Tropical Medicine and Health最新文献

Background: In sub-Saharan Africa, most people living with HIV (PLHIV) engage with healthcare regularly but their comorbidity history remains largely unknown. We systematically assessed the blood pressure and glucose levels of clinically stable PLHIV who had not been diagnosed with hypertension or diabetes across large urban HIV clinics in Dar es Salaam, Tanzania.

Methods: We analysed data collected from patients screened for enrolment into a randomised trial, which was testing metformin among patients with HIV and pre-diabetes. Participants attending the HIV clinics were recruited via systematic random and purposive body mass index (BMI)-enriched sampling between 4 November 2019 and 21 July 2020. All adults aged ≥ 18 years on antiretroviral therapy for ≥ 6 months were recruited. Screening procedures included standardised questionnaires, anthropometry, triplicate blood pressure measurements, fasting blood glucose (FBG) testing and a 2-h oral glucose tolerance test (OGTT). We conducted descriptive analyses on all participants who were screened. We used log-binomial regression to explore associations between participants' characteristics and cardiometabolic outcomes.

Results: A total of 1,279 individuals were screened, of whom 975 (76.2%) were tested for fasting blood glucose and form the analyses of this study. Their median age was 47 years (interquartile range: 42-54) and 731 (75.0%) were female. An elevated FBG (≥ 6.1 mmol/L) was found in 42.2% (95% confidence interval [CI]: 39.0-45.3%) of participants and 38.8% (95% CI: 35.7-42.0%) had an elevated 2-h oral glucose tolerance test (OGTT) (≥ 7.8 mmol/L). Overall, 54.6% (95% CI: 51.3-57.7%) met the criteria for abnormal glucose levels while diabetes prevalence ranged from 7 to 15%, depending on the diagnostic measure applied. Among the 921 participants who had not been diagnosed with hypertension, 37.7% (95% CI: 34.5-40.9%) had high blood pressure (≥140/90 mmHg) and 3.4% (95% CI 2.3-4.7%) had severe high blood pressure (≥180/120 mmHg). Although the BMI-enriched subgroups differed in anthropometric characteristics, prevalence estimates for dysglycaemia and hypertension were similar across the sampling strata.

Conclusions: This study highlights a substantial burden of previously undiagnosed high blood pressure and elevated fasting blood glucose among PLHIV in Dar es Salaam. While generalisability may be limited by the BMI-enriched sampling structure, these findings highlight the high burden of undetected comorbidities among this population.

Background: We previously reported alarmingly high carriage rates of Streptococcus pneumoniae (SP) serotype 19F and serogroup 6 isolates, which were not susceptible to multiple beta-lactams among children under five years of age in Vietnam. Multilocus sequence typing analysis revealed the predominance of two major lineages, ST320 and ST13223, among serotype 19F and serogroup 6 isolates, respectively. Investigating the association between nonsusceptible genotypes and clinical outcomes could help optimize patient care or lead to the development of new diagnostic tests.

Methods: We performed WGS on SP isolates randomly selected from the two major lineages and their related strains. FASTQ quality control and de novo assembly were performed using CLC Genomics Workbench ver. 7.5.1. Draft genome sequences were annotated using DFAST (DDBJ Fast Annotation and Submission Tool), which revealed the serogroups/serotypes and the sequences of the three major penicillin-binding protein genes and the sequence types. Draft sequences were aligned using MUMmer ver. 3.23, and putative recombination events and phylogenetic relationships excluding recombination regions were identified using Gubbins ver. 2.4.1. Finally, the association between a detected nonsusceptible genotype and the duration of hospital stay was evaluated in patients with acute respiratory infection.

Results: WGS analysis (serotype 19F/ST320, n = 22; serogroup 6/ST13223, n = 13; and isolates closely related to ST13223, n = 4) revealed substantial differences in genomic diversity and antimicrobial susceptibility between serogroup 6/ST13223 and serotype 19F/ST320 isolates, particularly the recombination-prone nature of serogroup 6/ST13223. Among the 23 recombination events observed in serogroup 6/ST13223, only those spanning the pbp2x region (15.5 kb and 6.4 kb) were associated with high MICs for multiple beta-lactams. A subset of ST13223 isolates and all ST320 isolates carried the identical pbp2x allele 16, which was significantly associated with a lack of susceptibility to the combination of penicillin, cefotaxime, and meropenem (p < 0.0001; odds ratio 11.5; 95% confidence interval [CI] 3.35-39.3). No significant association was demonstrated between the presence of this pbp2x allele and prolonged hospitalization (p = 0.6123).

Conclusions: We revealed that the widespread nonsusceptibility to multiple beta-lactams among SP isolates circulating in central Vietnam was primarily driven by the dynamics of the pbp2x gene. However, the nonsusceptible pbp2x allele had little effect on clinical outcome.

