Acta tropica最新文献

Pediatric schistosomiasis in hard-to-reach communities is poorly understood, hampering tailored interventions. This study investigated the prevalence, intensity, health impact, and risk factors for schistosomiasis in preschool-aged children (PSAC) residing in hard-to-reach areas and populations of Homa Bay County, Kenya. A cross-sectional study was conducted among 476 PSAC aged 2-5 years across 6 islands in Lake Victoria, Homa Bay County, Kenya. Kato-Katz and urine filtration techniques diagnosed Schistosoma mansoni and S. haematobium infections respectively. Fecal occult blood (FOB) was tested to assess morbidity, and questionnaires captured sociodemographic and household water, sanitation, and hygiene data. Logistic regression models explored risk factors. The overall prevalence of S. mansoni was 26.0 %, varying considerably between islands; Ringiti had the highest prevalence (62.1 %), while Sukru had the lowest (7.7 %). No S. haematobium infections were diagnosed. Light infections were most common (15.4 %), followed by moderate (8.5 %) and heavy infections (2.2 %). Significantly increased odds for infection were observed in children aged four (aOR = 4.4, 95 % CI: 1.7-11.2) and five years (aOR = 5.6, 95 % CI: 2.2-14.5), in girls (aOR = 2.5, 95 % CI: 1.3-4.8), and in children living in Ringiti (aOR = 6.1, 95 % CI: 1.8-15.0). We noted a strong association between S. mansoni infection and FOB (aOR= 3.3, 95 % CI: 1.6-7.0). We found a high burden of schistosomiasis among PSAC in hard-to-reach communities of Homa Bay County, emphasizing the urgent need to include them in control programs. FOB could be a promising indicator for assessing schistosomiasis-related morbidity in this age group.

In the current study, the analytical sensitivity, analytical specificity, reproducibility, anti-interferences ability, and clinical performance of the QIAstat-Dx Gastrointestinal Panel (GIP) system were evaluated using pooled stool samples. Results showed that the pooled sample test detected the selected ten targets exclusively, with no cross reaction with any other targets of common enteropathogens. The analytical sensitivity of the pooled sample test on QIAstat-Dx GIP system was 10² CFU/ml for Shigella spp., 10³ CFU/ml for Salmonella spp., Y. enterocolitica, Enterotoxigenic Escherichia coli, Enteropathogenic E. coli, 10⁴ CFU/ml for V. cholerae, 10² copies/ml for Norovirus, 10³ copies/ml for Rotavirus, Astrovirus, Sapovirus, respectively. The Coefficients of variation (CV) during the detection of V. cholerae, Salmonella spp., Y. enterocolitica, Enterotoxigenic E. coli, Enteropathogenic E. coli, Shigella spp., Rotavirus, Norovirus, Astrovirus, and Sapovirus detection was 2.3 %, 2.7 %, 3.9 %, 4.2 %, 1.7 %, 2.6 %, 6.7 %, 1.4 %, 1.3 % and 2.7 %, respectively, indicating the high reproducibility of the pooled sample test, except for Rotavirus. When potentially interfering agents were added, the shifted Ct value was less than the cut off value, suggesting the good anti-interferences ability. During clinical evaluation, the pooled sample test was 97.8 % concordant with gold standard methods (bacterial culture for bacteria and qPCR for viruses). Our results suggest that QIAstat-Dx GIP system could be used for pooled sample test for enteropathogens screening, which would be more economical and could improve throughput while provide comparable test performance.

Infections caused by Orthoflavivirus denguei can either manifest asymptomatically or present a wide spectrum of clinical manifestations. This variety of symptoms results from its complex pathogenesis, which is influenced by viral factors, in addition to host genetics and immunological factors. It is known that anti-inflammatory cytokines can play an immunomodulatory role throughout the course of dengue. Therefore, we investigated the single nucleotide polymorphisms (SNPs) -1082 A/G (rs1800896) and -819 C/T (rs1800871) in the interleukin-10 (IL10) gene and their possible relationship with the development of symptomatic dengue in a Brazilian population. This study, carried out in northeastern Brazil, involved 333 volunteers, including 74 patients with dengue without warning signs (DWWS), 45 patients with dengue with warning signs (DWAS), 85 patients with asymptomatic dengue infection (ASY) and 129 health controls. The genomic DNA was extracted and the SNPs were genotyped using quantitative real-time polymerase chain reaction (qPCR). The data obtained were used to conduct statistical analyses of the genotype and allele frequencies. We observed an association of A/G and G/G genotypes of the -1082 A/G SNP of the IL10 gene with susceptibility to symptomatic dengue and DWAS regarding the asymptomatic dengue. The G allele of this SNP has also been identified as a risk factor for symptomatic dengue, DWWS and DWAS. Regarding the analyses between the SNPs -1082 A/G and -819 C/T of the IL10 gene, there was an association of the G-C haplotype with symptomatic dengue, DWWS and DWAS, as well as a correlation of the A-C haplotype with asymptomatic dengue. Moreover, the data indicate an association between the presence of the G allele and the development of symptoms, compared to those without the G allele. Our results indicate the presence of the G allele of SNP -1082 A/G of the IL10 gene as a risk factor for the clinical development of symptomatic dengue in the studied population and show the importance of genomics association studies involving asymptomatic individuals.

