[Association between hair trace element and all-cause death in elderly people in Hainan].

Objective: To explore the association between hair trace element and all-cause death in the elderly in Hainan Province. Methods: The subjects of the study were elderly people from China Hainan Centenarian Cohort Study, a total of 163 elderly were included. The association between hair trace element level and all-cause death was analyzed by using Cox proportional risk regression model. Results: After fully adjusting the covariates, the multiple Cox proportional hazards regression analyses showed that selenium (Se), manganese (Mn), strontium (Sr) concentrations in hair were significantly associated with all-cause mortality, the hazard ratio (HR) were 0.72 (95%CI: 0.54-0.98, P=0.035), 1.50 (95%CI: 1.07-2.11, P=0.020) and 0.54 (95%CI: 0.37-0.79, P=0.001), respectively. Subgroup and cross analysis showed that hair copper (Cu) were significant association with death in the people with anemia, the HR were 1.81 (95%CI: 1.13-2.88, P=0.013). And, hair Mn interacted with anemia, the HR was 0.46 (95%CI: 0.22-0.94, P=0.033). Conclusions: Se, Mn and Sr concentrations in hair were associated with the elevated risk for all-cause death in the elderly in Hainan. Se, Mn and Sr concentrations in hair can be used as a reference index for the prediction of the death risk of long-lived elderly in community, suggesting that the daily diet of elderly people are rich and diverse, in order to maintain normal and balanced trace element content in the body.

[Association analysis between sex hormone levels and all-cause mortality in Hainan female centenarians].

Objective: To investigate the distribution characteristics of sex hormones and their relationship with all-cause mortality in Hainan female centenarians. Methods: All the subjects were from China Hainan Centenarian Cohort Study. A total of 717 female centenarians were included in the final analysis. Kaplan-Meier method was used to draw the survival curve, and Cox proportional hazard regression was used to analyze the relationship between sex hormones and survival time. Results: The M(Q1, Q3) of estradiol and progesterone among female centenarians was 32.60 (18.40, 58.70) pmol/L and 0.62 (0.32, 1.01) nmol/L. The estradiol (pmol/L) and progesterone (nmol/L) in the survival and death groups were 26.65 vs.37.80, 0.54 vs.0.69, respectively, with statistical differences (P<0.05). Cox multivariate analysis showed that estradiol and progesterone were significantly associated with death (P<0.05), the hazard ratio (HR) of estradiol Q4 was 1.58 (95%CI: 1.17-2.15), and the HR of progesterone Q3 was 1.53 (95%CI: 1.10-2.12), HR for Q4 was 1.63 (95%CI: 1.15-2.32). Subgroup and cross-analysis showed that estradiol was statistically significant with hypertension, diabetes, and low high-density lipoprotein cholesterol (P<0.05), and progesterone interacted with diabetes (P=0.016), while testosterone interacted with low high-density lipoprotein cholesterol (P=0.034). Conclusion: It is suggested that the estrogen levels of female centenarians in Hainan were associated with a higher mortality risk and an increased risk of cardiovascular metabolic disease (such as diabetes, hypertension, and abnormal lipid metabolism).

[Association between nutritional status and depression among centenarians in Hainan Province].

Objective: To explore the relationship between nutritional status and depression of centenarians in Hainan Province. Methods: A total of 1 002 elderly people in Hainan Province who were 100 years of age or older on June 1, 2014 were included in the study. The basic condition questionnaire, Mini Nutritional Assessment Short-Form (MNA-SF), Instrumental Activities of Daily Living-Lawton scale (Lawton-IADL) and Geriatric Depression Scale (GDS-15) were used to collect the subjects' demographic characteristics, disease history, nutritional status, functional status of daily activities, and depression, respectively. The restricted cubic spline fitting logistic regression model was used to analyze the relationship between the scores of MNA-SF and depression. The multivariable logistic regression model was used to analyze the relationship between nutritional status and depression in the total population and different subgroups of daily activity function. Results: The M (Q1, Q3) of subjects' age was 102 (101, 104) years old, among which 82.0% (822) were women. The prevalence of malnutrition, impaired daily activities, and depression was 20.8% (208 cases), 64.7% (648 cases) and 28.5%(286 cases), respectively. Restricted cubic spline fitting logistic regression model showed a linear association between the scores of the MNA-SF and depression (P=0.251). The higher the MNA-SF score was, the lower the risk of depression was in centenarians. Multivariable logistic regression model analysis showed that after adjusting for sex, education level, diabetes, hypertension, coronary heart disease, visual function, hearing function, and functional status of daily activities, malnutrition was positively associated with the development of depression in the total population and the subgroup with impaired daily activities [OR (95%CI) was 1.50 (1.07-2.11) and 1.56 (1.09-2.24), respectively], but not in the subgroup with good daily activities [OR (95%CI): 0.77 (0.21-2.80)]. Conclusion: Malnutrition is positively associated with depression, especially in the centenarians with impaired daily activities.

