Recent Cholera Publications on PubMed

A commensal-encoded genotoxin drives restriction of Vibrio cholerae colonization and host gut microbiome remodeling

March 7, 2022

Proc Natl Acad Sci U S A. 2022 Mar 15;119(11):e2121180119. doi: 10.1073/pnas.2121180119. Epub 2022 Mar 7.


SignificanceIn a polymicrobial battlefield where different species compete for nutrients and colonization niches, antimicrobial compounds are the sword and shield of commensal microbes in competition with invading pathogens and each other. The identification of an Escherichia coli-produced genotoxin, colibactin, and its specific targeted killing of enteric pathogens and commensals, including Vibrio cholerae and Bacteroides fragilis, sheds light on our understanding of intermicrobial interactions in the mammalian gut. Our findings elucidate the mechanisms through which genotoxins shape microbial communities and provide a platform for probing the larger role of enteric multibacterial interactions regarding infection and disease outcomes.

PMID:35254905 | PMC:PMC8931321 | DOI:10.1073/pnas.2121180119

Evaluation of Antimicrobial Susceptibility Profile in Salmonella Typhi and Salmonella Paratyphi A: Presenting the Current Scenario in India and Strategy for Future Management

March 3, 2022

J Infect Dis. 2021 Nov 23;224(Supple 5):S502-S516. doi: 10.1093/infdis/jiab144.


BACKGROUND: Systematic studies to estimate the disease burden of typhoid and paratyphoid in India are limited. Therefore, a multicenter study on the Surveillance of Enteric Fever in India was carried out to estimate the incidence, clinical presentation, and antimicrobial resistance (AMR) trend. The data presented here represent the national burden of AMR in Salmonella Typhi and Salmonella Paratyphi A.

METHODS: Antimicrobial susceptibility testing was performed for S. Typhi and S. Paratyphi A (n = 2373) isolates collected prospectively during a 2-year period from November 2017 to January 2020.

RESULTS: Of 2373 Salmonella isolates, 2032 (85.6%) were identified as S. Typhi and 341 (14.4%) were S. Paratyphi A. Approximately 2% of S. Typhi were multidrug-resistant (MDR), whereas all 341 (100%) of S. Paratyphi A isolates were sensitive to the first-line antimicrobials. Among 98% of ciprofloxacin nonsusceptible isolates, resistance (minimum inhibitory concentration [MIC] >0.5 µg/mL) was higher in S. Typhi (37%) compared with S. Paratyphi A (20%). Azithromycin susceptibility was 99.9% and 100% with a mean MIC of 4.98 μg/mL for S. Typhi and 7.39 μg/mL for S. Paratyphi A respectively. Ceftriaxone was the only agent that retained 100% susceptibility. Moreover, beta-lactam/beta-lactamase inhibitors showed potent in vitro activity against the study isolates.

CONCLUSIONS: Data obtained from this systematic surveillance study confirms the declining trend of MDR Salmonella isolates from India. The higher prevalence of ciprofloxacin nonsusceptibility enforces to limit its use and adhere to the judicious usage of azithromycin and ceftriaxone for enteric fever management.

PMID:35238369 | PMC:PMC8892543 | DOI:10.1093/infdis/jiab144

Antibiotics for Fever Among Children: Findings From the Surveillance for Enteric Fever in India Cohorts

March 3, 2022

J Infect Dis. 2021 Nov 23;224(Supple 5):S494-S501. doi: 10.1093/infdis/jiab115.


BACKGROUND: Acute febrile illness in children is frequently treated with antibiotics. However, the inappropriate use of antibiotics has led to the emergence of multidrug-resistant pathogens.

METHODS: We measured use of antibiotics for fever in 4 pediatric cohorts that were part of the Surveillance for Enteric Fever in India (SEFI) network. In this network, 24 062 children were followed up weekly, capturing information on fever and other morbidity between October 2017 and December 2019.

RESULTS: An antibiotic was given in 27 183 of the 76 027 (35.8%) episodes of fever. The incidence of fever-related antibiotic use was 58.0 (95% confidence interval [CI], 57.2-58.6) per 100 child-years. The median time to initiation of antibiotics was 4 days, and in 65% of those who received an antibiotic it was initiated by the second day. Antibiotics were continued for <3 days in 24% of the episodes. Higher temperature, younger age, male sex, joint family, higher education, internet access, and availability of personal conveyance were associated with antibiotic treatment for fever.

