Weighted gene co-expression network analysis identifies important modules and hub genes involved in the regulation of breast muscle yield in broilers.

Objective: Increasing breast meat production is one of the primary goals of the broiler industry. Over the past few decades, tremendous progress has been made in genetic selection and the identification of candidate genes for improving the breast muscle mass. However, the molecular network contributing to muscle production traits in chickens still needs to be further illuminated. Methods: A total of 150 1-day-old male 817 broilers were reared in a floor litter system. At the market age of 50 d, eighteen healthy 817 broilers were slaughtered and the left pectoralis major muscle sample from each bird was collected for RNA-seq sequencing. The birds were then plucked and eviscerated and the whole breast muscle was removed and weighed. Breast muscle yield was calculated as the ratio of the breast muscle weight to the eviscerated weight. To identify the co-expression networks and hub genes contributing to breast muscle yield in chickens, we performed weighted gene co-expression network analysis (WGCNA) based on the 18 transcriptome datasets of pectoralis major muscle from eighteen 817 broilers. Results: The WGCNA analysis classified all co-expressed genes in the pectoral muscle of 817 broilers into 44 modules. Among these modules, the turquoise and skyblue3 modules were found to be most significantly positively (r=0.78, p=1e-04) and negatively (r=-0.57, p=0.01) associated with breast meat yield, respectively. Further analysis identified several hub genes (e.g., DLX3, SH3RF2, TPM1, CAV3, MYF6, and CFL2) that involved in muscle structure and muscle development were identified as potential regulators of breast meat production. Conclusion: The present study has advanced our understanding of the molecular regulatory networks contributing to muscle growth and breast muscle production and will contribute to the molecular breeding of chickens in the future.

Identification of Key Modules and Hub Genes Involved in Regulating the Color of Chicken Breast Meat Using WGCNA.

Meat color is one of the most important economic traits in chickens. However, the gene network and regulatory mechanisms contributing to meat color traits in chickens remain largely unknown. In the present study, we performed weighted gene co-expression network analysis (WGCNA) based on RNA-Seq datasets of 16 pectoralis major muscle samples from two yellow-feather chicken breeds to identify the modules and hub genes related to meat color in chickens. A total of 18,821 genes were used to construct the weighted gene co-expression network, and 29 co-expression gene modules were identified. Among these modules, five modules including blue, brown, steel blue, paleturquoise and orange modules were found to be significantly correlated with meat color traits. Furthermore, several genes within the association module involved in the regulation of mitochondrial activity (e.g., ATP5L, UQCR10 and COX7C) and lipid oxidation (e.g., CAV3, RBP4A and APOH) were identified as hub genes that may play a crucial role in the regulation of meat color. These results provide valuable information to improve our understanding of gene expression and regulation in relation to meat color traits and contribute to future molecular breeding for improving meat color in chickens.

Color Doppler ultrasound and contrast-enhanced ultrasound in the diagnosis of lacrimal apparatus tumors.

Color Doppler ultrasound and contrast-enhanced ultrasound (CEUS) in the diagnosis of lacrimal apparatus tumors were investigated. In total, 48 patients undergoing preoperative two-dimensional and color Doppler ultrasound and CEUS examinations were included in this study. Conventional ultrasound and CEUS characteristics of 48 patients pathologically and clinically diagnosed with lacrimal apparatus tumors were retrospectively analyzed. Results of conventional ultrasound of 29 cases with pleomorphic adenoma of lacrimal gland showed moderate-hypoechogenic solid masses in lacrimal gland; CEUS displayed two enhancement modes: High, fast-developed slow-extinct and overall uniform enhancement (20/29, 68.97%) and high, fast-developed slow-extinct, centripetal, uniform or non-uniform enhancement (9/29, 31.03%); after enhancement, the mass edge was clear without changes in size. Results of conventional ultrasound of 6 cases with adenoid cystic carcinoma of lacrimal gland showed hypoechogenic solid masses with unclear edge, irregular form, non-uniform echo, and abundant blood flow signals; the CEUS displayed high, fast-developed fast-extinct and overall uniform enhancement; after enhancement, mass edge was unclear and masses were larger than that in two-dimensional ultrasound. Results of conventional ultrasound of 10 cases with lacrimal sac cyst showed non-uniform, hypoechogenic masses, or cystic solid mixed masses with clear edge but no blood flow signal; the CEUS displayed peripheral circular enhancement and no enhancement inside. Results of conventional ultrasound of 3 cases with adenocarcinoma of lacrimal sac showed hypoechogenic solid masses with unclear edge, irregular form, non-uniform echo inside, and abundant blood flow signals in lacrimal sac; CEUS displayed high, fast-developed fast-extinct and overall uniform enhancement; after enhancement, masses with irregular shapes were obviously larger than that in two-dimensional ultrasound. CEUS shows the microcirculation of tumors and surrounding tissues. Combination of two-dimensional and color Doppler ultrasound can improve the preoperative qualitative diagnosis of tumors and provide references for the selection of operation methods and determination of tumor resection scope.