Background: Pediculosis capitis remains widespread globally, and the emergence of resistance genes continues to impede eradication efforts. This case of plica polonica offers insight into the complexity and challenges of pediculosis in endemic settings where resistant lice are present.

Case presentation: We report the case of a 13-year-old girl from a suburban area of Bangkok with long-standing pediculosis that progressed to plica polonica due to prolonged lack of intervention. Molecular analysis of the sampled lice demonstrated a 100% homozygous knockdown resistance (kdr) mutation. Several of her classmates also described recurrent infestations despite previous permethrin use, and permethrin exposure in this case showed limited effect, as lice remained viable after the recommended treatment period. The condition resolved after incorporating physical modalities.

Conclusion: Pediculosis in endemic areas is at a high suspicion for resistance. Chemical treatment alone may not lead to a cure, and caretakers should emphasize other treatment forms to achieve a cure. Such an approach may help prevent further mutations due to inbreeding within the headlice population with resistance genes from the unoptimized chemical treatment.

Background: Rotavirus is the leading cause of acute gastroenteritis among children under five years of age globally. In Kenya, rotavirus vaccination was introduced in 2014 using Rotarix® (G1P[8]), with a subsequent national transition to Rotavac® (G9P[11]) vaccine, in 2023. Evidence on post-introduction rotavirus disease burden, strain diversity, and Rotavac® vaccine effectiveness in Kenya remains limited. This study assessed the burden of rotavirus gastroenteritis and vaccine effectiveness of the rotavirus vaccine among children under five years of age in Nairobi's urban slums, after the rollout of the Rotavac® vaccine.

Methods: In this cross-sectional surveillance study, 353 stool samples were collected from children under five years of age presenting with acute gastroenteritis at selected health facilities in Mukuru informal settlement, Nairobi, between October 2023 and November 2024. The samples were analyzed using TaqMan array card PCR and multiplexed semi-nested RT-PCR. Vaccine effectiveness for overall rotavirus vaccination and Rotavac® specifically was estimated using a post-hoc test-negative case-control analysis.

Results: Rotavirus was detected in 19.5% (69/353; 95% CI 15.5-24.1%) of the samples. The highest detection occurred among children aged 12-23 months at 24.4% (30/123; 95% CI 17.1-33.0%), with significant differences across age groups (p = 0.023). Rotavirus prevalence was significantly lower among vaccinated children 18.4% (60/327; 95% CI 14.3-23.0%), compared with unvaccinated children 34.6% (9/26; 95% CI 17.2-55.7%) (p = 0.044). The predominant strain was G2P[4] (29.0%; 20/69), which also dominated among the vaccinated children (31.7%; 19/60), while G12P[6] was most frequent among unvaccinated children (33.3%; 3/9). Newly detected strains included G2P[8] and G12P[8], and two equine-like strains (G3P[8]eG3 and G2G3P[4]P[8]eG3). Short electropherotypes predominated. First-dose vaccine coverage was 92.6% (327/353) while the last-dose coverage was 76.2% (269/353). Estimated Rotavac® vaccine effectiveness was 74.1% (95% CI 16.3-92.0%), and overall rotavirus vaccine effectiveness was 57.6% (95% CI 18.1-99.8%).

Conclusion: Rotavirus remains a significant cause of gastroenteritis among children in Nairobi's urban informal settlements. The circulation of diverse and emerging strains underscores the need for continued molecular surveillance to monitor vaccine performance and guide future immunization strategies.

Background: We developed a Suitable Conditions Index (SCI) to predict dengue transmission in our prior work. However, the initial SCI was not refined with other important abiotic parameters. Therefore, in this study we refined the index by calculating three variants: temperature-based baseline daily average SCI (BDA-SCI), precipitation-weighted daily average SCI (PWDA-SCI), and waterbody-weighted daily average SCI (WWDA-SCI).

Methods: We used the district-wise data for two South Asian dengue-endemic countries: Bangladesh and Sri Lanka. Temperature-suitable days specific to Aedes aegypti (17.05-34.61 ℃) and Aedes albopictus (15.84-31.51 ℃) were averaged (BDA-SCI) and weighted by district-level precipitation (PWDA-SCI) and waterbody data (WWDA-SCI). We assessed the association between dengue incidence and each SCI, along with other covariates using negative binomial regression models. Furthermore, a binomial logistic regression model (BLR) was used to measure the predictive accuracy of each SCI.

