Transactions of The Royal Society of Tropical Medicine and Hygiene最新文献

Background: Yellow fever (YF) is a highly lethal arboviral disease that is transmitted to humans by the bites of infected mosquitoes. However, the drivers of epidemic episodes are not well understood. In this ecological study, we analysed spatial and temporal patterns of the largest yellow fever outbreaks in the 21st century in Brazil.

Methods: We describe the spatial and temporal patterns of 2178 human YF cases, 2911 non-human primate (NHP) cases and immunization coverage using the Global and Local Moran's Index, directional distribution and logistic regression models.

Results: Spatially distinct clusters were detected along heterogeneous forestland and ecological corridors. Human YF occurrence increased with a higher abundance and diverse genera of NHP YF cases along with seven other variables: lower vaccination coverage, lower elevation, moderate annual mean temperature, higher annual precipitation, increased vector abundance, low to moderate urbanization and forested land.

Conclusions: Our results suggest that human YF epidemics are largely driven by vaccination coverage and environmental conditions that aid transmission in vectors and hosts. This sustains the local sylvatic cycle across administrative and political boundaries. These results reinforce the need to study YF spillover and dispersion dynamics at the human-animal-environment interface to improve disease control and devise multisectoral mitigation strategies.

Background: The WHO recently recommended the widespread use of new classes of long-lasting insecticidal nets (LLINs) to control malaria, but there is little evidence of their efficacy in pregnant women. This study aimed to assess the impact of two dual active ingredient (AI) LLINs on poor birth outcomes under pragmatic conditions.

Methods: A community-based cross-sectional survey was conducted during March-May 2023 in 1644 women of reproductive age who delivered in the 3 y following net distribution. Multivariate logistic regression models with random effects were used to assess the dual AI LLINs effects on poor pregnancy birth outcomes.

Results: Poor birth outcomes prevalence during pregnancy was 21.9%. Dual AI LLINs did not provide protection against poor birth outcomes in comparison with standard LLINs. However, among women who reported using allocated study nets, the odds of poor pregnancy birth outcomes were reduced in the pyriproxyfen-pyrethroid LLIN (adjusted OR [aOR] 0.50, 95% CI 0.31 to 0.82) and chlorfenapyr-pyrethroid LLIN (aOR 0.67, 95% CI 0.43 to 1.04) groups.

Conclusion: Poor birth outcomes were similar for women living in the dual AI LLIN groups and those in the pyrethroid-only LLIN group, regardless of the type of net used. However, women using allocated dual AI LLINs were better protected than those using standard LLINs. National malaria control programmes should consider these new-generation LLINs for malaria control during pregnancy.

Background: India has initiated a programme to eliminate sickle cell disease (SCD) by 2047. As the programme progresses with screening, treatment, management and preventive activities will eventually be initiated. However, the community's knowledge and involvement are important for effective implementation of these public health interventions. The overall knowledge related to SCD among the Indian tribal communities is inadequate and can be enhanced through community-based interventions. This article reports the impact of a comprehensive community-based SCD care intervention on improving SCD-related awareness and knowledge among Indian tribal communities in six SCD-endemic tribal-dominated districts.

Methods: A multicentric community-based and health system strengthening intervention, a quasi-experimental design comparing pre- and post-intervention outcomes within intervention groups and with the control group, was conducted to improve the health system's capacity to screen and manage SCD and to improve the community's acceptance of screening and management through community mobilisation, including information, education and communication (IEC). This article utilised pre- and post-intervention data (from 9837 and 9696 participants in pre- and post-intervention surveys in both control and intervention areas) on community knowledge of SCD. The difference-in-differences (DID) methodology was used to assess the net change in outcomes.

Results: There was a significant increase in knowledge among people exposed to the intervention and a significant increase in the proportion of people who heard of SCD after the intervention, with a DID estimate of 55.5. A similar impact was reported for improved knowledge on the cause of SCD (DID=61.4), diagnostic methods (DID=60.5), symptoms (DID=55.5), treatment (DID=57.7), prevention (DID=59.7) and various aspects of these issues.

Conclusions: This study demonstrates the effectiveness of a community-based intervention programme aimed at improving SCD-related knowledge among the tribal communities. The findings underscore the importance of targeted awareness programmes in addressing gaps in knowledge. Strong community mobilisation and IEC activities are key components of SCD care programmes.

Background: Zambia faces persistently high malaria morbidity and mortality rates, worsened by inadequate prevention and treatment resources, and high transmission. We aimed to assess the impact of three long-lasting insecticidal net (LLIN) distribution campaigns in four Zambian provinces from 2010 to 2021.

Methods: We employed binomial regression and interrupted time series to analyze monthly malaria incidence across four provinces in Zambia (Eastern, Luapula, Northern and Northwestern) with a combined population of 5965257 within 1357 health facility catchment areas, utilizing data from the national Health Management Information System. We analyzed the association between LLIN distribution and trends in malaria incidence in terms of monthly cases confirmed by rapid diagnostic testing during January 2010-December 2021.

Results: There was a significant reduction in malaria incidence rates following LLIN distribution. Temporal trends and seasonal patterns also influenced malaria transmission. Results showed a statistically significant decline in monthly malaria incidence rates following implementation of LLIN distribution, attributable to the immediate protective effects of nets; the binomial regression model showed up to 35% reduction in seasonally adjusted malaria incidence (rate ratio: 0.65, 95% CI 0.50 to 0.85; p=0.002).