CONCLUSIONS: In developing countries where antibiotic use is not regulated, broad-spectrum antibiotics are initiated early, and often inappropriately, in febrile illness. Frequent and inappropriate use of antibiotics may increase risk of antimicrobial resistance.

PMID:35238360 | PMC:PMC8892537 | DOI:10.1093/infdis/jiab115

Geographically Weighted Regression Modeling of Spatial Clustering and Determinants of Focal Typhoid Fever Incidence

March 3, 2022

J Infect Dis. 2021 Nov 23;224(Supple 5):S601-S611. doi: 10.1093/infdis/jiab379.


BACKGROUND: Typhoid is known to be heterogenous in time and space, with documented spatiotemporal clustering and hotspots associated with environmental factors. This analysis evaluated spatial clustering of typhoid and modeled incidence rates of typhoid from active surveillance at 4 sites with child cohorts in India.

METHODS: Among approximately 24 000 children aged 0.5-15 years followed for 2 years, typhoid was confirmed by blood culture in all children with fever >3 days. Local hotspots for incident typhoid cases were assessed using SaTScan spatial cluster detection. Incidence of typhoid was modeled with sociodemographic and water, sanitation, and hygiene-related factors in smaller grids using nonspatial and spatial regression analyses.

RESULTS: Hotspot households for typhoid were identified at Vellore and Kolkata. There were 4 significant SaTScan clusters (P < .05) for typhoid in Vellore. Mean incidence of typhoid was 0.004 per child-year with the highest incidence (0.526 per child-year) in Kolkata. Unsafe water and poor sanitation were positively associated with typhoid in Kolkata and Delhi, whereas drinking untreated water was significantly associated in Vellore (P = .0342) and Delhi (P = .0188).

CONCLUSIONS: Despite decades of efforts to improve water and sanitation by the Indian government, environmental factors continue to influence the incidence of typhoid. Hence, administration of the conjugate vaccine may be essential even as efforts to improve water and sanitation continue.

PMID:35238357 | PMC:PMC8892548 | DOI:10.1093/infdis/jiab379

Prevalence and molecular characterization of Vibrio cholerae from fruits and salad vegetables sold in Jakarta, Indonesia, using most probable number and PCR

March 3, 2022

BMC Res Notes. 2022 Mar 3;15(1):63. doi: 10.1186/s13104-022-05955-y.


OBJECTIVE: Cholera is an intestinal infection caused by Vibrio cholerae, it is usually occurs in developing countries that lack of sanitation. In developing country including Indonesia, awareness importance of sanitation is still low. Unfortunately, research related to the detection of V. cholerae from fruit and vegetables in Indonesia is still rare. In this study, MPN method was used to determine the prevalence of V. cholerae followed by single and multiplex PCR to detect virulence genes, including toxR, ctxA, tcpA, hlyA, ace, ompU, and zot.

RESULTS: We found 3 fruits and 2 vegetables positive for toxR gene. Fruit samples which were showed toxR positive found from East Jakarta while for vegetables, it was recovered from West Jakarta and Central Jakarta. Twenty-three isolates were recovered from toxR positive samples. The result of antibiotic resistance analysis showed that 4.35% of the isolates resistant to gentamicin, streptomycin (17.39%), trimethoprim (52.17%), ciprofloxacin (30.43%), ampicillin (13.04%), nalidixic acid (82.61%), and polymyxin B (91.30%). None of these isolates were resistant to kanamycin. Combination of MPN and Multiplex PCR method can be used to detect the prevalence and characterize the virulence properties of V. cholerae.

PMID:35236411 | DOI:10.1186/s13104-022-05955-y

Water, Sanitation, and Hygiene Practices in Urban Slums of Eastern India

March 3, 2022

J Infect Dis. 2021 Nov 23;224(Supplement_5):S573-S583. doi: 10.1093/infdis/jiab354.


BACKGROUND: The Sustainable Development Goals identified universal access to water and sanitation facilities as key components for improving health. We assessed water, sanitation, and hygiene (WASH) practices and associated determinants among residents of urban slums in Kolkata, India.