Results: The BDA-SCI for Ae. aegypti was highest in Sri Lanka at 0.96 (Standard deviation [SD] 0.04, range 0.85-1.00), compared to Bangladesh 0.68 (SD 0.06, range 0.61-0.87). For Ae. aegypti, WWDA-SCI (Relative risk [RR]_aegypti = 1.06, p = 0.056, Akaike Information Criteria [AIC] 1218.6) and BDA-SCI (RR_aegypti = 1.05, p = 0.008, AIC 1214.2) had a stronger association with dengue incidence in Bangladesh than PWDA-SCI (RR_aegypti = 1.06, p = 0.056, AIC 1232.2), whereas in Sri Lanka, PWDA-SCI (RR_aegypti = 1.06, p = 0.056, AIC 472.63) performed better (AIC_BDA-SCI: 481.36, AIC_WWDA-SCI: 475.89) in the multivariable model, similar to the findings for Ae. albopictus. The BLR model predicted districts with above-median dengue incidence, and model performance indicated that BDA-SCI achieved highest accuracy for Bangladesh, while WWDA-SCI performed best for Sri Lanka, based on higher sensitivity and the Area Under the Curve value.

Conclusions: Overall, the SCI method demonstrated a practical approach for identifying dengue vector suitability and transmission risk. Refining this index with location-specific climatic and environmental variables may enhance the model accuracy and may be used for future predictions under climate change scenarios. Thus, our refined SCI will assist in creating a reliable early warning system and inform the policymakers to initiate vector control strategies, including monitoring and eliminating dengue breeding sites and implementing biocontrol strategies within hotspots.

Background: Rift Valley fever (RVF) virus and Coxiella burnetii are high-priority zoonotic pathogens posing health and economic threats in Africa. Data from Ethiopia are limited. This study estimated the prevalence and associated factors of RVF virus and C. burnetii among humans and livestock in Eastern Ethiopia using a One Health approach.

Methods: A multi-site cross-sectional study was conducted from May 1 to November 30, 2023, in the Shinile district, Somali Region, and Dire Dawa Administration. Data and blood samples were collected from 512 humans, and blood samples were collected from 1130 livestock. Sera and nucleic acids were tested using enzyme-linked immunosorbent assays (ELISA) and polymerase chain reaction (PCR), respectively. Logistic regression models were used to identify factors associated with RVF virus and C. burnetii IgG seropositivity.

Results: Apparent RVF virus IgG seroprevalence was 5.1% (26/512) in humans and 7.8% (88/1130) in livestock, while C. burnetii Phase I and II IgG seroprevalence was 30.3% (155/512) and 32.9% (372/1130), respectively. Camels showed the highest seropositivity to RVF virus IgG (17.7%; 52/294) and C. burnetii Phase I and II IgG (39.5%; 116/294). Co-seropositivity was 1.8% (9/512) in humans and 3.7% (42/1,130) in livestock. All PCR tests were negative. Rift Valley fever virus IgG seropositivity was associated with handling aborted materials (OR = 3.7; 95% CI 1.4-9.6; p = 0.007) and high mosquito abundance (OR = 4.5; 95% CI 2.0-10.1; p < 0.001). Camels had the highest odds of RVF virus IgG seropositivity (OR = 8.0, 95% CI 3.5-18.2; p < 0.001). Human C. burnetii Phase I and II IgG seropositivity was associated with female sex (OR = 2.4; 95% CI 1.6-3.6; p < 0.001), raw milk consumption (OR = 2.2; 95% CI 1.4-3.5; p < 0.001), cohabitation with animals (OR = 1.7; 95% CI 1.1-2.5; p = 0.01), and handling animal carcasses (OR = 2.3; 95% CI 1.4-3.5; p < 0.001).

Conclusions: The seroprevalence of RVF virus was low, whereas the seroprevalence of C. burnetii was high. High camel seropositivity underscores their role in pathogen transmission. One Health surveillance and targeted interventions are recommended to control the risk of future outbreaks.

Background: Giardiasis and cryptosporidiosis are often misdiagnosed by stool ova and parasite test (classical O&P). Multiplex PCR and rapid antigen immunochromatography (rapid-IC) could offer high diagnostic accuracy; however, their cost and restricted coverage, especially for parasites, limit routine use. This study evaluated the efficacy of adapted fluorescent antibody microscopy using ARK Checker® C/G-DyLight® 488 (FAM-TEST). The reagent is a liquid-form conjugated antibodies which directly detect Giardia cysts and Cryptosporidium oocysts under fluorescence microscopy.

Methods: A total of 694 stool samples submitted for microbiological examination were screened by FAM-TEST, in which specimens were mixed with DyLight-488-labeled antibodies and examined microscopically. Samples with discordant results among these methods were additionally tested by conventional PCR with Sanger sequencing to verify infection status.

