Recent Cholera Publications on PubMed

STRUGGLE AGAINST CHOLERA EPIDEMICS IN IMPERIAL TIME KHARKIV AS A SIGNIFICANT FACTOR OF PUBLIC HEALTH: HISTORICAL EXPERIENCE

June 5, 2021

Wiad Lek. 2021;74(5):1241-1244.

ABSTRACT

OBJECTIVE: The aim: The aim of the research is to determine and systematize administrative and medical measures aimed at curbing cholera in the city of Kharkiv in the time of the Russian Empire, to assess the relevance of the experience in fighting the disease, to determine the impact of epidemics and anti-epidemic measures on Kharkiv residents' public health.

PATIENTS AND METHODS: Materials and methods: General scientific and specific historical methods were used, and methods of related sciences were applied as well. The main methods of historical research included, in particular, historical analytical, chronological and comparative historical; methods of medical statistics, etc. The historiography of the issue was analyzed, unpublished archival materials, local press were studied.

CONCLUSION: Conclusions: Despite the progress made, mortality remained high in general, proving the public health system had to be reorganized. The death rate shocked the local community so much that the authorities had to apply an information blockade. Anti-epidemic components included explanatory work by priests and police, sanitary measures, measures on strict compliance with observation and quarantine, food supplies to the blocked city and free medicine dispensation, involvement of all available medical institutions, and the establishment of special temporary facilities, actual mobilization of medical personnel. It was impossible to act in the other way, because the treatment methods seemed to be ineffective, like today, under the COVID-19 pandemic. When the medical component is proved ineffective in fighting the epidemic, relatively effective administrative measures, tried and tested over the centuries reasonably seem to be useful, and this experience has not lost its relevance.

PMID:34090298

Epidemiology and genetic characterisation of human sapovirus among hospitalised acute diarrhoea patients in Bangladesh, 2012-2015

June 3, 2021

J Med Virol. 2021 Jun 3. doi: 10.1002/jmv.27125. Online ahead of print.

ABSTRACT

Human sapovirus, which causes acute gastroenteritis, is not well studied and poorly understood. This study aims to investigate the contribution of sapovirus in diarrhoea, their clinical association and genotypic diversity. Faecal specimens (n = 871) were randomly selected from diarrhoeal patients who attended icddr,b hospital in Dhaka, Bangladesh during January 2012 - December 2015 and tested for the presence of sapovirus RNA using real-time PCR. Sapovirus RNA was identified in 2.3% (n = 20) of the samples. Seventy-five percent of the sapovirus positive cases were co-infected with other pathogens; such as rotavirus, norovirus, ETEC, adenovirus, Shigella spp. and Vibrio Cholerae. A vast genetic diversity was observed among sapovirus with at least seven common genotypes (GI.1, GI.2, GI.7, GII.1, GII.4, GII.6, and GIV), and a new genotype GII.NA1. Some of the GI.1 strains detected were similar to GI.4 in the polymerase region sequence and were confirmed as recombinant strains. Our findings suggest that the overall contribution of sapovirus in hospitalized diarrhoeal illness is low but highlight enormous genetic diversity. This article is protected by copyright. All rights reserved.

PMID:34081341 | DOI:10.1002/jmv.27125

An Epidemiological Analysis of SARS-CoV-2 Genomic Sequences from Different Regions of India

June 2, 2021

Viruses. 2021 May 17;13(5):925. doi: 10.3390/v13050925.

ABSTRACT

The number of Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) cases is increasing in India. This study looks upon the geographic distribution of the virus clades and variants circulating in different parts of India between January and August 2020. The NPS/OPS from representative positive cases from different states and union territories in India were collected every month through the VRDLs in the country and analyzed using next-generation sequencing. Epidemiological analysis of the 689 SARS-CoV-2 clinical samples revealed GH and GR to be the predominant clades circulating in different states in India. The northern part of India largely reported the 'GH' clade, whereas the southern part reported the 'GR', with a few exceptions. These sequences also revealed the presence of single independent mutations-E484Q and N440K-from Maharashtra (first observed in March 2020) and Southern Indian States (first observed in May 2020), respectively. Furthermore, this study indicates that the SARS-CoV-2 variant (VOC, VUI, variant of high consequence and double mutant) was not observed during the early phase of virus transmission (January-August). This increased number of variations observed within a short timeframe across the globe suggests virus evolution, which can be a step towards enhanced host adaptation.

