Recent Cholera Publications on PubMed
Int J Health Plann Manage. 2021 Jul 22. doi: 10.1002/hpm.3289. Online ahead of print.
Recently, there has been a surge in cholera cases in Nigeria. With the exhausting health resources and the overwhelming attention towards COVID-19, Nigeria is in danger of worsening the epidemiological profile of cholera in the country. Thus, it is pertinent to address the surge to prevent further weakening of the country's health system. In this paper, we, therefore, explore the various interrelated factors accounting for the surge in Nigeria. It is therefore suggested that multifaceted public health strategies be employed that leverage the current level of disease preparedness and response capacities to the COVID-19 pandemic to reduce the impacts of cholera. These measures will not only help in strengthening the country's health system but also enhance the achievement of the relevant strategies toward eradicating cholera.
Non-cholera Vibrio species - currently still rare but growing danger of infection in the North Sea and the Baltic Sea
Internist (Berl). 2021 Jul 16. doi: 10.1007/s00108-021-01086-x. Online ahead of print.
BACKGROUND: The abundance of non-cholera Vibrio spp. in the aquatic environment shows a positive correlation with water temperatures. Therefore, climate change has an important impact on the epidemiology of human infections with these pathogens. In recent years large outbreaks have been repeatedly observed during the summer months in temperate climate zones.
OBJECTIVE: To inform medical professionals about the potentially life-threatening diseases caused by non-cholera Vibrio spp.
MATERIAL AND METHODS: Review of the current literature on infections with non-cholera Vibrio spp. in general and on the epidemiological situation in Germany in particular.
RESULTS: Non-cholera Vibrio spp. predominantly cause wound and ear infections after contact with contaminated seawater and gastroenteritis after consumption of undercooked seafood. As there have not been mandatory notification systems for these pathogens in Germany up to March 2020, a high number of unreported cases must be assumed. Immunosuppressed and chronically ill patients have a much higher risk for severe courses of diseases. If an infection with non-cholera Vibrio spp. is suspected anti-infective treatment should be promptly initiated and surgical cleansing is often necessary for wound and soft tissue infections.
CONCLUSION: Due to the ongoing global warming an increased incidence of human infections with non-cholera Vibrio spp. must be expected in the future. Medical professionals should be aware of these bacterial pathogens and the potentially life-threatening infections in order to enable timely diagnostics and treatment.
Environ Sci Pollut Res Int. 2021 Jul 15. doi: 10.1007/s11356-021-15395-z. Online ahead of print.
Infectious diarrhea (ID) is an intestinal infectious disease including cholera, typhoid and paratyphoid fever, bacterial and amebic dysentery, and other infectious diarrhea. There are many studies that have explored the relationship between ambient temperature and the spread of infectious diarrhea, but the results are inconsistent. It is necessary to systematically evaluate the impact of temperature on the incidence of ID. This study was based on the PRISMA statement to report this systematic review. We conducted literature searches from CNKI, VIP databases, CBM, PubMed, Web of Science, Cochrane Library, and other databases. The number registered in PROSPERO is CRD42021225472. After searching a total of 4915 articles in the database and references, 27 studies were included. The number of people involved exceeded 7.07 million. The overall result demonstrated when the temperature rises, the risk of infectious diarrhea increases significantly (RRcumulative=1.42, 95%CI: 1.07-1.88, RRsingle-day=1.08, 95%CI: 1.03-1.14). Subgroup analysis found the effect of temperature on the bacillary dysentery group (RRcumulative=1.85, 95%CI: 1.48-2.30) and unclassified diarrhea groups (RRcumulative=1.18, 95%CI: 0.59-2.34). The result of the single-day effect subgroup analysis was similar to the result of the cumulative effect. And the sensitivity analysis proved that the results were robust. This systematic review and meta-analysis support that temperature will increase the risk of ID, which is helpful for ID prediction and early warning in the future.
Global projections of temperature-attributable mortality due to enteric infections: a modelling study
Lancet Planet Health. 2021 Jul;5(7):e436-e445. doi: 10.1016/S2542-5196(21)00152-2.