Results: Diagnostic accuracy was assessed by reference to multiplex PCR results and compared with that of rapid-IC. FAM-TEST identified Giardia and/or Cryptosporidium in 35 samples. In addition, 49 FAM-TEST-negative samples from a randomly selected month were included as negative controls. For Giardia, all FAM-TEST results were identical to those of rapid-IC, including three false negatives [88.0% sensitivity, 100% specificity, 100% positive predictive value (PPV), and 95.2% negative predictive value (NPV)]. For Cryptosporidium, FAM-TEST showed 93.8% sensitivity, 100% specificity, 100% PPV, and 98.6% NPV, which were comparable with those of rapid-IC. Notably, conventional PCR for Giardia sequences produced negative results for three samples considered to yield FAM-TEST false negatives, raising another possibility of multiplex PCR false positives or extremely low pathogen burden.

Conclusion: Concurrent use of FAM-TEST with classical O&P offers a cost-effective, practical diagnostic approach for enteric parasites, which especially strengthens diagnostic accuracy for giardiasis/cryptosporidiosis.

Background: Schistosoma mansoni infection is highly prevalent in sub-Saharan Africa and is associated with significant intestinal morbidity in children. Current monitoring tools primarily assess infection status and intensity, which may underestimate the disease burden. Fecal occult blood (FOB) is a reliable indicator of bowel morbidity; however, its utility in intestinal schistosomiasis remains inadequately characterized. This study aimed to evaluate FOB as a surrogate marker of S. mansoni-induced intestinal morbidity among children in endemic areas of Kenya.

Methods: A pre-post intervention study was conducted among preschool-aged (3-5 years) and school-aged (9-14 years) children in the Mbita Health Demographic Surveillance System along the shores and islands of Lake Victoria, Suba North sub-county, western Kenya. A total of 611 children from 10 primary schools were screened for S. mansoni infection before praziquantel treatment, and 584 were re-evaluated 6 weeks post-treatment. In addition to parasitological examination for S. mansoni, FOB testing, malaria diagnosis, point-of-care hemoglobin measurement, and soil-transmitted helminth assessments were performed both before and after treatment. Associations between S. mansoni infection and FOB positivity were analyzed using Pearson's Chi-square test and logistic regression.

Results: S. mansoni infection prevalence was high before treatment, affecting 66.5% of preschool-aged and 77.4% of school-aged children. Among S. mansoni-infected children, more than three-quarters tested positive for FOB. Six weeks after praziquantel treatment, the prevalence of both S. mansoni infection and FOB positivity declined significantly (infection: 19-21%; FOB: 25-29%; P < 0.01). Before treatment, preschool-aged children residing on islands had twice the odds of FOB positivity compared to those on the mainland (AOR = 2.0; 95% CI 1.2-3.4; P = 0.01), although this association was no longer evident post-treatment.

Conclusions: Our findings demonstrate a significant association between S. mansoni infection and FOB positivity. These results suggest that FOB testing could be a useful indicator for monitoring treatment-associated reductions in intestinal morbidity due to S. mansoni in endemic settings.

This correspondence critically reflects on the recent article by Medina et al. (2025), "Pre- and post-COVID-19 pandemic identification of dengue hotspots and exploration of determinants in Quezon City." While acknowledging the study's timely contribution to understanding dengue dynamics in an urban context, the commentary identifies several key limitations. These include the absence of a clear theoretical framework, insufficient adjustment for confounding variables, reliance on a single data type without triangulation, weak translation of findings into actionable policy, and notable omissions in the literature review. Addressing these gaps in future research-through stronger theoretical grounding, rigorous methodological control, integration of multiple data sources, and closer alignment with policy and recent evidence-will enhance the scientific depth and practical relevance of dengue epidemiology.

Background: Exposure to animal and human feces in the household environment is associated with diarrheal diseases in young children. The objective of this study was to identify exposure pathways to fecal pathogens for young children that are significant contributors to diarrheal disease to allow for targeted water, sanitation, and hygiene (WASH) interventions on these pathways.

Methods: The WASHmobile Preventative Intervention for Cholera for 7 Days prospective cohort study was conducted in urban Bukavu, South Kivu province, Democratic Republic of the Congo. The cohort study of 794 children under 5 years of age included monthly diarrhea surveillance and unannounced spot checks to assess WASH behaviors and conditions over a 12-month period. Caregiver report of child mouthing of fomites was also obtained during monthly visits.

Results: The presence of animals in the child's sleeping space (odds ratio (OR): 1.87; 95% confidence interval (CI): 1.14, 3.08), unimproved sanitation (OR: 2.27; 95% CI 1.19, 4.33), and consumption of food outside the household (OR: 1.88; 95% CI 1.16, 3.06) were significantly associated with diarrhea during the subsequent month.Chickens [OR: 3.38; 95% CI: 2.05, 5.59) and cats [OR 3.9; 95% CI: 1.46, 10.46] in the child's sleeping space was also associated with significantly higher odds of diarrhea in the subsequent month.

Conclusions: These results demonstrate the need for WASH interventions targeted at reducing child contact with animal feces in the indoor household environment and improved sanitation, to reduce exposure to fecal pathogens for susceptible pediatric populations.