METHODS: Information on WASH practices was collected in 2 surveys (2018 and 2019) from participants of a prospective enteric fever surveillance conducted in 2 municipal wards of Kolkata. A composite WASH practice score was computed and a hierarchical stepwise multiple linear regression model constructed to identify key determinants of improved WASH score.

RESULTS: Over 90% of households had access to piped water; 6% reported access to continuous supply. Adult women (61% in 2018; 45% in 2019) spent 20 minutes daily to fetch water. Access to improved latrines was almost universal, although 80% used shared facilities. Unhealthy disposal of children's stools was reported in both rounds. Food hygiene practices were high, with most (>90%) washing uncooked items before eating; frequent consumption of street food items was reported.

CONCLUSIONS: The study area reported high WASH coverage. Unhygienic behavioral patterns predisposing to food- or water-borne diseases were also noted. Awareness building and sustainable community mobilization for food hygiene needs to be emphasized to ensure community well-being.

PMID:35238356 | DOI:10.1093/infdis/jiab354

Enablers and barriers towards ensuring routine immunization services during the COVID-19 pandemic: findings from a qualitative study across five different states in India

March 2, 2022

Trans R Soc Trop Med Hyg. 2022 Mar 2:trac011. doi: 10.1093/trstmh/trac011. Online ahead of print.


BACKGROUND: The coronavirus disease 2019 (COVID-19) pandemic has led to disruption in delivering routine healthcare services including routine immunization (RI) worldwide. Understanding the enablers and barriers for RI services during a pandemic is critically important to develop context-appropriate strategies to ensure uninterrupted routine services.

METHODS: A community-based, cross-sectional descriptive study was conducted in five different states of India, nested within an ongoing multicentric study on RI. Telephone in-depth interviews among 56 health workers were carried out and the data were analyzed using a content analysis method.

RESULTS: During the COVID-19 pandemic, healthcare providers encountered many challenges at the health system, community and individual level when rendering RI services. Challenges like the limited availability of personal protective equipment and vaccines, deployment for COVID-19 duty at system level, the difficulty in mobilizing people in the community, fear among people at community level, mobility restrictions and limited family support, as well as the stress and stigma at individual level, were barriers to providing RI services. By contrast, the issuing of identification cards to health staff, engaging community volunteers, the support given to health workers by their families and training on COVID-19, were factors that enabled health workers to maintain RI services during the pandemic.

CONCLUSIONS: When addressing the COVID-19-related public health emergency, we should not lose sight of the importance of services like RI.

PMID:35235677 | DOI:10.1093/trstmh/trac011

Pandemics, policy, and the power of paradigm: will COVID-19 lead to a new scientific revolution?

March 1, 2022

Ann Epidemiol. 2022 May;69:17-23. doi: 10.1016/j.annepidem.2022.02.005. Epub 2022 Feb 26.


Critical historical analysis of the 19th-century cholera and 21st-century coronavirus-19 (COVID-19) pandemics suggests that in conflicts over pandemic-mitigation policies, the professional backgrounds of principal opponents reveal dominant and minority scientific paradigms, presaging possible epistemological shifts. Epistemic conflict over cholera helped spur biomedical expertise as the dominant paradigm for U.S. public health science and policy beginning in the 20th century. This paradigm was reflected in federal government reliance on infectious disease physicians as the primary scientific decision makers in the COVID-19 pandemic. Similarly, epistemic conflict over challenges to behavioral and social well-being in 2020 may highlight discordance between the dominant biomedical paradigm used in making federal policy and the inherently holistic impact of that policy on population health, suggesting need for a new paradigm of multidisciplinary scientific engagement. Because population-wide public health initiatives affect many aspects of health-physiological, psychological, behavioral, and social-that are best measured and interpreted by experts in these respective fields, multidisciplinary scientific engagement would facilitate optimal, holistic evaluation of policy benefits and harms. This multidisciplinary approach, analogous to that currently recommended in medical management of chronic disease, would advance epidemiological research to inform evidence-based policy for public health crises in which U.S. population-wide interventions are contemplated.