BACKGROUND: Mortality due to enteric infections is projected to increase because of global warming; however, the different temperature sensitivities of major enteric pathogens have not yet been considered in projections on a global scale. We aimed to project global temperature-attributable enteric infection mortality under various future scenarios of sociodemographic development and climate change.
METHODS: In this modelling study, we generated global projections in two stages. First, we forecasted baseline mortality from ten enteropathogens (non-typhoidal salmonella, Shigella, Campylobacter, cholera, enteropathogenic Escherichia coli, enterotoxigenic E coli, typhoid, rotavirus, norovirus, and Cryptosporidium) under several future sociodemographic development and health investment scenarios (ie, pessimistic, intermediate, and optimistic). We then estimated the mortality change from baseline attributable to global warming using the product of projected annual temperature anomalies and pathogen-specific temperature sensitivities.
FINDINGS: We estimated that in the period 2080-95, the global mean number of temperature-attributable deaths due to enteric infections could be as low as 6599 (95% empirical CI 5441-7757) under the optimistic sociodemographic development and climate change scenario, or as high as 83 888 (67 760-100 015) under the pessimistic scenario. Most of the projected temperature-attributable deaths were from shigellosis, cryptosporidiosis, and typhoid fever in sub-Saharan Africa and South Asia. Considerable reductions in the number of attributable deaths were from viral infections, such as rotaviral and noroviral enteritis, which resulted in net reductions in attributable enteric infection mortality under optimistic scenarios for Latin America and the Caribbean and East Asia and the Pacific.
INTERPRETATION: Temperature-attributable mortality could increase under warmer climate and unfavourable sociodemographic conditions. Mitigation policies for limiting global warming and sociodemographic development policies for low-income and middle-income countries might help reduce mortality from enteric infections in the future.
FUNDING: Japan Society for the Promotion of Science, Japan Science and Technology Agency, and Spanish Ministry of Economy, Industry, and Competitiveness.
Distribution of virulence factors and its relatedness towards the antimicrobial response of enterotoxigenic Escherichia coli (ETEC) strains isolated from patients in Kolkata, India
J Appl Microbiol. 2021 Jul 9. doi: 10.1111/jam.15206. Online ahead of print.
AIM: Enterotoxigenic Escherichia coli (ETEC) is one of the most widely recognized diarrheal pathogens in developing countries. Advancement of ETEC vaccine development depends on the antigenic determinants of the ETEC isolates from a particular geographical region. So, the aim here was to comprehend the distribution of virulence determinants of the clinical ETEC strains of this region. Additionally, attempt was made to find any correlation with the antimicrobial response pattern.
METHODS AND RESULTS: Multiplex PCR was employed to identify virulence determinants followed by confirmatory singleplex PCR. For observation of antibiotic response, the Kirby-Bauer method was used. Out of 379 strains, 46% strains harboured both the enterotoxins ST and LT, whereas 15% were LT only. Among the major colonization factors, CS6 (41%) was the most prevalent followed by CFA/I (35%) and CFA/III was the lowest (3%). Among the minor colonization factors, CS21 (25%) was most prevalent, while CS15 showed the lowest (3%) presence. Among the non-classical virulence factors, EatA (69%) was predominant. ETEC strains harbouring CS6 showed resistance towards commonly used drug Ciprofloxacin (70%).
CONCLUSION: CS6 and elt+est toxin genes co-occurred covering 51% of the isolates. CS21 was found in most strains with est genes (43%). EatA was found to occur frequently when ST was present alone or with LT. CS6-harboring strains showed an independent correlation to antimicrobial resistance.
SIGNIFICANCE AND IMPACT OF STUDY: This study would aid in identifying the commonly circulating ETEC isolates of Kolkata, India, and their prevalent virulence determinants. Knowledge of antibiotic resistance pattern would also help in the appropriate use of antibiotics. Further, the study would aid in identifying the multivalent antigens suitable for region-specific ETEC vaccine with maximum coverage.
Sachet water consumption as a risk factor for cholera in urban settings: Findings from a case control study in Kinshasa, Democratic Republic of the Congo during the 2017-2018 outbreak
PLoS Negl Trop Dis. 2021 Jul 8;15(7):e0009477. doi: 10.1371/journal.pntd.0009477. eCollection 2021 Jul.
