Tropical Medicine and Health最新文献

Background: Dengue is a serious public health problem worldwide, including Panama. During the last years, the number of dengue cases has increased. This may be due to the presence of mosquito populations resistant to insecticides. The aim of this study was to characterize the resistance status, its enzymatic mechanisms and Kdr mutations in wild populations of Aedes aegypti and Aedes albopictus.

Methods: Standard WHO bioassays were performed using insecticide-treated filter papers to determine resistance in populations Ae. aegypti and Ae. albopictus to pyrethroids insecticides, organophosphates, to the carbamate propoxur and to the organochlorine DDT. Biochemical assays were conducted to detect metabolic resistance mechanisms and real-time PCR was performed to determine the frequencies of the Kdr mutations Val1016IIe and F1534C.

Results: The strains Ae. aegypti El Coco showed confirmed resistance to deltamethrin (78.5% mortality) and lambda-cyhalothrin (81%), Aguadulce to deltamethrin (79.3%), David to deltamethrin (74.8%) and lambda-cyhalothrin (87.5%) and Puerto Armuelles to permethrin (83%). Aedes aegypti El Empalme showed confirmed resistance to pirimiphos-methyl (62.3% mortality), chlorpyrifos-methyl (55.5%) and propoxur (85.3%). All strains of Ae. albopictus showed possible resistance to PYs and five strains to DDT. Only Ae. albopictus Canto del Llano showed confirmed resistance to pirimiphos-methyl (70% mortality) and malathion (62%). Esterase activity was variable across sites with the most frequent expression of α-EST compared to β-EST in Ae. aegypti populations. In Ae. Albopictus, the expressed enzymes were β-EST and MFOs. Through ANOVA, significant differences were established in the levels of enzymatic activity of α- and β-EST, MFOs and GST, with p < 0.001 in the Ae. aegypti and Ae. albopictus. The Kdr Val1016IIe mutation was detected in Ae. aegypti Aguadulce, El Coco and David. The odds ratio for the Val1016Ile mutation ranged from 0.8 to 20.8 in resistant mosquitoes, indicating the association between pyrethroid phenotypic resistance and the kdr mutation.

Conclusion: The presence of a varied and generalized resistance, enzymatic mechanisms and the Val1016IIe mutation may be associated with the intensive use and possibly misuse of the different insecticides applied to control Aedes populations. These results highlight the need to develop a program for resistance management. Also, alternative approaches to mosquito control that do not involve insecticides should be explored.

Background: Suboptimal water, sanitation, and hygiene (WASH) practices constitute a serious public health risk, affecting one-third of the world's population. Remarkable progress has been made to improve WASH; however, challenges remain, with rapid population growth adding pressure on WASH systems. This study explores the current state of WASH practices and diseases in Africa, identifies challenges, and proposes public health recommendations for sustainable implementation.

Main body: The staggering burden of WASH-related diseases in low- and middle-income countries (LMICs), particularly in Africa, threatens public health, with millions of deaths and disability-adjusted life years (DALYs) attributed to poor WASH practices annually. Notable challenges plaguing WASH practices in the region include poverty, malnutrition, poor data reporting, illiteracy, climate change, and poor healthcare financing. This results in adverse health consequences, including waterborne infections like cholera, typhoid, dysentery, and diarrheal diseases. Additionally, neglected tropical diseases (NTDs) such as intestinal worms, schistosomiasis, trachoma, lost productivity, and environmental pollution from soil and underground water contamination have been implicated. Geographical disparities, cultural norms, and inadequate funding further complicate efforts to improve WASH infrastructure and practices. Globally concerted efforts are required to address these issues and permit WASH practices to protect human health by preventing infectious diseases and contributing to economic growth. Strong financial frameworks, skills training, and tools like WASH Fit are recommended for a stronger WASH approach in Africa.

Conclusion: The consequences of poor WASH extend beyond public health, impacting economic growth, gender equality, and environmental sustainability. WaterAid's policy recommendations prioritizing government administration, institutional capacity enhancement, and more financial resources are expedient.

Background: Cytomegalovirus (CMV) is the most common congenital infection in pregnancy with potential long-term adverse effects on the fetus. There is limited data on CMV seroprevalence in pregnant women in Singapore, with last reported study dating back over two decades. We look at the latest CMV seroprevalence in antenatal population in Singapore.

Methods: Between January 2021 and August 2021, 385 pregnant women receiving antenatal care at Singapore General Hospital were randomly selected for CMV IgG test to be performed on their blood samples collected during the first trimester of their pregnancies. Positivity for CMV IgG represents past exposure prior to pregnancy.