LOW SERUM BRAIN-DERIVED NEUROTROPHIC FACTOR BUT NOT BRAIN-DERIVED NEUROTROPHIC FACTOR GENE VAL66MET POLYMORPHISM IS ASSOCIATED WITH DIABETIC RETINOPATHY IN CHINESE TYPE 2 DIABETIC PATIENTS.

BACKGROUND/PURPOSE: The aim of our research was to investigate the potential role of brain-derived neurotrophic factor (BDNF) in diabetic retinopathy (DR). Measurement of serum circulating levels of BDNF and analysis of polymorphism of BDNF gene (Val66Met) were applied and compared with diabetic patients without DR. METHODS: From February 2014 and March 2015, all eligible patients with Type 2 diabetic mellitus at our hospital were consecutively recruited (N = 404). Their serum BDNF levels were detected by enzyme-linked immunosorbent assay. BDNF val66met polymorphism genotyping was conducted according to the laboratory's standard protocol. At baseline, demographic and clinical data were taken. The relationship of BDNF with DR was investigated with the use of logistic regression models. Receiver operating characteristic curves were used to test the overall accuracy of BDNF and other markers. RESULTS: Diabetic patients with DR and vision-threatening DR had significantly lower BDNF levels on admission (P < 0.0001 both). The BDNF genotyping results showed that there was no difference between the diabetic patients with DR and those without DR. Multivariate logistic regression analysis adjusted for common risk factors showed that serum BDNF levels were independent risk factors for DR (odds ratio = 0.86; 95% confidence interval [CI]: 0.80-0.92; P < 0.0001) and vision-threatening DR (odds ratio = 0.79; 95% CI: 0.75-0.85; P < 0.0001). Brain-derived neurotrophic factor improved the area under the receiver operating characteristic curve of the diabetes duration for DR from 0.69 (95% CI: 0.60-0.76) to 0.85 (95% CI: 0.79-0.90; P < 0.01) and for vision-threatening DR from 0.77 (95% CI: 0.67-0.87) to 0.86 (95% CI: 0.80-0.92; P < 0.01). CONCLUSION: The present study demonstrated that, rather than Val66Met polymorphism, decreased serum levels of BDNF were associated with DR and vision-threatening DR in Chinese Type 2 diabetic patients, suggesting a possible role of BDNF in the pathogenesis of DR complications.

PLD4 promotes M1 macrophages to perform antitumor effects in colon cancer cells.

Phospholipase D4 (PLD4) is a newly identified protein expressed in microglia. However, the function of PLD4 in tumor-associated macrophages (TAMs) is unknown. In the present study, we revealed that the expression of PLD4 was located in macrophages in the colon cancer mesenchymal and lymph nodes as shown by immunohistochemical analysis. furthermore, its expression was associated with clinical staging of colon cancer. Then, THP-1 as a cell model induced into TAMs. Western blot and RT-PCR analysis showed that PLD4 was mainly presented in M1 phenotype TAMs. The secretion of pro-inflammatory cytokines in M1 macrophages was significantly reduced after the expression of PLD4 inhibited by PLD4-siRNA. Furthermore, co-cultured with condition-medium from control or PLD4-siRNA M1 macrophages for 24 h, cell apoptosis, cycle and proliferation of cancer cells improved compared to control. These results indicated that PLD4 could be involved in the activation process of M1 phenotype macrophages.

