Schistosoma japonicum is endemic in the Philippines, China and Indonesia, and infects more than 40 mammalian host species, all of which can act as reservoirs of infection. In China, water buffaloes have been shown to be major reservoirs of human infection. However, in the Philippines, carabao have not been considered important reservoir hosts for S. japonicum due to the low prevalence and infection intensities reported, the only exception being a qPCR-based study indicating 51% of carabao were S. japonicum-positive. However, the low prevalence found for the same animals when using conventional copro-parasitological techniques means that there is still confusion about the role of carabao in the transmission of schistosomiasis japonicum. To address this inconsistency, and to shed light on the potential role of carabao in the transmission of S. japonicum in the Philippines, we undertook a pilot survey, collecting fecal samples from animals in Western Samar Province and we used a combination of molecular and copro-parasitological techniques to determine the prevalence and intensity of S. japonicum. We found a high prevalence of S. japonicum in the carabao using a validated real-time PCR (qPCR) and a copro-parasitological tool, the formalin-ethyl acetate sedimentation (FEA-SD) technique. A much lower prevalence of S. japonicum was recorded for the same fecal samples using conventional PCR, the Kato-Katz technique and miracidial hatching. These results suggest that, due to their low diagnostic sensitivity, traditional copro-parasitological techniques underestimate infection in carabao. The use of FEA-SD and qPCR provides a more accurate diagnosis. Based on these findings, the role of bovines in the transmission of S. japonicum appears to be more important in the Philippines than previously recognized, and this may have significant implications for the future control of schistosomiasis there, particularly as, in contrast with previous surveys, we found an unprecedented high prevalence of S. japonicum in humans.

Schistosomes infect ϳ40 million women of childbearing age and result in the elaboration of proinflammatory cytokines that have been implicated in fetal growth restriction. In murine models and two observational studies in humans, schistosome infection during pregnancy was associated with reduced birth weight, although a recent treatment trial in Schistosoma mansoni did not detect this association. We conducted an observational study among 99 pregnant women living in an area of Schistosoma japonicum endemicity in the Philippines. We enrolled women at 32 weeks gestation and measured S. japonicum and geohelminth infection intensity. We collected maternal peripheral blood at 32 weeks gestation and placental and cord blood at delivery to assess inflammatory status. At delivery, we collected a placental-tissue sample and measured birth weight. In multivariate models adjusted for geohelminths, maternal schistosomiasis was associated with increased levels of inflammatory cytokines in maternal peripheral (tumor necrosis factor alpha [TNF-␣] and interleukin 10 [IL-10]), placental (TNF-␣, IL-6, TNF-␣ receptor II [RII], and IL-1␤), and cord (IL-1␤ and TNF-␣ RII) blood, as well as acute subchorionitis and increased TNF-␣ production by syncytiotrophoblasts assessed by immunohistochemistry (all P < 0.05). After adjusting for confounders, placental IL-1␤, and TNF-␣ production by syncytiotrophoblasts was independently associated with decreased birth weight (both P < 0.05). Our data indicate that maternal schistosomiasis results in a proinflammatory signature that is detectable in maternal, placental, and fetal compartments, and a subset of these responses are associated with decreased birth weight. This potential mechanistic link between maternal schistosomiasis and poor birth outcomes will contribute to the debate regarding treatment of maternal schistosome infections.Healthy successful pregnancies are characterized by a placental microenvironment that is biased toward a T-helper cell type 2 (Th2) cytokine milieu (16,23). Parasitic diseases, including malaria and leishmaniasis, alter the placental Th2 bias toward a proinflammatory microenvironment and are associated with poor pregnancy outcomes (29,39,48). These data are consistent with animal models of pregnancy that establish that increased systemic and placental gamma interferon (IFN-␥) and tumor necrosis factor alpha (TNF-␣) levels produce poor pregnancy outcomes (10, 50). They are also consistent with the marked increase in prematurity and IUGR accompanying human pregnancies complicated by systemic proinflammatory diseases, such as systemic lupus erythematosis, rheumatoid arthritis, and falciparum malaria (18,33,55).Human schistosomiasis, caused by three main species of tissue-invasive parasitic trematodes, infects over 200 million individuals, including ϳ40 million women of childbearing age, and remains a significant cause of morbidity and mortality in developing countries (35). Human infection with schistosomes results in the elaboration of proinflammatory cytokines, inc...

