Tropical Medicine and Health最新文献

The study by Nikièma et al. demonstrates the absence of Wuchereria bancrofti infection in Anopheles mosquitoes a decade after cessation of mass drug administration (MDA) in Burkina Faso. This rare longitudinal evidence underscores the utility of molecular xenomonitoring (MX) as a sensitive early-warning tool that complements traditional transmission assessment surveys (TAS). MX enables detection of recrudescence earlier than human-based diagnostics, particularly in low-prevalence settings, and offers opportunities for integration with malaria vector surveillance. Ethical and operational challenges associated with human landing catches highlight the need for alternative trapping methods to maintain MX sensitivity safely. Sustaining lymphatic filariasis elimination globally will depend on institutionalizing MX alongside TAS, ensuring robust surveillance, and safeguarding long-term programmatic gains.

Background: Scrub typhus is an important zoonotic disease with rising incidence globally. Meteorological factors may influence its transmission dynamics. However, inconsistencies across studies and limited quantitative evidence highlight the need for further investigation.

Objective: To systematically evaluate the linear and nonlinear associations between various meteorological factors and scrub typhus incidence, explore lagged effects and potential sources of heterogeneity, and analyze inconsistencies in existing findings.

Method: We searched PubMed, Scopus, Web of Science, and Embase for studies published up to February 2025. Relevant articles were identified based on predefined inclusion and exclusion criteria. We conducted linear meta-analyses to assess the effects of unit changes in meteorological factors and dose-response meta-analyses to evaluate cumulative lagged risks across different exposure levels. Subgroup and sensitivity analyses were conducted to explore sources of heterogeneity and assess result robustness.

Results: Seventeen studies were included, covering China, Korea, Laos, and India. Eleven studies contributed to linear meta-analyses, and six to dose-response analyses. Ambient temperature (RR 1.08, 95% CI 1.02-1.16), land surface temperature (RR 1.06, 95% CI 1.02-1.09), precipitation (RR 1.01, 95% CI 1.01-1.02), relative humidity (RR 1.07, 95% CI 1.04-1.11), and atmospheric pressure (RR 1.06, 95% CI 0.91-1.23) were positively associated with the risk of scrub typhus. Wind speed (RR 0.59, 95% CI 0.49-0.71) and sunshine duration (RR 0.92, 95% CI 0.77-1.10) exhibited negative associations. Dose-response meta-analysis revealed inverted U-shaped relationships for ambient temperature and relative humidity, and a unimodal pattern for precipitation, with risk increasing continuously at high levels. Significant lag effects were observed: precipitation had the most immediate effect (lag0: RR 1.05), while ambient temperature (lag1: RR 1.18) and relative humidity (lag2: RR 1.28) peaked with a 1- to 2-month delay. Geographic variation was identified as a major source of between-study heterogeneity.

Conclusion: Although this study has certain limitations, including the small number of included studies, their concentration mainly in China, and the presence of substantial heterogeneity, the results provide evidence of linear and nonlinear associations between meteorological factors and scrub typhus incidence, and highlight the roles of geographical variation and lag effects. These findings offer quantitative evidence and scientific support for disease prevention and control in the context of climate change.

We commend Oh et al.'s recent analysis of TB preventive treatment (TPT) in the Western Pacific Region, but note important gaps and ways forward. We first caution that reliance on routine program data may overestimate gains. For example, China's passive surveillance misses ≈20% of cases [1]. Prospective cohorts or integrated surveillance including clinical databases could validate coverage estimates. We also urge attention to overlooked risk groups beyond children and PLHIV (as highlighted by Oh et al. [2]), groups like healthcare workers, prisoners, and people with diabetes warrant targeted TPT pilots (e.g., occupational health or prison-based programs). In the Philippines, ~ 36% of TB patients first seek private care [3], so partnering with private clinics and pharmacies is essential to reach all contacts. Likewise, MDR-TB contacts were underemphasized; WHO now strongly recommends a 6-month levofloxacin regimen for MDR contacts [4]. We encourage pilot studies of this regimen (as in Mongolia [5]) and operational research on MDR-TPT. Finally, policy does not guarantee practice as Cambodia and Lao PDR have guidelines, yet stockouts and training gaps persist [6, 7]. Embedding TPT in universal health insurance and conducting cost effectiveness studies will support sustainable scale-up. In sum, by suggesting concrete examples and research strategies for each country, we aim to refine Oh et al.'s insights into actionable steps for TPT acceleration.

