Hasil untuk "Arctic medicine. Tropical medicine"

Yuka Sano, Hawraa Al-Alawi, Misao Himeno et al.

Abstract Introduction Flaviviruses such as dengue virus (DENV), Zika virus (ZIKV), Japanese encephalitis virus (JEV), and Yellow fever virus (YFV) are mosquito-borne RNA viruses causing major public health threats in major parts of the world. While DENV and ZIKV have been detected in urine samples, data on the presence and stability of flaviviruses in the water environment are limited. Methods In this study, we determined the stability and infectivity of flavivirus in different water environments by utilizing RT-qPCR and plaque assay to explore the feasibility of environmental detection and surveillance of flaviviruses. Results Viral RNA could be detected for up to 49-days, at 4 °C, 25 °C and 37 °C temperatures, and infectious particles could be detected for up to 7 days. While our findings showed that flaviviral RNA has higher stability and better detection rates at lower temperatures, the infectious capacity of flaviviruses was comparatively short at 7 days. Conclusions Our results indicate that flaviviruses retains limited infectivity in general water environments and highlight the feasibility of detection and surveillance in various epidemiologic and environmental settings.

Fernando Pereira Frassetto, Sergio Rosemberg

Abstract Background Yellow fever is a viral hemorrhagic fever caused by yellow fever virus, a mosquito-borne flavivirus. Despite an effective vaccine, major outbreaks continue to occur around the world. Even though it is not a proven neurotropic virus, neurological symptoms in more severe clinical forms are frequent. The understanding of this apparent paradox is still rarely addressed in literature. Methods The brains of thirty-eight patients with yellow fever confirmed by RT-PCR, who underwent autopsy, were analyzed morphologically to identify and characterize neuropathological changes. The data were compared with brains collected from individuals without the disease, as a control group. Both cases and controls were subdivided according to the presence or absence of co-concurrent septic shock, to exclude changes of the sepsis associated encephalopathy. To verify possible morphological differences between the yellow fever cases groups, between the control groups, and between the cases and the controls, we applied the statistical tests Fisher's exact test and chi-square, with p values < 0.05 considered statistically significant. Results All cases and controls presented, at least focally, neuropathological changes, which included edema, meningeal and parenchymal inflammatory infiltrate and hemorrhages, and perivascular inflammatory infiltrate. We did not find an unequivocal aspect of encephalitis. The only parameter that, after statistical analysis, can be attributed to yellow fever was the perivascular inflammatory infiltrate. Conclusions The neuropathological findings are sufficient to justify the multiple clinical neurologic disturbances detected in the YF cases. Since most of the parameters evaluated did not show statistically significant difference between cases and controls, an explanation for most of the neuropathological findings may be the vascular changes, consequent to shock induced endotheliopathy, associated with stimulation of the immune system inherent to systemic infectious processes. The statistical difference obtained in yellow fever cases regarding perivascular infiltrate can be can be explained by the immune activation inherent to the condition.

Evariste Tshibangu-Kabamba, Bui Hoang Phuc, Vo Phuoc Tuan et al.