Stromal interaction molecule 1 plays an important role in gastric cancer progression.

Studies have shown that stromal interaction molecule 1 (STIM1) is expressed in a variety of cancers and is related to tumor growth. The present study aimed to investigate the expression and roles of STIM1 in gastric carcinoma. Immunohistochemistry and western blotting revealed that STIM1 was expressed at higher levels in gastric cancer tissues (82%) than these levels in normal gastric tissues (42%). In addition, STIM1 was also expressed in tumor vascular endothelial cells. The effects of STIM1 on proliferation, apoptosis, adhesion, invasion and migration of gastric cancer cells were detected by MTT assay, flow cytometry, cell adhesion assay and Transwell assay, respectively. The results shown that STIM1 knockdown did not alter proliferation or apoptosis, but promoted cell adhesion and inhibited migration and invasion in the gastric cancer cells. In addition, STIM1 knockdown did not alter the expression or phosphorylation of mitogen-activated protein kinase (MEK) or extracellular signal-regulated kinase (ERK), implying that STIM1 affected gastric cancer cell migration through a pathway independent of the MEK/ERK pathway.

Genetic polymorphisms in the PDZK1 gene and susceptibility to gout in male Han Chinese: a case-control study.

PDZK1 acts as a scaffolding protein for a large variety of transporter and regulatory proteins, and has been identified in the kidney. The PDZK1 locus has been determined to be associated with the serum urate concentration. However, the evidence supporting this protein's association with gout is equivocal. In the current study, we investigated the association between two single nucleotide polymorphisms (SNPs) (rs12129861 and rs1967017) in the PDZK1 gene with gout in a male Chinese Han population. A total of 824 subjects were enrolled in this case-control study (400 gout cases and 424 controls). PDZK1 genotyping was carried out by polymerase chain reaction (PCR) and ligase detection reaction (LDR) assays methods. The relationships were evaluated using the pooled odds ratios (ORs) and their 95 % confidence intervals (CI). The results of our case-control study demonstrated that the gout and control groups exhibited significant differences in the distribution of genotypes at rs12129861 (OR = 0.727, P = 0.015) and rs1967017 (OR = 0.705, P = 0.016), suggesting that PDZK1 genetic polymorphisms were associated with increased risks of gout in male Han Chinese. However, there were no differences in the distribution of genotypes at rs12129861 (odds ratio (OR) = 0.744, P > 0.05) and rs1967017 (OR = 0.706, P > 0.05) in patients with gout with kidney stones and without kidney stones.

Histopathology of melanosis coli and determination of its associated genes by comparative analysis of expression microarrays.

Melanosis coli (MC) refers to the condition characterized by abnormal brown or black pigmentation deposits on the colonic mucosa. However, the histopathological findings and genes associated with the pathogenesis of melanosis coli remain to be fully elucidated. The present study aimed to examine the histopathological features and differentially expressed genes of MC. This involved performing hematoxylin and eosin staining, specific staining and immunohistochemistry on tissues sections, which were isolated from patients diagnosed with MC. DNA expression microarray analysis, western blotting and immunofluorescence assays were performed to analyze the differentially expressed genes of melanosis coli. The results demonstrated that the pigment deposits in MC consisted of lipofuscin. A TUNEL assay revealed that a substantial number of apoptotic cells were present within the macrophages and superficial lamina propria of the colonic epithelium. Expression microarray analysis revealed that the significantly downregulated genes were CYP3A4, CYP3A7, UGT2B11 and UGT2B15 in melanosis coli. Western blotting and immunofluorescence assays indicated that the expression of CYP3A4 in the normal tissue was higher than in the MC tissue. The results of the present study provided a comprehensive description of the histopathological characteristics and pathogenesis of MC and for the first time, to the best of our knowledge, demonstrated that the cytochrome P450­associated genes were significantly downregulated in melanosis coli. This novel information can be used to assist in further investigations of melanosis coli.