Although schistosomiasis is effectively treated with Praziquantel, rapid reinfection with rebound morbidity precludes effective control based on chemotherapy alone and justifies current efforts to develop vaccines for these parasites. Using a longitudinal treatment-reinfection study design with 616 participants 7 to 30 years of age, we evaluated the relationship between cytokine responses to Schistosoma japonicum soluble adult worm extract (SWAP), Sj97, Sj22.6, and Sj67, measured 4 weeks after treatment with Praziquantel, and resistance to reinfection in a population from Leyte, The Philippines, where S. japonicum is endemic. S. japonicum transmission was high: 54.8% and 91.1% were reinfected within 6 and 18 months, respectively. A Th2 bias in the following cytokine ratios, interleukin-4 (IL-4)/IL-12, IL-5/IL-12, IL-13/IL-12, IL-4/gamma-IFN (IFN-␥), IL-5/ IFN-␥, and IL-13/IFN-␥, in response to SWAP predicted a 1.4-to 2.9-month longer time to reinfection (P < 0.05) and a 27 to 55% lower intensity of reinfection (P < 0.05). Similarly, a Th2 bias in response to Sj97 predicted a 1.6-to 2.2-month longer time to reinfection (P < 0.05) and a 30 to 41% lower intensity of reinfection (P < 0.05). Only a high IL-5/IL-10 ratio in response to Sj22.6 predicted a 3.0-month-longer time to reinfection (P ‫؍‬ 0.03). Cytokine responses to Sj67 were not associated with protection. In a large population-based treatment-reinfection study we found that Th2 responses to SWAP and Sj97 consistently predicted resistance to reinfection. These findings underscore Th2-type immune responses as central in human resistance to S. japonicum and support Sj97 as a leading vaccine candidate for this parasite.

We conducted a prospective cohort study in Leyte, the Philippines, among 611 Schistosoma japonicum-infected participants 7-30 years old, all of whom were treated with praziquantel at baseline. To detect hepatic fibrosis, abdominal ultrasound was performed at baseline and 12 months after treatment. Stool for assessment of S. japonicum infection was collected at baseline and at 3, 6, 9, and 12 months after treatment. Cytokines (interleukin [IL]-4, IL-5, IL-10, IL-13, tumor necrosis factor- alpha , and interferon- gamma ) produced by peripheral-blood mononuclear cells in response to soluble worm antigen preparation (SWAP), soluble egg antigen (SEA), and control medium were measured once 4 weeks after treatment. IL-4 to SWAP and IL-10 to both SWAP and SEA were associated with the presence of baseline fibrosis after adjustment for potential confounding variables (P<.03, for all). In participants with fibrosis at baseline, IL-4 to SWAP and IL-5 and IL-13 to both SWAP and SEA were associated with persistent fibrosis at 12 months after treatment (P<.05, for all). Males showed consistently stronger T helper 2 (Th2) cytokine responses to both SWAP and SEA than did females (P<.02, for all). These results suggest an independent role for Th2-biased cytokine responses to S. japonicum antigens in persistent hepatic fibrosis and indicate that Th2 cytokines may contribute to the male-biased prevalence of fibrosis.