PMID:34067745 | DOI:10.3390/v13050925

SARS-CoV-2 sero-prevalence among general population and healthcare workers in India, December 2020 - January 2021

May 22, 2021

Int J Infect Dis. 2021 May 19:S1201-9712(21)00442-2. doi: 10.1016/j.ijid.2021.05.040. Online ahead of print.

ABSTRACT

BACKGROUND: Earlier serosurveys in India revealed SARS-CoV-2 seroprevalence of 0.73% during May-June and 7.1% during August-September 2020. We conducted the third serosurvey during Dec 2020 and Jan 2021, to estimate the seroprevalence of SARS-CoV-2 infection among general population and healthcare workers (HCWs) in India.

METHODS: We conducted the serosurvey in the same 70 districts selected for the first and second serosurveys. From each district, we enrolled at least 400 individuals aged ≥ 10 years from general population and 100 HCWs from sub-district level health facilities. Sera from general population were tested for presence of IgG antibodies against nucleocapsid (N) and spike protein (S1-RBD) of SARS-CoV-2, whereas sera from HCWs were tested for anti-S1-RBD. We estimated weighted seroprevalence adjusted for assay characteristics.

RESULTS: Of the 28,598 sera from general population, 4585 (16%) had IgG antibodies against N, 6647 (23.2%) against S1-RBD and 7436 (26%) against either. The weighted and assay characteristic adjusted seroprevalence against either of the antibodies was 24.1 (95%CI: 23.0%-25.3%). Among 7385 HCWs, the seroprevalence of anti-S1-RBD IgG antibodies was 25.6% (95% CI: 23.5%-27.8%).

CONCLUSIONS: Nearly one in four individuals aged > = 10 years from general population as well as HCWs in India were exposed to SARS-CoV-2 by December 2020.

PMID:34022338 | DOI:10.1016/j.ijid.2021.05.040

Intranasal immunization with inactivated chlamydial elementary bodies formulated in VCG-chitosan nanoparticles induces robust immunity against intranasal Chlamydia psittaci challenge

May 18, 2021

Sci Rep. 2021 May 17;11(1):10389. doi: 10.1038/s41598-021-89940-8.

ABSTRACT

Vaccines based on live attenuated Chlamydia elementary bodies (EBs) can cause disease in vaccinated animals and the comparably safer inactivated whole EBs are only marginally protective. Recent studies show that a vaccine formulation comprising UV-inactivated EBs (EB) and appropriate mucosal delivery systems and/or adjuvants induced significant protective immunity. We tested the hypothesis that intranasal delivery of UV-inactivated C. psittaci EB formulated in Vibrio cholerae ghosts (VCG)-chitosan nanoparticles will induce protective immunity against intranasal challenge in SPF chickens. We first compared the impact of VCG and CpG adjuvants on protective immunity following IN mucosal and IM systemic delivery of EB formulated in chitosan hydrogel/microspheres. Immunologic analysis revealed that IN immunization in the presence of VCG induced higher levels of IFN-γ response than IM delivery or the CpG adjuvanted groups. Also, vaccine efficacy evaluation showed enhanced pharyngeal bacterial clearance and protection against lung lesions with the VCG adjuvanted vaccine formulation, thereby establishing the superior adjuvanticity of VCG over CpG. We next evaluated the impact of different concentrations of VCG on protective immunity following IN mucosal immunization. Interestingly, the adjuvanticity of VCG was concentration-dependent, since protective immunity induced following IN mucosal immunization showed dose-dependent immune responses and protection. These studies reveal that formulation of inactivated chlamydial antigens with adjuvants, such as VCG and chitosan increases their ability to induce protective immune responses against challenge.

PMID:34001988 | DOI:10.1038/s41598-021-89940-8

Influence of Community-Led Total Sanitation and Water Coverages in the Control of Cholera in Madarounfa, Niger (2018)

May 17, 2021

Front Public Health. 2021 Apr 29;9:643079. doi: 10.3389/fpubh.2021.643079. eCollection 2021.

