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Purpose: Animal reservoirs are important targets for controlling and eliminating schistosomiasis. Prevalence studies showed that dogs (Canis familiaris) and water buffaloes (Bubalus bubalis) are important reservoirs of S. japonicum. Previous studies have validated the use of the recombinant proteins Sj1TR, Sj7TR, and SjTPx-1 in ELISA as diagnostics for dogs and water buffaloes from schistosomiasis-endemic areas. In this study, we aimed to determine the seroprevalence of S. japonicum among dogs and water buffaloes in New Corella, Davao del Norte, Philippines, using the recombinant proteins Sj1TR, Sj7TR, and SjTPx-1 in ELISA format., Methods: Fecal and serum samples were collected from dogs (n = 63) and water buffaloes (n = 57). Schistosome-positive samples were detected using formalin-ether concentration technique (FECT), stool polymerase chain reaction, and enzyme-linked immunosorbent assay (ELISA) using soluble egg antigen (SEA), rSj1TR, rSj7TR, and rSjTPx-1. Positivity rates, sensitivity, specificity, predictive values, accuracy, and kappa values were calculated., Results: Mean positivity rates for schistosome infection were high for both dogs (x = 15.40%) and water buffaloes (x = 6.32%). On dogs, the sensitivity and specificity of the tests are as follows: 66.67% and 100% for rSj7TR-ELISA, while 100% and 93.33% for rSjTPx-1-ELISA, respectively. rSjTPx-1-ELISA showed the highest agreement with stool PCR among all diagnostic tests, with an overall kappa value of 0.824. On water buffaloes, the sensitivity and specificity of both rSj1TR-ELISA and rSjTPx-1-ELISA are 100.0% and 98.15%. Both tests also had an overall kappa value of 0.84., Conclusion: To ensure elimination and prevention of schistosomiasis in humans, the use of validated serological diagnostics such as recombinant antigen ELISA is preferable for field detection in animals, especially in resource-limited areas., (© 2024. The Author(s), under exclusive licence to Springer Nature Switzerland AG.)

Secretory enzymes from Schistosoma japonicum are promising candidate antigens in the diagnosis of schistosomiasis. Our previous studies have proven that thioredoxin peroxidase-1 (SjTPx-1) is useful for the detection of this parasitic disease in humans, water buffaloes, and dogs. In this study, we evaluated two more secretory enzymes namely phosphoglycerate mutase (SjPGM) and phytochelatin synthase (SjPCS) with SjTPx-1 as the reference antigen. SjPGM was shown to have good diagnostic potentials in animal samples in previous studies, whereas SjPCS was chosen because of its absence in the mammalian hosts. Serum samples including 96 endemic negative controls, 107 schistosomiasis japonica positive samples, and 31 samples positive for other parasitic trematode infections (Clonorchis sinensis, Opisthorchis viverrini, Paragonimus westermani) were tested with the antigens using enzyme-linked immunosorbent assay. Results showed that SjPCS detected more positive samples and had fewer cross-reactions than SjPGM. With 85.05% sensitivity and 93.55% specificity, SjPCS can therefore be used in the detection of human schistosomiasis., (© 2022. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Palawan is the malaria-endemic province with the highest prevalence of malaria in the Philippines, and microscopists (community health workers) have been allowed to deliver early diagnosis and prompt treatment of malaria throughout the province since 1999. To improve the quality of care, the present mixed-methods study attempted to identify the factors associated with satisfaction of patients in Palawan with their microscopists by analyzing the patients' perspectives. First, a quantitative cross-sectional study was conducted among 48 ex-patients and their nine microscopists. Ex-patients were asked about their satisfaction with care, and microscopists were asked about their job satisfaction and ability. Structural equation modeling was conducted for data analysis. Second, a qualitative cross-sectional study was performed using narrative interviews. Data were analyzed using the NVivo 10 software program. As a result, both studies revealed high patient satisfaction with microscopists. The quantitative study showed that ex-patients' satisfaction with their microscopists was independently enhanced by two factors: high ability in malaria microscopic observation and low household wealth of the patients. Particularly, specific subpopulations (those with lower household wealth, relatively old people, and ethnic minorities) were more satisfied with the microscopists' care. The qualitative study strengthens this finding by showing that their microscopists offered prompt and precise diagnosis and effective treatment for free. In conclusion, microscopists were shown to have an important role in narrowing the disparities in malaria care in Palawan. It is important to maintain/enhance the ability of microscopists in malaria microscopy to satisfy their patients.