Schistosomiasis remains a public health concern in developing countries, and rapid reinfection fostered by continued exposure to contaminated water sources necessitates a vaccine to augment current mass treatmentbased control strategies. We report isotype-specific (immunoglobulin A [IgA], IgE, IgG1, IgG4, and IgG) antibody responses to soluble worm antigen preparation and the recombinant vaccine candidates rSj97, rSj67, and rSj22 from a Schistosoma japonicum-infected cohort in Leyte, the Philippines, where schistosomiasis is endemic. Sera were collected from infected individuals 1 month posttreatment with praziquantel, and antibody responses were measured using a bead-based multiplex platform. Reinfection was monitored by stool sampling every 3 months, and data up to 1 year were included in the analysis (n ‫؍‬ 553). In repeated-measures models, individuals with detectible IgE responses to rSj97 had a 26% lower intensity of reinfection at 12 months posttreatment compared to nonresponders after adjusting for age, gender, village, exposure, pretreatment infection intensity, and clustering by household (P ‫؍‬ 0.018). In contrast, IgG4 responses to rSj97 as well as rSj67 and rSj22 were associated with markedly increased reinfection intensity. When stratified by IgG4 and IgE responder status, individuals with IgE but not IgG4 responses to rSj97 (n ‫؍‬ 16) had a 77% lower intensity of reinfection at 12 months compared to individuals with IgG4 responses but not IgE responses (n ‫؍‬ 274), even after adjusting for potential confounders (P ‫؍‬ 0.016). Together with our previously described protective cytokine responses, these data further support paramyosin as a leading vaccine candidate for human schistosomiasis japonica and underscore the importance of careful adjuvant selection to avoid the generation of blocking IgG4 antibody responses.

Studies addressing the relation between chronic schistosomiasis japonica and nutritional status are limited. We conducted a longitudinal treatment-reinfection study in Leyte, the Philippines, among 477 Schistosoma japonicum-infected subjects aged 7-20 y, to evaluate changes in nutritional status after treatment with praziquantel. Stool, Tanner stage, anthropometric indices, and hemoglobin (Hb) were evaluated at baseline, 4 wk post-treatment, and every 3 mo for 18 mo. Height-for-age Z-score (HAZ) and BMI Z-score (BMIZ) were calculated. Change scores relative to baseline were created for all outcome measures. Multilevel repeated-measures analyses were used to adjust for socioeconomic status, sex, either pubertal status or age, and household-level clustering. Z-scores improved modestly but significantly over time. BMIZ in children wasted at baseline improved the most [0.41 (0.26-0.56) Z-score unit] and HAZ improved only in children stunted at baseline [0.17 (0.l2-0.21) Z-score unit]. Hb improvement peaked at 15 mo and occurred only in subjects that were anemic at baseline [peak improvement: 8.3 (6.0-10.6) g/L] and in males [peak improvement 4.7 (2.9-6.6) g/L]. Reinfection, evaluated as egg count over time and egg count 3 mo earlier to assess a delay in effect, was inversely associated with improvement in Hb (P = 0.06 and 0.004, respectively). High-intensity reinfection at 18 mo was associated with significantly less absolute growth from baseline compared with lower-intensity and no reinfection. Based on the peak Hb improvement at 15 mo post-treatment, annual treatment intervals are recommended to reduce schistosomiasis-associated nutritional morbidity.

Schistosomiasis is associated with undernutrition, but the mechanisms involved remain unknown. We analyzed baseline and follow-up data from a longitudinal treatment-reinfection study in N = 477 Schistosoma japonicum-infected subjects 7-20 years of age from Leyte, the Philippines. After baseline treatment with praziquantel, follow-up visits were scheduled every 3 months for 18 months; stool, venous blood, and anthropometric measurements were collected at each visit. Cytokine production by peripheral blood mononuclear cells (PBMCs) stimulated with specific S. japonicum antigens was measured once 4 weeks after treatment. After adjustment for confounders, S. japonicum intensity was associated with decreased serum albumin and Z-scores (all P < 0.05) and with increased serum C-reactive protein (CRP) and interleukin (IL)-6. CRP was associated with decreased albumin and Z-scores (all P < 0.01). Production of IL-1b and tumor necrosis factor (TNF)-alpha in response to worm antigen was associated with decreased albumin (both P < 0.005) and height-for-age Z-score (TNF-alpha only, P = 0.05). S. japonicum-associated undernutrition may, in part, result directly from inflammation.

Because TIMP-1 inhibits most matrix metalloproteases, which are responsible for collagen degradation, these data suggest that schistosome-associated hepatic fibrosis results, in part, from excessive inhibition of collagen remodeling. These data further suggest that TIMP-1 is a promising biomarker for assessing risk of hepatic fibrosis in schistosomiasis and, potentially, other infectious and noninfectious causes of liver disease.