ABSTRACT

Every year, cholera affects 1.3-4.0 million people worldwide with a particularly high presence in Africa. Based on recent studies, effective targeting interventions in hotspots could eliminate up to 50% of cases in Sub-Saharan Africa. Those interventions include Water, Sanitation, and Hygiene (WASH) programs whose influence on cholera control, up to the present, has been poorly quantified. Among the few studies available, D'Mello-Guyett et al. underline how the distribution of hygiene kits is a promising form of intervention for cholera control and that the integration of a WASH intervention at the point of admission of suspected cases is new in cholera control efforts, particularly in outbreaks and complex emergencies. Considering the limited number of studies on Community-Led Total Sanitation (CLTS) and water coverages related to cholera control, the aim of our work is to determine whether these interventions in cholera hotspots (geographic areas vulnerable to disease transmission) have significant impact on cholera transmission. In this study, we consider data collected on 125 villages of the Madarounfa district (Niger) during the 2018 cholera outbreak. Using a hurdle model, our findings show that full access to improved sanitation significantly decreases the likelihood of cholera by 91% (P < 0.0001) compared to villages with no access to sanitation at all. Considering only the villages affected by cholera in the studied area, cholera cases decrease by a factor of 4.3 in those villages where there is partial access to at least quality water sources, while full access to improved water sources decreases the cholera cases by a factor of 6.3 when compared to villages without access to water (P < 0.001). In addition, villages without access to safe water and sanitation are 6.7 times (P < 0.0001) more likely to get cholera. Alternatively, villages with full sanitation and water coverage are 9.1 (P < 0.0001) less likely to get cholera. The findings of our study suggest that significant access to improved water and sanitation at the village level offer a strong barrier against cholera transmission. However, it requires full CLTS coverage of the village to observe a strong impact on cholera, as partial access only has a limited impact.

PMID:33996720 | PMC:PMC8118121 | DOI:10.3389/fpubh.2021.643079

Regional Distribution of Causes of Death for Small Areas in Brazil, 1998-2017

May 14, 2021

Front Public Health. 2021 Apr 27;9:601980. doi: 10.3389/fpubh.2021.601980. eCollection 2021.

ABSTRACT

Background: What is the spatial pattern of mortality by cause and sex in Brazil? Even considering the main causes of death, such as neoplasms, cardiovascular diseases, external causes, respiratory diseases, and infectious diseases, there are still important debate regarding the spatial pattern of mortality by causes in Brazil. Evidence shows that there is an overlap in transitional health states, due to the persistence of infectious diseases (e.g., dengue, cholera, malaria, etc.,) in parallel with the increase in chronic degenerative diseases. The main objective of this paper is to analyze the spatio-temporal evolution of three groups of causes of death in Brazil across small areas from 1998 to 2017, by sex. Methods: We use publicly available data from the System Data Mortality Information (SIM-DATASUS) from 1998 to 2017. We focus on this period due to the better quality of information, in addition to all deaths are registered following the Tenth Revision of the International Classification of Diseases (ICD-10). We estimate standardized mortality rates by sex and cause aggregated into three main groups. We use a ternary color scheme to maximize all the information in a three-dimensional array of compositional data. Results: We find improvements in mortality from chronic degenerative diseases; faster declines are observed in the Southern regions of the country; but the persistence of high levels of mortality due to infectious diseases remained in the northern parts of the country. We also find impressive differences in external causes of deaths between males and females and an increase in mortality from these causes in the interior part of the country. Conclusions: This study provides useful information for policy makers in establishing effective measures for the prevention of deaths and public health planning for deaths from external and non-communicable causes. We observed how the distribution of causes of death varies across regions and how the patterns of mortality also vary by gender.

PMID:33987159 | PMC:PMC8111819 | DOI:10.3389/fpubh.2021.601980

Multidrug-resistant enteric pathogens in older children and adults with diarrhea in Bangladesh: epidemiology and risk factors

May 10, 2021

Trop Med Health. 2021 May 10;49(1):34. doi: 10.1186/s41182-021-00327-x.

ABSTRACT

BACKGROUND: Antimicrobial resistance (AMR) is a global public health threat and is increasingly prevalent among enteric pathogens in low- and middle-income countries (LMICs). However, the burden of multidrug-resistant organisms (MDROs) in older children, adults, and elderly patients with acute diarrhea in LMICs is poorly understood. This study's aim was to characterize the prevalence of MDR enteric pathogens isolated from patients with acute diarrhea in Dhaka, Bangladesh, and assess a wide range of risk factors associated with MDR.