In the Andean region of South America, guinea pigs (Cavia porcellus) are raised as livestock in close contact with other domestic animals and humans. Although the susceptibility of guinea pigs to being affected by a wide range of diseases is well known as a laboratory animal model, there are a few reports about the potential role of zoonotic pathogens in livestock guinea pigs. In this work, we analyzed the nasopharyngeal carriage of respiratory pathogenic viruses and bacteria in guinea pigs from farms in Ecuador. We isolated streptococci and aerococci cultures that were analyzed for species identification by MALDI-TOF MS. Several species, including Streptococcus pneumoniae, S. pseudopneumoniae, S. oralies, and S. mitis were found. Moreover, strains resistant to antibiotics like levofloxacin, erythromycin, and sulfamethoxazole-trimethoprim were also found. Our results suggest the role of guinea pigs as a zoonotic reservoir for occupational exposure to respiratory pathogens in the Andean region of South America, where guinea pig farming is an important industry.

Hantavirus Pulmonary Syndrome (HPS) is a Pan-American emerging infectious disease with a high mortality rate caused by rodent-borne viruses of the genus Orthohantavirus. In Argentina, almost half of the HPS infections occur in the northwestern endemic region. In this study, we evaluated rodent composition, abundance, and antibody prevalence in wild rodents in three subtropical sites: primary forest, secondary forest, and crop fields. From February 2022 to June 2023, we settled a total of 150 traps for three nights every two months reaching a capture-effort of 5,400 trap-nights. We took blood samples from all captured rodents, registered morphological measures, then marked and released. We captured 103 rodents of 5 species (Oligoryzomys chacoensis, Calomys fecundus, Calomys musculinus, Akodon simulator, and Euryoryzomys legatus). The overall antibody prevalence was 10.18 %; with C. fecundus and A. simulator being the species most frequently found to present antibodies, and they were also the dominant species in the captured rodent community. The secondary forest was, by far, the most productive site with 83.5 % of all captures, followed by crop fields (10.68 %) and primary forest (5.82 %). We found that antibody prevalence for C. fecundus was positively correlated to body mass (weight) and size (total length). Another important result of our work is that we report presence of hantavirus antibodies in E. legatus, which represents the first record for this species. These results highlight the importance of continuous monitoring of rodents populations and provide a framework for the planning and implementation of public health prevention campaigns of field workers.

Sand flies, the principal vectors of Leishmania spp., are widely endemic in the Balkans and its neighbouring area. Among many factors, meteorological constraints shape sand fly distribution and activity, and are therefore important to assess to understand sand fly occurrence and prevent transmission of pathogens. To determine the daily limits of sand fly activity in Southeast Europe, we used entomological trapping data of eight species from seven countries, as well as temperature, precipitation, global radiation, wind speed, and sea level pressure data of the E-OBS gridded dataset. While 91.3 % of analyzed sites represented humid subtropical-continental ecotypes, heterogenous meteorological activity thresholds were found between species. By ranking the species based on their meteorological limits, Phlebotomus balcanicus and Ph. papatasi showed the widest general meteorological tolerance, whereas the activity of Sergentomyia minuta, Ph. tobbi, and Ph. simici were observed to be most sensitive to meteorological changes. However, principal ordinate analysis suggested that Ph. neglectus and Ph. mascittii had the widest ecological niches related to their activity constraints, and Ph. tobbi and Ph. simici had the narrowest. Phlebotomus mascitti and Se. minuta exhibited the most notable overall dissimilarity of the meteorological requirements of activity. The ensemble tests showed that the feature importance of different meteorological factors varies by sand fly species related to their activity. This study should help to better understand small-scale differences in sand fly occurrence in Southeast Europe to support future surveys and targeted surveillance to assess pathogen transmission in endemic areas.