PMID:35231588 | PMC:PMC8882036 | DOI:10.1016/j.annepidem.2022.02.005

The positive effect of malaria IPTp-SP on birthweight is mediated by gestational weight gain but modifiable by maternal carriage of enteric pathogens

February 26, 2022

EBioMedicine. 2022 Feb 22;77:103871. doi: 10.1016/j.ebiom.2022.103871. Online ahead of print.


BACKGROUND: Poor pregnancy and birth outcomes are common in sub-Saharan Africa and have complex aetiologies. Sulfadoxine-pyrimethamine (SP), given for intermittent preventive therapy of malaria in pregnancy (IPTp), is one of few existing interventions that improves outcomes of both mother and baby despite widespread SP-resistant malaria. Compelling evidence exists that malaria-independent pathways contribute to this protective effect, but the exact sources of non anti-malarial protection remained unknown. We hypothesized that the beneficial effect of SP on birthweight is mediated by SP activity on maternal factors, including increased gestational weight gain and antibiotic activity on pathogens in the maternal gut.

METHODS: Expectant mothers from a larger randomized control trial comparing the efficacy of IPTp-SP to IPTp with dihydroartemisinin-piperaquine (DP) were also enrolled in this sub-study study at their first antenatal care visit before commencement of IPTp (n = 105). Participants were followed monthly until delivery. Weights and mid-to-upper-arm circumferences (MUAC) were recorded. Monthly stool samples were collected and screened for five Escherichia coli pathotypes, Shigella spp., Vibrio cholerae, Salmonella, Campylobacter coli/jejuni, and three protozoa (Giardia spp., Entameba histolytica, and Cryptosporidium spp.) using previously validated molecular assays.

FINDINGS: IPTp-SP vs. IPTP-DP was associated with higher maternal gestational weight gain (GWG) and nutritional indicators (MUAC and body-mass index, BMI). GWG was found to be a mediator of the birthweight and IPTp-SP relationship, as the birthweight of SP infants, but not DP infants, varied according to maternal GWG. The burden of maternal enteric infections was high. The three most commonly observed pathogens were enteroaggregative E. coli (EAEC), atypical enteropathogenic E.coli/enterohaemorrhagic E. coli (aEPEC/EHEC), and typical enteropathogenic E.coli (tEPEC). We found that SP reduced the prevalence of EAEC in a dose-dependent manner. After 3 or more doses, SP-recipients were 90% less likely to be infected with EAEC compared to DP-recipients (ORadj = 0.07, CI95 = 0.12, 0.39, p = 0.002). Compared to DP, this coincided with higher maternal gestational weight gain (GWG) and nutritional indicators (MUAC and body-mass index, BMI). The beneficial effect of SP on maternal GWG, MUAC and BMI, was lower if SP mothers had detectable EAEC, aEPEC/EHEC, tEPEC, and LT-ETEC at baseline. Maternal EAEC and tEPEC at baseline associated with lower birthweight for babies of both SP mothers and DP mothers. When comparing IPTp regimens, the positive effect of SP on birthweight compared to DP was only observed for infants of women who did not test positive for EAEC at baseline (adjusted mean birthweight difference SP vs. DP = 156.0 g, CI95 = -18.0 g, 336.9 g, p = 0.087), though confidence intervals crossed the null.

INTERPRETATION: Our findings indicate that in pregnant Malawian women, IPTp-SP vs. IPTp-DP is consistently associated with higher MUAC, BMI, and GWG following the WHO-recommended regimen of at least 3 doses, but carriage of maternal gut pathogens before initiation of IPTp lessens this effect. Because GWG was a mediator of the association between birthweight and SP, we show that SP's previously proven positive effect on birthweight is by promoting maternal weight gain. Overall, our results present one plausible pathway SP exerts malaria-independent protection against poor birth outcomes in the context of its waning antimalarial activity and warrants further investigation.

FUNDING: A full list of funding bodies that contributed to this study can be found in the Acknowledgements section.

PMID:35217408 | DOI:10.1016/j.ebiom.2022.103871

Population genomics of the food-borne pathogen <em>Vibrio fluvialis</em> reveals lineage associated pathogenicity-related genetic elements

February 25, 2022

Microb Genom. 2022 Feb;8(2). doi: 10.1099/mgen.0.000769.


