Comparison of the heart rate-monitoring and factorial methods: assessment of energy expenditure in highland and coastal Ecuadoreans.

Accurate estimates of total daily energy expenditure (TDEE) are critical to studies of the nutritional adaptation of human populations. This study compared the standard factorial method with the recently developed flex-HR technique in a sample of 32 adults (16 males, 16 females) from rural, agricultural communities of highland and coastal Ecuador. Although energy expenditures obtained from the two methods were highly correlated (r = 0.759, P < 0.0001), the 1985 FAO/WHO/UNU factorial method significantly underestimated TDEE relative to the heart rate-monitoring technique (10.27 +/- 2.54 compared with 11.91 +/- 3.96 MJ/d, P < 0.001). The degree of underestimation was greater in males, who had higher energy expenditures. Similarly, underestimation was greater in the highland farmers, who were studied during a period of heavy agricultural work. The differences in energy expenditure estimates translated into a 10% difference in estimated energy adequacy. Additional research is needed to identify the potential sources of bias in the factorial method and to further develop other techniques for accurately estimating energy expenditure under field conditions.

HLA class II antigens are associated with resistance or susceptibility to hepatosplenic disease in a Chinese population infected with Schistosoma japonicum.

The major histocompatibility Class II alleles of 108 individuals living in an area endemic for schistosomiasis japonica in China were determined to identify possible immunogenetic associations with advanced schistosomiasis. Two alleles, HLA-DRB1*1202 (P = 0.002) and HLA-DQA*0601 (P = 0.001) were strongly associated with resistance to advanced disease. In contrast, HLA-DQB1*05031 (P = 0.02) was associated with susceptibility to advanced schistosomiasis. The remaining alleles showed no association with advanced disease. Allele DRB1*1202 co-occurred with allele DQA1*0601; therefore, their independent protective effects could not be ascertained. In contrast, alleles DQA1*0601 and DQB1*05031 never co-occurred and had opposite and significant effects on the occurrence of disease.

Epidemiology of Schistosoma japonicum in China: morbidity and strategies for control in the Dongting Lake region.

Dongting Lake, covering a very large surface water area of 2691km(2), is located in Hunan Province in the southern part of the People's Republic of China. It is the second-largest freshwater lake in China and plays an important role in regulating the amount of water in the Yangtze River, China's longest river. The annual water level of the lake changes by as much as 15m, rising in summer and falling in winter. Asian schistosomiasis has been endemic in the Dongting Lake region for centuries and it has had a devastating effect on the public health of the local people. After a difficult struggle for more than four decades, a concerted programme, supported by the World Bank Loan and instigated in 1992, has resulted in remarkable progress in the control of the disease in many endemic areas of the region. However, the great challenge remains to consolidate and maintain the achievements made to date. The Schistosoma japonicum intermediate host (Oncomelania hupensis hupensis) snail habitats are huge, estimated at 1768km(2) in 1996; these are increasing at a rate of 34.7km(2) annually due to high silt deposition from the Yangtze River itself and from the connecting rivers in Hunan province, and construction of embankments in the Dongting Lake region. It is anticipated that the construction of the Three Gorges Super Dam, the largest engineering project ever undertaken, will substantially extend the range of the snail habitats and increase the number of new schistosomiasis cases. In many areas, human re-infections with S. japonicum after drug (praziquantel) treatment remain unacceptably high (up to 20% of those treated are re-infected annually) due to occupational (mainly fishing) water contact. This paper reviews the history and the current status of schistosomiasis control in the lake region, it explores the epidemiological factors which influence the prevalence of the infection and the disease it causes, and it provides insight into future approaches to control which might finally eradicate the infection.

HLA class II antigens positively and negatively associated with hepatosplenic schistosomiasis in a Chinese population.