Background: This study was conducted to investigate the overall job satisfaction and its associated factors among microscopists as community health workers who specialize in malaria microscopic diagnosis and treatment in Palawan, the Philippines. The study offered new insights to further lessen the burden of malaria and improve treatment by enhancing their commitment and satisfaction., Methods: A quantitative study was conducted with 217 microscopists who were asked about their sociodemographic characteristics, ability as microscopists (service quality, knowledge of malaria and ability to diagnose malaria by microscopy [malaria microscopy]) and job satisfaction. Structural equation modelling (SEM) was conducted to analyse these factors. A qualitative study was also conducted and four focus group discussions (FGDs) were carried out., Results: SEM identified that the job satisfaction of microscopists was enhanced by ability in malaria microscopy, the annual parasite index and belonging to ethnic minorities. In the FGDs, high job satisfaction was seen in their devotion to the community and increasing knowledge about malaria., Conclusions: Providing opportunities to improve malaria microscopy ability would increase the overall job satisfaction of microscopists and eventually improve the quality of care., (© The Author(s) 2020. Published by Oxford University Press.)

This study aimed to determine the prevalence of Entamoeba histolytica in BASECO, an urban slum community situated in Manila Harbor, Manila, Philippines using stool enzyme-linked immunosorbent assay (ELISA). It also aimed to determine if age, sex, and geographic location are contributory factors to the prevalence of E. histolytica. Stool samples were collected from 627 urban slum community residents of BASECO. Samples were viewed under light microscopy and the different parasites observed were identified. Stool ELISA was done using E. histolytica II antigen detection kits (TECHLAB®). Using E. histolytica II kits, E. histolytica had a prevalence of 9.09% (5/55) among the microscopically-positive samples for E. histolytica/E. dispar indicating a greater prevalence for the nonpathogenic species. No significant difference was observed in the prevalence of infection across all three variables: age, sex and geographic location. The overall prevalence of E. histolytica in BASECO, Manila, Philippines is 0.797% (5/627) which is lower than previous studies done on estimating the prevalence of E. histolytica using various techniques.

In this study, we investigated the use of recombinant antigens thioredoxin peroxidase-1 (rSjTPx-1) and tandem repeat rSj1TR in evaluating the antibody positivity rates of Schistosoma japonicum infection among water buffaloes from four endemic areas in the Philippines, two municipalities with high endemicity (Calatrava, Negros Occidental and Catarman, Northern Samar) and two municipalities nearing elimination with no cases of human schistosomiasis (Talibon and Trinidad, Bohol). These recombinant antigen ELISA assays were compared with other diagnostic tests including SEA-ELISA, FECT, and fecal-based PCR. Results showed that rSj1TR-ELISA has the highest agreement with PCR in all study areas. Furthermore, significant positivity rates among water buffaloes were seen in Talibon and Trinidad, indicating that water buffaloes are maintaining the schistosome parasites in transmission areas even in the absence of human infection. Hence, serological assay using a more sensitive and specific rSj1TR-ELISA can be used for animal surveillance to prevent emergence and re-emergence of human schistosomiasis., (Copyright © 2020 Angeles, Goto, Kirinoki, Villacorte, Moendeg, Rivera, Chigusa and Kawazu.)

This study aimed to determine the prevalence of Entamoeba histolytica and Entamoeba dispar infections among residents in BASECO compound, Manila, Philippines using polymerase chain reaction (PCR). Formalin-ether concentration technique (FECT)-treated stool samples were examined under the light microscope to determine the presence of Entamoeba, helminths and other protozoan parasites. DNA was directly extracted from the FECT-treated samples and was subjected to PCR to determine E. histolytica and E. dispar infections. In this study, stool samples were collected from 2,232 residents of BASECO compound. Microscopic examination of FECT concentrated samples found 38 samples (1.703%) positive for E. histolytica/E. dispar. The E. histolytica/E. dispar microscopically positive samples were further analyzed by PCR and found 8 samples (0.358%) infected with E. histolytica and 23 samples (1.030%) infected with E. dispar. No statistically significant difference was observed in the sex distribution, while statistically significant difference was observed among the age group and area distribution of both the Entamoeba species. The results demonstrate PCR using DNA extracted from the formalin-fixed stools as an effective epidemiologic detection method of E. histolytica and E. dispar infections.

