Meta-analysis of variable-temperature PCR technique performance for diagnosising Schistosoma japonicum infections in humans in endemic areas

Background As China is moving onto schistosomiasis elimination/eradication, diagnostic methods with both high sensitivity and specificity for Schistosoma japonicum infections in humans are urgently needed. Microscopic identification of eggs in stool is proven to have poor sensitivity in low endemic regions, and antibody tests are unable to distinguish between current and previous infections. Polymerase chain reaction (PCR) technologies for the detection of parasite DNA have been theoretically assumed to show high diagnostic sensitivity and specificity. However, the reported performance of PCR for detecting S. japonicum infection varied greatly among studies. Therefore, we performed a meta-analysis to evaluate the overall diagnostic performance of variable-temperature PCR technologies, based on stool or blood, for detecting S. japonicum infections in humans from endemic areas. Methods We searched literatures in eight electronic databases, published up to 20 January 2021. The heterogeneity and publication bias of included studies were assessed statistically. The risk of bias and applicability of each eligible study were assessed using the Quality Assessment of Diagnostic Accuracy Studies 2 tool (QUADAS-2). The bivariate mixed-effects model was applied to obtain the summary estimates of diagnostic performance. The hierarchical summary receiver operating characteristic (HSROC) curve was applied to visually display the results. Subgroup analyses and multivariate regression were performed to explore the source of heterogeneity. This research was performed following the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines and was registered prospectively in PROSPERO (CRD42021233165). Results A total of 2791 papers were retrieved. After assessing for duplications and eligilibity a total of thirteen publications were retained for inclusion. These included eligible data from 4268 participants across sixteen studies. High heterogeneity existed among studies, but no publication bias was found. The pooled analyses of PCR data from all included studies resulted in a sensitivity of 0.91 (95% CI: 0.83 to 0.96), specificity of 0.85 (95% CI: 0.65 to 0.94), positive likelihood ratio of 5.90 (95% CI: 2.40 to 14.60), negative likelihood ratio of 0.10 (95% CI: 0.05 to 0.20) and a diagnostics odds ratio of 58 (95% CI: 19 to 179). Case-control studies showed significantly better performances for PCR diagnostics than cross-sectional studies. This was further evidenced by multivariate analyses. The four types of PCR approaches identified (convention PCR, qPCR, Digital droplet PCR and nested PCR) differed significantly, with nested PCRs showing the best performance. Conclusions Variable-temperature PCR has a satisfactory performance for diagnosing S. japonicum infections in humans in endemic areas. More high quality studies on S. japonicum diagnostic techniques, especially in low endemic areas and for the detection of dual-sex and single-sex infections are required. These will likely need to optimise a nested PCR alongside a highly sensitive gene target. They will contribute to successfully monitoring endemic areas as they move towards the WHO 2030 targets, as well as ultimately helping areas to achieve these goals.

Demographic patterns of human antibody levels to Simulium damnosum s.l. saliva in onchocerciasis-endemic areas: An indicator of exposure to vector bites

Background In onchocerciasis endemic areas in Africa, heterogenous biting rates by blackfly vectors on humans are assumed to partially explain age- and sex-dependent infection patterns with Onchocerca volvulus. To underpin these assumptions and further improve predictions made by onchocerciasis transmission models, demographic patterns in antibody responses to salivary antigens of Simulium damnosum s.l. are evaluated as a measure of blackfly exposure. Methodology/Principal findings Recently developed IgG and IgM anti-saliva immunoassays for S. damnosum s.l. were applied to blood samples collected from residents in four onchocerciasis endemic villages in Ghana. Demographic patterns in antibody levels according to village, sex and age were explored by fitting generalized linear models. Antibody levels varied between villages but showed consistent patterns with age and sex. Both IgG and IgM responses declined with increasing age. IgG responses were generally lower in males than in females and exhibited a steeper decline in adult males than in adult females. No sex-specific difference was observed in IgM responses. Conclusions/Significance The decline in age-specific antibody patterns suggested development of immunotolerance or desensitization to blackfly saliva antigen in response to persistent exposure. The variation between sexes, and between adults and youngsters may reflect differences in behaviour influencing cumulative exposure. These measures of antibody acquisition and decay could be incorporated into onchocerciasis transmission models towards informing onchocerciasis control, elimination, and surveillance.