To identify possible associations between host genetic factors and the onset of liver fibrosis following Schistosoma japonicum infection, the major histocompatibility class II alleles of 84 individuals living on an island (Jishan) endemic for schistosomiasis japonica in the Poyang Lake Region of Southern China were determined. Forty patients exhibiting advanced schistosomiasis, characterised by extensive liver fibrosis, and 44 age and sex-matched control subjects were assessed for the class II haplotypes HLA-DRB1 and HLA-DQB1. Two HLA-DRB1 alleles, HLA-DRB1*0901 (P=0.012) and *1302 (P=0.039), and two HLA-DQB1 alleles, HLA-DQB1*0303 (P=0.012) and *0609 (P=0.037), were found to be significantly associated with susceptibility to fibrosis. These associated DRB1 and DQB1 alleles are in very strong linkage disequilibrium, with DRB1*0901-DQB1*0303 and DRB1*1302-DQB1*0609 found as common haplotypes in this population. In contrast, the alleles HLA-DRB1*1501 (P=0.025) and HLA-DQB1*0601 (P=0.022) were found to be associated with resistance to hepatosplenic disease. Moreover, the alleles DQB1*0303 and DRB1*0901 did not increase susceptibility in the presence of DQB1*0601, indicating that DQB1*0601 is dominant over DQB1*0303 and DRB1*0901. The study has thus identified both positive and negative associations between HLA class II alleles and the risk of individuals developing moderate to severe liver fibrosis following schistosome infection.

The psychological impact of diagnostic ultrasound.

The psychological impact of ultrasound scanning in pregnancy was examined in low- and high-risk pregnancies. Women in each category were assigned consecutively to a condition of either low or high feedback. In the latter condition, the women received extensive verbal and visual feedback, whereas in the former, subjects were denied visual access to the monitor. Psychological changes were measured using the State Anxiety Inventory and the Subjective Stress Scale. When a male partner attended, he was included in the assessment. The emotional impact of ultrasound was influenced by the level of feedback provided, with those in the high-feedback condition indicating significantly less anxiety and more positive emotional experiences during the scan, compared with those who received less feedback.

Epidemiologic features of Schistosoma japonicum among fishermen and other occupational groups in the Dongting Lake region (Hunan Province) of China.

In this study we examined 1,909 individuals (53% males and 47% females) to determine the current status of Schistosoma japonicum among the people in five fishing villages situated on two islands (large, Qingshan island; small, Niangashan island) in the Dongting Lake region in Hunan Province, the People's Republic of China. The results of this study indicate that the overall prevalence for schistosomiasis on the two islands is 16%. Two distinct peaks in prevalence (29%) were observed at 25-35 years of age and again at 45-55 years of age for both the large and small islands. On the small island the overall prevalence (24%) varied significantly (P < 0.01) from the large island (15%). Fishermen had the highest prevalence (22.4%) among all the occupational groups examined but students produced the highest worm intensity (geometric mean = 69 eggs per gram [epg] of feces). There was a significant difference (P < 0.01) in the prevalence of schistosomiasis between males and females. In general, males had a much higher prevalence (22%) than females (8.9%). When the study populations were classified as uninfected, lightly infected (10-100 epg), moderately infected (101-400 epg), and heavily infected (> 401 epg) with S. japonicum, the distribution pattern was similar for each of the five villages. The majority (76-88%) of the population remains uninfected. Lightly infected individuals had the highest prevalence (7-12%) followed by moderately infected individuals (1-9%). Only a very small percentage of the population was heavily infected (0-2%). Hepatomegaly along the midsternal line (MSL > or = 3) was commonly seen in both uninfected (21%) and infected individuals (1939%). Subjects heavily infected with S. japonicum reported significantly higher (P < 0.05) cases of liver enlargement when compared with those uninfected. The reported cases of abdominal pain for both uninfected (9%) and infected individuals (4-19%) was relatively high. Lightly and moderately infected individuals reported significantly (P < 0.05 and P < 0.01, respectively) more episodes of abdominal pain than those uninfected. The occurrence of diarrhea was low (5%) for uninfected individuals but this clinical feature was significantly (P < 0.01) more prevalent in both the lightly and heavily infected categories (8-17%).

A baseline study on the importance of bovines for human Schistosoma japonicum infection around Poyang Lake, China.

We hypothesize that bovine infections are responsible for the persistence of human schistosomiasis transmission in the Yangtze marshlands of China. To test this hypothesis, we are carrying out a comparative intervention among four administrative villages in the Poyang Lake region, Jiangxi Province, two of which are experimental and two are control. The primary design involves treating, at the onset of the study, all the inhabitants in all four villages with praziquantel and all the bovines in two villages (the experimental or intervention villages). Following treatment, rates of reinfection in people of all villages, and in bovines in the experimental villages, will be assessed as will the ongoing prevalence of infection in bovines in the control villages. Before treatment, the prevalence and intensity of infection among humans and bovines was ascertained in the four villages. Our study design and baseline information are presented here, along with a description of the ecology of the study villages.