Human mesenchymal stem cells improve the neurodegeneration of femoral nerve in a diabetic foot ulceration rats.

Neuropathy is observed in 50% of diabetic patients with diabetic foot. This study attempted to explore the potential role of human mesenchymal stem cells-umbilical cord blood (hMSCs-UC) in femoral nerve (FN) neuropathy. The model rats were established by one time administration of streptozotocin and empyrosis on the dorsal hind foot. At 3d, 7d, 14d after treatment with hMSCs-UC or saline through left femoral artery, the serum NGF was examined by ELISA; NF-200 expression in FN was evaluated by immunohistochemistry; the diameter and roundness of FN, the ratio of capillary and muscular fiber of gastrocnemius were calculated under light microscope; and neuronal degenerations, such as demyelization, axonal atrophy, and loose arrangement of nerve fibers, were observed by electronic microscope. The results showed that, in hMSCs-UC-treated model rats, serum NGF was increased with higher positive rate of NF-200. Although the difference in FN diameters was not established among groups, improvement of roundness of FN was confirmed with increase in the numbers of capillary in FN-innervated gastrocnemius; additionally, degenerative neuropathy was significantly improved. Importantly, the functional study of electroneurogram (ENG) showed that, slowed conduction of FN in model rats was significantly restored by hMSCs-CU treatment. These data suggested that hMSCs-UC-treatment partially reverse the neuronal degeneration and nerve function of FN, which might be contributed by the upregulation of NGF with dramatic angiogenesis in FN-innervated gastrocnemius, consequently reversing neuronal structure and function, preventing or curing foot ulceration.

Synthesis and preliminary biological evaluation of 1,2,3-triazole-Jaspine B hybrids as potential cytotoxic agents.

Two series of more available novel 1,2,3-triazole-Jaspine B hybrids were efficiently synthesized employing click chemistry approach and evaluated for their cytotoxic activities against three human cancer cell lines (EC-9706, MGC-803 and MCF-7). Among them, compound 14h showed excellent inhibition against MCF-7 (IC50 = 1.93 µM) and was more potent than 5-Fu and Jaspine B against all three cancer cell lines. Further investigation of apoptosis assay and cell cycle analysis demonstrated that compound 14h caused cellular early and late apoptosis and arrested the cell cycle at G2/M phase in a concentration- and time-independent manner. This was the first report about the synthesis and in vitro cytotoxic evaluation of 1,2,3-triazole-Jaspine B hybrids.

Metformin may produce antidepressant effects through improvement of cognitive function among depressed patients with diabetes mellitus.

Diabetes mellitus and depressive disorders are both common chronic diseases that increase functional disability and social burden. Cognitive impairment is a potentially debilitating feature of depression. Previous evidence indicates that the antidiabetic drug metformin could be suitable for diabetic patients with cognitive impairment. However, there is no direct evidence from clinical studies that metformin treatment improves cognitive function in diabetic patients suffering from depression. In the present study, 58 participants diagnosed with depression and type 2 diabetes mellitus (T2DM) were recruited and divided into two groups, one treated with metformin and the other treated with placebo for 24 weeks. Cognitive function, depressive behaviour and diabetes improvement were evaluated. Chronic treatment with metformin for 24 weeks improved cognitive performance, as assessed by the Wechsler Memory Scale-Revised, in depressed patients with T2DM. In addition, metformin significantly improved depressive performance and changed the glucose metabolism in depressed patients with diabetes. Depressive symptoms were negatively correlated with cognitive performance in metformin-treated participants. Furthermore, associations were observed between the parameters of blood glucose metabolism and the depression phenotype. These findings suggest that chronic treatment with metformin has antidepressant behavioural effects and that improved cognitive function is involved in the therapeutic outcome of metformin. The results of the present study also raise the possibility that supplementary administration of antidiabetic medications may enhance the recovery of depression, comorbid with T2DM, through improvements in cognitive performance.