Introduction: Somalia, the 44th largest country in the world by land area, struggles with a heavy burden of infectious diseases. Since 1991, populations have lacked essential health services, exacerbated by recurring infectious-disease outbreaks. Recurrent outbreaks of measles, cholera, and polio have devastated public health, generating significant morbidity and mortality. Despite improvements through new graduates, these issues remain unresolved. This study examines the impact of climate change on infectious-disease outbreaks in Somalia focusing on cholera, measles, and polio-to fill a gap in the literature by linking climate variability with outbreak dynamics and identifying weaknesses in Somalia's health system. The findings will inform targeted public-health strategies.

Method: Following PRISMA guidelines, we undertook a narrative review of English-language literature (1990 - March 2025). Searches in PubMed, Scopus, Web of Science and Google Scholar combined terms for infectious-disease outbreaks, climate change and Somalia/Horn of Africa. Of 202 records identified, 74 met inclusion criteria. Two reviewers independently screened, extracted data and applied six-step inductive coding in NVivo 12, synthesizing findings into thematic domains.

Results: Four interlinked themes emerged. (1) Fragile health system: < 0.4 doctors, nurses and midwives per 10 000 population, poorly equipped facilities and patchy surveillance. (2) Control measures: routine immunization completeness ≈20%; limited oral-cholera-vaccine and WASH coverage sustain transmission. (3) Political instability and conflict: insecurity, decentralized coordination and ≥ 2.6 million IDPs hamper rapid response. (4) Impact of climate change: drought-induced water scarcity and flood-related latrine breaches create year-round face-oral exposure, while climate shocks divert resources and swell susceptibility pools.

Conclusion: Outbreak control in Somalia now hinges on integrating climate adaptation with health-system strengthening. Climate-proofed WASH infrastructure, mobile vaccination and surveillance linked to hydro-meteorological alerts, a National Outbreak Operations Centre, and ring-fenced financing are urgent priorities. Without such measures each extreme-weather event will erase hard-won gains; with them, Somalia can break the climate-outbreak feedback loop.

Background: Community health workers (CHWs) are vital for improving maternal and child health (MCH) in underserved settings; however, gender norms often influence their functioning. In the Lao PDR, Village Health Volunteers (VHVs) serve as frontline CHWs in rural areas. Xepon District is a remote border area with Vietnam, characterized by underserved conditions, limited health access, and predominantly ethnic minority populations. The VHV workforce in this district is largely male, which restricts culturally acceptable outreach to women and underscores the need to test a paired male-female model. To address this gender-related limitation, a provincial pilot program introduced male-female VHV/VHW pairs to strengthen MCH outreach.

Objectives: This study aims to explore how the male-female paired VHV model functions in remote ethnic minority communities and its contributions to maternal health promotion.

Methods: A qualitative descriptive study was conducted in 19 pilot villages in Xepon District, Savannakhet Province, from June to October 2024. Semi-structured interviews were held with 42 participants, including mothers, their partners, VHVs, village leaders, health center staff, and district/provincial health officials. Interviews were transcribed, translated, and analyzed using inductive thematic analysis based on Braun and Clarke's six-phase framework.

Results: Four key themes emerged: (1) building trust and comfort through gender-matched interactions; (2) gender-specific responsibilities and task sharing between paired VHVs; (3) strengthening family support and health system linkages through female VHV/VHWs engagement; and (4) challenges and support needs for strengthening the VHV Program. Female VHV/VHWs played a crucial role in culturally sensitive maternal outreach, whereas male VHVs facilitated engagement with male household members and community leaders. Paired implementation enhanced service utilization and helped shift household norms. However, challenges persisted, including gender selection barriers, literacy gaps, and limited institutional support for paired training and supervision.