Serological diagnosis of Schistosoma japonicum infections in China.

This paper reports the results of the dot enzyme-linked immunosorbent assay (dot-ELISA) for the serological diagnosis of 50 acute and 50 chronic Schistosoma japonicum-infected patients employing keyhole limpet haemocyanin (KLH) and soluble egg antigen (SEA) as the specific antigens. The sensitivity of both antigens for the detection of both forms of this infection was 100% and 90%, respectively, using a test serum dilution of 1:100. When the serum dilution was adjusted to 1:500, the sensitivity of the KLH dot-ELISA was 82% and 15%, respectively. Thus, the different manifestations of this disease can be easily distinguished. None of the 44 uninfected control sera gave a positive result with the KLH dot-ELISA, though 6 (14%) did so with the SEA dot-ELISA. Cross reactivity rates of 13% and 23% were observed for clonorchiasis (n = 30) and paragonimiasis (n = 22). Therefore, the overall diagnostic effectiveness of both the KLH dot-ELISA and SEA dot-ELISA for the detection of S. japonicum infection in endemic regions in China was 97% and 92%, respectively.

Diagnosis of schistosomiasis japonica in Chinese schoolchildren by administration of a questionnaire.

This paper describes a rapid, simple, cost-effective questionnaire for screening school-aged children at risk for Asian schistosomiasis in China. Five hundred and thirty-two children, aged 8-14 years, were selected from 3 schools in an area moderately endemic for Schistosoma japonicum in Hunan province. The questionnaire, comprising 15 multiple-choice questions, was administered by teachers in order to collect both ethnographic and epidemiological data relevant to current S. japonicum infections. This was followed by Kato-Katz thick smear stool examinations, miracidium hatching tests, and soluble egg antigen-enzyme linked immunosorbent assays in order to validate the efficacy of the questionnaire approach. The results from a combination of all 3 procedures indicated that the overall schistosomiasis prevalence in the 3 schools was 29.9% (138/472). Six risk factors (episodes of diarrhoea, frequency of water contact, school grade attained, weakness, past history of S. japonicum infection(s), and whether a subject had been previously treated for schistosomiasis) in the questionnaire were determined by logistic regression to be highly statistically significant predictors of individual current infection. The sensitivity (93.7%), specificity (91.9%) and low cost (c. US$ 0.6/true positive case) associated with the 6 variables model make the questionnaire approach a very useful diagnostic tool for screening marshland and lake communities at high risk for schistosomiasis in China before selective treatment with praziquantel or diagnostic follow-up. An even simpler 3 variables 'yes/no' model was derived from the questionnaire and found to be nearly as good at predicting individual infection (sensitivity 86.2% and specificity exceeding 97.6%) and extremely simple to use. If validated in other ecological settings in China the questionnaire, modified or as presented here, could be adopted by the national schistosomiasis control programme.

Human susceptibility to Schistosoma japonicum in China correlates with antibody isotypes to native antigens.

Antibody isotypic responses (IgE, IgA, IgG1, IgG2, IgG3 and IgG4) to Schistosoma japonicum antigens--adult worm (AWA), soluble egg (SEA) and the recombinant proteins TEG (22.6-kDa tegumental antigen, Sj22) and PMY (paramyosin, Sj97)--were measured (in 1998) in a cohort of 179 Chinese subjects 2 years post-treatment. Subjects in the highest intensity re-infection group (> 100 eggs per gram faeces) had significantly higher levels of IgG1 and IgG4 against AWA. Analysis of IgG4/IgE ratios for AWA and SEA linked IgG4 excess to re-infection and IgE excess to non-re-infection. Two years after chemotherapeutic cure, 29 subjects, who were re-infected or never infected but highly water-exposed, were classified as epidemiologically susceptible (n = 15) or epidemiologically insusceptible to infection (n = 14). IgG4 levels against native antigens (AWA and SEA) were higher in susceptible and IgE levels were higher in insusceptible but antibody responses to the recombinant proteins (PMY and TEG) showed no clear pattern or difference between susceptibility groups. These and earlier findings provide evidence that immunity develops against schistosomiasis japonica in China and that susceptibility/resistance correlates with antibody isotypes against native schistosome antigens.