METHODS: This study was a secondary analysis of data collected from children over 5 years, adults, and elderly patients with acute diarrhea at the International Centre for Diarrhoeal Disease Research, Bangladesh Dhaka Hospital between March 2019 and March 2020. Clinical, historical, socio-environmental information, and a stool sample for culture and antimicrobial susceptibility testing were collected from each patient. Univariate statistics and multiple logistic regression were used to assess the prevalence of MDR among enteric pathogens and the association between independent variables and presence of MRDOs among culture-positive patients.

RESULTS: A total of 1198 patients had pathogens isolated by stool culture with antimicrobial susceptibility results. Among culture-positive patients, the prevalence of MDR was 54.3%. The prevalence of MDR was highest in Aeromonas spp. (81.5%), followed by Campylobacter spp. (72.1%), Vibrio cholerae (28.1%), Shigella spp. (26.2%), and Salmonella spp. (5.2%). Factors associated with having MDRO in multiple logistic regression included longer transport time to hospital (>90 min), greater stool frequency, prior antibiotic use prior to hospital presentation, and non-flush toilet use. However, pseudo-R2 was low 0.086, indicating that other unmeasured variables need to be considered to build a more robust predictive model of MDR.

CONCLUSIONS: MDR enteric pathogens were common in this study population with clinical, historical, and socio-environmental risk factors associated with MDROs. These findings may help guide clinical decision-making regarding antibiotic use and selection in patients at greatest risk of complications due to MDROs. Further prospective research is urgently needed to determine what additional factors place patients at greatest risk of MDRO, and the best strategies to mitigate the spread of MDR in enteric pathogens.

PMID:33966631 | DOI:10.1186/s41182-021-00327-x

Memorials to John Snow - Pioneer in anaesthesia and epidemiology

May 7, 2021

J Med Biogr. 2021 May 7:9677720211013807. doi: 10.1177/09677720211013807. Online ahead of print.

ABSTRACT

John Snow was an English physician and a founding father of epidemiology, whose name is inextricably linked with tracing the source of the 1854 cholera outbreak in Soho, which killed over 600 people. Despite his recommendation to remove the water pump handle and thus reduce the spread of cholera, his theory of faecal-oral transmission was not widely believed until after his death. Furthermore, he also pioneered substantial achievements in the development of anaesthesia. He studied both chloroform and ether, improving the accuracy of their delivery. In his obstetric practice, he achieved the feat of obtaining satisfactory analgesia with a safer technique and is remembered for administering chloroform to Queen Victoria, during the delivery of her last two children. There are several interesting and unusual memorials to Snow, ranging from replica water pumps, blue plaques and a public house named after him. The most recent new memorial was erected in 2017, in his home town of York, which commemorates his origins and his subsequent contribution to curbing the cholera outbreak. All the memorials commemorate his achievements, which remain relevant today. Public health and epidemiology expertise is required in the current world of the COVID-19 pandemic, where his legacy remains as important as ever.

PMID:33960862 | DOI:10.1177/09677720211013807

The past and present of pandemic management: health diplomacy, international epidemiological surveillance, and COVID-19

April 30, 2021

Hist Philos Life Sci. 2021 Apr 30;43(2):64. doi: 10.1007/s40656-021-00416-4.

ABSTRACT

The establishment of international sanitary institutions, which took place in the context of rivalry among the great European powers and their colonial expansion in Asia, allowed for the development of administrative systems of international epidemiological surveillance as a response to the cholera epidemics at the end of the nineteenth century. In this note, I reflect on how a historical analysis of the inception of international epidemiological surveillance and pandemic management helps us to understand what is happening in the COVID-19 pandemic today.

PMID:33929621 | DOI:10.1007/s40656-021-00416-4

An outbreak of acute jaundice syndrome (AJS) among the Rohingya refugees in Cox's Bazar, Bangladesh: Findings from enhanced epidemiological surveillance

April 29, 2021

PLoS One. 2021 Apr 29;16(4):e0250505. doi: 10.1371/journal.pone.0250505. eCollection 2021.