A cellular automaton model of Schistosoma japonicum infection.

Due to the life cycle complexity of Schistosoma japonicum and the characteristics of schistosomias is immuno-epidemiology, it is very challenging to give a group of certain rules and thus describe the transmission dynamics of S. japonicum with modelling approaches. Most existing epidemiological models for schistosomias is based on differential equations only track average worm burden without taking into account the individual variations, thus bear limitations on individual infection status monitoring and interpretation. In this paper, an improved stochastic model based on cellular automaton (I-SjCA, briefly) has been introduced to describe the transmission dynamics of human schistosomiasis japonica in an endemic area in China. This model reflects the process of the pathogen invasion from exposure to worm development and worm death when the infection is cleared; it also incorporates seasonality of infection, and stochastic behaviour of each individual in the study field. We show that based on the data collected from the 706 study participants, the model-predicted prevalence and intensity of S. japonicum in the 2nd year of investigation is comparable with the observation. Furthermore, we illustrate the use of model for evaluating possible control strategies for schistosomiasis in context of simulated prevalence and individual infection probability. The simulation results suggest that chemotherapy should cover no less than 85% of the S. japonicum infected population to guarantee an effective drug control program, and the best time for annual chemotherapy with praziquantel is the beginning of spring in the endemic area. Our findings indicate that I-SjCA model based on the cellular automaton can effectively simulate the transmission process. It is anticipated that our cellular automaton transmission model can serve as a tool for understanding schistosomiasis transmission dynamics and thus be conductive to build an effective control program.

Schistosoma japonicum soluble egg antigens attenuate IFN-γ-induced MHC class II expression in RAW 264.7 macrophages.

Innate immune response plays the key role in initiating and guiding the immune response. Elucidating the innate immune related molecular events involved in the interaction between the parasite and the host will aid in the development of an effective vaccine and anti-schistosome pharmaceuticals. In this study, we examined the regulatory effect of Schistosoma japonicum soluble egg antigen (SEA) on MHC class II expression in macrophage cell line RAW 264.7. We demonstrated that SEA possesses the ability to down-regulate IFN-γ-induced MHC class II expression in RAW 264.7 cells. The production of IL-10 and IL-6 in RAW 264.7 cells, induced by SEA, was responsible for mediating the down-regulation of MHC class II. Our findings suggest that in RAW 264.7 cells (1) IFN-γ provides a condition for lower concentrations of SEA to attenuate MHC class II expression; (2) SEA attenuated IFN-γ-induced MHC class II expression and the IL-10 and IL-6 production is mediated at least partly by the interaction of SEA with TLR4; and (3) SEA attenuated IFN-γ-induced MHC class II expression at the transcriptional level.

[Development of a software standardizing optical density with operation settings related to several limitations].

OBJECTIVE: To develop a software that can be used to standardize optical density to normalize the procedures and results of standardization in order to effectively solve several problems generated during standardization of in-direct ELISA results. METHODS: The software was designed based on the I-STOD method with operation settings to solve the problems that one might encounter during the standardization. Matlab GUI was used as a tool for the development. The software was tested with the results of the detection of sera of persons from schistosomiasis japonica endemic areas. RESULTS: I-STOD V1.0 (WINDOWS XP/WIN 7, 0.5 GB) was successfully developed to standardize optical density. A serial of serum samples from schistosomiasis japonica endemic areas were used to examine the operational effects of I-STOD V1.0 software. The results indicated that the software successfully overcame several problems including reliability of standard curve, applicable scope of samples and determination of dilution for samples outside the scope, so that I-STOD was performed more conveniently and the results of standardization were more consistent. CONCLUSION: I-STOD V1.0 is a professional software based on I-STOD. It can be easily operated and can effectively standardize the testing results of in-direct ELISA.

[Multi-dimensional evaluation system for schistosomiasis japonica transmission dynamic model].

