American Journal of Tropical Medicine and Hygiene最新文献

Dengue fever is a substantial emerging and reemerging arboviral virus in tropical and subtropical areas that seriously threatens public health worldwide. India is experiencing rising dengue epidemics in urban and rural regions linked to all four serotypes. The objective is to examine the serotypes and genotypes of the circulating dengue virus (DENV) at a tertiary care center in eastern Uttar Pradesh, India, from 2020 to 2021. This retrospective cross-sectional observational study involved dengue patients from January 2021 to December 2022. The genetic analysis of the circulating DENV was conducted by amplifying the partial CprM (511-bp) gene using nested reverse transcriptase polymerase chain reaction (RT-PCR), followed by sequencing. Only those positive for NS1 antigen (n = 581) were included in the study. A total of 204 cases (35.1%) were seropositive, with 96 cases (37.4%) out of 257 in 2021 and 108 cases (33.3%) out of 324 in 2022. With 119 cases (58.3%), men were most affected. The nested RT-PCR for dengue revealed three DENV-1 to DENV-3, except for DENV-4. DENV-2 and DENV-3 were the most predominant serotypes, with 98 (48%) and 94 (46%) cases, respectively. Conversely, DENV-1 was the least prevalent with cases 3 (1.6%). Unfortunately, 35 (17.2%) of the 204 cases died. DENV-2 had the highest mortality rate, with 23 deaths (65.7%). In cases with DENV-3, nine (25.7%) died. This study revealed regional disparities in DENV serotype prevalence in India. If regional differences in the most common serotypes and genotypes are identified early in the season, molecular surveillance may predict major dengue outbreaks and severity.

The soil is the primary environmental reservoir for many parasites transmitted to humans that cause disease. Our environmental study used a multiparallel real-time quantitative polymerase chain reaction assay to detect parasite DNA in soil collected from the outdoor built environments of 34 houses in rural Yucatan, Mexico. The number of positive houses (n, %) per parasite species was 18 (53%) for Acanthamoeba spp.; four (12%) for Blastocystis spp. and Ascaris lumbricoides; three (9%) for Toxocara canis; and one (3%) for Ancylostoma spp., Trichuris trichiura, Entamoeba histolytica, and Giardia intestinalis. No DNA from Necator americanus, Strongyloides stercoralis, Toxocara cati, or Cryptosporidium spp. was detected. A total of 65% of houses were positive for at least one parasite, 15% had poly-parasites, and up to six different parasites were detected in a single sample. This is one of the first reports of parasite DNA detected in soil samples from the outdoor environment in Yucatan, highlighting the presence of parasites with both zoonotic and medical significance for rural communities.

Human strongyloidiasis is an important intestinal parasitic disease that affects public health globally and is transmitted through contact with infective larvae on contaminated soil. Immunocompromised hosts can experience hyperinfection, which can lead to fatal systemic strongyloidiasis. Here, an innovative point-of-care (POC) test kit, the strongyloidiasis immunochromatographic blood test (the NIE-SsIR whole-blood ICT) kit is described. The kit was used to detect anti-Strongyloides IgG antibody in whole-blood samples (WBSs) instead of serum to diagnose strongyloidiasis. The kit is based on a mixture of two recombinant Strongyloides stercoralis protein antigens (NIE and SsIR) and colloidal-gold-labeled conjugates of anti-human IgG antibody to evaluate diagnostic values with simulated and fresh anticoagulated WBSs. The NIE-SsIR whole-blood ICT kit showed potentially high diagnostic values with simulated WBSs, obtained by spiking patients' sera with red blood cells. The sensitivity, specificity, and positive and negative predictive values were 93.0%, 93.7%, 88.6%, and 96.2%, respectively, at the prevalence of disease simulated under the laboratory conditions of 34.5%. In addition, 18 of 20 fresh anticoagulated WBSs from strongyloidiasis cases were positive, and all 15 WBSs from healthy volunteers were negative. The NIE-SsIR whole-blood ICT kit is a simple and convenient POC testing tool and can possibly be used with fingerstick blood samples, thereby not requiring the drawing of venous blood and separation of the serum. The NIE-SsIR whole-blood ICT kit can assist clinical diagnosis in remote areas and field settings without sophisticated equipment.