ABSTRACT

In the summer of 2017, an estimated 745,000 Rohingya fled to Bangladesh in what has been described as one of the largest and fastest growing refugee crises in the world. Among numerous health concerns, an outbreak of acute jaundice syndrome (AJS) was detected by the disease surveillance system in early 2018 among the refugee population. This paper describes the investigation into the increase in AJS cases, the process and results of the investigation, which were strongly suggestive of a large outbreak due to hepatitis A virus (HAV). An enhanced serological investigation was conducted between 28 February to 26 March 2018 to determine the etiologies and risk factors associated with the outbreak. A total of 275 samples were collected from 18 health facilities reporting AJS cases. Blood samples were collected from all patients fulfilling the study specific case definition and inclusion criteria, and tested for antibody responses using enzyme-linked immunosorbent assay (ELISA). Out of the 275 samples, 206 were positive for one of the agents tested. The laboratory results confirmed multiple etiologies including 154 (56%) samples tested positive for hepatitis A, 1 (0.4%) positive for hepatitis E, 36 (13%) positive for hepatitis B, 25 (9%) positive for hepatitis C, and 14 (5%) positive for leptospirosis. Among all specimens tested 24 (9%) showed evidence of co-infections with multiple etiologies. Hepatitis A and E are commonly found in refugee camps and have similar clinical presentations. In the absence of robust testing capacity when the epidemic was identified through syndromic reporting, a particular concern was that of a hepatitis E outbreak, for which immunity tends to be limited, and which may be particularly severe among pregnant women. This report highlights the challenges of identifying causative agents in such settings and the resources required to do so. Results from the month-long enhanced investigation did not point out widespread hepatitis E virus (HEV) transmission, but instead strongly suggested a large-scale hepatitis A outbreak of milder consequences, and highlighted a number of other concomitant causes of AJS (acute hepatitis B, hepatitis C, Leptospirosis), albeit most likely at sporadic level. Results strengthen the need for further water and sanitation interventions and are a stark reminder of the risk of other epidemics transmitted through similar routes in such settings, particularly dysentery and cholera. It also highlights the need to ensure clinical management capacity for potentially chronic conditions in this vulnerable population.

PMID:33914782 | DOI:10.1371/journal.pone.0250505

John Snow: Anesthesiologist, Epidemiologist, Scientist, and Hero

April 29, 2021

Anesth Analg. 2021 Apr 29. doi: 10.1213/ANE.0000000000005586. Online ahead of print.

ABSTRACT

A 19th century physician was crucial to the establishment of 2 medical specialties-anesthesiology and public health. Everyone whose interest in public health has increased in the last year will be amazed at Dr John Snow's career in anesthesiology. Those who recognize him as the first full-time physician anesthetist will be struck by his development of medical mapping during the Cholera Pandemic of 1848, resulting in one of the fundamental techniques of epidemiology and public health that has continued through today. Snow's accomplishments in anesthesiology and epidemiology reflected a concatenation of science, focus, and creativity. His training in the early 19th century integrated science, medicine, and his keen interest in respiratory physiology. His early clinical exposure to colliery workers in Newcastle was likely influenced by the earlier development of pneumatic medicine. He was committed to the notion that chemistry, especially the use of medicinal gases, would be transformative for medicine. Thus, he was "primed" when the news of the American anodyne ether reached London in 1846. When the third cholera pandemic reached London shortly thereafter, in the fall of 1848, his academic and practical understanding of gas chemistry and pharmacology, respiratory physiology, and anesthetic agents led him to question the popularly promulgated miasma-based theories of transmission. His methodical investigations, research, and perseverance were mirrored in his scholarly work, numerous presentations, and public advocacy. He articulated many scientific principles essential to the early practice of anesthesia-anesthetic potency, quantitative dosing of anesthetic agents, engineering principles required for conserving the latent heat of vaporization, and minimizing the contribution of anesthetic equipment to airway resistance. He moved easily and methodically between these worlds of physiology, chemistry, engineering, clinical medicine, and public health. In his role as the first medical epidemiologist, Snow understood the power of medical mapping and the graphic presentation of data. He was a pioneer in 2 nascent fields of medicine that were historically and remain contemporarily connected.

PMID:33913916 | DOI:10.1213/ANE.0000000000005586

Emerging and Re-emerging Infectious Diseases in the WHO Eastern Mediterranean Region, 2001-2018

April 27, 2021

Int J Health Policy Manag. 2021 Mar 6. doi: 10.34172/ijhpm.2021.13. Online ahead of print.