[Prevalence of diabetes and associated factors in Hainan centenarians].

Objective: To investigate basic characteristics of diabetes prevalence and associated factors in centenarians in Hainan province of China. Methods: All the subjects were from China Hainan Centenarian Cohort Study. A total of 1 002 centenarians were included in the final analysis, who were divided into three groups: diabetes group, impaired fasting glucose (IFG) group, and normal glucose group according to the guideline. Results: The average age of centenarians was (102.77±2.55) years, and the proportion of females was 82.0%. There were 95 centenarians who suffered from diabetes, and the prevalence rate was 9.5%. There were 81 centenarians who had IFG, and the prevalence rate was 8.1%. The mean fasting plasma glucose (FPG) level of centenarians was (5.12±1.44) mmol/L, while 43.5% of centenarians had FPG levels ranging from 4.00 to 5.00 mmol/L and 22.1% of centenarians had the FPG levels ranging from 5.00 to 6.00 mmol/L. Increased triglyceride level and abdominal obesity might be associated with the risk for diabetes. Conclusion: The glycometabolism in centenarians in Hainan was better than that in other age groups, and no gender specific difference was observed.

[Distribution characteristics of blood pressure in Hainan centenarians].

Objective: To explore the blood pressure levels and the influencing factors of hypertension among Hainan centenarians, and provide basic data for the further blood pressure related studies of the centenarian population. Methods: The baseline data were from China Hainan Centenarian Cohort Study (CHCCS). This cross-sectional data, based on the community population, was a complete sample study of centenarians, including questionnaire survey, physical examination and physiological index detection. A total of 1 002 centenarians were recruited to describe the blood pressure level. According to the guidelines for the prevention and treatment of hypertension in Chinese adults in 2018, the prevalence of hypertension was analyzed. Results: The median levels of systolic blood pressure, diastolic pressure and pulse pressure were 152.0, 76.0 and 76.5 mmHg, respectively. Blood pressure level was higher in females than in males. The prevalence of hypertension was 71.9%, mainly in isolated systolic hypertension with the prevalence of 60.1%. The results of multivariate analysis showed that the risk of hypertension in women was higher than that in men (OR=1.624, 95%CI: 1.155-2.283), and the risk of hypertension in the northern (OR=0.625, 95%CI: 0.434-0.901) and central areas (OR=0.586, 95%CI: 0.346-0.993) was lower than that of the Eastern. Conclusion: The prevalence of hypertension, mainly in isolated systolic hypertension, showing gender and regional distribution differences.

[Association between serum albumin level and health-related quality of life in Hainan centenarians: a cross-sectional study].

Objective: To investigate the association between serum albumin levels and health-related quality of life in centenarians in Hainan province, China. Methods: We conducted a full sample centenarian cohort study in a community population in Hainan from 2014 to 2016, which included 1 002 centenarians for questionnaire surveys, physical examinations and biological tests. The EQ-5D-VAS scale was used to evaluate health-related quality of life, and multiple linear regression and multiple logistic regression analyses were used to analyze the association between serum albumin levels and health-related quality of life. Results: There was a positive linear relationship between serum albumin levels and EQ-5D/VAS score. The normalized ß values in the fully adjusted model was 0.156 (P<0.001). In the multivariate logistic regression analysis, after fully adjusting the covariates, the risk of health related life quality impairment in the lower albumin group was 2.369 times(95%CI: 1.424-3.939) than that in the higher albumin group. Gender stratified analyses showed that the OR was 4.406 (95%CI: 1.537-12.631) in male centenarians and 2.035 (95%CI: 1.125-3.680) in female centenarians. Conclusion: Lower serum albumin level was associated with impaired health-related quality of life in centenarians in Hainan.

[Distribution characteristics of blood lipid profile in Hainan centenarians].