Two-year impact of praziquantel treatment for Schistosoma japonicum infection in China: re-infection, subclinical disease and fibrosis marker measurements.

We studied a community cohort of 193 individuals exposed to endemic Schistosoma japonicum infection in the Dongting Lake region of China to assess subclinical morbidity and the 2-year benefit of curative therapy (praziquantel) administered in 1996. Prevalence and intensity of S. japonicum infection before treatment were 28% and 192 eggs per gram faeces (epg), respectively. Two years after cure, 22% of the cohort were re-infected, but with a lighter intensity (67 epg). Sixty-four subjects (37%) showed significant improvement in ultrasound parenchyma images after treatment and 51 subjects (54%) showed significant improvement of periportal fibrosis. Left-lobe enlargement also reversed (P < 0.05) and splenomegaly reversed in 6 of 8 cases and developed in only 1. Two years post-treatment a dilated portal vein became less frequent, but the decline was not significant (16% vs 11%, P < 0.05). The serum levels of laminin and collagen IV associated with re-infection and intensity and hyaluronic acid levels correlated with ultrasound findings (P < 0.01). Overall, treatment induced a marked decrease in subclinical hepatosplenic morbidity attributable to S. japonicum although low-intensity re-infection after treatment remained relatively frequent. Stratified analysis and logistic models evaluated potential confounding factors for assessment of treatment effects on hepatic fibrosis. S. japonicum infection and moderate-heavy alcohol intake interacted: improvement in parenchymal morbidity was impeded among drinkers (P < 0.05). Chemotherapy focused on at-risk residents controls prevalent subclinical hepatic fibrosis but re-infection indicates the need for complementary control strategies.

Faecal egg aggregation in humans infected with Schistosoma japonicum in China.

In this study we examine the variation in Schistosoma japonicum egg counts caused by differences in worm loads between individuals and the variability of egg counts within individuals with a given worm load. Six villages were selected from an area moderately endemic for Asian schistosomiasis in the Dongting Lake region (Hunan province), China. From a total population of 3451 individuals (53.8% male; x = 31 years), 163 subjects were identified as consistently stool egg-positive based on three successive positive Kato-Katz (KK) smears (41.67 mg/smear) obtained from one stool specimen. The distribution of eggs among individuals was found to be strongly aggregated (k = 0.27), but the distribution within the three smears was found to be only slightly aggregated (k = 2.59), indicating only minor clustering of eggs in stools. The relatively slight clustering of eggs within stool specimens suggests that a single KK smear may be quite adequate for detecting individuals moderately to heavily infected (> 100 eggs/g stool (epg)), as needed for a strategy of morbidity control. However, for estimating the true prevalence of infection in a community, or for obtaining an accurate estimate of egg excretion for research studies, multiple KK smears are warranted.

Measuring exposure to Schistosoma japonicum in China. III. Activity diaries, snail and human infection, transmission ecology and options for control.

We used activity diaries and snail detection to relate water contact and Schistosoma japonicum infection among a cohort of 178 residents on two islands in the Dongting Lake, China. Water exposure to each of 12 mapped water zones around the islands was calculated (m(2) min/day) for each subject. Infected Oncomelania hupensis hupensis snails in this area are focal and were found in only five of the 12 zones, with the highest rate being 5.7%. Thirty-one subjects (17%) were re-infected with a mean intensity of 63.2 epg. Mean water contact was 7.9 m(2) min/day; 98% of water exposure was due to economic activity and only 2% due to swimming or bathing, washing and other necessities of daily life. Males had more exposure and infection than females (P<0.05). Infected subjects had more exposure (10.2 m(2) min/day) than those not infected (7.44 m(2) min/day) (P<0.05). Compared with uninfected subjects, those infected had 2.9 times more exposure in infected-snail zones (P<0.01). Also, human infection intensity (epg) correlated well with exposure to infected snail zones (r=0.552, P<0.01). People <20 years old had the highest re-infection (21.4%) and intensity (3.77 epg). Median exposure for 20-49-year-olds (9.00 m(2) min/day) was nearly double that of those aged <20 or >50 years old (5.5 m(2) min/day). We conclude that map-referenced water contact and snail evaluation boosts accuracy of activity-diary measurements in large transmission foci for the Asian schistosome. Protecting against faecal contamination of snail inhabited sites, and against occupational exposure for island residents, should be a priority of future research. Potential strategies for migrating buffaloes and families living on visiting fishing boats are explored.

