryptosporidium using a previously developed Western blotting method. The presence or absence of bands at 15-17 kD and/or 27 kD was recorded for the 1,944 sera tested. Definite bands at 15-17 kD and/or 27 kD were detected in 981 (50.5%) of the sera. A total of 33.2% of sera from Com 1 (community using deep wells) were positive using the same criteria compared with 53.5% (Com 2) and 52.5% (Com 3) of sera from the two communities using surface drinking water. Both bands (15-17 kD plus 27 kD) were detected in 582 sera (29.9%) from the three communities: 14.1% of sera from Com 1 compared with 32.7% from Com 2 and 31.5% from Com 3. These findings are consistent with a lower risk of exposure to Cryptosporidium from drinking water obtained from deep well sources. However, analysis of results by calendar quarter showed a significant (P < 0.001) increase in the number of Com 3 positive sera (compared with Com 1) following the waterborne outbreak. Without this outbreak-related observation, a significant overall difference in seropositivity would not have been seen. We also observed that in sera from the community affected by the outbreak, the presence on immunoblots of both Cryptosporidium bands appeared to be the best indicator of recent infection. Seroprevalence rates using an ELISA to detect IgG to Giardia were estimated using the same sera. Overall 30.3% (590 of 1,944) of sera were positive by the ELISA. A total of 19.1% of sera from Com 1, 34.7% from Com 2 and 16.0% from Com 3 were seropositive. Rates for both Com 3 and Com 1 did not change significantly over time. In Com 2, rates decreased significantly (P < 0.001) during the last half of the study period (third and fourth calendar quarters). The reasons for the decrease in seroprevalence in Com 2 sera are presently not known. These studies show intriguing associations between seroprevalence, outbreak-related laboratory serologic data, and patterns of parasite contamination of drinking water. Further studies are required to validate the serologic approach to risk assessment of waterborne parasitic infections at a community level.

Studies of Giardia spp. and Cryptosporidium spp. in two adjacent watersheds.

Two adjacent British Columbia, Canada, watersheds with similar topographical features were studied. Both the Black Mountain Irrigation District (BMID) and the Vernon Irrigation District (VID) serve rural agricultural communities which are active in cattle ranching. The present study was carried out in five phases, during which a total of 249 surface water samples were tested in the study watersheds. The aims of these phases were to determine levels of parasite contamination in raw water samples collected from the intakes as well as from other sites in each watershed and to investigate cattle in the watersheds as potential sources of parasite contamination of surface drinking water supplies. Giardia cysts were not detected in the raw water samples collected from lake sources at the headwaters of both watersheds but were found in 100% (70 or 70) of water samples collected at the BMID intake and 97% (68 of 70) of water samples collected at the VID intake. Significantly higher levels (P < 0.05) of Giardia cysts were found at the BMID intake (phase 1, 7 to 2,215 cysts per 100 liters; phase 3, 4.6 to 1,880 cysts per 100 liters) when compared with that of the VID intake (2 to 114 cysts per 100 liters). The BMID watershed has a more complex system of surface water sources than the VID watershed. Cattle have access to creeks in the BMID watershed, whereas access is restricted in the VID watershed. Collection of raw water samples from a creek upstream and downstream of a cattle ranch in the BMID watershed showed that the downstream location had significantly higher (P < 0.05) levels (0.6 to 42.9 cysts per 100 liters and 1.4 to 300.0 oocysts per 100 liters) of both Giardia cysts and Cryptosporidium oocysts than those of the upstream location (0.5 to 34.4 cysts per 100 liters and 0.5 to 34.4 oocysts per 100 liters). Peak concentrations of both parasites coincided with calving activity. Fecal samples, collected from cattle in both watersheds, showed 10% (3 of 30) in the BMID and 50% (5 of 10) in the VID watersheds to be Giardia positive. No Cryptosporidium-positive fecal samples were found. Giardia cysts isolated from the BMID watershed were repeatedly infective to gerbils in contrast to those from the VID watershed. The 10 BMID drinking water Giardia isolates retrieved into culture and biotyped showed zymodeme and karyotype heterogeneity. The differences in patterns of parasite contamination and cattle management practices contribute to the unique watershed characteristics observed between two areas which are topographically similar and geographically adjacent.

Longitudinal studies of Giardia contamination in two community drinking water supplies: cyst levels, parasite viability, and health impact.