Beside diagnostic uncertainties due to the lack of a perfect gold standard test for Helicobacter pylori infection, the diagnosis and the prevalence estimation for this infection encounter particular challenges in Africa including limited diagnostic tools and specific genetic background. We developed and evaluated the accuracy of an enzyme-linked immunosorbent assay (ELISA) system tailored for H. pylori genetics in Africa (HpAfr-ELISA). Strains belonging to main genetic populations infecting Africans were exploited as sources for whole-cell antigens to establish in-house the ELISA system. A phase II unmatched case-control study explored the diagnostic accuracy of the HpAfr-ELISA using a training set of samples collected from dyspeptic patients from Kinshasa, the Democratic Republic of Congo (DRC) who had been tested with invasive standard tests (i.e., histology, culture, and rapid urease test) in 2017. Then the assay was cross-validated through a community-based survey assessing the prevalence of H. pylori and associated factors in 425 adults from Mbujimayi, DRC in 2018. Bayesian inferences were used to deal with statistical uncertainties of estimates (true prevalence, sensitivity, and specificity) in the study population. At its optimal cut-off-value 20.2 U/mL, the assay achieved an estimated sensitivity of 97.6% (95% credible interval [95%CrI]: 89.2; 99.9%) and specificity of 90.5% (95%CrI: 78.6; 98.5). Consistent outcomes obtained at repeated tests attested the robustness of the assay (negative and positive agreements always > 70%). The true prevalence of H. pylori was estimated 53.8% [95%CrI: 42.8; 62.7%]. Increasing age (adjusted odds ratio [aOR] > 1.0 [95% confidence interval (CI): > 1.0; 1.1]; p<0.001), overcrowding households (aOR = 3.2 [95%CI: 2.0; 5.1]; p<0.001), and non-optimal hand hygiene (aOR = 4.5 [95%CI: 2.0; 11.4]; p = 0.001) were independently associated with the H. pylori-seropositivity. The novel ELISA system has demonstrated good diagnostic accuracy and potential usefulness for management and mitigation strategies for H. pylori infection in African settings.

Vanessa Lima-Neiva, Helena Keiko Toma, Lúcia Maria Abrantes Aguiar et al.

An outbreak of Chagas disease, possibly involving its vector Triatoma brasiliensis brasiliensis, was identified in the state of Rio Grande do Norte (RN). Given the historical significance of this vector in public health, the study aimed to evaluate its role in the transmission dynamics of the protozoan Trypanosoma cruzi in an area undergoing desertification in the Seridó region, RN, Brazil. We captured triatomines in sylvatic and anthropic ecotopes. Natural vector infection was determined using parasitological and molecular methods and we identified discrete typing units (DTUs) of T. cruzi by analyzing the COII gene of mtDNA, 24Sα rDNA, and mini-exon gene. Their blood meals sources were identified by amplification and sequencing of the mtDNA cytochrome b gene. A total of 952 T. b. brasiliensis were captured in peridomestic (69.9%) and sylvatic ecotopes (30.4%). A wide range of natural infection rates were observed in peridomestic (36.0% - 71.1%) and sylvatic populations (28.6% - 100.0%). We observed the circulation of TcI and TcII DTUs with a predominance of Tcl in sylvatic and peridomestic environments. Kerodon rupestris, rocky cavy (13/39), Homo sapiens, human (8/39), and Bos taurus, ox (6/39) were the most frequently detected blood meals sources. Thus, Triatoma b. brasiliensis is invading and colonizing the human dwellings. Furthermore, high levels of natural infection, coupled with the detection of TcI and TcII DTUs, and also the detection of K. rupestris and H. sapiens as blood meals sources of infected T. b. brasiliensis indicate a risk of T. cruzi transmission to human populations in areas undergoing desertification.

Jacques Sevestre, Caroline Bernardi, Morgane Gillet et al.

Abstract Background Malaria is a potentially lethal parasitic disease due to infection by Plasmodium parasites, transmitted by Anopheles mosquito vectors. Various preventative measures may be recommended for travellers who visit endemic areas. The diagnosis is generally evoked in the context of a febrile patient returning from an endemic zone. Nevertheless, symptoms and clinical signs may be difficult to interpret, and fatal cases may only be diagnosed retrospectively with laboratory techniques, specific pathological features and patient history. The present work reports a case of fatal cerebral malaria diagnosed post-mortem, along with the techniques that allowed identification of the causative agent. Case presentation A 29 year-old male was found dead in his rental home during a vacation in Southern France. In the absence of explainable cause, an autopsy was performed, which did not retrieve major lesions. In the context of frequent business-related travels in tropical Africa, several samples were adressed for parasitological examination. Microscopy techniques, along with immunochromatographic and molecular biology assays, led to post-mortem diagnosis of fatal cerebral malaria. It was discovered in retrospect that the patient had not used preventative measures against malaria when travelling in endemic zones, and had not been provided with proper travel medicine counseling prior to his travel. Conclusion A vast proportion of imported malaria cases reported in France concerns patients who did not use preventive measures, such as bed nets, repellents or chemoprophylaxis. Given the wide availability of prevention tools in developed countries, and the important number of declared imported malaria cases, there is no doubt traveller awareness still needs to be raised. Moreover, healthcare professionals should always question travel history in febrile patients. The authors advocate for recurrent information campaigns for travellers, and physician training for a better prevention and diagnosis of malaria cases.