Antibody isotype responses, infection and re-infection for Schistosoma japonicum in a marshland area of China.

Antibody isotype responses to adult worm antigen (AWA) of Schistosoma japonicum and two recombinant proteins (paramyosin (PMY) and a 22 kDa tegumental membrane-associated antigen (TEG)) were analyzed in 137 individuals from an area moderately endemic for schistosomiasis in the Dongting Lake region, Hunan Province, China. The prevalence and geometric mean (GM) intensity of infection before the implementation of curative chemotherapy were 28.5% and 234.4 epg, respectively, but 9 months after treatment the prevalence (6.6%) and intensity (38.3 epg) had decreased. There was no significant difference in either the prevalence or intensity of infection between males and females. Specific IgG (total), IgG4, IgG2, IgA and IgE responses to AWA, PMY and TEG were measured by ELISA. Males produced significantly (P < 0.05) more anti-AWA total IgG, IgE, IgA, IgG4 and IgG2 antibodies, and anti-TEG IgG2 antibody than their female counterparts. The OD450 levels of anti-AWA, PMY and TEG antibody isotypes did not present clear age-dependent trends except for peak levels of anti-AWA IgG4 antibodies evident among subjects 20-29 years of age. The total IgG and IgG4 antibody profiles against AWA correlated well with current S. japonicum infections while anti-AWA IgG2, IgA and IgE antibodies did not show such an association. Anti-AWA-specific IgE antibody levels were positively correlated (r = 0.55) with anti-AWA specific IgG4 antibody levels. In addition, the overall percentage of responders (using a cut-off value obtained from normal controls) to all isotypes to AWA were higher than those observed for both the recombinant antigens. Only 18.2%, 16.8% and 7.3% of the study population were IgE responders to AWA, PMY and TEG. A longer follow-up period is required before we can more fully understand the role of IgE, if any, in protective immunity against schistosomiasis japonica.

Measuring exposure to S. japonicum in China. I. Activity diaries to assess water contact and comparison to other measures.

We introduce a new method, activity diaries, in order to evaluate human water contact among fishing communities in an area moderately endemic for Schistosoma japonicum in the Dongting Lake region of Southern China. Two hundred and forty-nine subjects (76% male) were followed prospectively over a 9-month-period in order to verify exposure and reinfection. Exposure was determined crudely with questionnaires, direct 12-h water observations, and more precisely with activity diaries and an adjusted exposure model which took into account the time of day, the duration of contact and the percent body surface area in contact with water. Cohort subjects filled in activity diaries for an average of 85 days as compared with 2 days for the direct water observations. The typical unadjusted mean daily water contact (duration) based on the activity diaries was 53 min with 62% of this time spent in fishing. In contrast, the direct water observations revealed an average daily duration of 149 min with 53% of the time spent in fishing. Human water contact patterns (min/day) by site, activity and body part exposed were examined with the activity diaries. Individuals in the 36-49-year-old age range had the highest degree of water contact. Most of this daily contact occurred by males on the hands (mean+/-S.D.; 83.53+/-67.80 min/day) while fishing (mean+/-S.D.; 87.84+/-8.88 min/day) on the lake (mean+/-S.D.; 85.98+/-69.90 min/day). There was a strong positive log correlation (r=0.95) between the crude and adjusted (based on our derived exposure model) diary outcomes for the entire study sample, however, at higher exposure levels this relationship was differentially weaker (r=0.70). Results from this study suggest that current methods used in evaluating schistosomiasis exposure in China may overestimate and bias measures of the risk of infection. Activity diaries adjusted for the time of day, duration and the percent body surface area exposed are cost-effective and practical instruments to accurately quantify human exposure in the vast lake regions of Southern China where most of the endemic schistosomiasis japonica occurs.

Measuring exposure to S. japonicum in China. II. Activity diaries, pathways to infection and immunological correlates.