ABSTRACT

BACKGROUND: Countries in the World Health Organization (WHO) Eastern Mediterranean Region (EMR) are predisposed to highly contagious, severe and fatal, emerging infectious diseases (EIDs), and re-emerging infectious diseases (RIDs). This paper reviews the epidemiological situation of EIDs and RIDs of global concern in the EMR between 2001 and 2018.

METHODS: To do a narrative review, a complete list of studies in the field was we prepared following a systematic search approach. Studies that were purposively reviewed were identified to summarize the epidemiological situation of each targeted disease. A comprehensive search of all published studies on EIDs and RIDs between 2001 and 2018 was carried out through search engines including Medline, Web of Science, Scopus, Google Scholar, and ScienceDirect.

RESULTS: Leishmaniasis, hepatitis A virus (HAV) and hepatitis E virus (HEV) are reported from all countries in the region. Chikungunya, Crimean Congo hemorrhagic fever (CCHF), dengue fever, and H5N1 have been increasing in number, frequency, and expanding in their geographic distribution. Middle East respiratory syndrome (MERS), which was reported in this region in 2012 is still a public health concern. There are challenges to control cholera, diphtheria, leishmaniasis, measles, and poliomyelitis in some of the countries. Moreover, Alkhurma hemorrhagic fever (AHF), and Rift Valley fever (RVF) are limited to some countries in the region. Also, there is little information about the real situation of the plague, Q fever, and tularemia.

CONCLUSION: EIDs and RIDs are prevalent in most countries in the region and could further spread within the region. It is crucial to improve regional capacities and capabilities in preventing and responding to disease outbreaks with adequate resources and expertise.

PMID:33904695 | DOI:10.34172/ijhpm.2021.13

Vaccine development for emerging infectious diseases

April 13, 2021

Nat Med. 2021 Apr;27(4):591-600. doi: 10.1038/s41591-021-01301-0. Epub 2021 Apr 12.

ABSTRACT

Examination of the vaccine strategies and technical platforms used for the COVID-19 pandemic in the context of those used for previous emerging and reemerging infectious diseases and pandemics may offer some mutually beneficial lessons. The unprecedented scale and rapidity of dissemination of recent emerging infectious diseases pose new challenges for vaccine developers, regulators, health authorities and political constituencies. Vaccine manufacturing and distribution are complex and challenging. While speed is essential, clinical development to emergency use authorization and licensure, pharmacovigilance of vaccine safety and surveillance of virus variants are also critical. Access to vaccines and vaccination needs to be prioritized in low- and middle-income countries. The combination of these factors will weigh heavily on the ultimate success of efforts to bring the current and any future emerging infectious disease pandemics to a close.

PMID:33846611 | DOI:10.1038/s41591-021-01301-0

Quantification of Vibrio cholerae cholix exotoxin by sandwich bead-ELISA

April 8, 2021

J Med Microbiol. 2021 Apr;70(4). doi: 10.1099/jmm.0.001311.

ABSTRACT

Introduction. Cholix toxin (ChxA) is an ADP-ribosylating exotoxin produced by Vibrio cholerae. However, to date, there is no quantitative assay available for ChxA, which makes it difficult to detect and estimate the level of ChxA produced by V. cholerae.Hypothesis/Gap Statement. It is important to develop a reliable and specific quantitative assay to measure the production level of ChxA, which will help us to understand the role of ChxA in V. cholerae pathogenesis.Aim. The aim of this study was to develop a bead-based sandwich ELISA (bead-ELISA) for the quantification of ChxA and to evaluate the importance of ChxA in the pathogenesis of V. cholerae infection.Methodology. Anti-rChxA was raised in New Zealand white rabbits, and Fab-horse radish peroxidase conjugate was prepared by the maleimide method to use in the bead-ELISA. This anti-ChxA bead-ELISA was applied to quantify the ChxA produced by various V. cholerae strains. The production of ChxA was examined in different growth media such as alkaline peptone water (APW), Luria-Bertani broth and AKI. Finally, the assay was evaluated using a mouse lethality assay with representative V. cholerae strains categorized as low to high ChxA-producers based on anti-ChxA bead-ELISA.Results. A sensitive bead-ELISA assay, which can quantify from 0.6 to 60 ng ml-1 of ChxA, was developed. ChxA was mostly detected in the extracellular cell-free supernatant and its production level varied from 1.2 ng ml-1 to 1.6 µg ml-1. The highest ChxA production was observed when V. cholerae strains were cultured in LB broth, but not in APW or AKI medium. The ChxA-producer V. cholerae strains showed 20-80 % lethality and only the high ChxA II-producer was statistically more lethal than a non-ChxA-producer, in the mice model assay. ChxA I and II production levels were not well correlated with mice lethality, and this could be due to the heterogeneity of the strains tested.Conclusion. ChxA I to III was produced mostly extracellularly at various levels depending on strains and culture conditions. The bead-ELISA developed in this study is useful for the detection and quantification of ChxA in V. cholerae strains.