Objective: To explore the prevalence of lipid profile and the influencing factors of dyslipidemia in centenarians in Hainan province, and provide basic data for the study of the lipid profile in centenarians. Methods: The data of this study were from the baseline data of China Hainan Centenarian Cohort Study from June 2014 to December 2016. A total of 1 002 centenarians were recruited. According to the guidelines for the prevention and treatment of dyslipidemia in Chinese adults in 2016, the prevalence of lipid profile were described and the prevalence of dyslipidemia with different clinical classifications were compared, and the main influencing factors were analyzed. Results: The median levels of TC, TG, LDL-C and HDL-C were 4.60 mmol/L, 1.05 mmol/L, 2.77 mmol/L and 1.41 mmol/L, respectively, in centenarians in Hainan. Blood lipid profile level was higher in females than in males. With the increase of BMI, TC, TG and LDL-C increased significantly, while HDL-C decreased significantly. The total prevalence of dyslipidemia was 19.1%. Smoking, BMI and area distribution were the main influencing factors of dyslipidemia. Conclusion: The prevalence of dyslipidemia in centenarians in Hainan was at a low level compared with other countries, and the blood lipid profile level was higher in females than in males.

[Reference intervals for anemia-related routine blood test indicators in Hainan oldest-old and Hainan centenarians].

Objective: To investigate reference intervals for anemia-related routine blood test indicators in Hainan oldest-old and Hainan centenarians. Methods: A cross-sectional data set of China Hainan Centenarians Cohort Study (CHCCS) was used. Household interview, physical examinations, and blood sample analysis were conducted in accordance with standardized procedures. The hemoglobin level, red blood cell count, and hematocrit were analyzed with automatic biochemical analyzer and the reference intervals were determined following CLSI C28-A3 guidelines using a non-parametric method. Results: A total of 715 centenarians, including 137 males (19.2%), and 767 long-lived individuals aged ≥80 years, including 312 males (40.7%), were surveyed. The reference interval of hemoglobin level was 89.1-173.5 g/L in males and 94.4-146.0 g/L in females, respectively, in long-lived individual group. The reference interval of hemoglobin level was 68.4-145.6 g/L in males and 81.0-140.0 g/L in females, respectively, in centenarian group. Conclusion: The reference intervals of hemoglobin level, red blood cell count, and hematocrit were set for the first time for the oldest-old and centenarians in Hainan, which was lower than that currently used in adults.

[Relationship between obesity related anthropometric indicators and depression risk in Hainan centenarians].

Objective: To analyze the association of waist circumference, BMI, waist-hip ratio, waist-height ratio, calf circumference and waist-calf circumference ratio (WCR) with depression risk in centenarians in Hainan province. Methods: A total of 1 002 centenarians in Hainan were selected by cluster sampling. GDS-15 was used to investigate the depression. Multivariate linear regression and logistic regression analyses were conducted to evaluate the correlation between anthropometric indicators and depression risk. Restricted cubic spline was used to analyze and visualize the linear relationship. Results: After adjusting demographic characteristics (gender, age, ethnic group, marital status, educational level and type of residence) and lifestyle (smoking and drinking), the standard ß of BMI, WC, WHR, WHtR, calf circumference and WCR associated with GDS-15 were -0.069, -0.032,0.009, -0.009, -0.099 and 0.060, respectively, and the P values of BMI and calf circumference were <0.05. With the increase of calf circumference, the risk of depression decreased, OR value was 0.94 (95% CI:0.90-0.98), and after adjustment, the results were still significant. Classified variable analysis indicated with the decrease of calf circumference and the increase of WCR, the risk of depression increased gradually, the trend P values were 0.038 and 0.042, respectively. Conclusion: Central obesity (waist circumference and WCR) and periphery obesity (calf circumference) have differed effects on depression in centenarians, and increased calf circumference is a protective factor for depression in female centenarians, attention should be paid to the mental health of the elderly women with lower calf circumference.

Underweight in Men Had a Closer Relationship with Falls than Women in Centenarians.