Pediatric Leprosy Profile in the Postelimination Era: A Study from Surabaya, Indonesia

Children who live in leprosy-endemic areas are susceptible to infection due to early and frequent exposure to Mycobacterium leprae. Indonesia is on the verge of eliminating this disease (prevalence rate < 1/10,000 population), but pediatric leprosy continues to occur in low-endemic areas. This study aimed to evaluate pediatric leprosy over a decade in a tertiary hospital in Surabaya, Indonesia. A retrospective study of leprosy in children under 15 years old between 2010 and 2019 was conducted in the Morbus Hansen Division, Outpatient Clinic at Dr. Soetomo Hospital in Surabaya, Indonesia. Seventy pediatric leprosy cases were identified between 2010 and 2019, consisting of 58 multibacillary (MB)-type cases and 12 paucibacillary (PB)-type cases. Slit skin smear (SSS) was positive in 26 cases. There were two cases of grade-2 disability and 15 cases of leprosy reaction (erythema nodosum leprosum) in children at the time of diagnosis. There was an insignificant decline in the number of pediatric leprosy cases in the last 10 years. Cases and disabilities in children were found in some leprosy pocket areas even though the national elimination rate has been achieved. MB infections, disability, and treatment defaults were common problems in pediatric leprosy.

Immunogenicity and waning immunity from the oral cholera vaccine (Shanchol™) in adults residing in Lukanga Swamps of Zambia

Introduction In cholera endemic areas, the periodicity of cholera outbreaks remains unpredictable, making it difficult to organize preventive efforts. Lack of data on duration of protection conferred by oral cholera vaccines further makes it difficult to determine when to deploy preemptive vaccination. We report on the immunogenicity and waning of immunity to Shanchol™ in Lukanga Swamps. Methods We enrolled a cohort of 223 participants aged between 18 and 65 years old from whom serum samples were collected at baseline, day 28 before administration of the second dose, and consecutively at 6, 12, 24, 30, 36, and 48 months. Vibriocidal antibody titres were measured and expressed as geometric mean titres. Box plots and 95% CI were computed at each visit for both Inaba and Ogawa. Seroconversion was defined as a four fold or greater increase in antibody titres compared to baseline titres. Results Overall, seroconversion against V. cholerae Inaba and Ogawa after 1st dose was 35/134 (26%) and 34/134 (25%) respectively. We observed a statistical difference in seroconversion between the two subgroups of baseline titres (low <80 and high ≥80) for both Inaba (p = 0.02) and Ogawa (p<0.0001). From a baseline of 13.58, anti-Ogawa GMT increased to 21.95 after the first dose, but rapidly waned to 14.52, 13.13, and 12.78 at months 6, 12 and 24 respectively, and then increased to 13.21, 18.67 and 23.65 at months 30, 36 and 48 respectively. A similar trend was observed for anti-Inaba GMT across the same time points. Conclusion We found that Shanchol™ was immunogenic in our study population and that vibriocidal antibodies may not be a good marker for long-term immunity. The observed rise in titres after 36 months suggests natural exposure, and this may be a critical time window opening for natural transmission in an endemic areas. We recommend re-vaccination at this time point in high risk areas.