Humans and dogs live very close together and share various pathogens causing zoonotic parasitoses like schistosomiasis. A previous population genetics study done for schistosomes in the Philippines suggested that there is a high transmission level of Schistosoma japonicum among humans and dogs proving that the latter are important reservoirs for this zoonotic parasite. A more sensitive and specific test detecting schistosome infection in dogs will therefore strengthen the zoonotic surveillance, which might help in the possible elimination of this ancient disease. In this study, recombinant thioredoxin peroxidase-1 (SjTPx-1) and tandem repeat proteins (Sj1TR, Sj2TR, Sj4TR, Sj7TR) previously tested on human and water buffalo samples were used to assess its diagnostic applicability to dogs. Fifty-nine dog serum and stool samples were collected in the schistosomiasis-endemic municipalities of Calatrava, Negros Occidental and Catarman, Northern Samar in the Philippines and examined using the ELISA as compared to microscopy and fecal sample-based PCR. Samples positive for Babesia gibsoni and Dirofilaria immitis were also used to check for cross-reaction. Results showed that SjTPx-1 (80% sensitivity, 92.3% specificity) and Sj7TR (73.3% sensitivity, 92.3% specificity) have good potentials for diagnosing S. japonicum infection in dogs. These diagnostic antigens will therefore improve the surveillance in the transmission of the parasites from dogs to humans.

In this study, the diagnostic value of Schistosoma japonicum cathepsin B (SjCatB) was evaluated as an antigen for the early detection of S. japonicum infection. SjCatB is a key protease used by the cercaria to penetrate the intact skin of the host for transdermal infection. The early exposure of the host's immune system to this enzyme may elicit early production of antibodies against this molecule. Therefore, the recombinant SjCatB (rSjCatB) was expressed in Escherichia coli with N-terminal 6xHis-tag. rSjCatB was tested for its performance as a diagnostic antigen using indirect enzyme-linked immunosorbent assay (ELISA) with sera from experimentally infected mice collected at > 8 weeks post-infection. Showing 100% sensitivity and 95.0% specificity in the ELISA, rSjCatB was then evaluated with sera from experimentally infected mice collected at 1-7 weeks post-infection to determine how early the antibodies can be detected. Results showed that as early as 6 weeks post-infection, 2 of the 3 infected mice were found to be positive with the antibodies against SjCatB. Furthermore, the potential of the recombinant antigen in detecting human schistosomiasis was evaluated with archived serum samples collected from individuals who had been diagnosed with S. japonicum infection by stool examination. Results showed 86.7% sensitivity and 96.7% specificity suggesting its high diagnostic potential for human schistosomiasis. In addition, SjCatB showed minimal cross-reaction with the sera collected from patients with other parasitic diseases. In conclusion, the results of this study suggest that SjCatB will be useful in the development of a sensitive and specific early detection test for S. japonicum infection.

