Recent Cholera Publications on PubMed

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Findings from the 2017 HIV estimation round & trend analysis of key indicators 2010-2017: Evidence for prioritising HIV/AIDS programme in India.

July 29, 2020
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Findings from the 2017 HIV estimation round & trend analysis of key indicators 2010-2017: Evidence for prioritising HIV/AIDS programme in India.

Indian J Med Res. 2020 Jun;151(6):562-570

Authors: Sahu D, Kumar P, Chandra N, Rajan S, Shukla DK, Venkatesh S, Nair S, Kumar A, Singh J, Reddy S, Godbole S, Elangovan A, Saha MK, Rai S, Lakshmi PVM, Gambhir T, Ammassari S, Joshi D, Das A, Bakshi P, Chakraborty S, Palkar A, Singh SK, Reddy DCS, Kant S, Pandey A, Vardhana Rao MV

Abstract
Background & objectives: The National AIDS Control Organisation (NACO) and the ICMR-National Institute of Medical Statistics, the nodal agency for conducting HIV estimations in India, have been generating HIV estimates regularly since 2003. The objective of this study was to describe India's biennial HIV estimation 2017 process, data inputs, tool, methodology and epidemiological assumptions used to generate the HIV estimates and trends of key indicators for 2010-2017 at national and State/Union Territory levels.
Methods: Demographic Projection (DemProj) and AIDS Impact Modules (AIM) of Spectrum 5.63 software recommended by the United Nations Programme on HIV and AIDS Global Reference Group on HIV Estimates, Modelling and Projections, were used for generating HIV estimations on key indicators. HIV sentinel surveillance, epidemiological and programme data were entered into Estimation Projection Package (EPP), and curve fitting was done using EPP classic model. Finally, calibration was done using the State HIV prevalence of two rounds of National Family Health Survey (NFHS) -3 and -4 and Integrated Biological and Behavioural Surveillance (IBBS), 2014-2015.
Results: The national adult prevalence of HIV was estimated to be 0.22 per cent in 2017. Mizoram, Manipur and Nagaland had the highest prevalence over one per cent. An estimated 2.1 million people were living with HIV in 2017, with Maharashtra estimated to have the highest number. Of the 88 thousand annual new HIV infections estimated nationally in 2017, Telangana accounted for the largest share. HIV incidence was found to be higher among key population groups, especially people who inject drugs. The annual AIDS-related deaths were estimated to be 69 thousand nationally. For all indicators, geographic variation in levels and trends between States existed.
Interpretation & conclusions: With a slow decline in annual new HIV infections by only 27 per cent from 2010 to 2017 against the national target of 75 per cent by 2020, the national target to end AIDS by 2030 may be missed; although at the sub-national level some States have made better progress to reduce new HIV infection. It calls for reinforcement of HIV prevention, diagnosis and treatment efforts by geographical regions and population groups.

PMID: 32719229 [PubMed - in process]

Prevalence and antimicrobial profile of Shigella isolates in a tertiary care hospital of North Karnataka: A 12-year study.

July 29, 2020
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Prevalence and antimicrobial profile of Shigella isolates in a tertiary care hospital of North Karnataka: A 12-year study.

Indian J Med Microbiol. 2020 Jan-Mar;38(1):101-108

Authors: Jain PA, Kulkarni RD, Dutta S, Ganavali AS, Kalabhavi AS, Shetty PC, Shubhada C, Hosamani MA, Appannanavar SB, Hanamaraddi DR

Abstract
Context: Shigella is a common cause of bacillary dysentery. Although it is reported worldwide, the majority of the infections are seen in developing countries with Shigella flexneri being the most common isolate. Prevalence of Shigella species and their antibiotic susceptibility profiles vary according to geographic area and season.
Aims: In the present study, the epidemiology and antimicrobial profile of Shigella from stool samples received at our hospital for a period of 12 years (January 2006 to December 2017) was evaluated.
Subjects and Methods: A total of 4578 stool samples were collected from the cases of acute gastroenteritis and diarrhoea. Samples were processed for culture and sensitivity according to standard microbiological techniques. The presumptive identification of Shigella species was done using standard conventional biochemical tests and confirmed using antisera.
Results: A total of 189 (4.2%) samples yielded Shigella spp. Isolation of Shigella spp. were more frequent from males (58.2%). S. flexneri was the commonest species isolated (47.6%) followed by Shigella sonnei(11.6%), Shigella dysenteriae (4.2%) and Shigella boydii (2.1%). Non-typeable Shigella was commonly recovered. The isolates showed high resistance to ampicillin (76.7%) and co-trimoxazole (75%) while highest susceptibility was observed to ceftriaxone (79.2%).
Conclusions: S. flexneri was the most prevalent species isolated at this centre. Shigella isolates from the study showed alarming resistance to recommended antibiotics. Non-typeable Shigella accounted for 34.4% isolates. Molecular discrimination between Shigella and Escherichia coli is essential.