OBJECTIVE: To evaluate the simulation effect of Schistosoma japonicum Cellular Automata (SjCA) model by using the multi-dimensional evaluation system. METHODS: Several selected indicators, including the Youden index, sensitivity, specificity, accuracy rate and prevalence distance were applied to assess the validity of the SjCA model. The effectiveness of each indicator for model evaluation was compared. RESULTS: Different indicators in the multi-dimensional evaluation system generated assorted combination of optimized parameters for the SjCA model. The best model according to prevalence distance (99.97%) did not guarantee the ultimate fit when using accuracy rate (79.70%) as the evaluation indicator. CONCLUSIONS: The multi-dimensional evaluation system is helpful for accurately assessing the simulation results of the discrete stochastic models such as SjCA, and is promising to be universalized to evaluate other similar epidemic dynamics models.

Seroprevalence of cysticercosis in children and young adults living in a helminth endemic community in leyte, the Philippines.

Cysticercosis is a significant public health problem in countries where pigs are raised for consumption and remains an important cause of neurological disease worldwide. The Philippines is considered an endemic area for cysticercosis because cases in both humans and pigs have been reported; however, epidemiologic information stays limited. We conducted a pilot survey of the seroprevalence of human cysticercosis in a village in Leyte, the Philippines, by measuring antibody specific for Taenia solium cyst-fluid antigen. There were 497 subjects aged 7-30 years in our study and most subjects were infected with one or more helminths. The overall cysticercosis seroprevalence in this population was 24.6% (95% CI: 20.82% ~ 28.58%) with no significant difference based on age, sex, or other helminth coinfection status. Although the sample may not be representative of the whole community, the findings suggest that cysticercosis is a significant, but underrecognized public health concern in the Philippines.

Simultaneous detection of serum immunoglobulin G antibodies to Cryptosporidium parvum by multiplex microbead immunoassay using 3 recognized specific recombinant C. parvum antigens.

Cryptosporidiosis is a significant diarrheal disease in both humans and other mammals worldwide. In the present study, we established and validated a multiplex microbead immunoassay (MIA) for surveillance of Cryptosporidium parvum infections. In the multiplex MIA, 3 specific recombinant proteins, CP23, SA35, and SA40, were used as the capture antigens simultaneously. The antibody directed against CP23 is an index of historic infection, and those against SA35 and SA40 are indices of recent infection. The multiplex MIA yielded essentially identical results with that of monoplex MIA using these 3 recombinant proteins, and the reproducibility of the multiplex MIA results was high when standardized with a calibration curve. With multiplex MIA, we detected that the pediatric population showed a higher percentage of recent infections (seropositive rates of antibodies directed against CP23, SA35, and SA40 were 6.28%, 23.19%, and 22.71%, respectively, n = 207), whereas the adult population showed a higher percentage of historic infections (seropositive rates of antibodies directed against CP23, SA35, and SA40 were 24.40%, 11.48%, and 16.75%, respectively, n = 209).

Evaluation of Kato-Katz examination method in three areas with low-level endemicity of schistosomiasis japonica in China: A Bayesian modeling approach.

The Kato-Katz technique is widely used to determine faecal egg counts of intestinal schistosomiasis. Although numerous studies have reported considerable underestimation of the 'true' infection prevalence while using this method, little is known regarding how many infections are missed as a function of the overall endemicity of intestinal schistosomiasis. In the present study, we used a Bayesian modeling approach to assess how much the Kato-Katz technique underestimates the prevalence of Schistosoma japonicum in three low endemic areas, characterized by different levels of infection. We found that up to 83% of S. japonicum infections were missed in an average when only a single Kato-Katz thick smear was examined. We further analyzed inter- and intra-specimen variation using agreement analysis. The results revealed a clear trend of higher agreement with infection intensity. In addition, our data also confirmed that intra-specimen consistency was better than that of inter-specimen. Our results suggest that a single Kato-Katz thick smear could only detect a certain small part of infections in areas with low endemicity; the disagreement of Kato-Katz results are mainly driven by day-to-day variation of eggs in stool; and light intensities are characterized by very high underestimation rates. There is a pressing need to develop more sensitive diagnostic tools for accurate detection of light infection intensities of schistosome infections.