Background: Microscopists have active roles in bringing malaria diagnosis and treatment closer to households in Palawan, the highest malaria-endemic province in the Philippines. To accelerate the elimination of malaria in Palawan, we performed a study based on the bottom-up approach to provide profound data to strengthen this community-based malaria control from the microscopists' point of view., Methods: We performed a qualitative cross-sectional study in Palawan. Four focus group discussions with 50 microscopists were conducted in Palawan from November 2010 to February 2011. During the discussions, the following open-ended questions were addressed: motivation for applying to be microscopists in the "Past" category; job satisfaction, role, problems, and saddest and happiest experiences working as microscopists in the "Present" category; and willingness towards task shifting in the "Future" category. Data were transcribed and analyzed by framework analysis using the NVivo software program., Results: The present study innovatively proposed the following strategies: reinforcement strategy (adequate supplies and settings), highly prioritized additional strategies (improving social status of microscopists, issuing a travel budget, and including indigenous populations), regional additional strategies (additional malaria control in the southern region and task shifting in the northern region), and less prioritized additional strategies (employment policy and health checkup)., Conclusion: A bottom-up approach using microscopists' perceptions would be a valuable method to propose practical and effective additional strategies for strengthening community-based malaria control., Competing Interests: The present study was approved by the Research Ethics Committee of the University of Tokyo (No. 3001) and upheld by the Palawan Provincial Health Office. All participants clearly understood the principles of confidentiality and voluntary participation. Nobody related to this malaria control strategy project was involved while the microscopists were answering the questions posed to them.Not applicable.The authors declare that they have no competing interests.Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Asian schistosomiasis caused by Schistosoma japonicum is a serious zoonotic disease endemic in China, the Philippines and parts of Indonesia. Mass drug administration in endemic areas resulted to decline in disease severity and intensity. The low intensity of infection limits the use of current parasitological methods for schistosomiasis diagnosis. Detection of parasite circulating antigens might provide more informative result as it may indicate the true status of infection. In this study, S. japonicum thioredoxin peroxidase-1 (SjTPx-1) a 22 kDa secreted antioxidant enzyme expressed throughout the life stages of the parasite was evaluated for its potential use as a biomarker for schistosomiasis japonica infection. Rabbit polyclonal antibody and mouse monoclonal antibodies (mAbs) were raised against the recombinant SjTPx-1 (rSjTPx-1). The antibodies produced against the recombinant antigen was confirmed to detect the native SjTPx-1 in crude adult worm lysate. Likewise, the specific binding of mAbs to parasite TPx-1 and not to mammalian peroxiredoxin-1 orthologues was also confirmed. The double antibody sandwich ELISA developed in this study was able to detect at least 1 ng/ml of rSjTPx-1. In addition, this method was able to detect the antigen from all serum samples of experimentally infected rabbit and mice. The diagnostic potential of SjTPx-1 in human clinical samples was also evaluated, in which 4 out of 10 stool-confirmed serum samples had detectable levels of the antigen. The results suggest that SjTPx-1 can be a potential biomarker for Asian zoonotic schistosomiasis.

Background: Microsatellites have been found to be useful in determining genetic diversities of various medically-important parasites which can be used as basis for an effective disease management and control program. In Asia and Africa, the identification of different geographical strains of Schistosoma japonicum, S. haematobium and S. mansoni as determined through microsatellites could pave the way for a better understanding of the transmission epidemiology of the parasite. Thus, the present study aims to apply microsatellite markers in analyzing the populations of S. japonicum from different endemic areas in the Philippines for possible strain differentiation., Methodology/ Principal Findings: Experimental mice were infected using the cercariae of S. japonicum collected from infected Oncomelania hupensis quadrasi snails in seven endemic municipalities. Adult worms were harvested from infected mice after 45 days of infection and their DNA analyzed against ten previously characterized microsatellite loci. High genetic diversity was observed in areas with high endemicity. The degree of genetic differentiation of the parasite population between endemic areas varies. Geographical separation was considered as one of the factors accounting for the observed difference between populations. Two subgroups have been observed in one of the study sites, suggesting that co-infection with several genotypes of the parasite might be present in the population. Clustering analysis showed no particular spatial structuring between parasite populations from different endemic areas. This result could possibly suggest varying degrees of effects of the ongoing control programs and the existing gene flow in the populations, which might be attributed to migration and active movement of infected hosts from one endemic area to another., Conclusions/ Significance: Based on the results of the study, it is reasonable to conclude that genetic diversity could be one possible criterion to assess the infection status in highly endemic areas. Genetic surveillance using microsatellites is therefore important to predict the ongoing gene flow and degree of genetic diversity, which indirectly reflects the success of the control program in schistosomiasis-endemic areas.