Conclusion: The male-female VHV/VHWs model may enhance access to MCH services by engaging men and women in complementary roles tailored to local contexts. To maximize its potential, institutional commitment is needed to formalize pair-based training, address gender barriers in recruitment, and strengthen community- and policy-level support systems for CHWs. Given the 2023 PHC policy, embedding gender-sensitive and context-specific approaches into guidelines and training manuals may be critical for aligning service delivery with sociocultural realities and ensuring responsiveness to the unique needs of remote communities.

Background: Men who have sex with men (MSM) in Ghana continue to face a disproportionately high HIV burden, with an estimated prevalence of 18.1% far exceeding the national average of 1.7%. Transactional sex (TS), defined as the exchange of sex for money, goods, or services, is a key behavioral risk factor for HIV acquisition. However, nationally representative data on its prevalence, correlates, and health consequences among MSM in Ghana remain scarce. This study aimed to identify sociodemographic and behavioral predictors of TS and assess its association with laboratory-confirmed HIV and syphilis.

Methods: We conducted a cross-sectional bio-behavioral survey using respondent-driven sampling (RDS) among 3,448 MSM aged ≥ 18 years across Ghana's ten traditional regions (August 2022-July 2023). Weighted descriptive statistics and multivariable logistic regression models were used to analyze correlates of TS and its association with HIV/syphilis. HIV and syphilis were diagnosed on-site using a rapid dual HIV-syphilis serological test, followed by confirmatory HIV testing with OraQuick and SD Bioline per Ghana's national HIV testing guidelines.

Results: Nearly half (44.8%) of participants reported engaging in TS. TS Prevalence was highest among adolescents (18-19 years: 50.8%), those with basic education (52.9%), and MSM in Greater Accra (63.9%). Older age (≥ 35 years) was associated with 63% lower odds of TS (aOR: 0.37, 95% CI 0.21-0.68, p = 0.001), while tertiary education was protective (aOR: 0.52, 95% CI 0.32-0.86, p = 0.010). TS odds increased significantly with multiple sexual partners, high alcohol use, forced sex, and poor HIV knowledge. Although TS was not independently associated with HIV (aOR: 1.16, 95% CI 0.92-1.47) or syphilis (aOR: 1.12, 95% CI 0.83-1.52), it co-occurred with other established factors.

Conclusion: TS is prevalent among MSM in Ghana, driven by structural and behavioral factors such as young age (18-19), low education, urban residence, alcohol use, stigma, and sexual role. While not directly linked to HIV/syphilis risk in this study, TS serves as a significant indicator of vulnerability due to its clustering with other risks. Targeted interventions addressing these social and structural drivers, especially education and urban-focused outreach, are critical to reducing HIV transmission in this population.

Background: Medicine shortages remain a pervasive global public health challenge, particularly affecting import-dependent countries with limited local manufacturing capacity. Namibia's reliance on pharmaceutical imports makes it vulnerable to supply chain disruptions across human and veterinary health sectors.

Aim: This study explores availability and factors contributing to medicine shortages in Namibia from the perspectives of regulators and pharmaceutical suppliers.

Methods: An exploratory qualitative study was conducted between August and October 2024. In-depth semi-structured interviews were carried out with 11 key stakeholders in the pharmaceutical sector involved in procurement, distribution, and regulation across public and private sectors, including animal health. Thematic analysis was employed.

Results: Five themes emerged: persistent shortages affecting both sectors with pronounced public sector challenges, particularly for chronic disease treatments (antihypertensives, insulin, anti-tuberculosis medicines, antiretrovirals); general supply chain constraints including limited local manufacturing, small market size, and global active ingredient shortages; public sector barriers including absence of formal procurement contracts and manual systems; regulatory bottlenecks encompassing processing delays and capacity constraints; and veterinary sector vulnerabilities despite economic importance.

Conclusions: Stakeholders identified medicine shortages as resulting from interconnected systemic challenges encompassing procurement, regulatory, infrastructural, and market-based constraints. Key patterns emerged: Namibia's regional reclassification appears to have increased supply vulnerabilities; absence of formal procurement contracts has led to reliance on emergency mechanisms; and regulatory capacity limitations may compound supply challenges. These interconnected factors suggest the need for coordinated multi-domain interventions, though further research is needed to quantify these relationships. Findings may inform policy considerations for improving medicine security in similar resource-constrained settings.