Results: Overall CMV seroprevalence was 71.7% (276/385) (95% CI 067, 0.76, p value < 0.001). The trend of CMV IgG positivity increased with age, 68.3% (95% CI 0.60, 0.76, p value < 0.001) in those aged 20-29, 72.5% (95% CI 0.66, 0.78, p value < 0.001) in the 30-39 age group, and 79.0% (95% CI 0.67, 0.76, p value 0.012) in women over 40.

Conclusions: There is a declining trend in CMV seroprevalence among pregnant women in Singapore, which indicates that a substantial portion of this population faces the risk of primary maternal CMV infection during pregnancy. Emerging research suggests that prenatal treatment with valacyclovir effectively reduces the likelihood of vertical transmission. Considering this evidence, it is imperative to reevaluate the recommendations for universal maternal CMV screening during pregnancy.

Background: Sierra Leone has improved child health outcomes in recent decades. However, diarrhoeal diseases remain a public health concern, particularly among children under five. This study investigates the trends and inequalities in oral rehydration therapy and continued feeding for children under five with diarrhoea in Sierra Leone in 2008, 2013 and 2019.

Methods: The analysis utilised data from the Sierra Leone Demographic Health Survey rounds conducted in 2008, 2013, and 2019. The software utilised for the calculation of various measures of inequality, including simple difference, ratio, population-attributable risk, and population-attributable fraction, was the World Health Organization Health Equity Assessment Toolkit. An inequality assessment was conducted for six stratifiers: maternal age, maternal economic status, maternal level of education, place of residence, sex of the child, and sub-national region.

Results: Our findings reveal that children under five with diarrhoea receiving oral rehydration therapy and continued feeding increased from 56.5% in 2008 to 59.7% in 2019 in Sierra Leone. Children of mothers aged 20-49 had more coverage over time than those with mothers aged 15-19. Children of mothers who are wealthy, more educated, and living in urban areas show a decrease in coverage with time compared to the poor, the lowly educated, and those residing in rural areas. Male children had higher coverage than female children. Regional inequality decreased slightly from 21.5 percentage points in 2008 to 21.2 percentage points in 2019.

Conclusion: The findings revealed a mixed picture of progress in oral rehydration therapy and continued feeding for children under five in Sierra Leone. While national coverage has increased, inequalities persist. Children of older mothers and those from disadvantaged backgrounds have experienced improvements, while children of younger, wealthier, and more educated mothers in urban areas have seen a decline in coverage. The gender and regional inequalities remain. Expanding community-based health programs, providing subsidised or free supplies, and strengthening health systems in underserved areas are key strategies to ensure equitable and effective healthcare for all children in Sierra Leone.

Background: A number of antibody test kits for detecting prior SARS-CoV-2 infection and post-immunization status have been commercialized. Indirect immunoperoxidase assay (IIP) is a conventional method to test antibodies. We evaluated the diagnostic accuracy and antibody titer profile of the IIP in COVID-19 and pre- and post-vaccination.

Methods: We conducted a hospital-based observational study in Fukushima prefecture, Japan. We enrolled COVID-19 inpatients who tested positive by PCR. We used serum samples collected > 10 years before the pandemic as the negative control. We also included volunteers vaccinated at the hospital. All participants were tested using an IIP with whole-cell antigen of the six SARS-CoV-2 variants isolated in Japan during the epidemic and an IgG ELISA kit. Negative controls and vaccinated volunteers were also tested using a lateral flow assay (LFA) kit. We conducted receiver operating characteristic (ROC) analysis to evaluate diagnostic accuracy and performed logistic regression analysis to explore factors associated with antibody titer.

Results: We included 146 COVID-19 inpatients, 38 negative controls, and 36 vaccinated volunteers. Most participants had the highest titer for IgG and IgM in the wild type-A antigen among the six variants. The sensitivity, specificity, and accuracy of the IgG ELISA kit were 60.3%, 100%, and 68.5%; of the IIP for IgG with the cutoff titer at 1:80, 82.2%, 94.7%, and 84.8%, respectively. The ROC curves of the ELISA and IIP for IgG were almost identical. In the IgG tests of the 36 volunteers, 35 were positive for ELISA and IIP and 34 for LFA after two vaccinations. IgM titers in the IIP were <  = 1:40 in 114 patients and 32 volunteers after two vaccinations; therefore, the IgM titer is unsuitable for diagnosis. In COVID-19 patients, age, days from disease onset, >  = 7 days after the second vaccination, and immunosuppressants for comorbidity were associated with IgG titer of >  = 1:640 in the IIP.

Conclusions: The diagnostic accuracy of the IIP for detecting IgG antibodies in COVID-19 or after two vaccinations is equivalent to that of an ELISA. Further investigations are required to address the association between antibody titers in the IIP and their protective or harmful effects against COVID-19.