Introduction: Palawan, where health care facilities are still limited, is one of the most malaria endemic provinces in the Philippines. Since 1999, microscopists (community health workers) have been trained in malaria diagnosis and feasibility of early diagnosis and treatments have been enhanced throughout the province. To accelerate the universal access of malaria patients to diagnostic testing in Palawan, positive health seeking behavior should be encouraged when malaria infection is suspected., Methods: In this cross-sectional study, structured interviews were carried out with residents (N = 218) of 20 remote malaria-endemic villages throughout Palawan with a history of suspected malaria from January to February in 2012. Structural equation modeling (SEM) was conducted to determine factors associated with appropriate treatment, which included: (1) socio-demographic characteristics; (2) proximity to a health facility; (3) health seeking behavior; (4) knowledge on malaria; (5) participation in community awareness-raising activities., Results: Three factors independently associated with appropriate treatment were identified by SEM (CMIN = 10.5, df = 11, CFI = 1.000, RMSEA = .000): "living near microscopist" (p < 0.001), "not living near private pharmacy" (p < 0.01), and "having severe symptoms" (p < 0.01). "Severe symptoms" were positively correlated with more "knowledge on malaria symptoms" (p < 0.001). This knowledge was significantly increased by attending "community awareness-raising activities by microscopists" (p < 0.001)., Conclusions: In the resource-limited settings, microscopists played a significant role in providing appropriate treatment to all participants with severe malaria symptoms. However, it was considered that knowledge on malaria symptoms made participants more aware of their symptoms, and further progressed self-triage. Strengthening this recognition sensitivity and making residents aware of nearby microscopists may be the keys to accelerating universal access to effective malaria treatment in Palawan.

The zoonotic characteristic of the human parasite Schistosoma japonicum infecting a significant number of wild and domestic animals highlights the need to develop a unified surveillance in multiple host species for a strengthened schistosomiasis control. It has been shown in several studies that water buffaloes and dogs are considered important reservoirs in the transmission of the schistosome parasite to humans. Recombinant antigens like thioredoxin peroxidase-1 (SjTPx-1) and tandem repeat proteins (Sj1TR, Sj7TR) have been shown to be good diagnostic antigens individually in humans, water buffaloes, and dogs in previous studies. Mixing these antigens together in a cocktail-ELISA might not only improve their diagnostic potentials but rather produce a multi-host species detection means for zoonotic schistosomiasis. In this study, we aimed to develop and optimize cocktail-ELISA by testing different combinations of these recombinant antigens in humans, water buffaloes, and dogs. As compared with the diagnostic potential calculated for each of the three recombinant antigens used, their combination has presented improved specificities, positive predictive values, and kappa values. Using samples collected from various endemic areas in the Philippines, results showed that the combination of SjTPx-1/Sj7TR/Sj1TR has the highest sensitivity in humans (84.1 %), water buffaloes, and dogs (80 %) and specificity (100 %) in all host species. This study therefore suggests the use of cocktail-ELISA in improving the zoonotic surveillance in schistosomiasis endemic areas.

The current status of schistosomiasis in highly endemic areas is difficult to determine by ovum detection because of the superficially low parasite load after mass drug administration, whereas the parasite transmission rates are still high. Cell-free parasite DNA is fragments of parasite-derived DNA existing in the host's body fluids. We conducted population-based studies to test the presence of cell-free schistosome DNA in endemic areas of Sorsogon Province, the Philippines. Schistosome DNA in the serum and urine of Kato-Katz (KK)-positive subjects was detected by PCR (100% sensitivity). Schistosome DNA was also detected from KK-negative subjects (9/22 serum and 10/41 urine samples). Schistosome DNA was found to be network echogenic pattern (NW)-positive (serum 53.3%, urine 42.9%) or NW-negative (serum 25.5%, urine 20.8%) and enzyme-linked immunosorbent assay (ELISA)-positive (serum 47.1%, urine 40%) or ELISA-negative (serum 33.3%, urine 13.3%). These results indicate that cell-free schistosome DNA is a promising diagnostic marker for active schistosome infection in the case of light infection., (Copyright © 2014 Elsevier B.V. All rights reserved.)