PMID:33830907 | DOI:10.1099/jmm.0.001311

Research priorities for control of zoonoses in South Africa

April 6, 2021

Trans R Soc Trop Med Hyg. 2021 May 8;115(5):538-550. doi: 10.1093/trstmh/trab039.

ABSTRACT

BACKGROUND: Zoonoses pose major threats to the health of humans, domestic animals and wildlife, as seen in the COVID-19 pandemic. Zoonoses are the commonest source of emerging human infections and inter-species transmission is facilitated by anthropogenic factors such as encroachment and destruction of wilderness areas, wildlife trafficking and climate change. South Africa was selected for a 'One Health' study to identify research priorities for control of zoonoses due to its complex disease burden and an overstretched health system.

METHODS: A multidisciplinary group of 18 experts identified priority zoonotic diseases, knowledge gaps and proposed research priorities for the next 5 y. Each priority was scored using predefined criteria by another group of five experts and then weighted by a reference group (n=28) and the 18 experts.

RESULTS: Seventeen diseases were mentioned with the top five being rabies (14/18), TB (13/18), brucellosis (11/18), Rift Valley fever (9/11) and cysticercosis (6/18). In total, 97 specific research priorities were listed, with the majority on basic epidemiological research (n=57), such as measuring the burden of various zoonoses (n=24), followed by 20 on development of new interventions. The highest research priority score was for improving existing interventions (0.77/1.0), followed by health policy and systems research (0.72/1.0).

CONCLUSION: Future zoonotic research should improve understanding of zoonotic burden and risk factors and new interventions in public health. People with limited rural services, immunocompromised, in informal settlements and high-risk occupations, should be the highest research priority.

PMID:33822232 | PMC:PMC8083559 | DOI:10.1093/trstmh/trab039

Genomic diversity and molecular epidemiology of Pasteurella multocida

April 6, 2021

PLoS One. 2021 Apr 6;16(4):e0249138. doi: 10.1371/journal.pone.0249138. eCollection 2021.

ABSTRACT

Pasteurella multocida is a bacterial pathogen with the ability to infect a multitude of hosts including humans, companion animals, livestock, and wildlife. This study used bioinformatic approaches to explore the genomic diversity of 656 P. multocida isolates and epidemiological associations between host factors and specific genotypes. Isolates included in this study originated from a variety of hosts, including poultry, cattle, swine, rabbits, rodents, and humans, from five different continents. Multi-locus sequence typing identified 69 different sequence types. In-silico methodology for determining capsular serogroup was developed, validated, and applied to all genome sequences, whereby capsular serogroups A, B, D, and F were found. Whole genome phylogeny was constructed from 237,670 core single nucleotide variants (SNVs) and demonstrated an overall lack of host or capsular serogroup specificity, with the exception of isolates from bovine sources. Specific SNVs within the srlB gene were identified in P. multocida subsp. septica genomes, representing specific mutations that may be useful for differentiating one of the three known subspecies. Significant associations were identified between capsular serogroup and virulence factors, including capsular serogroup A and OmpH1, OmpH3, PlpE, and PfhB1; capsular serogroup B and HgbA and PtfA; and capsular serogroup F and PtfA and PlpP. Various mobile genetic elements were identified including those similar to ICEPmu1, ICEhin1056, and IncQ1 plasmids, all of which harbored multiple antimicrobial resistance-encoding genes. Additional analyses were performed on a subset of 99 isolates obtained from turkeys during fowl cholera outbreaks from a single company which revealed that multiple strains of P. multocida were circulating during the outbreak, instead of a single, highly virulent clone. This study further demonstrates the extensive genomic diversity of P. multocida, provides epidemiological context to the various genotyping schemes that have traditionally been used for differentiating isolates, and introduces additional tools for P. multocida molecular typing.