Recent findings by Suppiah et al. revealed DENV-2 positive samples misclassified as "Undetermined Serotype" when using commercial dengue molecular serotyping assays. This highlights the noninclusion and resulting misclassification of this viral strain as a dengue virus serotype using available molecular tools. Drawing parallels from the notification of the same assay failure against sylvatic DENV-2 strains in Senegal, West Africa, this correspondence advocates for updating the existing tools to account for this viral variant. Development of multiplex assays including both urban and sylvatic strains may enhance dengue virus surveillance and provide real time monitoring of the prevalence of sylvatic viral lineages among recorded dengue infections in surveillance data.

Background: Previous studies have analyzed the association between sun exposure and ischemic heart disease (IHD). However, the association has not been assessed globally and may differ when adjusting for spatial dependency. This study aimed to clarify whether this global association remains even while incorporating spatial adjustment.

Methods: The most recent age-adjusted IHD mortality data (per 100,000) by country (1987-2022) were obtained from the World Health Organization (WHO) database as the dependent variable. As the independent variable, global solar radiation (GSR) data (MJ/m²/day; mean of 1994-2018) were retrieved from the Global Solar Atlas, with values clipped to each capital's location. Covariates included smoking prevalence, alcohol consumption, salt intake, gross domestic product, and health expenditure. To assess associations by sex, ordinary least squares (OLS) regression and three spatial regression models (spatial lag model, spatial error model, and spatial Durbin model) were applied. Additionally, an income-level stratified analysis was conducted. All analyses were performed with R version 4.5.0.

Results: After listwise deletion of missing values, 94 countries remained. The mean (SD) IHD mortality rates for males and females were 96.5 (80.4) and 52.4 (48.0), respectively. The mean (SD) GSR was 15.9 (3.7). In the OLS model, GSR showed a significant negative association with IHD mortality (males: β =  - 8.82, p = 0.002; females: β =  - 6.31, p < 0.001). The spatial lag model was the best fit for both sexes, and the association persisted (males: β =  - 4.78, p = 0.041; females: β =  - 3.86, p = 0.005). Stratified analysis largely supported these findings. However, coefficients substantially decreased after spatial adjustment.

Conclusions: Sun exposure retained a significant inverse association with ischemic heart disease mortality after adjusting for spatial dependency, although adjustment markedly reduced the strength of association. However, our results require careful interpretation due to several limitations in the study.

Background: Amebic liver abscess (ALA) is a serious complication of Entamoeba histolytica infection. In rare cases, ALA may rupture into the thoracic cavity, leading to a high risk of death. Differentiating intrathoracic ALA rupture from reactive pleural effusion is essential for predicting the clinical course and appropriate management.

Case presentation: A 46-year-old bisexual man with well-controlled human immunodeficiency virus infection presented with pain in the right shoulder and upper abdomen. Imaging revealed a solitary liver abscess with diaphragmatic rupture, right pleural effusion, and portal vein thrombosis. Results of stool microscopy, antigen testing, and cytology of pleural and liver aspirates were inconclusive. However, E. histolytica was identified in the stool, liver abscess aspirate, and pleural fluid using polymerase chain reaction tests. Despite the initial therapy with metronidazole, the thoracic fluid volume increased considerably, necessitating thoracic and hepatic drainage. After stabilization, anticoagulation therapy with edoxaban for portal vein thrombosis and luminal therapy with paromomycin were initiated. The patient showed progressive clinical improvement, and follow-up imaging confirmed shrinkage of the liver abscess and resolution of the thrombus and diaphragmatic rupture. No recurrence was observed during the 6-month follow-up period.

Conclusions: We reported the case of a patient with a rapidly progressive ALA with intrathoracic rupture. In cases of ALA with thoracic rupture, performing drainage is important, considering that pleural effusion may progress rapidly. This case highlights the need for comprehensive management involving timely antimicrobial and anticoagulation therapy in cases of vascular thrombosis.