BACKGROUND: Behavioural risk factors for cholera are well established in rural and semi-urban contexts, but not in densely populated mega-cities in Sub-Saharan Africa. In November 2017, a cholera epidemic occurred in Kinshasa, the Democratic Republic of the Congo, where no outbreak had been recorded for nearly a decade. During this outbreak, we investigated context-specific risk factors for cholera in an urban setting among a population that is not frequently exposed to cholera.
METHODOLOGY/PRINCIPAL FINDINGS: We recruited 390 participants from three affected health zones of Kinshasa into a 1:1 matched case control study. Cases were identified from cholera treatment centre admission records, while controls were recruited from the vicinity of the cases' place of residence. We used standardized case report forms for the collection of socio-demographic and behavioural risk factors. We used augmented backward elimination in a conditional logistic regression model to identify risk factors. The consumption of sachet water was strongly associated with the risk of being a cholera case (p-value 0.019), which increased with increasing frequency of consumption from rarely (OR 2.2, 95% CI 0.9-5.2) to often (OR 4.0, 95% CI 1.6-9.9) to very often (OR 4.1, 95% CI 1.0-16.7). Overall, more than 80% of all participants reported consumption of this type of drinking water. The risk factors funeral attendance and contact with someone suffering from diarrhoea showed a p-value of 0.09 and 0.08, respectively. No socio-demographic characteristics were associated with the risk of cholera.
CONCLUSIONS/SIGNIFICANCE: Drinking water consumption from sachets, which are sold informally on the streets in most Sub-Saharan African cities, are an overlooked route of infection in urban cholera outbreaks. Outbreak response measures need to acknowledge context-specific risk factors to remain a valuable tool in the efforts to achieve national and regional targets to reduce the burden of cholera in Sub-Saharan Africa.
A Novel Luminescence-Based Serum Bactericidal Assay for Vibrio cholerae Reduces Assay Variation, Is Time- and Cost-Effective, and Directly Measures Continuous Titer Values
Am J Trop Med Hyg. 2021 Jul 8:tpmd210136. doi: 10.4269/ajtmh.21-0136. Online ahead of print.
Cholera remains a significant public health burden worldwide, and better methods for monitoring cholera incidence would enhance the effectiveness of public health interventions. The serum bactericidal assay (SBA) has been used extensively for Vibrio cholerae vaccine assessments and serosurveillance. Current SBA approaches for V. cholerae rely on colony enumeration or optical density (OD600nm) readings to measure viable bacteria following complement-mediated lysis. These methods provide titer values that are constrained to discrete dilution values and rely on bacterial outgrowth, which is time consuming and prone to variation. Detection of bacterial proteins following complement-mediated lysis presents a faster and potentially less variable alternative approach independent of bacterial outgrowth. Here, we present an SBA that measures luciferase luminescence driven by lysis-released adenylate kinase. This approach is faster and less variable than growth-dependent SBAs and directly measures continuous titer values. This novel SBA method can potentially be applied to other bacteria of interest.
Management of Helicobacter pylori infection: The Bhubaneswar Consensus Report of the Indian Society of Gastroenterology
Indian J Gastroenterol. 2021 Jul 5. doi: 10.1007/s12664-021-01186-4. Online ahead of print.
The Indian Society of Gastroenterology (ISG) felt the need to organize a consensus on Helicobacter pylori (H. pylori) infection and to update the current management of H. pylori infection; hence, ISG constituted the ISG's Task Force on Helicobacter pylori. The Task Force on H. pylori undertook an exercise to produce consensus statements on H. pylori infection. Twenty-five experts from different parts of India, including gastroenterologists, pathologists, surgeons, epidemiologists, pediatricians, and microbiologists participated in the meeting. The participants were allocated to one of following sections for the meeting: Epidemiology of H. pylori infection in India and H. pylori associated conditions; diagnosis; treatment and retreatment; H. pylori and gastric cancer, and H. pylori prevention/public health. Each group reviewed all published literature on H. pylori infection with special reference to the Indian scenario and prepared appropriate statements on different aspects for voting and consensus development. This consensus, which was produced through a modified Delphi process including two rounds of face-to-face meetings, reflects our current understanding and recommendations for the diagnosis and management of H. pylori infection. These consensus should serve as a reference for not only guiding treatment of H. pylori infection but also to guide future research on the subject.