In this study we examine the pathways to schistosomiasis exposure and infection among residents residing on two islands (large, Qingshan; small, Niangashan) in the Dongting Lake region (Hunan province) of China. An exposure model, based on activity diaries, was used to quantify an individual's square-metre-minute (sq.m.min) daily water contact. Subjects living on the small island had a significantly higher (P=0.0002) degree of exposure (mean+/-S.D., 13.2+/-11.0 sq.m.min) than individuals dwelling on the large island (mean+/-S.D., 5.5+/-7.1 sq.m.min). Participants identified as stool egg positive (mean+/-S.D., 8.3+/-10.4 sq.m.min) had higher exposures than for those never treated (mean+/-S.D., 2.2+/-3.4 sq.m.min) for schistosomiasis, and these high exposures rose steadily to peak at 35-49 years of age and decline after age 50. This exposure pattern differs markedly from those reported for African or South American schistosomiasis. The majority of human water contact occurs on the lake. Egg-positive subjects reported significantly higher (P < 0.05) episodes of water contact on the lake versus their egg-negative counterparts, who reported significantly higher (P < 0.01) exposure at the aquaculture ponds. The results of path analysis revealed that sex, age, island of residence and whether a fisherman or not were the most highly significant independent predictors of lake exposure. This accounted for approximately 40% (R2=0.39) of the total lake exposure. Exposure to lake water was a strong predictor (P=0.0006) of past infection and a modest predictor (P=0.05) of current infection.

An examination of current control strategies for Asian schistosomiasis in the Dongting lake region of China. II. A five year follow-up survey on Qingshan island.

In 1995-1996 we conducted an epidemiological survey in two communities (1656 individuals) on Qingshan island, Hunan province P.R. China, in order to determine the efficacy of current control strategies since their upgrading in 1991. In 1996, the overall prevalence for Schistosoma japonicum, Ascaris lumbricoides, Ancylostoma duodenale, and Trichuris trichiura had decreased moderately since 1991. The age-specific prevalence for S. japonicum for each of the representative age groups decreased slightly, but there was a significant reduction in these prevalences for the 5-9 (P < 0.01), 55-59 (P < 0.05) and the over 60 (P < 0.01) age groups. The 1996 intensities of infection for schistosomiasis were higher for all the age categories except for those aged 0-4 and 25-29 years of age. When the study population was further classified according to the percent uninfected, lightly infected (8-100 eggs/g (epg)), moderately infected (101-400 epg) and heavily infected (> 400 epg) for S. japonicum, there were fewer (5.6%) people infected in 1996 but the proportions of moderately (21.3 vs. 15.5%) and heavily (7.6 vs. 2.3%) infected individuals were higher than those observed in 1991. The reported cases of weakness and hepatomegaly (MSL > or = 3) were significantly lower (P < 0.01) in 1996 for both uninfected and infected (all intensities) individuals. General episodes of diarrhoea were also significantly lower in 1996 for those lightly (P < 0.05) and heavily (P < 0.01) infected. Likewise, the occurrence of splenomegaly (Hackett's > or = 2) was significantly lower among uninfected (P < 0.01) and heavily infected (P < 0.05) patients. In summary, although significant progress has been made in controlling schistosomiasis and other helminth infections in this highly endemic focus for schistosomiasis, there is still room for improvement. Chemotherapy for bovines and humans, mollusciding for Oncomelania control and health education should be initiated and upgraded if the health and well being of these island communities is to further improve.

PIP: The effectiveness of schistosomiasis control strategies implemented in 1991 were evaluated in a 1995-96 epidemiological study involving 1656 persons from two fishing villages on Qingshan Island in China's Hunan Province. In 1991, the prevalences of Schistosoma japonicum, Ascaris lumbricoides, A. duodenale, and Trichuris trichiura were 17.5%, 90.9%, 0.3%, and 46.5%, respectively. By 1996, these prevalences had dropped to 14.6%, 26.8%, 0.2%, and 4.0%, respectively. Despite an overall reduction in S. japonicum incidence, especially in the 5-9 and 55-59 year age groups, the proportion of moderate and heavy intensity infection was higher in 1996 than 1991, suggesting current dosages of praziquantel should be increased among the severely infected. Also recorded were reductions in S. japonicum-related morbidity--including weakness, hepatomegaly, diarrhea, and splenomegaly--among infected and uninfected persons. Since 1991, treatment coverage has increased for those aged 20 years and under and decreased among those older than 60 years. Recommended to ensure further public health advances are expanded treatment opportunities for humans, initiation of treatment of domestic animals and bovines, initiation of mollusciding in newly identified snail-positive habitats before the peak transmission period, and expanded health education programs.