Background: Congenital toxoplasmosis occurs when a pregnant woman becomes infected with Toxoplasma gondii (T. gondii) for the first time. Treatment typically involves antimicrobial medications, with spiramycin commonly used to prevent transmission. However, spiramycin's effectiveness is limited due to poor placental penetration. Clindamycin, another antibiotic, can cross the placenta but reaches the fetus at only half the maternal concentration. Encapsulating the drug in chitosan-coated niosomes (Cs-Nio) could enhance its effectiveness by targeting specific organs and ensuring sustained release. To address the challenges of using clindamycin, a niosome-coated chitosan system was investigated for treating congenital toxoplasmosis caused by the VEG strain of T. gondii in an animal model.

Methods: Pregnant mice were infected with VEG strain of T. gondii on the 12th day of pregnancy, followed by treatment with various drugs across six groups. The treatments included chitosan-coated niosomes loaded clindamycin (Cs-Nio-Cli) and other controls. Parasitological evaluations (microscopic examination and real-time PCR), along with histopathological and immunological assessments were conducted to assess treatment efficacy. Finally, statistical analysis was conducted using GraphPad Prism 8.0 and SPSS 26, comparing test and control groups with T test and Mann-Whitney test. A p ≤ 0.05 was considered statistically significant.

Results: The study found that treatment with Cs-Nio-Cli significantly reduced the number of T. gondii cysts in the brain and eyes (97.59% and 92.68%, respectively) compared to the negative control group. It also mitigated inflammatory changes, prevented cell death, and reduced vascular cuffs in the brain. In addition, Cs-Nio-Cli treatment decreased bleeding, placental thrombosis, and inflammatory cell infiltration in the placenta while improving eye tissue health by reducing retinal folds and bleeds. Immunologically, nanoclindamycin treatment resulted in lower TNF-α cytokine levels and higher IL-10 levels, indicating an enhanced anti-inflammatory response.

Conclusions: Although Cs-Nio-Cli demonstrates promise in reducing the transmission of congenital toxoplasmosis and mitigating the effects of congenital toxoplasmosis, additional research is necessary to determine the optimal treatment regimens for the complete eradication of the parasite in the fetus.

Background: Physical symptoms of dengue have been documented extensively, but knowledge gaps on dengue-associated mental health hazards remain. We investigated the frequency of psychiatric symptoms (depression, anxiety, and stress) and neurocognitive performance during the first year after a dengue episode.

Methods: Using DASS-21 scores at 3, 6, and 12 months, we assessed depression, anxiety, and stress in anti-dengue IgM-positive adults and matched controls during the 2021 dengue season in Esmeraldas Province, Ecuador. Patients with DASS-21 scores ≤ 4 were considered normal; those with scores of 5-7, 8-10, and ≥ 11 indicated mild, moderate, and severe depression, respectively; cutoff scores for anxiety and stress were ≥ 5 and ≥ 9, respectively. We also assessed 'delayed matching to sample' (DMS) and 'spatial working memory' (SWM) using the Cambridge Neuropsychological Test Automated Battery.

Results: We enrolled 102 cases and 78 controls. At 3 months, 90 cases and 70 controls were available for follow-up, among these 40/90 (44.4%) cases and 12/70 (17.1%) controls had DASS-21 scores ≥ 5 (RR 2.7, 95% CI [1.5-4.7]). Dengue remained a predictor for depression after adjusting for age, sex, and COVID-19 status. We observed no difference in anxiety between the groups, but stress scores increased at month 3 (RR 1.87, 95% CI [1.01-3.4]). DASS-21 scores normalized during follow-up. DMS and SWM did not differ between groups at 3 and 6 months. At month 12, cases had lower SWM than controls did (p value < 0.001).

Conclusions: Care providers should be aware of dengue-associated mood disorders and facilitate timely referral to mental health services. Future longitudinal studies are warranted to validate our observations regarding the impact of dengue on mental health and neurocognitive status in affected patients.

Background: Acinetobacter baumannii continued to be an important Gram-negative pathogen of concern in the clinical context. The resistance of this pathogen to carbapenems due to the production of carbapenemases is considered a global threat. Despite the efforts to track carbapenemase synthesis among A. baumannii in the Philippines, local data on its molecular features are very scarce. This study aims to characterize A. baumannii clinical isolates from a Philippine tertiary hospital through genotyping of the pathogen's carbapenemase genes.

Methods: Antibiotic susceptibility profiling, phenotypic testing of carbapenemase production, and polymerase chain reaction assays to detect the different classes of carbapenemase genes (class A bla_KPC, class B bla_NDM, bla_IMP, bla_VIM, and class D bla_OXA-23-like, bla_{OXA-24/40-like}, bla_OXA-48-like, bla_OXA-51-like, ISAba1-bla_OXA-51-like, bla_OXA-58-like) were performed in all collected A. baumannii, both carbapenem resistant and susceptible (n = 52).