Vibrio fluvialis is a food-borne pathogen with epidemic potential that causes cholera-like acute gastroenteritis and sometimes extraintestinal infections in humans. However, research on its genetic diversity and pathogenicity-related genetic elements based on whole genome sequences is lacking. In this study, we collected and sequenced 130 strains of V. fluvialis from 14 provinces of China, and also determined the susceptibility of 35 of the strains to 30 different antibiotics. Combined with 52 publicly available V. fluvialis genomes, we inferred the population structure and investigated the characteristics of pathogenicity-related factors. The V. fluvialis strains exhibited high levels of homologous recombination and were assigned to two major populations, VflPop1 and VflPop2, according to the different compositions of their gene pools. VflPop2 was subdivided into groups 2.1 and 2.2. Except for VflPop2.2, which consisted only of Asian strains, the strains in VflPop1 and VflPop2.1 were distributed in the Americas, Asia and Europe. Analysis of the pathogenicity potential of V. fluvialis showed that most of the identified virulence-related genes or gene clusters showed high prevalence in V. fluvialis, except for three mobile genetic elements: pBD146, ICEVflInd1 and MGIVflInd1, which were scattered in only a few strains. A total of 21 antimicrobial resistance genes were identified in the genomes of the 182 strains analysed in this study, and 19 (90%) of them were exclusively present in VflPop2. Notably, the tetracycline resistance-related gene tet(35) was present in 150 (95%) of the strains in VflPop2, and in only one (4%) strain in VflPop1, indicating it was population-specific. In total, 91% of the 35 selected strains showed resistance to cefazolin, indicating V. fluvialis has a high resistance rate to cefazolin. Among the 15 genomes that carried the previously reported drug resistance-related plasmid pBD146, 11 (73%) showed resistance to trimethoprim-sulfamethoxazole, which we inferred was related to the presence of the dfr6 gene in the plasmid. On the basis of the population genomics analysis, the genetic diversity, population structure and distribution of pathogenicity-related factors of V. fluvialis were delineated in this study. The results will provide further clues regarding the evolution and pathogenic mechanisms of V. fluvialis, and improve our knowledge for the prevention and control of this pathogen.

PMID:35212619 | DOI:10.1099/mgen.0.000769

Genomic and Phenotypic Insights for Toxigenic Clinical Vibrio cholerae O141

February 24, 2022

Emerg Infect Dis. 2022 Mar;28(3):617-624. doi: 10.3201/eid2803.210715.


Vibrio cholerae remains a major public health threat worldwide, causing millions of cholera cases each year. Although much is known about the evolution and pathogenicity of the O1/O139 serogroups of V. cholerae, information is lacking on the molecular epidemiology of non‒O1/O139 strains isolated from patients who have diarrheal illnesses. We performed whole-genome sequence analysis and in vivo infections to investigate characteristics of V. cholerae O141 isolated from sporadic diarrheal cases in 4 countries. The strains formed a distinct phylogenetic clade distinguishable from other serogroups and a unique multilocus sequence type 42, but interstrain variation suggests that O141 isolates are not clonal. These isolates encode virulence factors including cholera toxin and the toxin-coregulated pilus, as well as a type 3 secretion system. They had widely variable capacities for intestinal colonization in the infant mouse model. We propose that O141 isolates comprise a distinct clade of V. cholerae non‒O1/O139, and their continued surveillance is warranted.

PMID:35202520 | DOI:10.3201/eid2803.210715

Environmental and health risks posed to children by artisanal gold mining: A systematic review

February 17, 2022

SAGE Open Med. 2022 Feb 9;10:20503121221076934. doi: 10.1177/20503121221076934. eCollection 2022.


There are an estimated 5 million children working in artisanal and small-scale gold mines worldwide; however, the hazards are poorly characterized and often underreported. We systematically reviewed the literature on reports of hazards among children as a consequence of such activities through PubMed database using pre-defined search terms. We identified 113 articles published between 1984 and 2021 from 31 countries. Toxicological hazards were reported in 91 articles, including mercury, lead, and arsenic. Infectious hazards, noted in 18 articles, included malaria, cholera, and hepatitis. Six articles reported occupational hazards, including malnutrition, heat stroke, and reactive airway disease. Three articles reported traumatic hazards, including cave-ins, burns, animal attacks, falls, and weapon-inflected wounds. Those findings likely indicate a profound underreporting of the prevalence and consequences of such hazards among children. More work is needed both to characterize the burdens of those hazards and to address the underlying drivers of child labor in those settings.