Giardia cyst concentrations were determined in an inventory of 153 raw and 91 chlorinated drinking water samples collected at 86 sites from throughout the western Canadian province of British Columbia. Sixty-four percent of raw water samples were cyst positive (69% of sites). Cyst concentrations were lower in chlorinated than in raw water. The viability of cysts in drinking water samples assessed by infectivity in Mongolian gerbils (Meriones unguiculatus) was decreased in chlorinated water. Two rural communities using Giardia-contaminated surface drinking water sources were selected for longitudinal studies including drinking water testing and serological studies of residents. Three hundred thirty-six raw and treated samples from these communities were collected over 24 months. Cyst concentrations and viability were assessed in a 12-month study of each community. Parasite concentrations were lower in chlorinated water than in raw water in both communities. Cyst concentrations were lower in reservoir-settled water than in raw water. Viability, assessed by animal infectivity and corrected for inoculum, decreased following reservoir settling as well as after chlorination. A bolus or spiking phenomenon of cysts was observed in both community drinking water systems and deserves further study. A striking seasonal pattern was seen in one community but not in the second. The seroprevalence data and number of laboratory-confirmed cases identified in each year-long community study are consistent with the possibility that low-level endemic transmission is occurring.

Lactate dehydrogenase activity and isozyme patterns in tissues and bronchoalveolar lavage fluid from rats treated with monocrotaline pyrrole.

Monocrotaline pyrrole (MCTP), a putative, toxic metabolite of monocrotaline, induces delayed and progressive lung injury, vascular remodeling, and pulmonary hypertension in rats. The lung injury is characterized by increased wet lung-to-body weight ratio followed by increases in lactate dehydrogenase (LDH) activity and protein concentration in the cell-free bronchoalveolar lavage fluid (BALF) and increased cellularity of BALF. We evaluated total LDH activity and isozyme patterns in the tissues, cell lysates, sera and cell-free BALF of rats after treatment with MCTP to determine the source of increased LDH activity. Male Sprague-Dawley rats were given a single injection of MCTP (3.5 mg/kg) or an equal volume of the N,N-dimethylformamide (DMF) vehicle in the tail vein on Day 0. Rats were killed at 4, 8, or 14 days after toxicant administration, and several markers of lung injury, LDH activity, and isozyme patterns of various tissues, cells, and body fluids were determined. At 8 and 14 days, the lungs from MCTP-treated rats had multifocal, irregularly shaped lesions of hemorrhage and consolidation. At Day 14 only, the hearts of MCTP-treated rats appeared enlarged and there was right cardioventricular hypertrophy. Rats treated with MCTP had no macroscopic lesions in kidneys, liver, or skeletal muscle. Compared to controls, MCTP-treated animals had no change in total LDH activity or isozyme patterns of samples of lungs, heart, skeletal muscle, liver, kidneys, or erythrocyte lysates. Changes in LDH activity in the cell-free BALF and BALF cell pellet from rats treated with MCTP were characterized by increases in isozymes LDH4 and LDH5 and an elevated LDH4/LDH5 ratio in the BALF only. Our results suggest the most probable source of the increased LDH activity in cell-free BALF of MCTP-treated rats originates from the lung tissue and is consistent with a contribution from the pulmonary vascular endothelium, a source rich in LDH4. A combination of plasma, macrophages, and neutrophils in the pulmonary tissue may also have made minor contributions to the increase in cell-free BALF LDH activity, particularly to the activity of LDH5.

Giardiasis outbreak from a chlorinated community water supply.

A giardiasis outbreak from a chlorinated, unfiltered surface water supply in Penticton, British Columbia (pop. 25,000) from June to August 1986 resulted in 362 laboratory-confirmed cases. A telephone survey estimated an attack rate of over 12%. A reservoir pond containing Giardia-infected beaver was implicated as the source. A case-control study with 65 cases did not find any significant associations. A retrospective case-finding survey of records from eight (out of 35) general physicians estimated that 1,500 physician visits occurred and produced an epidemic curve in close parallel with that from laboratory-confirmed and reported cases. Despite improvements on the reservoir, another outbreak occurred when this water source was reinstituted in October for several weeks, confirming our conclusion that it was the source of the first outbreak. Various options for reducing the risk of future outbreaks are being explored including full water treatment.

Assessment of the feasibility of determination of cholesterol and other blood constituents by near-infrared reflectance analysis.