Results: Results showed that the majority of the carbapenem-resistant strains phenotypically produced carbapenemases (up to 84% in carbapenem inactivation methods) and possessed the ISAba1-bla_OXA-51-like gene complex (80%). Meanwhile, both carbapenem-resistant and carbapenem-susceptible isolates possessed multi-class carbapenemase genes including bla_NDM (1.9%), bla_VIM (3.9%), bla_{OXA-24/40-like} (5.8%), bla_OXA-58-like (5.8%), bla_KPC (11.5%), and bla_OXA-23-like (94.2%), which coexist with each other in some strains (17.3%). In terms of the intrinsic bla_OXA-51-like (oxaAb) genes, 23 unique alleles were reported (bla_OXA-1058 to bla_OXA-1080), the majority of which are closely related to bla_OXA-66. Isolates possessing these alleles showed varying carbapenem resistance profiles.

Conclusions: In summary, this study highlighted the importance of molecular genotyping in the characterization of A. baumannii by revealing the carbapenemase profiles of the pathogen (which may not be captured accurately in phenotypic tests), in identifying potent carriers of transferrable carbapenemase genes (which may not be expressed straightforwardly in antimicrobial susceptibility testing), and in monitoring unique pathogen epidemiology in the local clinical setting.

Background: Freshwater snails are the first obligatory intermediate hosts in the trematode life cycle. Several parasitic diseases transmitted by these snails are endemic in Africa, and their distribution closely follows that of the intermediate hosts. These diseases represent a major public health problem and cause significant socio-economic losses in Africa, particularly schistosomiasis and fascioliasis. In this review, we will describe the main roles of freshwater snails in the life cycle of trematode parasites, and the geographical distribution of these diseases in Africa. We will also discuss the different techniques for detecting parasitic infections in snails, as well as the various methods of controlling snails and the larval stages of parasites.

Methods: We carried out a literature search for articles dealing with parasitic diseases transmitted by freshwater snail hosts in Africa. The search was conducted in databases such as PubMed, Web of Science and Google Scholar using various search terms combined by Boolean operators. Our search was limited to peer-reviewed articles less than 10 years old. Articles published to date in the fields of control of parasitic diseases transmitted by freshwater snails were included. Results were presented in narrative and in table format.

Results: The results of the database search identified 1007 records. We included 84 studies in this review. These studies generally focused on freshwater snails and the diseases they transmit. We described the geographical distribution of 43 freshwater species belonging to nine snail families, as well as the parasites that infect them. Several methods for diagnosing parasites in their snail hosts have been described, including microscopic and molecular methods, as well as antibody and protein barcode-based techniques. Molluscicides have been described as the main strategy for snail control.

Conclusion: This study highlights several elements of knowledge about diseases transmitted by freshwater snails and their distribution. A good understanding of snail infection detection techniques and existing control methods is an essential component in adapting control strategies for these diseases.

Background: For safe drinking water, household water treatments (HWT) is important to reduce the risk of diarrhea in low-and-middle countries including Lao People's Democratic Republic (Lao PDR). However, the measurement of HWT relies chiefly on self-report in most nationwide surveys. Thus, the validity of self-reported measurement is of concern. The objective of this study was to determine the proportion of households with the presence of boiled water among households that report boiling practices in a rural area of the Lao PDR.

Methods: This study was conducted with randomly selected 108 households in the four villages in the catchment area of the two health centers, in Xepon district of the Savannakhet province, between September and October 2023. The inclusion criterion of the households was the households that report boiling as HWT. Surveyors conducted interviews with an adult household member and observations on boiled water through household visits, using a questionnaire. Descriptive statistics were conducted to summarize the collected information using the frequency with proportion for categorical variables and the median with interquartile range for continuous variables. Bivariate analyses were conducted to assess an association between each of the factors and the presence of boiled water, using Fisher's exact test.

Results: Among the 108 households that reported boiling practice, 91 households were able to show the surveyor self-reported boiled water. Thus, the proportion of households with the presence of boiled water was 90.1% (95% confidence interval: 82.5-95.1%). Households with a fixed schedule of boiling were significantly more likely to present boiled water, compared to households without (94.5% vs. 50.0%). Not all household members do not necessarily drink boiled water: approximately a quarter (25.7%) of the participants reported that some household members drink unboiled water.

Conclusions: This study showed that among households that reported boiling drinking water, 90.1% were able to present a container with self-reported boiled water. It suggests that the self-reported measure of boiling practices can be valid in the study villages.