The aim of the study was to assess the relationship between underweight and falls. It was a cross-sectional study in community-based participants from China Hainan Centenarian Cohort Study (CHCCS). A total of 942 centenarians (mean ages were 102.4 years in men and 102.9 years in women, 21.8% were semi-supercentenarians, and 3.2% were supercentenarians) were enrolled from July 2014 to December 2016. Height and weight were measured according to the standard protocol. Participants were interviewed face to face to self-report falls for recent 3 months. The risks of future falls were evaluated by Morse Fall Scale (MFS). The mean body mass index (BMI) was 19.04±2.79 kg/m2 in men and 18.07±3.27 kg/m2 in women. The 3-month incidences of once fall were 10.3% in men and 13.4% in women, recurrent falls were 15.4% in men and 13.4% in women, future high risks of falls were 36.6% in men and 44.3% in women. There were underweight by gender interactions on at least one fall (OR=1.39, 95% CI=1.04-1.86, P=0.026) and future high fall risk (OR=1.39, 95% CI=1.07-1.80, P=0.014). Men with underweight had higher ratios of at least one fall (OR=4.12, 95% CI=1.59-10.70, P=0.004), recurrent falls (OR=6.71, 95% CI=1.69-26.63, P=0.007) and high risk of future falls (OR=2.44, 95% CI=1.27-4.70, P=0.007), while women with underweight was only associated with high risk of future falls (OR=1.37, 95% CI=1.01-1.85, P=0.043). Compared with normal weight and overweight, underweight in men had a higher MFS Score (increased by average 7.6 points, P=0.010), yet this trend was not observed in women counterparts. Underweight was associated with incidences of 3-month and future high fall risk in centenarians, which was more pronounced in men. Underweight could be a marker in identifying potential falls in long-lived people, especially men, who need further measures to gaining weight to normal and preventing falling.

Trace Element Levels in the Elders over 80 from the Hainan Province of China.

Trace elements are key regulators of metabolism and physiological pathways, and their levels change during aging. Hair, as a biological sample, has attracted much attention due to its ease of collection and slow substance metabolism. Also, trace elements in hair can reveal the distribution of essential nutrients and toxic elements in the body pools. Therefore, we investigated the lifestyle and dietary status by questionnaire and measured 8 trace elements in hair and 6 elements in blood of a sample of elders over 80 residing in Hainan province of China. Our data showed that the concentration of Se, Fe and Pb dropped as people grow older, but Mn rose. Changes in trace elements may affect enzyme activity and biological pathways, and are associated with many diseases, including cancer and chronic diseases. In addition, association between age-related diseases and trace elements are increasingly being reported, suggesting that approaches of combining nutrition with longevity studies in the further study will help us to identify the mechanisms whereby trace elements affect the aging process.

[Prevalence of alcohol use and related factors in HIV positive and HIV negative males].

Objective: To understand the prevalence of alcohol use and related factors in HIV positive and HIV negative males. Methods: Baseline data were from the prospective cohort study of comparative HIV and aging research in Taizhou of Zhejiang province from January to December, 2017. The information about alcohol use in the last month was collected through a face-to-face questionnaire interview. Participants were categorized into non-current drinkers, light/moderate drinkers and heavy drinkers according to the US National Institute on Alcoholism and Alcohol Abuse (NIAAA) standard. Results: A total of 1 367 HIV positive males and 2 418 HIV negative males were included. Current alcohol use rate (35.2%, 481/1 367) and heavy alcohol use rate (5.0%, 24/481) were significantly lower in HIV positive males than in HIV negative males (48.0%, 1 161/2 418; 23.5%, 273/1 161), but the proportion of drinking wine and yellow rice wine were significantly higher (21.8%, 105/481; 9.1%, 44/481) in HIV positive males than in HIV negative males (13.5%, 157/1 161; 5.8%, 67/1 161). The multivariate multinomial logistic regression analysis results showed that larger waist circumference, current smoking and regular physical exercise were associated with heavy alcohol use behavior in HIV positive males, and age ≥30 years, current smoking, regular physical exercise, higher score of depressive symptoms, heterosexual transmission route and baseline CD(4)(+)T cells counts of 200-499 cells/µl were significantly associated with mild/moderate alcohol use behavior in HIV positive males. Conclusions: The alcohol use rate was significantly lower in HIV positive males than in HIV negative males in Taizhou. It is important to strengthen intervention on alcohol drinking behavior and chronic disease risk factors, such as larger waist circumference, smoking and so on.

[Characteristics of sleep disorder in HIV positive and HIV negative individuals: a cluster analysis].