Schistosomiasis is a neglected tropical disease caused by digenetic trematode from Schistosoma genus, as an etiological agent that uses snails as an intermediate host. In mollusc-trematode relationships, the miracidia attract in the aquatic media to a specific snail as an intermediate hosts, then penetrate its integument in the sporocyst form thereafter, the invasive sporocysts produce secreted/excreted products in order to survive and avoid the snails' immune system. The next larval stage is the cercariae that developed by sporocysts. Subsequently, the snail intermediate host suffers from biological, physiological, biochemical and immunological changes during the development of these parasite larval stages within their tissues. Snails and their parasites engage in an interactive innate and putative adaptive immune response that involves many immune mechanisms, such as the production of nitric oxide, lysozymes, phagocytosis, lectin formation and phenol oxidase activity. Schistosomes have developed a variety of strategies to evade and counteract these deliberate host reactions. These strategies include the secretion of many strong proteases, the use of an immune-resistant outer tegument, the molecular mimicry of host antigens, and the controlled release of certain immunomodulatory substances that influence immune cell activities. This review aims to characterize these important immune evasion mechanisms in order to comprehend the many immunological molecular determinants in the snail/schistosome interaction and to develop alternate management measures for schistosomiasis control.

Transmission of Trypanosoma cruzi involves diverse hosts, vectors and parasitic genotypes, in different environments. In recent decades, the distribution of T. cruzi has altered due to urbanization of affected people and vectors. We implemented a longitudinal intervention program between 2015 and 2022 which aimed to suppress (peri)domestic Triatoma infestans in the municipality of Avia Terai (Chaco Province, Argentina), and found a marginal risk of domestic vector-borne transmission across the rural-to-urban gradient after interventions. Here, we identified the parasite Discrete Typing Units (DTUs) in infected T. infestans collected throughout the intervention program (37 insects pre-intervention and 7 post-intervention). Identification of DTUs was conducted by two methodologies, using DNA extracted from T. infestans rectal ampoules. We also assessed the association between blood-feeding sources and DTUs. Complete DTU identification was achieved in 48 % of samples. The hybrid lineages TcV or TcVI and their combinations predominated (72 %), followed by TcI (16 %) and mixed infections of TcI and hybrid lineages (14 %). Half (50 %) of the houses harbored TcI infected bugs either alone or mixed with TcII/TcV/TcVI. Humans predominated as the bloodmeal sources in all insects with identified DTU. All DTUs (TcI, TcV and TcII/TcV/TcVI) were recorded in both rural and peri-urban environments, with 62 % of the houses having more than one DTU. These results confirm the predominance of hybrid lineages in domestic transmission cycles of the Argentine Chaco. However, the finding of several triatomines infected with TcI both pre- and post-intervention raises the question of which host(s) are involved in its transmission.

Chagas disease, vectored by kissing bugs, poses a public health problem across the Americas. The best way for reducing disease transmission is through vector control, which is currently based on the use of insecticides. However, insecticide resistance, and environmental and health issues, stress the need for new, environmentally-friendly methods for reducing vector-host contacts. Kissing bugs use the odor blend emitted by hosts to locate them. The proportions of the constituents of that blend are important to determine the attraction evoked by it. We aimed at assessing whether artificial alterations of those proportions could render an attractive host, unattractive for the kissing bug Triatoma infestans. Thus, the behavior of the bugs after adding a source of nonanal, a component of vertebrate odor detected by the bugs, to an attractive mouse was studied. For this, nymphs were tested using a dual-choice trap-olfactometer and different doses of nonanal. Addition of nonanal resulted in a dose- dependent reduction in the attraction of the bugs towards the mouse although it did not prevent the bugs from leaving their release zone nor it affected their (reduced) host preference near the host. Nonanal per se did not evoke any behavior at the doses tested. We suggest that the increase in the proportion of nonanal resulted in masking of the mouse odor. This approach could help reach a "push" effect within an effective push- pull strategy for kissing bugs. That strategy would help diminish the vector-host contacts and, therefore, Chagas disease incidence, in an environmentally-friendly manner. It remains to be established whether this strategy proves effective in the field when adequate odor dispensers and socially acceptable odors are used.

Mosquito-borne diseases pose a significant threat to global health, and traditional mosquito control methods often fall short of effectiveness. A promising alternative is the biological control strategy of transinfecting mosquitoes with Wolbachia, a bacterium capable of outcompeting harmful pathogens and reducing the ability of mosquitoes to transmit diseases. However, Wolbachia infections are sensitive to abiotic environmental factors such as temperature and humidity, which can affect their densities in mosquitoes and, consequently, their ability to block pathogens. This review evaluates the effectiveness of different Wolbachia strains transinfected into mosquitoes in reducing mosquito-borne diseases. It explores how Wolbachia contributes to mosquito population control and pathogen interference, highlighting the importance of mathematical models in understanding Wolbachia transmission dynamics. Additionally, the review addresses the potential impact on arboviral transmission and the challenges posed by environmental fluctuations in mosquito control programs.