Environmental prevalence of toxigenic Vibrio cholerae O1 in Bangladesh coincides with V. cholerae non-O1 non-O139 genetic variants which overproduce autoinducer-2
PLoS One. 2021 Jul 2;16(7):e0254068. doi: 10.1371/journal.pone.0254068. eCollection 2021.
Prevalence of toxigenic Vibrio cholerae O1 in aquatic reservoirs in Bangladesh apparently increases coinciding with the occurrence of seasonal cholera epidemics. In between epidemics, these bacteria persist in water mostly as dormant cells, known as viable but non-culturable cells (VBNC), or conditionally viable environmental cells (CVEC), that fail to grow in routine culture. CVEC resuscitate to active cells when enriched in culture medium supplemented with quorum sensing autoinducers CAI-1 or AI-2 which are signal molecules that regulate gene expression dependent on cell density. V. cholerae O1 mutant strains with inactivated cqsS gene encoding the CAI-1 receptor has been shown to overproduce AI-2 that enhance CVEC resuscitation in water samples. Since V. cholerae non-O1 non-O139 (non-cholera-vibrios) are abundant in aquatic ecosystems, we identified and characterized naturally occurring variant strains of V. cholerae non-O1 non-O139 which overproduce AI-2, and monitored their co-occurrence with V. cholerae O1 in water samples. The nucleotide sequence and predicted protein products of the cqsS gene carried by AI-2 overproducing variant strains showed divergence from that of typical V. cholerae O1 or non-O1 strains, and their culture supernatants enhanced resuscitation of CVEC in water samples. Furthermore, prevalence of V. cholerae O1 in the aquatic environment was found to coincide with an increase in AI-2 overproducing non-O1 non-O139 strains. These results suggest a possible role of non-cholera vibrios in the environmental biology of the cholera pathogen, in which non-O1 non-O139 variant strains overproducing AI-2 presumably contribute in resuscitation of the latent pathogen, leading to seasonal cholera epidemics. Importance. Toxigenic Vibrio cholerae which causes seasonal epidemics of cholera persists in aquatic reservoirs in endemic areas. The bacteria mostly exist in a dormant state during inter-epidemic periods, but periodically resuscitate to the active form. The resuscitation is enhanced by signal molecules called autoinducers (AIs). Toxigenic V. cholerae can be recovered from water samples that normally test negative for the organism in conventional culture, by supplementing the culture medium with exogenous AIs. V. cholerae belonging to the non-O1 non-O139 serogroups which do not cause cholera are also abundant in natural waters, and they are capable of producing AIs. In this study we characterized V. cholerae non-O1 non-O139 variant strains which overproduce an autoinducer called AI-2, and found that the abundance of the cholera pathogen in aquatic reservoirs correlates with an increase in the AI-2 overproducing strains. Our results suggest a probable role of these variant strains in the environmental biology and epidemiology of toxigenic V. cholerae, and may lead to novel means for surveillance, prevention and control of cholera.
Sci Total Environ. 2021 Jun 18;793:148500. doi: 10.1016/j.scitotenv.2021.148500. Online ahead of print.