PMID:35173966 | PMC:PMC8841918 | DOI:10.1177/20503121221076934

Assessment of effectiveness of Japanese encephalitis vaccination in West Bengal, India using sample positivity rate as an alternate measure

February 16, 2022

J Vector Borne Dis. 2021 Jul-Sep;58(3):199-205. doi: 10.4103/0972-9062.321751.


BACKGROUND & OBJECTIVES: Japanese encephalitis (JE), is a vaccine preventable mosquito borne arboviral disease. The State Health Department of West Bengal, India started a vaccination programme using live attenuated, single dose JE vaccine (SA-14-14-2) in children aged 1-below15 years since 2006 in five districts. The objectives were to compare Sample Positivity Rates (SPR) of Acute Encephalitis Syndrome (AES) cases for JE between vaccinated & unvaccinated districts and observe trend of SPR & Cumulative Incidence in vaccinated districts for three years.

METHODS: The study was based on the analysis of surveillance data from all tested AES cases including confirmed JE (IgM ELISA) from all JE testing facilities existent in the state during the study period (2011-13). Calculation of Cumulative Incidence, Odds Ratio (OR) with 95% CI, Preventive Fraction and Chi Square for trend (for SPR) was done. Trend of incidence was assessed by linear regression.

RESULTS: In three years, 5 vaccinated districts contributed 945 AES and 88 JE cases (SPR - 9.3%) compared to 1807 and 254 (SPR - 14.1%) JE cases in 14 unvaccinated districts. Effectiveness of vaccination was evident by gradual decline of Odds Ratio in favour of vaccinated districts. Vaccination effectiveness of 68% overall and 80% [OR = 0.20 (0.10 - 0.41)] in below 15 years were observed. Trend of SPR was found significantly declining in most of the vaccinated districts.

INTERPRETATION & CONCLUSION: Significant reduction in sample positivity rate over three years in most of the vaccinated districts indicated that the vaccination programme had been gradually effective.

PMID:35170456 | DOI:10.4103/0972-9062.321751

Inference is bliss: Simulation for power estimation for an observational study of a cholera outbreak intervention

February 16, 2022

PLoS Negl Trop Dis. 2022 Feb 16;16(2):e0010163. doi: 10.1371/journal.pntd.0010163. Online ahead of print.


BACKGROUND: The evaluation of ring vaccination and other outbreak-containment interventions during severe and rapidly-evolving epidemics presents a challenge for the choice of a feasible study design, and subsequently, for the estimation of statistical power. To support a future evaluation of a case-area targeted intervention against cholera, we have proposed a prospective observational study design to estimate the association between the strength of implementation of this intervention across several small outbreaks (occurring within geographically delineated clusters around primary and secondary cases named 'rings') and its effectiveness (defined as a reduction in cholera incidence). We describe here a strategy combining mathematical modelling and simulation to estimate power for a prospective observational study.

METHODOLOGY AND PRINCIPAL FINDINGS: The strategy combines stochastic modelling of transmission and the direct and indirect effects of the intervention in a set of rings, with a simulation of the study analysis on the model results. We found that targeting 80 to 100 rings was required to achieve power ≥80%, using a basic reproduction number of 2.0 and a dispersion coefficient of 1.0-1.5.

CONCLUSIONS: This power estimation strategy is feasible to implement for observational study designs which aim to evaluate outbreak containment for other pathogens in geographically or socially defined rings.

PMID:35171911 | DOI:10.1371/journal.pntd.0010163

Comparative Analysis of Spatial Distribution of Cholera by Temporal Fragments from 2000 to 2018

February 14, 2022

J Health Care Poor Underserved. 2022;33(1):167-181. doi: 10.1353/hpu.2022.0013.