Palawan has the highest malaria endemicity in the Philippines, and malaria remains a major health burden in the region. In 1999, 344 microscopists were trained in Palawan. This allowed for early diagnosis and prompt treatment throughout the island. To take a significant step toward the elimination of malaria on the island, microscopists implemented community awareness-raising activities aimed at preventing transmission of malaria. The objective of the present study was to determine the impact of these activities on the self-implemented preventive measures against malaria by the ex-patients of the microscopists. Structured interviews were carried out from January to February in 2012, in 20 remote malaria-endemic villages throughout Palawan. In total, 141 ex-patients who had previously been diagnosed malaria-positive by the microscopists, volunteered to participate in the present study. Structural equation modeling was conducted to determine factors associated with self-implemented preventive measures against malaria, which included: (1) place of residence; (2) socio-demographic characteristics; (3) knowledge on malaria; (4) participation in community awareness-raising activities for malaria prevention; and (5) satisfaction with microscopists. Structural equation modeling identified six significant factors independently associated with self-implemented preventive measures against malaria; ethnicity, knowledge on malaria transmission, knowledge on vector species, knowledge on vector's most active time, participation in awareness-raising activities for malaria prevention by microscopists, and satisfaction with microscopists. Tagalog ethnicity (the predominant ethnic group) was positively related to better self-implemented preventive measures. In conclusion, aside from providing early diagnosis and treatment, microscopists played a significant role in self-implemented preventive measures against malaria. The strengthening of awareness-raising activities by microscopists was suggested to be an effective strategy for reducing malaria re-infection in Palawan. These activities should be strengthened to improve preventive measures implemented by ex-patients traveling to mountain areas and to enhance the knowledge on malaria transmission particularly among indigenous residents., (Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.)

Background: Malaria remains one of the most prevalent and fatal diseases among the inhabitants of Palawan in the Philippines. Palawan, where healthcare services remain limited, has the highest malaria endemicity in the country. To eliminate malaria, effective prevention measures should be conducted alongside early diagnosis and prompt treatment, which are the major tasks of the trained microscopists in Palawan. However, while the microscopists have implemented community awareness-raising activities aimed at preventing transmission of malaria, the nature and quality of these activities have not been evaluated. The present study identified the factors associated with the strengthening of community awareness-raising activities for malaria prevention implemented by microscopists in Palawan., Methods: A cross-sectional study was conducted among 127 microscopists in Palawan. Data were collected using self-administered questionnaires from November 2010 to February 2011. For data analysis, structural equation modelling was conducted, based on the questionnaire results, to identify the impact of factors associated with the number of community malaria awareness-raising activities implemented by microscopists using the following assessment indicators: (1) place of assignment; (2) annual parasite index; (3) microscopists' capacity (service quality, knowledge on malaria, and ability in malaria microscopy); (4) self-preventive measures against malaria; and (5) job satisfaction., Results: High microscopists' capacity was found to be a significant factor for a greater number of community awareness-raising activities for malaria prevention. High microscopists' capacity was significantly explained by its two sub-components: high service quality (active detection, diagnosis and treatment, prescription of anti-malarial, and follow-up) and high ability in malaria microscopy (preparation and documentation, slide preparation and observation, safe handling and disposal, and knowledge on the morphology of infected red blood cells)., Conclusions: Microscopists' capacity was identified as a significant factor in community awareness-raising activities for malaria prevention. Thus, the strengthening of service quality and ability in malaria microscopy should be of the highest priority.

Plasmodium falciparum is one of the causative agents of malaria in humans. This parasite causes the most severe forms of the disease. In order to combat the disease, it is important to have knowledge about the parasite and its interaction with its host. In this study, we profiled 74 patients admitted to hospital in Tagum, Davao, Philippines who were confirmed to be infected with P. falciparum. We correlated the age, sex and parasite load with malaria severity and show that among these, only sex is correlated with disease severity in this population. In addition, we profiled the MSP-1 block 2 allele distribution in the population and found that the most abundant allele form was K1, followed by MAD20. The RO33 allele form was the rarest allele in this population.

Sj7TR is a 13 kDa repetitive region of a 31 kDa protein in Schistosoma japonicum known as Sjp&#95;0110390 that showed high sensitivity and specificity in antibody detection against schistosomiasis patients. However, the current database for S. japonicum genes characterized it only as an expressed protein. A more thorough understanding of this antigenic protein is therefore necessary to possibly give more information about the nature of this protein and its role in the parasite. In this study, immunolocalization and expression profiling were done for Sjp&#95;0110390 on the different stages of the parasite. Immunofluorescent assay showed that Sjp&#95;0110390 was expressed in the young stages of the parasites including the schistosomula, eggs, aquatic and intra-molluscan stages. This was supported by the reverse-transcriptase PCR which confirmed the stage-specific expression of Sjp&#95;0110390 and Western blot test which detected the protein in the extracted eggs proteins, but not in the adults. Furthermore, it was also highly expressed in infected Oncomelania hupensis nosophora snails suggesting that Sjp&#95;0110390 might have a role in the development of the parasite inside the intermediate host. This result also suggests that Sj7TR might be used not only for human diagnosis but to detect snail infection as well., (Copyright © 2012 Elsevier B.V. All rights reserved.)