PMID:33822782 | DOI:10.1371/journal.pone.0249138

Laboratory and Field Evaluation of the Crystal VC-O1 Cholera Rapid Diagnostic Test

April 5, 2021

Am J Trop Med Hyg. 2021 Apr 5:tpmd201280. doi: 10.4269/ajtmh.20-1280. Online ahead of print.

ABSTRACT

Cholera is a severe acute, highly transmissible diarrheal disease which affects many low- and middle-income countries. Outbreaks of cholera are confirmed using microbiological culture, and additional cases during the outbreak are generally identified based on clinical case definitions, rather than laboratory confirmation. Many low-resource areas where cholera occurs lack the capacity to perform culture in an expeditious manner. A simple, reliable, and low-cost rapid diagnostic test (RDT) would improve identification of cases allowing rapid response to outbreaks. Several commercial RDTs are available for cholera testing with two lines to detect either serotypes O1 and O139; however, issues with sensitivity and specificity have not been optimal with these bivalent tests. Here, we report an evaluation of a new commercially available cholera dipstick test which detects only serotype O1. In both laboratory and field studies in Kenya, we demonstrate high sensitivity (97.5%), specificity (100%), and positive predictive value (100%) of this new RDT targeting only serogroup O1. This is the first field evaluation for the new Crystal VC-O1 RDT; however, with these high-performance metrics, this RDT could significantly improve cholera outbreak detection and improve surveillance for better understanding of cholera disease burden.

PMID:33819171 | DOI:10.4269/ajtmh.20-1280

Identifying and quantifying the factors associated with cholera-related death during the 2018 outbreak in Nigeria

April 2, 2021

Pan Afr Med J. 2020 Dec 22;37:368. doi: 10.11604/pamj.2020.37.368.20981. eCollection 2020.

ABSTRACT

INTRODUCTION: cholera outbreaks in Nigeria are often associated with high case fatality rates; however, there is a dearth of evidence on context-specific factors associated with the trend. This study therefore aimed to identify and quantify the factors associated with cholera-related deaths in Nigeria.

METHODS: using a cross-sectional design, we analysed surveillance data from all the States that reported cholera cases during the 2018 outbreak, and defined cholera-related death as death of an individual classified as having cholera according to the Nigeria Centre for Disease Control case definition. Factors associated with cholera-related death were assessed using multivariable logistic regression and findings presented as adjusted odds ratios (ORs) with 95% Confidence Intervals (95% CIs).

RESULTS: between January 1 and November 19, 2018, 41,394 cholera cases were reported across 20 States, including 815 cholera-related deaths. In the adjusted multivariable model, older age, male gender, living in peri-urban areas or in flooded states, infection during the rainy season, and delay in seeking health care by >2 days were positively associated with cholera-related death; whereas living in urban areas, hospitalisation in the course of illness, and presentation to a secondary hospital were negatively associated with cholera-related death.

CONCLUSION: cholera-related deaths during the 2018 outbreak in Nigeria appeared to be driven by multiple factors, which further reemphasises the importance of adopting a multisectoral approach to the design and implementation of context-specific interventions in Nigeria.

PMID:33796181 | PMC:PMC7992435 | DOI:10.11604/pamj.2020.37.368.20981

Difference-in-Difference in the Time of Cholera: a Gentle Introduction for Epidemiologists

April 1, 2021

Curr Epidemiol Rep. 2020 Dec;7(4):203-211. doi: 10.1007/s40471-020-00245-2. Epub 2020 Sep 23.

ABSTRACT

PURPOSE OF REVIEW: The goal of this article is to provide an introduction to the intuition behind the difference-in-difference method for epidemiologists. We focus on the theoretical aspects of this tool, including the types of questions for which difference-in-difference is appropriate, and what assumptions must hold for the results to be causally interpretable.

RECENT FINDINGS: While currently under-utilized in epidemiologic research, the difference-in-difference method is a useful tool to examine effects of population-level exposures, but relies on strong assumptions.

SUMMARY: We use the famous example of John Snow's investigation of the cause of cholera mortality in London to illustrate the difference-in-difference approach and corresponding assumptions. We conclude by arguing that this method deserves a second-look from epidemiologists interested in asking causal questions about the impact of a population-level exposure change on a population-level outcome for the group that experienced the change.

PMID:33791189 | PMC:PMC8006863 | DOI:10.1007/s40471-020-00245-2

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