Naturally acquired antibody response to a Plasmodium falciparum chimeric vaccine candidate GMZ2.6c and its components (MSP-3, GLURP, and Pfs48/45) in individuals living in Brazilian malaria-endemic areas

Background The GMZ2.6c malaria vaccine candidate is a multi-stage Plasmodium falciparum chimeric protein which contains a fragment of the sexual-stage Pfs48/45-6C protein genetically fused to GMZ2, a fusion protein of GLURP and MSP-3, that has been shown to be well tolerated, safe and immunogenic in clinical trials performed in a malaria-endemic area of Africa. However, there is no data available on the antigenicity or immunogenicity of GMZ2.6c in humans. Considering that circulating parasites can be genetically distinct in different malaria-endemic areas and that host genetic factors can influence the immune response to vaccine antigens, it is important to verify the antigenicity, immunogenicity and the possibility of associated protection in individuals living in malaria-endemic areas with different epidemiological scenarios. Herein, the profile of antibody response against GMZ2.6c and its components (MSP-3, GLURP and Pfs48/45) in residents of the Brazilian Amazon naturally exposed to malaria, in areas with different levels of transmission, was evaluated. Methods This study was performed using serum samples from 352 individuals from Cruzeiro do Sul and Mâncio Lima, in the state of Acre, and Guajará, in the state of Amazonas. Specific IgG, IgM, IgA and IgE antibodies and IgG subclasses were detected by Enzyme-Linked Immunosorbent Assay. Results The results showed that GMZ2.6c protein was widely recognized by naturally acquired antibodies from individuals of the Brazilian endemic areas with different levels of transmission. The higher prevalence of individuals with antibodies against GMZ2.6c when compared to its individual components may suggest an additive effect of GLURP, MSP-3, and Pfs48/45 when inserted in a same construct. Furthermore, naturally malaria-exposed individuals predominantly had IgG1 and IgG3 cytophilic anti-GMZ2.6c antibodies, an important fact considering that the acquisition of anti-malaria protective immunity results from a delicate balance between cytophilic/non-cytophilic antibodies. Interestingly, anti-GMZ2.6c antibodies seem to increase with exposure to malaria infection and may contribute to parasite immunity. Conclusions The data showed that GMZ2.6c protein is widely recognized by naturally acquired antibodies from individuals living in malaria-endemic areas in Brazil and that these may contribute to parasite immunity. These data highlight the importance of GMZ2.6c as a candidate for an anti-malarial vaccine.

Geography and ecology of invasive Pseudosuccinea columella (Gastropoda: Lymnaeidae) and implications in the transmission of Fasciola species (Digenea: Fasciolidae) – a review

Pseudosuccinea columella is considered invasive and has become an important intermediate host of both Fasciola species in many regions of the world. This systematic review assessed the geographical distribution of P. columella, and its implications in the transmission of Fasciola hepatica and Fasciola gigantica, globally. A literature search was conducted on Google Scholar, JSTOR and PubMed databases using Boolean operators in combination with predetermined search terms for thematic analysis. Results show that P. columella has been documented in 22 countries from Europe (3), Africa (8), Oceania (2), North America (3) and South America (6). Furthermore, this snail species has shown to adapt to and inhabit a vast array of freshwater bodies including thermal lakes and ditches with acidic soils. Studies showed that P. columella transmits F. hepatica, with natural and experimental infections documented in sub-Saharan Africa, Europe, South America and North America. Experimental infection studies in Cuba showed the presence of P. columella populations resistant to F. hepatica infection. Furthermore, some populations of this invasive snail collected from F. hepatica endemic locations in Brazil, Venezuela, Australia, South Africa, Colombia and Argentina were found without Fasciola infection. As a result, the role played by this snail in the transmission of Fasciola spp. in these endemic areas is still uncertain. Therefore, further studies to detect natural infections are needed in regions/countries where the snail is deemed invasive to better understand the veterinary and public health importance of this snail species in Fasciola-endemic areas and determine the global dispersion of resistant populations of P. columella.