PMID: 32719216 [PubMed - in process]

An ethnographic exploration of diarrheal disease management in public hospitals in Bangladesh: From problems to solutions.

July 28, 2020
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An ethnographic exploration of diarrheal disease management in public hospitals in Bangladesh: From problems to solutions.

Soc Sci Med. 2020 Jul 10;260:113185

Authors: Biswas D, Hossin R, Rahman M, Bardosh KL, Watt MH, Zion MI, Sujon H, Rashid MM, Salimuzzaman M, Flora MS, Qadri F, Khan AI, Nelson EJ

Abstract
INTRODUCTION: Diarrheal disease is one of the most common causes of hospital admission globally. The barriers that influence guideline-adherent care at resource limited hospitals are poorly defined, especially during diarrheal disease outbreaks. The objective of this study was to characterize challenges faced in diarrheal disease management in resource-limited hospitals and identify opportunities to improve care.
METHODS: The study was conducted during a diarrheal disease outbreak period at ten public district hospitals distributed across Bangladesh. A rapid ethnographic approach included observations and informal interviews with clinicians, staff nurses and patients. In the first phase, observations identified common and unique challenges in diarrheal management at the ten sites. In the second phase, four hospitals were purposively selected for additional ethnographic study. Systematic observations over 420 total hours were collected from patient-clinician interactions (n = 76) and informal interviews (n = 138). Applied thematic analysis identified factors that influenced hospitalbased diarrhea management.
RESULTS: Normalization of guideline deviation was observed at all ten sites, including prescription of non-indicated antibiotics and intravenous (IV) fluids. Conflict between 'what should be done' and 'what can be done' was the most common challenge identified. Clinical assessments and patient treatment plans were established at admission in a median of 2 minutes (n = 76), often without a physical examination (57%; n=43/76). Factors that prevented adherence to clinical guidelines included human resource constraints, conflicts of interests, overcrowding, and inadequate hygiene and sanitation in the emergency department and wards.
CONCLUSION: This study identified challenges in hospital-based management of diarrheal disease and opportunities to improve care in seemingly change-resilient hospital settings. The results reveal important areas for intervention and policy engagement that may have additive benefit for both hospitals and their patients. These interventions include targeting barriers to clean-water, sanitation and hygiene that prevent clinicians from adopting guidelines out of concern for hospital acquired infections.

PMID: 32712557 [PubMed - as supplied by publisher]

Achieving coordinated national immunity and cholera elimination in Haiti through vaccination: a modelling study.

July 28, 2020
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Achieving coordinated national immunity and cholera elimination in Haiti through vaccination: a modelling study.

Lancet Glob Health. 2020 Aug;8(8):e1081-e1089

Authors: Lee EC, Chao DL, Lemaitre JC, Matrajt L, Pasetto D, Perez-Saez J, Finger F, Rinaldo A, Sugimoto JD, Halloran ME, Longini IM, Ternier R, Vissieres K, Azman AS, Lessler J, Ivers LC

Abstract
BACKGROUND: Cholera was introduced into Haiti in 2010. Since then, more than 820 000 cases and nearly 10 000 deaths have been reported. Oral cholera vaccine (OCV) is safe and effective, but has not been seen as a primary tool for cholera elimination due to a limited period of protection and constrained supplies. Regionally, epidemic cholera is contained to the island of Hispaniola, and the lowest numbers of cases since the epidemic began were reported in 2019. Hence, Haiti may represent a unique opportunity to eliminate cholera with OCV.
METHODS: In this modelling study, we assessed the probability of elimination, time to elimination, and percentage of cases averted with OCV campaign scenarios in Haiti through simulations from four modelling teams. For a 10-year period from January 19, 2019, to Jan 13, 2029, we compared a no vaccination scenario with five OCV campaign scenarios that differed in geographical scope, coverage, and rollout duration. Teams used weekly department-level reports of suspected cholera cases from the Haiti Ministry of Public Health and Population to calibrate the models and used common vaccine-related assumptions, but other model features were determined independently.
FINDINGS: Among campaigns with the same vaccination coverage (70% fully vaccinated), the median probability of elimination after 5 years was 0-18% for no vaccination, 0-33% for 2-year campaigns focused in the two departments with the highest historical incidence, 0-72% for three-department campaigns, and 35-100% for nationwide campaigns. Two-department campaigns averted a median of 12-58% of infections, three-department campaigns averted 29-80% of infections, and national campaigns averted 58-95% of infections. Extending the national campaign to a 5-year rollout (compared to a 2-year rollout), reduced the probability of elimination to 0-95% and the proportion of cases averted to 37-86%.
INTERPRETATION: Models suggest that the probability of achieving zero transmission of Vibrio cholerae in Haiti with current methods of control is low, and that bolder action is needed to promote elimination of cholera from the region. Large-scale cholera vaccination campaigns in Haiti would offer the opportunity to synchronise nationwide immunity, providing near-term population protection while improvements to water and sanitation promote long-term cholera elimination.
FUNDING: Bill & Melinda Gates Foundation, Global Good Fund, Institute for Disease Modeling, Swiss National Science Foundation, and US National Institutes of Health.