Near-infrared reflectance spectrometry of blood serum can yield values for serum cholesterol that correlate reasonably well (r = 0.96) with those from common reference analytical methods. However, the variability of serum can cause ostensibly validated calibrations to fail on new samples. The determination of blood components such as cholesterol and triglycerides by near-infrared reflectance is complicated by their low concentrations, the variety of forms in which they appear, and by the natural variability of the blood matrix. These difficulties, when combined with the problems encountered in obtaining a representative sample from a given individual, can make it almost impossible to select, by a regression procedure, a wavelength combination that is characteristic of the complete blood matrix. The failure of the regression process to find characteristic wavelengths generates a false-sample problem in which even small changes at the analytical wavelengths produce a grossly unreliable cholesterol or triglyceride determination.

An alternative method for assaying cerebrospinal fluid protein in the presence of methotrexate.

Therapeutic concentrations of methotrexate can cause significant positive interference in cerebrospinal fluid (CSF) protein values when assayed in the Du Pont aca. Conversely, our modified turbidimetric method, in which trichloroacetic acid (TCA) plus a sample blank containing dilute hydrochloric acid is used in place of TCA, exhibits little or no interference from methotrexate. This was verified by assaying solutions that contained a constant amount of protein (approximately 430 mg/L) and various amounts of methotrexate (0.0-2.3 x 10(-4) mol/L) by both the Du Pont aca and the manual turbidimetric method. As expected, the aca results showed increasing protein values with increasing methotrexate, whereas the manual method gave results approximating the expected protein value irrespective of the methotrexate concentration.

Inhibition of cholesterol oxidase in a patient with Cushing's syndrome.

Serum from a patient with Cushing's syndrome who was being treated with mitotane contained components that interfered with determination of cholesterol in the Du Pont aca. A measured concentration of cholesterol of 4.19 g/L in the undiluted serum increased to a calculated concentration of 9.50 g/L in diluted serum. Adding additional cholesterol oxidase (EC 1.1.3.6) overcame the reaction inhibition in the undiluted sample; adding additional cholesterol esterase (EC 3.1.1.13) had no effect. There is the potential for clinically significant underestimation of cholesterol with the aca in such patients, because the interference may remain undetected. On the other hand, the aca accurately quantified undiluted specimens containing as much as 10 g of cholesterol per liter when mitotane was not present.

Exercise-induced changes in common laboratory tests.

Examination of 19 serum biochemical and hematologic parameters in a group of white male runners, ranging in age from 23 to 47 years, just prior to and immediately after a 13-mile "mini-marathon," demonstrated a significant increase, by paired Student t-test, in mean values of: K+, BUN, creatinine, CK, LDH, AST (SGOT), alkaline phosphatase, bilirubin, uric acid and leukocyte counts. Prevailing environmental conditions were such as to produce no significant hemoconcentration. Using this group's statistics and this hospital laboratory's upper limits of normal, the percentage of values above two SDs are, for the resting state: K+ 7%, BUN 7%, creatinine 0%, CK 21%, LDH 21%, AST 0%, alkaline phosphatase 0%, bilirubin 7%, uric acid 7%, and leukocyte count 0%. Post-exertional values above normal limits are: K+ 7%, BUN 21%, creatinine 21%, CK 93%, LDH 86%, AST 0%, alkaline phosphatase 0%, bilirubin 14%, uric acid 36%, and leukocyte 71%. Consequently, abnormally high values for K+, BUN, creatinine, CK, LDH, bilirubin, uric acid, and leukocyte counts can often be expected in some patients who exercise heavily. The degree of the abnormality will depend on the level and length of exercise as well as the elapsed time between exercise and testing.

Delay in diagnosis and long-term survival in breast cancer.

The records of all 1591 women with a histologically confirmed primary breast neoplasm who received their primary treatment at the main referral centre in British Columbia and were diagnosed in the years 1945, 1950, 1955, 1960, 1965, 1970, or 1975 were reviewed. The interval from appearance of the first symptom to diagnosis decreased from 1945 to 1960, but no change was seen from 1960 to 1975. An analysis of survival from the date of first symptom showed that long-term survival was greater in patients with a shorter delay between the appearance of symptoms and diagnosis. The demonstration that shorter delay does improve survival, even when assessed from the appearance of the first symptom, yet delay times have not been falling recently, suggests that educational efforts are inefficient.