The Oriental rat flea, Xenopsylla cheopis, is known worldwide as an efficient plague vector, including in Madagascar, where the disease remains a public health concern. Chemical control is the primary response method against X. cheopis in Madagascar. Previous bioassays focusing on different flea populations from Madagascar showed phenotypic resistance to various insecticides, including deltamethrin and fenitrothion, which, respectively, represent the previous and current chemicals for flea vector control. Despite apparent insecticide resistance, the associated mechanisms of this resistance remain poorly known. The aims of this study were to adjust diagnostic doses of deltamethrin and fenitrothion and to investigate the metabolism-based insecticide resistance of X. cheopis in Madagascar. Five available laboratory-reared flea strains of X. cheopis were selected, and their susceptibility statuses to deltamethrin and fenitrothion were determined using the WHO standard bioassay. Diagnostic doses of each insecticide were determined by the probit method, in accordance with concentration gradients. Biochemical microplate-based assays were performed to detect overproduction of cytochrome P450, alpha-/beta-esterases, and glutathione S-transferase (GST), which are signatures of metabolic resistance. The five tested strains showed different susceptibility statuses against deltamethrin and fenitrothion. The diagnostic doses were estimated to be 0.07% for deltamethrin and 1.56% for fenitrothion. Increased activities of cytochrome P450, beta-esterase, and GST enzymes in the resistant strains were revealed in comparison with those of the susceptible strain. In conclusion, readjusted diagnostic doses will help to better understand the susceptibility status of X. cheopis to deltamethrin and fenitrothion. The overproduction of cytochrome P450, beta-esterase, and GST observed on deltamethrin-resistant flea strains suggests metabolic resistance.

Antimicrobial-resistant (AMR) bacteria are prevalent in household and environmental settings in low-income locations. However, there are limited data on individuals' understanding of AMR bacteria exposure risks in these settings. A cross-sectional study was conducted to identify individual risk perception of AMR bacteria and its associated behavioral determinants at the household level in urban, peri-urban, and rural Malawi. We conducted interviews with 529 participants from 300 households (n = 100 households/site). The risk, attitude, norms, ability, and self-regulation model was used to assess psychosocial factors underlying AMR bacteria exposure through animal feces, river water, and drain water. Analysis of variance was used to assess the difference between doers and non-doers of the three targeted behaviors: use and contact with river water, contact with drain water, and contact with animal feces. There was limited understanding regarding human-environmental interactions facilitating AMR bacteria transmission across all sites, and as such, the perceived risk of contracting AMR infection was low (41%; P = 0.189). Human contact with animal feces was seen as risky (64%) compared with contact with river and drain water (17%). Urban participants perceived that they were at greater risk of AMR bacteria exposure than their rural counterparts (P = 0.001). The perception of social norms was favorable for the targeted behaviors (P = 0.001), as well as self-reported attitude and ability estimates (self-efficacy; P = 0.023), thus indicating the role of psychosocial factors influencing the human-environment interaction in AMR bacteria transmission. Our findings underscore the need for combined infrastructural improvements and behavior-centered AMR bacteria education to drive behavioral changes, benefiting both AMR infection mitigation and broader One Health initiatives.

In refugee and internally displaced person settlements, hygienic water handling and free residual chlorine (FRC) are crucial for protecting water against recontamination after distribution up to the household point-of-consumption. We conducted a secondary analysis of water quality and water handling data collected in refugee camps in South Sudan, Jordan, and Rwanda using statistical and process-based modeling to explore how water handling practices affect FRC decay and household FRC outcomes. The two practices that consistently produced a significant effect on FRC decay and household FRC were storing water in direct sunlight and transferring water between containers during household storage. Samples stored in direct sunlight had 0.22-0.31 mg/L lower household FRC and had FRC decay rates between 2 and 3.7 times higher than samples stored in the shade, and samples that were transferred between containers had 0.031-0.51 mg/L lower household FRC and decay rates 1.65-3 times higher than non-transferred samples in sites in which the effect was significant, suggesting that humanitarian responders should aim to provide additional water storage containers to prevent water transferring in households and encourage water-users not to store water in direct sunlight. By contrast, the effect of the three recommended hygienic water handling behaviors (clean, covered containers and drawing by tap or pouring) was mixed or inconclusive. These inconclusive results were likely due to imbalanced or unreliable approaches to gathering the data, and we recommend that hygienic water handling practices that mechanistically provide a physical barrier against recontamination should always be promoted in humanitarian settings.

Dengue virus (DENV) is the most common arbovirus globally, with its incidence growing dramatically in recent decades. Although the effects of DENV infection during pregnancy are unclear, reported associations with adverse health outcomes include miscarriage, prematurity, and low birth weight. In this study, we used an IgG ELISA to identify mothers exposed to DENV during pregnancy by testing samples obtained from a previous study that followed a cohort of pregnant women in Kenya to investigate parasitic infections during pregnancy. We compared adverse pregnancy and infant health outcomes between seronegative mothers and those who seroconverted. Of the 289 participants tested for DENV exposure during pregnancy, we estimated that ∼12 women (4%) would have been exposed to DENV during their gestation period. However, we found that 34 mothers (11.8%) had been exposed to DENV during pregnancy. None of these mothers were hospitalized during pregnancy because of severe DENV infection, suggesting that many may have undergone asymptomatic seroconversion. The demographic risk factors of socioeconomic status, education level, bed net use, and maternal age were not associated with mild or asymptomatic DENV in pregnancy. Although mild or asymptomatic DENV during pregnancy was not associated with late prematurity, reduced postnatal childhood developmental measures, or adverse maternal pregnancy outcomes, we observed an increased risk of low birth weight. The larger-than-expected burden of DENV in pregnancy in this coastal Kenyan cohort and the observed potential risk of low birth weight provide evidence that a more comprehensive study is warranted to fully understand DENV infection during pregnancy.