An evaluation of Schistosoma japonicum infections in three villages in the Dongting lake region of China. I. Prevalence, intensity and morbidity before the implementation of adequate control strategies.

We examined three Chinese villages (one farming village and two fishing villages) in an area highly endemic for schistosomiasis japonica in order to study the prevalence, intensity of infection and the associated morbidities before the implementation of adequate control strategies. Socio-economic status, medical histories including the frequency and type of water contact, physical examinations, parasitological examinations and questionnaires relevant to the knowledge of schistosomiasis were performed on a random sample of 1542 individuals (45% female; 55% male). The prevalence of Schistosoma japonicum was 9.4% in the farming village and 16.5 and 26.2% in the fishing villages. Eighty-three percent of the infected population had light infections (8-100 eggs per gram stool (epg)) and only 6% had heavy infections (> 400 epg). Both the prevalence and intensity of infection varied significantly (P < 0.01) with the frequency of water contact. All the morbidity indicators (weakness, inability to work, diarrhoea, hepatomegaly and splenomegaly) were significantly higher (P < 0.01) among those infected with S. japonicum. Knowledge of schistosomiasis, in general, was unsatisfactory in all three villages; 12.4% of the population was infected when their knowledge of schistosomiasis was good, whereas 26.6% of the population was infected when their knowledge was poor. Further, it appears that schistosomiasis control based on selective chemotherapy (praziquantel) of randomly selected stool-positive individuals was ineffective in significantly reducing the prevalence of S. japonicum and its associated clinical manifestations in the villages under study.

Production of interleukin-10 by peripheral blood mononuclear cells from residents of a marshland area in China endemic for Schistosoma japonicum.

Interleukin-10 (IL-10) cytokine production was assessed using peripheral blood mononuclear cells (PBMC) from 67 individuals living in an area endemic for schistosomiasis japonica in China (Dongting Lake, Hunan Province), and 11 control subjects from a non-endemic part of the same Province. Production of IL-10 was measured following in vitro stimulation of PBMC using whole parasite extract (SWAP) or a panel of recombinant Schistosoma japonicum antigens (22-kDa tegumental membrane-associated antigen, glyceraldehyde-3-phosphate dehydrogenase, paramyosin, 14-kDa fatty acid-binding protein and 28-kDa glutathione S-transferase) which are of recognized interest in the development of protective immunity to schistosomiasis. Significantly, PBMC isolated from the exposed population compared with the non-exposed population produced higher levels of IL-10. There was a trend towards higher mean levels of IL-10 release in putatively resistant (insusceptible) (consistently egg negative but highly exposed) individuals compared with susceptible (egg-positive) subjects from the exposed population. Analysis of individual exposure (the duration of water contact and the percent body surface area in contact with water, expressed as m2 h/day) vs. IL-10 production indicated a weak but consistent and statistically significant inverse correlation, with lower levels of exposure being associated with higher levels of IL-10. These results suggest an association between IL-10 production and resistance to S. japonicum in subjects from this Chinese population exposed to infection.

Evaluation of alpha interferon for the treatment of chronic hepatitis B infection in Christchurch.

AIM: To evaluate alpha interferon for the treatment of chronic replicative hepatitis B infection in Christchurch patients. METHODS: Ten patients were divided into two groups depending upon whether their average pretreatment ALT levels were greater than twice the upper limit of normal (group 1, 6 subjects) or less than twice the upper limit of normal (group 2, 4 subjects). Interferon alpha-2a (4.5 mega units) was administered three times a week for 24 weeks with the addition of a preceding priming course of prednisone in group 2. RESULTS: At 6 months post treatment only one patient in group 1 had seroconverted (HBeAg to anti-HBe), however, the remaining five patients seroconverted from 18-32 months after therapy. This response was associated with normalisation of the transaminases and in 5/6 subjects a fall in the HBV DNA levels. In group 2 one subject seroconverted by 6 months despite a shortened course of Interferon. A delayed seroconversion (18 months) was observed in one patient and another had a partial response with the development of anti-HBe but associated with persistence of HBeAg. The remaining patient has not responded. CONCLUSIONS: Interferon alpha-2a was effective in promoting a seroconversion HBeAg to anti-HBe in patients with chronic hepatitis B and transaminases elevated to twice the upper limit of normal, although in most cases this response was delayed. Larger studies will be required to determine the role of steroid priming in those with less active disease.