Cholera is caused by V.cholerae (serogroups O1 and O139) and has a close relationship with socio-environmental conditions, especially basic sanitation. Analytical methodologies for collecting quantitative data on health indicators are widely used to support epidemiological surveillance actions in human health. This work aims to verify the fluctuation of the spatial distribution of cholera in the world, by temporal fragments, between 2000 and 2018. During the analyzed period, approximately 5.3 billion cases with 75.6 thousand deaths occurred, with emphasis on the regions of Africa, South Asia, and the Caribbean, showing that the disease is still a serious public health problem, especially in populations in precarious situations. Although the methodology employed in this study presents practical obstacles of underreporting and integration between the different collection platforms, it is an important tool in the construction of health surveillance measures for infectious diseases.

PMID:35153212 | DOI:10.1353/hpu.2022.0013

Epidemiology of floods in sub-Saharan Africa: a systematic review of health outcomes

February 11, 2022

BMC Public Health. 2022 Feb 10;22(1):268. doi: 10.1186/s12889-022-12584-4.


BACKGROUND: Floods have affected 2.3 billion people worldwide in the last 20 years, and are associated with a wide range of negative health outcomes. Climate change is projected to increase the number of people exposed to floods due to more variable precipitation and rising sea levels. Vulnerability to floods is highly dependent on economic wellbeing and other societal factors. Therefore, this systematic review synthesizes the evidence on health effects of flood exposure among the population of sub-Saharan Africa.

METHODS: We systematically searched two databases, Web of Science and PubMed, to find published articles. We included studies that (1) were published in English from 2010 onwards, (2) presented associations between flood exposure and health indicators, (3) focused on sub-Saharan Africa, and (4) relied on a controlled study design, such as cohort studies, case-control studies, cross-sectional studies, or quasi-experimental approaches with a suitable comparator, for instance individuals who were not exposed to or affected by floods or individuals prior to experiencing a flood.

RESULTS: Out of 2306 screened records, ten studies met our eligibility criteria. We included studies that reported the impact of floods on water-borne diseases (n = 1), vector-borne diseases (n = 8) and zoonotic diseases (n = 1). Five of the ten studies assessed the connection between flood exposure and malaria. One of these five evaluated the impact of flood exposure on malaria co-infections. The five non-malaria studies focused on cholera, scabies, taeniasis, Rhodesian sleeping sickness, alphaviruses and flaviviruses. Nine of the ten studies reported significant increases in disease susceptibility after flood exposure.

CONCLUSION: The majority of included studies of the aftermath of floods pointed to an increased risk of infection with cholera, scabies, taeniasis, Rhodesian sleeping sickness, malaria, alphaviruses and flaviviruses. However, long-term health effects, specifically on mental health, non-communicable diseases and pregnancy, remain understudied. Further research is urgently needed to improve our understanding of the health risks associated with floods, which will inform public policies to prevent and reduce flood-related health risks.

PMID:35144560 | DOI:10.1186/s12889-022-12584-4

Spanish Flu in Tehran from 1918 to 1920

February 7, 2022

Arch Iran Med. 2022 Jan 1;25(1):71-75. doi: 10.34172/aim.2022.10.


The Spanish flu spread from September 23, 1918 to 1920. This disease was one of the historical catastrophes in Iran, and a large number of people in Tehran were infected. Evidence also shows that 5000-10000 out of the 250000 infected people died in Tehran over three years. Besides, an increase was detected in the prevalence of other diseases such as pericarditis, orchitis, mastoiditis, meningitis, optic neuritis, paralysis of the palate, mania, cholera, and dysentery. Overall, five percent of the city were destroyed, and the population and economic development were severely damaged. This study aims to evaluate the importance of the history of local medicine in Tehran, the spread of Spanish flu, World War I, and presence of Russian, Ottoman, and British troops in Iran during the flu outbreak. The critical role of Britain in artificial famine, malnutrition, and drug embargo was assessed, as well.

PMID:35128914 | DOI:10.34172/aim.2022.10

Modalities and preferred routes of geographic spread of cholera from endemic areas in eastern Democratic Republic of the Congo

February 7, 2022

PLoS One. 2022 Feb 7;17(2):e0263160. doi: 10.1371/journal.pone.0263160. eCollection 2022.