Background: The presence of animal reservoirs in Schistosoma japonicum infection has been a major obstacle in the control of schistosomiasis. Previous studies have proven that the inclusion of control measures on animal reservoir hosts for schistosomiasis contributed to the decrease of human cases. Animal surveillance should therefore be included to strengthen and improve the capabilities of current serological tests., Methodology/principal Findings: Thioredoxin peroxidase-1 (SjTPx-1) and four tandem repeat proteins (Sj1TR, Sj2TR, Sj4TR, Sj7TR) were initially evaluated against human sera. The previous test showed high sensitivity and specificity for antibody detection against SjTPx-1 and Sj7TR. In this study, the immunodiagnostic potential of these recombinant proteins was evaluated using enzyme-linked immunoassay on 50 water buffalo serum samples collected in Cagayan, the Philippines as compared with the soluble egg antigen (SEA). For specificity, 3 goat serum samples positive with Fasciola hepatica were used and among the antigens used, only SEA showed cross-reaction. Stool PCR targeting the S. japonicum 82 bp mitochondrial NAD 1 gene was done to confirm the true positives and served as the standard test. Twenty three samples were positive for stool PCR. SjTPx-1 and Sj1TR gave the highest sensitivity among the recombinant proteins tested for water buffalo samples with 82.61% and 78.26% respectively which were higher than that of SEA (69.57%)., Conclusions/significance: These results prove that SjTPx-1 works both for humans and water buffaloes making it a good candidate antigen for zoonotic diagnosis. Sj1TR showed good results for water buffaloes and therefore can also be used as a possible candidate for detecting animal schistosome infection.

Specific mutations in the pfcrt and pfmdr1 genes have been reported to be associated with chloroquine-resistant falciparum malaria parasites worldwide. These genetic markers are considered to be useful tools for the elucidation of several aspects of the epidemiology of drug resistant malaria. In this study, Plasmodium falciparum isolates from three distinct areas of the Philippines were analyzed for drug-resistance-associated genetic mutations, and their association with the in vitro chloroquine (CQ) response. Two novel pfcrt 72-76 allelic types, CVMDT and SVMDT, were detected. The frequency of the pfcrt K76T mutation in the isolates that were successfully tested for in vitro CQ susceptibility was found to be 100% in Kalinga, 80% in Palawan, and 87% in Mindanao. The frequency of the pfmdr1 N86Y mutation was 39% in Kalinga, 35% in Palawan, and 93% in Mindanao isolates. No mutations were found at positions 1042 and 1246 of pfmdr1. However, there were no significant associations found between polymorphisms in these genes and in vitro CQ susceptibility. The results of this study indicate that mutations in pfcrt and pfmdr1 are not predictive of in vitro CQ resistance in Philippine isolates and may therefore not be suitable as molecular markers for surveillance.

Background: In the Philippines, malaria morbidity and mortality have decreased since the 1990s by effective malaria control. Several epidemiological surveys have been performed in the country, but the characteristics of the Plasmodium falciparum populations are not yet fully understood. In this study, the genetic structure of P. falciparum populations in the Philippines was examined., Methods: Population genetic analyses based on polymorphisms of 10 microsatellite loci of the parasite were conducted on 92 isolates from three provinces (Kalinga, Palawan, and Davao del Norte) with different malaria endemicity., Results: The levels of genetic diversity and the effective population sizes of P. falciparum in the Philippines were similar to those reported in the mainland of Southeast Asia or South America. In the low malaria transmission area (Kalinga), there was a low level of genetic diversity and a strong linkage disequilibrium (LD) when the single-clone haplotype (SCH) was used in the multilocus LD analysis, while in the high malaria transmission areas (Palawan and Davao del Norte), there was a high level of genetic diversity and a weak LD when SCH was used in the multilocus LD analysis. On the other hand, when the unique haplotypes were used in the multilocus LD analysis, no significant LD was observed in the Kalinga and the Palawan populations. The Kalinga and the Palawan populations were, therefore, estimated to have an epidemic population structure. The three populations were moderately differentiated from each other., Conclusion: In each area, the level of genetic diversity correlates with the local malaria endemicity. These findings confirm that population genetic analyses using microsatellite loci are a useful tool for evaluating malaria endemicity.