Evaluation of IgG-ELISA for the diagnosis of Schistosoma japonicum in a high prevalence, low intensity endemic area of China.

Antibody-based diagnostic methods for detecting infection with Schistosoma japonicum have been developed and integrated into the national control program in China; however, the utility of these methods compared with conventional coprological methods remains unclear. In two consecutive years, we compared the performance characteristics of Kato-Katz with a commercially available enzyme-linked immunosorbent assay (ELISA) that detects anti-egg antigen IgG antibodies in a high prevalence, low intensity village in China (1025 subjects in 2005 and 652 subjects in 2006). In comparison with Kato-Katz based on duplicate stool specimens, each read in triplicate, the sensitivity of IgG-ELISA was high, ranging from 79.3% to 87.4% but with a relatively low specificity of 38.9% to 53.5%. The positive predictive value ranged from 20.8% to 24.6% while the negative predictive value ranged from 93.1% to 94.4%. When analyzed as continuous variables, there was a poor correlation between EPG (eggs per gram feces) and antibody level in both years (r(2005)=0.23 and r(2006)=0.41). We detected a trend toward reduced sensitivity at lower infection intensity as measured by Kato-Katz in 2005 (P=0.262) and 2006 (P=0.287). We evaluated changes in antibody levels and the prevalence of positive antibody in the cohort of subjects examined in both 2005 and 2006 (n=565). The prevalence of positive antibody but not the continuous antibody level, decreased in individuals who were uninfected at both time points or who transitioned from infected to uninfected as assessed by Kato-Katz. In this cohort, the distribution of antibody levels measured in 2006 among individuals who were positive by Kato-Katz in 2006 broadly overlapped with the distribution of antibody levels in individuals who were negative by Kato-Katz in both 2005 and 2006. Our results indicate fairly poor performance characteristics of the anti-egg antigen IgG-ELISA for the detection of active infection with S. japonicum in our community based sample and are in contrast with other reports based on more selected populations. The high prevalence but low intensity of S. japonicum in our study community reflects the evolving epidemiology of schistosomiasis in communities receiving intermittent treatment with praziquantel in China. We suggest marked caution in implementing anti-egg antigen IgG-ELISA based diagnosis for either individual level diagnosis or population-based targeting for national control programs.

Routine Kato-Katz technique underestimates the prevalence of Schistosoma japonicum: a case study in an endemic area of the People's Republic of China.

There is an evidence that the Kato-Katz technique lacks sensitivity and may hence be an unsuitable method for the assessment of the 'real infection status' in community with low-intensity infections. In this study, six Kato-Katz thick smears (examination of two stool samples with three thick smears each) were used as the diagnostic 'gold' standard for estimating the prevalence of Schistosoma japonicum infection and the results were compared with results based on fewer Kato-Katz thick smear readings. A total of 1055 individuals in 2005 and 725 in 2006 from an endemic village were recruited for the study. The observed prevalence increased gradually with the number of Kato-Katz thick smears examined, and hence the rate of underestimation decreased accordingly. The prevalence based on single Kato-Katz thick smear readings was significantly lower than that obtained using five or six thick smears. The rate of underestimation based on using two and three Kato-Katz thick smears, a typical diagnostic effort in the national schistosomiasis control programme, was about 36.0% (28.4-48.9%) and 25.0% (15.9-40.7%). The number of Kato-Katz thick smears required to secure detection of a S. japonicum infection varies with the infection intensity level. Indeed, examination of a single thick smear was sufficient when the geometric mean of the fecal content of eggs per gram (EPG) was 250 or higher in infected individuals, while six Kato-Katz thick smears were required when the EPG score was lower than 10. In conclusion, our results confirm that the prevalence of S. japonicum infection in a community is generally considerably "underestimated". Moreover, our findings provide a benchmark for the proper application of the Kato-Katz technique and the rational evaluation of the epidemic situation, as well as a scientific basis for constructing a mathematic diagnostic model.