Droughts are associated with several health effects and Africa is uniquely vulnerable. Despite this, there has been no previous review of the literature on the health effects of drought in Africa. This study systematically reviewed the epidemiological research on the association between drought and adverse health effects in Africa (2012-2019). A total of fifteen articles were included in the review after screening 1922 published (peer-reviewed) and unpublished articles. These studies were all conducted in 9 Sub-Saharan African countries. The drought-related health effects identified were on adverse nutritional health (n = 8) including malnutrition resulting in reduced body size and wasting, stunting and underweight, mortality from food insecurity, anaemia from food insecurity and nutrition-related disability from food insecurity; drought and diseases due to microbial contamination of water (n = 6) including cholera, diarrhoeal diseases, scabies, vector-borne diseases and malaria-related mortality; and drought and health behaviours (n = 1) including HIV prevention and care behaviours. The study found limited evidence of a high prevalence of malnutrition, an increased prevalence of anaemia, cholera, scabies, dengue and an increased incidence in child disabilities during periods of drought. Additionally, there was limited evidence on improved child nutritional health with improved water and sanitation access, and an increased prevalence of child wasting, stunting and underweight in drought-prone areas. No evidence of drought on other health outcomes was found. However, all the studies had more than one limitation including weak study design, a lack of comparison to a drought period, uncertainty on the onset and end of drought, lack of control for confounding, presence of contextual factors, weak outcome and/or exposure measure, small sample size and lack of generalizability. This review found weak evidence for all health outcomes measured but highlights key areas for further research and contextual factors which need to be considered for interventions.
Sci Rep. 2021 Jun 24;11(1):13240. doi: 10.1038/s41598-021-92605-1.
Zimbabwe currently faces several healthcare challenges, most notably HIV and associated infections including tuberculosis (TB), malaria and recently outbreaks of cholera, typhoid fever and COVID-19. Fungal infections, which are also a major public health threat, receive considerably less attention. Consequently, there is dearth of data regarding the burden of fungal diseases in the country. We estimated the burden of fungal diseases in Zimbabwe based on published literature and 'at-risk' populations (HIV/AIDS patients, survivors of pulmonary TB, cancer, chronic obstructive pulmonary disease, asthma and patients receiving critical care) using previously described methods. Where there was no data for Zimbabwe, regional, or international data was used. Our study revealed that approximately 14.9% of Zimbabweans suffer from fungal infections annually, with 80% having tinea capitis. The annual incidence of cryptococcal meningitis and Pneumocystis jirovecii pneumonia in HIV/AIDS were estimated at 41/100,000 and 63/100,000, respectively. The estimated prevalence of recurrent vulvovaginal candidiasis (RVVC) was 2,739/100,000. The estimated burden of fungal diseases in Zimbabwe is high in comparison to other African countries, highlighting the urgent need for increased awareness and surveillance to improve diagnosis and management.
Risk perceptions and preventive practices of COVID-19 among healthcare professionals in public hospitals in Addis Ababa, Ethiopia
PLoS One. 2021 Jun 25;16(6):e0242471. doi: 10.1371/journal.pone.0242471. eCollection 2021.
Healthcare professionals are at higher risk of contracting the new coronavirus disease 2019 (COVID-19). Although appropriate preventive measures are the most important interventions to prevent coronavirus infection among healthcare workers, they are also highly concerned about the consequences of the pandemic. The aim of this cross-sectional study was to assess preventive practices, perceived risk and worry about COVID-19 crisis among healthcare professionals at six public hospitals in Addis Ababa, Ethiopia. A systematic random sampling technique was used to select 1,134 respondents (52.6% females). Data were collected between 9th and 20th June 2020 using self-administered questionnaires. Descriptive statistics were used to summarize the data. A multiple linear regression analysis was performed to identify factors associated with worry about COVID-19 crisis. The highest percentage of respondents were nurses (39.3%) and physicians (22.2%), followed by interns (10.8%) and midwives (10.3%). Wearing facemask (93%) and frequent hand washing (93%) were the commonly reported preventive practices. Perceived risk of becoming infected with coronavirus (88%) and the potential risk of infection to their family (91%) were very high. The mean (median) worry score about COVID-19 crisis was 2.37 (3.0), on 1 to 3 scale, with 1 (not worried) and 3 (highly worried). The majority worried a lot about the health system being overwhelmed by COVID-19 patients (92%), the health of their loved ones (90%) and losing someone due to COVID-19 (89%). Respondents who had previously provided clinical care to Ebola, SARS and cholera patients had significantly lower levels of worry about COVID-19 crisis than participants who had not (β = -1.38, P<0.001). Our findings reveal respondents' widespread practice of preventive measures, highest levels of perceived risk and worry about the COVID-19 crisis. Increased perceived risk and worry about COVID-19 might enable healthcare workers to adopt appropriate preventive measures more effectively against the disease.