Urbanization and microclimate variation in cities can influence mosquito behavior and parasite development, thus affecting malaria transmission. This study investigates how the impact of microclimate variations due to household roof types can aid in the survival of Anopheles stephensi and the development of Plasmodium vivax in an urban slum setting. Understanding these vital environmental interactions is essential for devising effective control strategies to achieve malaria elimination. Anopheles stephensi (F1) mosquitoes were membrane-fed with blood collected from P. vivax-infected patients before (day 0) and during (day 1) antimalarial treatment. The parasite development and mosquito survival were monitored in simulated microclimatic conditions of a variety of household roof types (thatched, asbestos, tiled) against standard laboratory conditions. Mosquito dissections were undertaken to detect oocysts and sporozoites in An. stephensi mosquitoes (oocyst: day 3-5, sporozoites: day 7-11). The maximum number of oocysts were detected in infected mosquitoes in thatched-roof conditions, whereas the largest oocyst was in the asbestos roof type. Circumsporozoite-ELISA results indicated the presence of sporozoites in infected mosquitoes for up to 29 days under standard conditions, 18 days in thatched-roof and asbestos roof conditions, and 14 days in tiled conditions. The univariate binary logistic regression model indicated a significant influence of microclimatic conditions of thatched roofs on parasite development. The Kaplan-Meier survival analysis revealed that the median survival of P. vivax-infected An. stephensi in thatched-roof conditions was 14 days, followed by asbestos (11 days) and tiled (10 days) roof conditions. In conclusion, thatched-roof houses were favorable for the development and survival of P. vivax-infected An. stephensi.

During the coronavirus disease 2019 pandemic, alcohol-based hand rub (ABHR) availability and use increased as a prevention measure. ABHR is a convenient, effective way to kill microbes on hands but is hampered by the presence of organic material, whereas handwashing with water and soap (HWWS) can physically remove microbes and dirt. Although ABHR is preferred in most health care settings, the suitability of ABHR use in community settings has not been measured. We compared characteristics between community members and health care personnel (HCP) to inform considerations for promoting ABHR in community settings. We included data from community locations and health care facilities in Kenya and Uganda collected between 2021 and 2022. Hand dirtiness swabs were measured using the Quantitative Personal Hygiene Assessment Tool (qPHAT), a visual scale where 0 is very visibly dirty and 10 is no visible dirt. Participants were also asked about the appropriate method to use when hands were visibly dirty. Hand swabs were collected from HCP and community members. Both groups had median qPHAT scores of five. Neither the adjusted odds of having a qPHAT score less than or equal to five (1.4, 95% CI: 0.8-2.2) nor the adjusted odds of responding correctly to the knowledge question (0.8, 95% CI: 0.4-1.4) differed significantly by setting. People in community settings may, therefore, have comparable hand dirtiness and knowledge of appropriate hand hygiene practices to use ABHR as a HWWS complement. Further investigation into guidance and use of supportive messaging should be considered as completed elsewhere.

In clinical settings, understanding the markers and clinical signs of infection is critical for timely diagnosis and treatment. However, a point-of-care diagnostic test is lacking for noma, a debilitating orofacial infectious disease. This retrospective study reviewed electronic medical records (EMRs) and paper medical records (PMRs) of noma patients from Facing Africa (235 EMRs), Yekatit 12 Hospital (68 PMRs), and Project Harar (33 PMRs) in Ethiopia to identify essential infection markers and clinical presentations of acute noma. The review identified seven acute noma patients aged 4-9 years. The patients presented with facial edema, pain, anorexia, ecchymosis, excessive salivation, and drooling, as well as specific symptoms such as visual disturbances, high fever, foul odor, halitosis, and local tenderness. Laboratory findings included elevated white blood cell counts (13,500-14,500 cells/mcL), C-reactive protein levels (107-148 mg/L), and erythrocyte sedimentation rates (65-90 mm/hour). At >85 ng/mL, procalcitonin levels were particularly high. Accurate diagnosis of noma requires a comprehensive approach that includes thorough clinical examination, appropriate disease stage classification, medical history review, and laboratory testing. The study highlights the critical infection markers and clinical presentations associated with acute noma that may aid in early diagnosis of the disease. Further research with a much larger number of participants is needed. However, given the difficulty in identifying acute noma cases due to the rapid progression and very high mortality of the disease and the challenge of accessing acute noma cases owing to various socioeconomic barriers, the results of this small study are still relevant.