Malaria is one of the major infectious diseases in the Philippines. It is being targeted for control through sustained early diagnosis, treatment and mosquito control. It is in this light that understanding the genetic background of the parasite population is important not only for basic biology of the organism but also for epidemiology and control of the disease. In the present study, molecular phylogenetic relationships of the 3 Plasmodium falciparum populations in the Philippines with the other populations in the world were inferred based on polymorphisms of 9 highly polymorphic microsatellite DNA loci in the parasite genome. A total of 92 P. falciparum isolates collected from 3 provinces (Kalinga, Palawan and Davao del Norte) in the Philippines, and 8 from other populations (3 African, 2 South American, 2 Papua New Guinean, and 1 Thai) that were previously reported, were used for the analysis. The phylogenetic tree showed that the 3 Philippine populations were genetically divergent from each other as compared to the other populations. The branching pattern of the tree suggests that the 3 Philippine populations were relatively close to the Thai population, rather than the Papua New Guinean populations, indicating that the ancestor of the 3 Philippines populations were introduced from Indochina peninsula, and not from countries located south of the Philippines such as Papua New Guinea or Indonesia.

Although the presence of multi-drug-resistant falciparum malaria has been reported in the Philippines, the distribution of drug-resistant malaria parasites has not yet been determined in Mindanao Island. In vitro susceptibility of P. falciparum to both chloroquine and mefloquine was assessed to forecast the spread of drug-resistant parasites in various foci in southeastern Mindanao Island. Of the 33 isolates of P. falciparum successfully tested, 10 (30%) were susceptible, 12 (36%) showed decreased susceptibility (80 nM < or = IC50 < 114 nM), and 11 (33%) were resistant (IC50 > or = 114 nM) to chloroquine. Ten (91%) of the resistant isolates and 9 (75%) of those with decreased susceptibility were from northern and northwestern Davao del Norte Province. Chloroquine-susceptible isolates were found among patients in the eastern parts of Davao del Norte and Davao Oriental provinces. Seven isolates from several foci in the study area were all mefloquine- susceptible (IC50 < 10 nM). This is the first report indicating the potential emergence of chloroquine-resistant P. falciparum on Mindanao Island, which is presently regarded as a drug-susceptible area.

The adhesion of Plasmodium falciparum-infected erythrocytes to vascular endothelium and to uninfected red blood cells (RBCs) plays a key role in the pathology of severe malaria. Adhesion is known to be mediated in part by the antigenically-variant erythrocyte membrane protein-1 (PfEMP-1), which is encoded by the var-gene family of P. falciparum. It has recently been reported that in vitro a single parasite simultaneously transcribes multiple var-genes but that, through a developmentally regulated process, the parasite selects only one PfEMP-1 that will to reach the surface of the host RBC. Were this to be true in vivo, one would expect a correlation between the type of var/PfEMP-1 that is expressed on the parasite-infected RBC and the severity of clinical disease. In order to test this assumption, we determined the sequence of the var-gene that was expressed by the parasites in patients' blood samples. Seven blood samples were collected from patients with or without severe clinical symptoms (cerebral malaria): two samples were from patients diagnosed as having imported falciparum malaria at the International Medical Center of Japan (IMCJ); the five others were from patients of the Davao Regional Hospital in Davao, the Philippines. The parasites (ring stage) in the blood samples were cultured for 24 hours; the matured trophozoites, in which the var-gene selection had taken place, served as material for mRNA isolation. The cDNA corresponding to the Duffy-binding-like (DBL)-1 domain of the var-gene was amplified by RT-PCR, using a region-specific primer set. The amplified cDNAs were cloned into the plasmid vector; the resultant clones (32) were sequenced on both strands. The results indicated that there was considerable diversity in the sequence of the DBL-1 domain among the clones, even among those from a single patient. In conclusion, it was difficult to demonstrate the correlation between the type of var-gene transcripts found in the RBCs of malaria patients and the severity of their symptoms.