Objective: To understand the characteristics of sleep disorder in HIV positive and negative individuals, and compare the distributions and epidemiologic characteristic of different subtypes of sleep disorder between two groups. Methods: Baseline data were from the prospective cohort study of comparative HIV and aging research in Taizhou of Zhejiang province from January to December, 2017. A total of 459 HIV positive patients and 798 HIV negative controls with sleep disorders (Pittsburg Sleep Quality Index >5 or at least one question with answers of "most nights" or "every night" for Jenkins Sleep Scale) were included in the analysis. Cluster analysis was conducted to identify the different subtypes of sleep disorder based on 15 sleep-related questions. Results: A total of 1 257 participants were divided into three groups (clusters), i.e. difficulty falling asleep and sleep keeping group (cluster 1), the mild symptoms group (cluster 2), and restless night and daytime dysfunction group (cluster 3), accounting for 19.4% (89/459), 63.8% (293/459) and 16.8% (77/459) in HIV positive group and 13.8% (110/798), 60.5% (483/798) and 25.7% (205/798) in HIV negative group (χ(2)=16.62, P<0.001). In HIV positive group, the patients in cluster 1 and 3 were older and had higher frailty score, the patients in cluster 1 had highest level of depression, and the more patients in cluster 3 had low body weight or overweight (χ(2)=13.29, P=0.039; χ(2)=23.33, P<0.001; χ(2)=25.71, P<0.001; χ(2)=15.37, P=0.004). In HIV-negative group, similar findings were found for age, depressive symptoms and frailty score. In addition, the proportion of those who were illiteracy or with primary school education level was significantly high in cluster 1, and the proportion of abnormal waist-to-hip ratio was significantly higher in cluster 1 and 3 (χ(2)=30.59, P<0.001; χ(2)=11.61, P=0.003). Conclusions: The proportion of every subtype of sleep disorder in HIV positive individuals were different to those in HIV negative individuals. Mental and physical health status were the main factors affecting the prevalence of sleep disorder. It is necessary to conduct targeted interventions to improve sleep quality.

[Association between mitochondrial haplogroups and neurocognitive disorder in HIV positive individuals].

Objective: To investigate the distribution of mitochondrial haplogroups and their correlation with neurocognitive disorder (NCD) in HIV positive individuals. Methods: Baseline data were from the prospective cohort study of comparative HIV and aging research in Taizhou of Zhejiang province from January to December, 2017. A cross-sectional survey was performed in 448 HIV positive individuals. Sanger method was used for the sequencing and genotyping of whole mitochondrial genome of HIV positive individuals. NCD prevalence in the HIV positive individuals was assessed by Mini-mental State Examination (MMSE) in questionnaire interviews. Multivariable logistic regression analysis was performed to assess the associations between mtDNA haplogroups and NCD. Results: In this sample, mitochondrial haplogroups D (19.6%, 88/448), B (19.4%, 87/448) and F(17.0%, 76/448) were the most predominant haplogroups. The overall prevalence rate of NCD was 20.3% (91/448), and was high in haplogroups A (23.1%, 9/39), D (21.6%, 19/88), F (26.3%, 20/76) and M7 groups (26.1%, 12/46), respectively. In multivariable logistic regression analysis after adjusting confounding factors, such as age and gender, compared with haplogroup A, there were no differences in the prevalence rate of NCD among HIV positive individuals with haplogroup B, D, F, M7, M8, N9, and others. Conclusion: The study explored primarily correlation between mitochondrial haplogroups and NCD among HIV positive individuals and suggested that there is no significant association between mitochondrial haplogroups and NCD, but further longitudinal investigation with large sample size of HIV positive population is needed to confirm this finding.

[Study on sleep quality and related determinants among centenarians in Hainan province].

Objective: To investigate the sleep quality and related determinants among centenarians in Hainan. Methods: A cross-sectional study of centenarians from 16 cities/counties was carried out in Hainan province between June 2014 and June 2016. Data related to demography, chronic diseases and lifestyles of the centenarians were collected. Pittsburg sleep quality index (PSQI) was used to assess the quality of sleep while multivariable logistic Regression model was used to determine the risk factors on the quality of sleep. Results: Of the 730 centenarians in this study, 225 suffered from sleep disorders (30.8%). The average score of PSQI was (6.44±3.05), with the top three problems related to sleep as sleep inefficiency (48.5%), sleep latency (35.5%), and daytime dysfuntion (20.6%) among the centenarians. Results from the multivariate logistic analysis showed that incontinence, cardiovascular disease and chronic pain were risk factors, while habitual afternoon nap, and regular diet appeared as protective factors (P<0.05), related to sleep disorder. Conclusions: Quality of sleep had been a problem to the centenarians in Hainan. Intervention on risk factors of sleep disorder should be helpful on these centenarians.