Analisis Indikator Entomologi dan Sebaran Jentik Aedes aegypti pada Daerah Stratifi kasi Endemisitas Demam Berdarah Dengue di Kota Jayapura

The incidence rate (IR) of Dengue Hemorrhagic Fever in Papua Province in 2017 was8.04 per 100,000 population, with a case fatality rate (CFR) of 1.12%. In 2016, the Health Offi ce ofJayapura City declared six urban villages as high endemic areas, four urban villages as high sporadicareas, and ten villages as DHF-free areas from a total of 39 urban villages in Jayapura. This studyaims to analyze larval by House index [HI], Container index [CI], Breateu index (BI), and Maya index[MI] as well as the distribution of vector Ae. aegypti in endemic, sporadic and DHF-free areas inJayapura City. The design of this study was a cross-sectional study. This research was conducted fromJanuary to March 2019. Subjects (375 houses) were surveyed according to WHO guidelines basedon its endemicity stratifi cation. Observations of mosquitos’ larvae were done using visual and singlelarvae methods. The result of this research showed that endemic areas had their HI, CI and BI as muchas 43.3%, 16.5%, and 90.0%, respectively, with density fi gure is six. Sporadic areas had their HI,CI and BI as much as 35.4%, 10.9%, and 57.5%, respectively, with density fi gure is fi ve. DHF-freeareas had their HI, CI, and BI as much as 14.8%, 5.7%, and 35.2%, respectively, with density fi gureis fi ve. The Maya index for endemic and sporadic areas was categorized as moderate, while DHF-freeareas were low.

Factors related to the presence of mosquito eggs trapped in ovitraps DHF-endemic areas in Kendari City, Indonesia

Background: Dengue hemorrhagic fever (DHF), one type of infectious disease caused by the dengue virus, is still becoming a public health problem in Indonesia. The high number of dengue cases in Indonesia, especially in Kendari City itself, is closely related to environmental conditions, especially when it is known that the city has entered the rainy season.Objective: This study aimed to identify and analyze the factors associated with the presence of mosquito eggs trapped in ovitraps DHF-endemic area in Kendari City, Indonesia.Methods: This study used an analytic observational approach with a cross-sectional design. The research sample in this study was 50 houses located in endemic areas of Kendari selected using simple random sampling. Data were collected by observation using a checklist sheet and direct observation in each room of the respondent's house based on lighting, temperature, humidity, and physical environmental conditions, as well as the presence of mosquito eggs or larvae trapped in the ovitrap. The analysis was carried out in two stages, namely univariate analysis and bivariate analysis using the Chi-Square test.Result: From 50 houses observed, 13 houses (26%) had the presence of mosquito eggs, 42 houses (84%) had bad air temperature, 19 houses (38%) had poor humidity, and 35 houses (70%) had a higher frequency. In addition, the temperature, lighting, and environmental conditions did not have a significant relationship with the presence of mosquito eggs in ovitraps in endemic areas of Kendari City, with p-values of 0.94, 0.52, and 0.39, respectively. In contrast, the humidity factor has a significant relationship with the presence of eggs with a p-value of 0.000.Conclusion: There was a significant relationship between humidity and the presence of mosquito eggs in ovitraps in endemic areas of Kendari City, Indonesia. It is recommended that residents increase Mosquito Nest Eradication (PSN) activities, perform selective abatization, and disseminate information about DHF through counseling or other activities conveyed through health workers with full support from community leaders and adjusted to the level of education of the local population.

Incidence of Histoplasmosis in a Cohort of People with HIV: From Estimations to Reality

Among people with HIV, histoplasmosis represents an important cause of mortality. Previous studies provided estimates of the disease incidence. Here, we compared those estimates with the results obtained from a screening program implemented in Guatemala, which included histoplasmosis detection for people with HIV. To compare the results of this program with previous estimations, a literature search was performed and reports concerning histoplasmosis incidence were analyzed. The screening program enrolled 6366 patients. The overall histoplasmosis incidence in the screening program was 7.4%, which was almost double that estimated in previous studies. From 2017 to 2019, the screening program showed an upward trend in histoplasmosis cases from 6.5% to 8.8%. Histoplasmosis overall mortality among those who were newly HIV diagnosed showed a decrease at 180 days from 32.8% in 2017 to 21.2% in 2019. The screening approach using rapid diagnostic assays detects histoplasmosis cases more quickly, allowing a specific treatment to be administered, which decreases the mortality of the disease. Therefore, the use of these new techniques, especially in endemic areas of histoplasmosis, must be implemented.