Conclusions: Regular and timely replacement of nets is essential to maintain their protective benefits. This study highlights the key importance of LLINs for malaria control as part of wider strategies in Zambia and elsewhere.

Background: In dengue-endemic regions like Vietnam, viral haemorrhagic fevers (VHFs) with overlapping clinical presentations often lead to misdiagnoses. This study investigated alternative VHF pathogens in patients clinically suspected of dengue but negative by standard diagnostics during a 2016 outbreak in central Vietnam.

Methods: Among 198 hospitalized patients, 52 dengue virus (DENV)-negative cases were tested using enzyme-linked immunosorbent assays for immunoglobulin G (IgG)/IgM against seven VHFs and molecular assays for pan-flaviviruses and hantaviruses. Positive amplicons were sequenced and subjected to phylogenetic analysis.

Results: High flavivirus IgG seropositivity was observed, especially for Japanese encephalitis virus (96%), DENV, tick-borne encephalitis virus and West Nile virus (92% each), with notable cross-reactivity. IgM responses were specific, with 37% of patients positive for anti-JEV and 33% for anti-DENV. Pan-flavivirus reverse transcription polymerase chain reaction confirmed DENV-1 RNA in four patients. One patient tested positive for hantaviral RNA and seropositive for both IgG and IgM. Sequencing and phylogenetic analysis identified Orthohantavirus seoulense (SEOV) as the causative agent, clustering with SEOV strains from Vietnam and Indonesia. The detection of SEOV highlights co-circulation of rodent-borne viruses during arboviral outbreaks.

Conclusions: This study highlights significant serological cross-reactivity among flaviviruses and underdiagnosed circulation of hantaviruses such as SEOV. Enhanced multimodal diagnostic surveillance of pathogens remains essential.

Background: Cerebral malaria is a major cause of death in endemic areas. An animal model of cerebral malaria has been studied widely in which C57BL/6 mice are infected with the Plasmodium berghei ANKA strain. The histopathology and the response to interventions of human cerebral malaria and the murine model are very different. In 2012, a consensus guideline was published recommending that in order to represent better the clinical setting, interventions in the murine model should be tested together with antimalarial drug treatment and after development of the cerebral syndrome.

Methods: A systematic review of publications on human and murine cerebral malaria since 2010 was conducted.

Results: Clinical research on human cerebral malaria has declined and still no adjuvant intervention has proved effective. Meanwhile, since 2010, 149 interventions (118 adjuvants) have been evaluated in the mouse model, of which 142 (95%) were reportedly successful. Only 26% of interventions were evaluated after the development of the murine cerebral syndrome and 65% of the adjuvants were tested without a concomitant antimalarial.

Conclusion: The predictive value of the murine model in identifying adjuvant therapeutic interventions in human cerebral malaria is very poor.

Dengue is an infectious disease caused by the bite of a mosquito (Aedes aegypti) infected with the dengue virus and represents the world's most common arboviral infection. Dengue is most common in tropical and subtropical areas and it has become a threat to human life. This disease induces high immune system activation resulting in an inflammatory process. C-reactive protein (CRP) as a marker of inflammation in various diseases has been studied; however, there are few studies that analyse it as an effector molecule in inflammatory disease pathogenesis. This review summarizes the current published literature through 2025 (on PubMed, Embase and Web of Science) regarding the factors that affect the pathogenesis of dengue mediated by CRP. The role of CRP in dengue pathogenesis may be related to its effects on complement activation, alterations of the coagulation system, thrombocytopaenia, alteration of vascular permeability, induction of liver damage and its interaction with Fc receptors and dendritic cells. These data strongly suggest a role for CRP in dengue pathogenesis.

Background: Deployment of seasonal malaria chemoprevention (SMC) for young children using monthly sulphadoxine-pyrimethamine-amodiaquine (SPAQ) has recently been extended to Central and East Africa.

Methods: A pilot pharmacometric assessment was nested within a larger deployment of SMC in a high malaria transmission area in northern Mozambique. SPAQ was given to 460 healthy children in two large villages. Simultaneous filter-paper blood spot malaria quantitative PCRs, blood slide microscopy and antimalarial drug measurements were taken before, then 7 and 28 d after first SPAQ administration.

Results: After SPAQ, parasitaemia prevalence decreased from 68% to 41%. Among children followed successfully for 28 d, malaria parasitaemia prevalence declined from 71% to 44%. Preventive efficacy was 97% for Plasmodium ovale and 42% for Plasmodium falciparum. Reinfections (N=50 with sufficient DNA for genotyping) and recrudescences (N=3) often grew through high concentrations of desethylamodiaquine, yet all 250 P. falciparum isolates genotyped were Pfcrt 76K, a molecular marker of 4-aminoquinoline susceptibility. One-third (21/64) of microscopy-detectable breakthrough P. falciparum infections had patent gametocytaemia. There was a clear chemoprevention exposure-response relationship evident for desethylamodiaquine, but not for sulphadoxine or pyrimethamine.

Conclusions: In Nampula, northern Mozambique, amodiaquine had low parasitological efficacy and sulphadoxine and pyrimethamine did not contribute significantly to chemoprevention.