Cholera is endemic along the Great Lakes Region, in eastern Democratic Republic of the Congo (DRC). From these endemic areas, also under perpetual conflicts, outbreaks spread to other areas. However, the main routes of propagation remain unclear. This research aimed to explore the modalities and likely main routes of geographic spread of cholera from endemic areas in eastern DRC. We used historical reconstruction of major outbreak expansions of cholera since its introduction in eastern DRC, maps of distribution and spatiotemporal cluster detection analyses of cholera data from passive surveillance (2000-2017) to describe the spread dynamics of cholera from eastern DRC. Four modalities of geographic spread and their likely main routes from the source areas of epidemics to other areas were identified: in endemic eastern provinces, and in non-endemic provinces of eastern, central and western DRC. Using non-parametric statistics, we found that the higher the number of conflict events reported in eastern DRC, the greater the geographic spread of cholera across the country. The present study revealed that the dynamics of the spread of cholera follow a fairly well-defined spatial logic and can therefore be predicted.

PMID:35130304 | PMC:PMC8820636 | DOI:10.1371/journal.pone.0263160

An innovative approach in monitoring oral cholera vaccination campaign: integration of a between-round survey

February 6, 2022

BMC Public Health. 2022 Feb 5;22(1):238. doi: 10.1186/s12889-022-12610-5.


BACKGROUND: Monitoring and Evaluation (M&E) is essential in ensuring population's access to immunization. Surveys are part of this M&E approach but its timing limits the use of its results to improve the coverage of the evaluated campaign. An oral cholera vaccination campaign was organized in a health district of the Far North region of Cameroon and involved an innovative M&E approach. The aim of this project was to assess the feasibility and effect of using recommendations of a community-based immunization and communication coverage survey conducted after the first round of an OCV campaign on the coverage of the second-round of the campaign.

METHODS: Two community-based surveys were included in the M&E plan and conducted at the end of each of the campaign rounds. Data were collected by trained and closely supervised surveyors and reported using smartphones. Key results of the first-round survey were disseminated to campaign implementing team prior to the second round. The two rounds of the pre-emptive campaign were organized by the Cameroon Ministry of Public Health and partners with a two-week interval in the Mogode Health District of the Far North region of Cameroon in May and June 2017.

RESULTS: Of 120 targeted clusters, 119 (99.1%) and 117 (97.5%) were reached for the first and second rounds respectively. Among the Mogode population eligible for vaccination, the immunization coverage based on evidence (card or finger mark) were estimated at 81.0% in the first round and increased to 88.8% in the second round (X2=69.0 and p <0.00). For the second round, we estimated 80.1% and 4.3% of persons who were administered 2 doses and 1 dose of OCV with evidence respectively, and 3.8% of persons who have not been vaccinated. The distribution of campaign communication coverage per health area was shared with the campaign coordination team for better planning of the second round campaign activities.

CONCLUSIONS: It is feasible to plan and implement coverage survey after first round OCV campaign and use its results for the better planning of the second round. For the present study, this is associated to the improvement of OCV coverage in the second-round vaccination. If this is persistent in other contexts, it may apply to improve coverage of any health campaign that is organized in more than one round.

PMID:35123444 | PMC:PMC8817499 | DOI:10.1186/s12889-022-12610-5

Deconstructing the spatial effects of El Niño and vulnerability on cholera rates in Peru: Wavelet and GIS analyses

February 5, 2022

Spat Spatiotemporal Epidemiol. 2022 Feb;40:100474. doi: 10.1016/j.sste.2021.100474. Epub 2021 Dec 18.


This study examined the spatial effects of El Niño and vulnerability on cholera in Peru across the epidemic period of 1991 to 1998. Using Wavelet and GIS analyses, relationships between sea surface temperatures and department-level cholera rates were estimated. In addition, we constructed composite indices to assess spatial vulnerability during the 1997-98 extreme El Niño. The findings demonstrated strong temporal connections in 1997-98, most evident in northern Peru, and less clear connections from 1991-93. Spatially, we found patterns of difference, greater cholera risk in northern coastal Peru in 1997-98, compared to greater risk in central and southern coastal Peru in 1991-92. Overall, the spatial vulnerability analysis suggested preexisting social conditions and disaster impacts increased cholera exposure and infection in 1998. Our study supports the notion that the spatial nature of El Niño's impacts on cholera rates exacerbated cholera vulnerability following the emergence, rather than triggered the epidemic's onset in 1991.

PMID:35120682 | DOI:10.1016/j.sste.2021.100474