[Study on self-rated health and related factors in centenarians in Hainan province].

Objective: To investigate the self-rated health and related factors in centenarians in Hainan province. Methods: A cross-sectional study in centenarians from 18 cities and counties was carried out in Hainan between June 2014 and December 2016. They data about their demographics, chronic diseases, ability of daily life, mental health and sleep quality were collected in a household interview. Self-rated health status was classified into 5 degrees according to the subjective assessment by centenarians. Results: Of 991 centenarians in this study, 157 (15.8%) were in good self-rated health and 228 (23.0%) were in poor self-rated health. Multivariate logistic regression analysis showed that chronic pain, visual impairment, depression, limited ability of daily life and poor sleep quality were the factors associated with poor self-rated health in centenarians in Hainan (P<0.05). Conclusion: The proportion of centenarians in good self-rated health was low in Hainan, the influencing factors included chronic pain, visual impairment, depression, poor sleep quality and limited ability of daily life. It is necessary to conduct targeted intervention in centenarians in Hainan.

[China Hainan Centenarian Cohort Study: study design and preliminary results].

Objective: To investigate the health status, functional ability, mental psychology, health care and other longevity-related characteristics of individuals aged ≥100 years as well as risk factors in Hainan province, China. Methods: China Hainan Centenarian Cohort Study (CHCCS) is a community-based, prospective cohort study to establish multi-dimensional database consisting of questionnaire findings, anthropometric parameters and biological specimens as well as imaging features. With the household registration information provided by the Department of Civil Affairs of Hainan province, a baseline survey was conducted in centenarians in 18 counties in Hainan with the oldest old in 5 counties as controls between 2014 and 2017. The survey included face to face interview, physical examination and biological specimen collection. After the baseline survey, the participants of CHCCS were followed up at an interval of 2 years to collect the information about their living status, disease status or major death causes. Results: According to the information provided by the Department of Civil Affairs of Hainan province in 2014, the survey found that 1 473 centenarians were still living. By December 2016, 1 002 of them had agreed to be surveyed. The average age of 722 centenarians with complete information in the baseline survey was (102.7±2.7) years, the majority of them were females (83.0%), widows (88.8%), in Han ethnic group (84.5%), lived with family members (87.8%), illiterates (89.7%) and farmers (81.0%). Conclusion: CHCCS has provided longevity-related information of the large longevity population and collected the valuable and rare biological specimens with great urgency to establish an interdisciplinary platform and base for longevity, senility and healthy aging research.

An epidemiological investigation of congenital Schistosoma japonicum transmission in Hubei Province, PR China.

A cohort study was conducted in Hubei Province, China, following serious flooding of the Yangtze River in the autumn of 1998 to investigate the possibility of congenital transmission of Schistosoma japonicum in humans. The cohort investigated was comprised of 205 women and their 208 infants born between 1 September and 30 December 1998. Blood and fecal samples from all the women and their infants were collected and examined for S. japonicum infection. Positive specific antibody titers were found in 14 (6.8%) of the mothers, but no fecal egg excretion was observed. All infants had negative specific antibody titers and no S. japonicum eggs were found in their feces. Hence, the present study coud not confirm congenital S. japonicum transmission in humans. Further studies are highly wanted to study the impact of prenatal exposure of S. japonicum on the offspring.

Evaluation of a monoclonal antibody-based sandwich-ELISA for detection of circulating Schistosoma japonicum antigen (Sj31/32) in an endemic area of China.

A sandwich-ELISA specific for 31/32 kDa schistosome proteins was used to trace infections in a Chinese population living in a low endemicity area for schistosomiasis japonica. The study population included 304 persons for whom records were available from 1992 onwards. In 1994, 2 individuals were positive in the miracidial hatching assay performed with 30 g of stools. The ELISA gave positive results for 8 individuals, including these 2 with active infections. Of the remaining 6 ELISA-positive, 5 had excreted eggs and received praziquantel in 1993 and may have harboured residual worms in 1994. It is concluded that this ELISA is able, in a low prevalence situation, to identify the few infected individuals.