The impact of improved water supply on cholera and diarrhoeal diseases in Uvira, Democratic Republic of the Congo: a protocol for a pragmatic stepped-wedge cluster randomised trial and economic evaluation
Trials. 2021 Jun 21;22(1):408. doi: 10.1186/s13063-021-05249-x.
INTRODUCTION: Diarrhoeal disease remains a leading cause of mortality and morbidity worldwide. Cholera alone is estimated to cause 95,000 deaths per year, most of which occur in endemic settings with inadequate water access. Whilst a global strategy to eliminate cholera by 2030 calls for investment in improved drinking water services, there is limited rigorous evidence for the impact of improved water supply on endemic cholera transmission in low-income urban settings. Our protocol is designed to deliver a pragmatic health impact evaluation of a large-scale water supply intervention in Uvira (Democratic Republic of the Congo), a cholera transmission hotspot.
METHODS/DESIGN: A stepped-wedge cluster randomised trial (SW-CRT) was designed to evaluate the impact of a large-scale drinking water supply intervention on cholera incidence among the 280,000 inhabitants of Uvira. The city was divided into 16 clusters, where new community and household taps will be installed following a randomised sequence over a transition period of up to 8 weeks in each cluster. The primary trial outcomes are the monthly incidence of "confirmed" cholera cases (patients testing positive by rapid detection kit) and of "suspected" cholera cases (patients admitted to the cholera treatment centre). Concurrent process and economic evaluations will provide further information on the context, costs, and efficiency of the intervention.
DISCUSSION: In this protocol, we describe a pragmatic approach to conducting rigorous research to assess the impacts of a complex water supply intervention on severe diarrhoeal disease and cholera in an unstable, low-resource setting representative of cholera-affected areas. In particular, we discuss a series of pre-identified risks and linked mitigation strategies as well as the value of combining different data collection methods and preparation of multiple analysis scenarios to account for possible deviations from the protocol. The study described here has the potential to provide robust evidence to support more effective cholera control in challenging, high-burden settings.
TRIAL REGISTRATION: This trial is registered on clinicaltrials.gov ( NCT02928341 , 10th October 2016) and has received ethics approval from the London School of Hygiene and Tropical Medicine (8913, 10603) and from the Ethics Committee from the School of Public Health, University of Kinshasa, Democratic Republic of the Congo (ESP/CE/088/2015).
Characterization of V. cholerae O1 biotype El Tor serotype Ogawa possessing the ctxB gene of the classical biotype isolated from well water associated with the cholera outbreak in Kerala, South India
J Water Health. 2021 Jun;19(3):478-487. doi: 10.2166/wh.2021.263.
We investigated 22 water samples (17 well water and five pipe water - both chlorinated) and six soil samples from the surroundings of wells of the households of suspected patients from Palakkad district, Kerala (India), from where a cholera outbreak was reported during June-July 2016. A total of 25 Vibrio cholerae isolates were collected from three well water samples during a recent cholera outbreak. Biochemical and serological studies revealed that all of the isolates belonged to serogroup O1, biotype El Tor, serotype Ogawa. PCR assays confirmed the occurrence of ctxB, ctxA, hlyA, tcpA El Tor,VPI, ace, zot, ompW, rfbO1 and toxR genes in all isolates. The presence of the ctxB gene of the classical biotype in all of the El Tor isolates suggests that it is a new variant of El Tor biotype. Antibiogram profile of all V. cholerae O1 isolates revealed resistance towards five classes of antibiotics island and indicates that they were multidrug resistant. ERIC-PCR and PFGE finger prints showed the clonal relationship among the V. cholerae O1 isolates. The results of this study revealed the emergence of a new variant of El Tor biotype in the water samples from Palakkad district, from where a cholera outbreak was reported.
Regional sequencing collaboration reveals persistence of the T12 Vibrio cholerae O1 lineage in West Africa
Elife. 2021 Jun 18;10:e65159. doi: 10.7554/eLife.65159.
BACKGROUND: Despite recent insights into cholera transmission patterns in Africa, regional and local dynamics in West Africa-where cholera outbreaks occur every few years-are still poorly understood. Coordinated genomic surveillance of Vibrio cholerae in the areas most affected may reveal transmission patterns important for cholera control.