Kathryn W. Roberts, Cara Smith Gueye, Kimberly Baltzell et al.

Abstract Background In Namibia, as in many malaria elimination settings, reactive case detection (RACD), or malaria testing and treatment around index cases, is a standard intervention. Reactive focal mass drug administration (rfMDA), or treatment without testing, and reactive focal vector control (RAVC) in the form of indoor residual spraying, are alternative or adjunctive interventions, but there are limited data regarding their community acceptability. Methods A parent trial aimed to compare the effectiveness of rfMDA versus RACD, RAVC versus no RAVC, and rfMDA + RAVC versus RACD only. To assess acceptability of these interventions, a mixed-methods study was conducted using key informant interviews (KIIs) and focus group discussions (FGDs) in three rounds (pre-trial and in years 1 and 2 of the trial), and an endline survey. Results In total, 17 KIIs, 49 FGDs were conducted with 449 people over three annual rounds of qualitative data collection. Pre-trial, community members more accurately predicted the level of community acceptability than key stakeholders. Throughout the trial, key participant motivators included: malaria risk perception, access to free community-based healthcare and IRS, and community education by respectful study teams. RACD or rfMDA were offered to 1372 and 8948 individuals in years 1 and 2, respectively, and refusal rates were low (< 2%). RAVC was offered to few households (n = 72) in year 1. In year 2, RAVC was offered to more households (n = 944) and refusals were < 1%. In the endline survey, 94.3% of 2147 respondents said they would participate in the same intervention again. Conclusions Communities found both reactive focal interventions and their combination highly acceptable. Engaging communities and centering and incorporating their perspectives and experiences during design, implementation, and evaluation of this community-based intervention was critical for optimizing study engagement.

Raghunandanan Rama Varma, Parvathi Varma, Anil Kumar

Aldenyeslle Rodrigues de Albuquerque, José Victor de Mendonça Silva, Emiliano de Oliveira Barreto et al.

Abstract INTRODUCTION: Leprosy is a chronic infectious disease caused by Mycobacterium leprae.This study aimed to analyze the epidemiological, temporal, and spatial dynamics ofleprosy in a municipality in northeastern Brazil. METHODS: This is an ecological study on new leprosy cases in the population of Arapiraca (Alagoas, Northeast Region, Brazil), from 2008 to 2017. Data extracted from a national database were analyzed forepidemiological indicators, factors associated with physical disabilities, and spatialanalysis in the neighborhoods of Arapiraca. RESULTS: A total of 292 new cases of leprosy were recorded, particularly occurring among the following groups: women, the age group of 46-59 years, brown-skinned individuals, people with less than eight years of schooling, and urban residents; the new cases were also predominantly the tuberculoid form and were of the paucibacillary classification of the disease. Almost 1/3 of the people had some degree of physical disability, which was mainly associated with the group 60 years of age and older, black ethnicity, and the multibacillary clinical form of leprosy. The joinpoint regression showed a stationary temporal behavior of indicators. There was a heterogeneous spatial distribution with active transmission areas, especially in the neighborhoods Primavera, Baixão, Ouro Preto, and downtown. CONCLUSIONS: The epidemiological indicators revealed complexity in the process of leprosy development. These spatial and temporal studies are relevant to help in the planning, monitoring, and guidance of interventions in the municipality. The spatial analysis showed heterogeneous distribution in the analyzed neighborhoods.

Daniele Rocha, Gisely Cardoso de Melo, José Marcelo Hipólito Carneiro et al.

An amendment to this paper has been published and can be accessed via the original article.

W. Anderson

Horace K. Gifpen