METHODS: During a regional sequencing workshop in Nigeria, we sequenced 46 recent V. cholerae isolates from Cameroon, Niger, and Nigeria (37 from 2018 to 2019) to better understand the relationship between the V. cholerae bacterium circulating in these three countries.
RESULTS: From these isolates, we generated 44 whole Vibrio cholerae O1 sequences and analyzed them in the context of 1280 published V. cholerae O1 genomes. All sequences belonged to the T12 V. cholerae seventh pandemic lineage.
CONCLUSIONS: Phylogenetic analysis of newly generated and previously published V. cholerae genomes suggested that the T12 lineage has been continuously transmitted within West Africa since it was first observed in the region in 2009, despite lack of reported cholera in the intervening years. The results from this regional sequencing effort provide a model for future regionally coordinated surveillance efforts.
FUNDING: Funding for this project was provided by Bill and Melinda Gates Foundation OPP1195157.
Cas Lek Cesk. 2021 Spring;160(2-3):93-96.
The aim of the article is to describe the development of the principles of medicine based on the evidence (EBM) based on postulates of Robert Koch, Nobel prize winner, protagonist of the "Golden Age" medical bacteriology, founder of a concept of modern microbiology and infectology. Kochs work led to the discovery of a causal relationship between exposure to a specific pathogen and disease on the example of identifying the cause of anthrax - Bacillus anthracis, a disease whose symptoms vary depending on the mode of transmission (gastrointestinal ingestion, cutaneous form on contact and pulmonary manifestations when inhaled). Tuberculosis caused by Kochs bacillus, Mycobacterium tuberculosis, yet still affecting 1.7 billion people (about 25 % of the world's population), in 95 % of cases in developing countries, where poverty and high prevalence of HIV are part of everyday life. Koch also discovered Vibrio cholerae, the pathogen responsible for seven recorded pandemics, and hitherto sporadic epidemics in recent years. The main contribution of the Kochs four postulates formulation was the principle, which helped to reveal the causal relationship between the pathogenic microbe to protrude infectious disease and obtain reliable evidence in improving credibility of diagnosis of infectious diseases. Other stages in the development of EBM were formulated by Bradford Hill in his nine principles, which are valid as well for noncommunicable diseases. The subjects of discussion are limitations and restrictions of present EBM and its essentials and the use in rational preventive, diagnostic and treatment strategies.
Genetic characterization and phylogenetic variations of human adenovirus-F strains circulating in eastern India during 2017-2020
J Med Virol. 2021 Jun 17. doi: 10.1002/jmv.27136. Online ahead of print.
Human Adenovirus-F (genotype 40/41) is the second-most leading cause of paediatric gastroenteritis after rotavirus, worldwide, accounting for 2.8-11.8% of infantile diarrhoeal cases. Earlier studies across eastern India revealed a shift in the predominance of genotypes from HAdV41 in 2007-09 to HAdV40 in 2013-14. Thus, the surveillance for HAdV-F genotypes in this geographical setting was undertaken during 2017-2020 to analyse the viral evolutionary dynamics. A total of 3882 stool samples collected from children (<5 years) were screened for HAdV-F positivity by conventional PCR. The hypervariable regions of the hexon and the partial shaft region of long fiber genes were amplified, sequenced and phylogenetically analysed with respect to the prototype strains. A marginal decrease in enteric HAdV prevalence was observed (9.04%, n=351/3882) compared to the previous report (11.8%) in this endemic setting. Children <2 years were found most vulnerable to enteric HAdV infection. Reduction in adenovirus-rotavirus co-infection was evident compared to the sole adenovirus infection. HAdV-F genotypes 40 and 41 were found to co-circulate, but HAdV41 was predominant. HAdV40 strains were genetically conserved, whereas HAdV41 strains accumulated new mutations. On the basis of different set of mutations in their genome, HAdV41 strains segregated into 2 genome type clusters (GTCs). Circulating HAdV41 strains clustered with GTC1 of fiber gene, for the first time during this study period. This study will provide much needed baseline data on emergence and circulation of HAdV40/41 strains for future vaccine development. This article is protected by copyright. All rights reserved.
Vitamin C levels in a Central-African mother-infant cohort: Does hypovitaminosis C increase the risk of enteric infections?
Matern Child Nutr. 2021 Jun 17:e13215. doi: 10.1111/mcn.13215. Online ahead of print.
In the MITICA (Mother-to-Infant TransmIssion of microbiota in Central-Africa) study, 48 mothers and their 50 infants were followed from delivery to 6 months between December 2017 and June 2019 in Bangui (Central-African Republic). Blood tests and stool analyses were performed in mothers at delivery, and their offspring at birth, 11 weeks and 25 weeks. Stool cultures were performed in specific growth media for Salmonella, Shigella, E. coli, Campylobacter, Enerobacter, Vibrio cholerae, Citrobacter and Klebsiella, as well as rotavirus, yeasts and parasitological exams. The median vitamin C levels in mothers at delivery were 15.3 μmol/L (inter-quartile-range [IQR] 6.2-27.8 μmol/L). In infants, the median vitamin C levels at birth were 35.2 μmol/L (IQR 16.5-63.9 μmol/L). At 11 and 25 weeks, the median vitamin C levels were 41.5 μmol/L (IQR 18.7-71.6 μmol/L) and 18.2 μmol/L (IQR 2.3-46.6 μmol/L), respectively. Hypovitaminosis C was defined as seric vitamin C levels <28 μmol/L and vitamin C deficiency was defined as vitamin C levels <11 μmol/L according to the WHO definition. In mothers, the prevalence of hypovitaminosis-C and vitamin C deficiency at delivery was 34/45 (75.6%) and 19/45 (42.2%), respectively. In infants, the prevalence of hypovitaminosis-C and vitamin C deficiency at 6 months was 18/33 (54.6%) and 11/33 (33.3%), respectively. Vitamin C levels in mothers and infants were correlated at birth (Spearman's rho = 0.5; P value = 0.002), and infants had significantly higher levels of vitamin C (median = 35.2 μmol/L; IQR 16.5-63.9 μmol/L), compared to mothers (median = 15.3 μmol/L; IQR 6.2-27.8 μmol/L; P value <0.001). The offspring of vitamin C-deficient mothers had significantly lower vitamin C levels at delivery (median = 18.7 μmol/L; IQR 13.3-30.7 μmol/L), compared to the offspring of non-deficient mothers (median = 62.2 μmol/L; IQR 34.6-89.2 μmol/L; P value <0.001). Infants with hypovitaminosis-C were at significantly higher risk of having a positive stool culture during the first 6 months of life (adjusted OR = 5.3, 95% CI 1.1; 26.1; P value = 0.038).
BMC Infect Dis. 2021 Jun 14;21(1):570. doi: 10.1186/s12879-021-06259-5.
BACKGROUND: Cholera has been present and recurring in Zambia since 1977. However, there is a paucity of data on genetic relatedness and diversity of the Vibrio cholerae isolates responsible for these outbreaks. Understanding whether the outbreaks are seeded from existing local isolates or if the outbreaks represent separate transmission events can inform public health decisions.
RESULTS: Seventy-two V. cholerae isolates from outbreaks in 2009/2010, 2016, and 2017/2018 in Zambia were characterized using multilocus variable number tandem repeat analysis (MLVA) and whole genome sequencing (WGS). The isolates had eight distinct MLVA genotypes that clustered into three MLVA clonal complexes (CCs). Each CC contained isolates from only one outbreak. The results from WGS revealed both clustered and dispersed single nucleotide variants. The genetic relatedness of isolates based on WGS was consistent with the MLVA, each CC was a distinct genetic lineage and had nearest neighbors from other East African countries. In Lusaka, isolates from the same outbreak were more closely related to themselves and isolates from other countries than to isolates from other outbreaks in other years.
CONCLUSIONS: Our observations are consistent with i) the presence of random mutation and alternative mechanisms of nucleotide variation, and ii) three separate transmission events of V. cholerae into Lusaka, Zambia. We suggest that locally, case-area targeted invention strategies and regionally, well-coordinated plans be in place to effectively control future cholera outbreaks.