PMID: 32710864 [PubMed - in process]

High Burden of Non-communicable Diseases among a Young Slum Population in Haiti.

July 28, 2020
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High Burden of Non-communicable Diseases among a Young Slum Population in Haiti.

J Urban Health. 2019 12;96(6):797-812

Authors: McNairy ML, Tymejczyk O, Rivera V, Seo G, Dorélien A, Peck M, Petion J, Walsh K, Bolgrien A, Nash D, Pape J, Fitzgerald DW

Abstract
The objective of this study was to characterize the demographics and population health of four slum communities in Port-au-Prince, Haiti, including population density and the burden of communicable and non-communicable diseases. Four urban slums were surveyed using a population-representative design between July and October 2016. A multistage cluster area random sampling process was used to identify households and individuals for the survey. Household surveys included rosters of residents, household characteristics, adult and child deaths in the past year, child health, and healthcare access and utilization. Individual surveys of two randomly sampled adults from each household included sociodemographic data, maternal health, and adult health. Additionally, blood pressure, height, weight, and psychological distress were measured by study staff. Data were weighted for complex survey design and non-response. A total of 525 households and 894 individuals completed the survey (96% household and 90% individual response rate, respectively). The estimated population density was 58,000 persons/km2. Across slums, 55% of all residents were female, and 38% were adolescents and youth 10-24 years. Among adults, 58% were female with median age 29 years (22-38). The most common adult illnesses were severe psychological distress (24%), hypertension (20%), history of physical injury/trauma (10%), asthma (7%), history of cholera (4%), and history of tuberculosis (3%). Ten percent of adults had obesity (BMI > 30 kg/m2), and 7% currently smoked. The most common under-5 diseases during the last 3 months were respiratory and gastrointestinal illnesses (50% and 28%, respectively). One-third of households reported needing medical care for a child in the past year but not being able to access it, largely due to financial constraints. Unique features of these slums are a population structure dominated by adolescents and youth, a high proportion of females, and a high burden of non-communicable diseases including hypertension and psychological distress. Screening, diagnostic, and disease management interventions are urgently needed to protect and promote improved population health outcomes in these slum communities.

PMID: 31218502 [PubMed - indexed for MEDLINE]

Vibrio cholerae.

July 28, 2020
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Vibrio cholerae.

Trends Microbiol. 2019 09;27(9):806-807

Authors: Yoon SH, Waters CM

PMID: 31029488 [PubMed - indexed for MEDLINE]

Impact of Annual Bacterial Epizootics on Albatross Population on a Remote Island.

July 27, 2020
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Impact of Annual Bacterial Epizootics on Albatross Population on a Remote Island.

Ecohealth. 2020 Jul 23;:

Authors: Jaeger A, Gamble A, Lagadec E, Lebarbenchon C, Bourret V, Tornos J, Barbraud C, Lemberger K, Delord K, Weimerskirch H, Thiebot JB, Boulinier T, Tortosa P

Abstract
The reduced species richness typical of oceanic islands provides an interesting environmental setup to examine in natura the epidemiological dynamics of infectious agents with potential implications for public health and/or conservation. On Amsterdam Island (Indian Ocean), recurrent die-offs of Indian yellow-nosed albatross (Thalassarche carteri) nestlings have been attributed to avian cholera, caused by the bacterium Pasteurella multocida. In order to help implementing efficient measures for the control of this disease, it is critical to better understand the local epidemiology of P. multocida and to examine its inter- and intra-annual infection dynamics. We evaluated the infection status of 264 yellow-nosed albatrosses over four successive breeding seasons using a real-time PCR targeting P. multocida DNA from cloacal swabs. Infection prevalence patterns revealed an intense circulation of P. multocida throughout the survey, with a steady but variable increase in infection prevalence within each breeding season. These epizootics were associated with massive nestling dies-offs, inducing very low fledging successes (≤ 20%). These results suggest important variations in the transmission dynamics of this pathogen. These findings and the developed PCR protocol have direct applications to guide future research and refine conservation plans aiming at controlling the disease.

PMID: 32705577 [PubMed - as supplied by publisher]

Transmission dynamics of cholera with hyperinfectious and hypoinfectious vibrios: mathematical modelling and control strategies.

July 27, 2020
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Transmission dynamics of cholera with hyperinfectious and hypoinfectious vibrios: mathematical modelling and control strategies.

Math Biosci Eng. 2019 05 16;16(5):4339-4358

Authors: Lin JZ, Xu R, Tian XH

Abstract
Cholera is a common infectious disease caused by Vibrio cholerae, which has different infectivity. In this paper, we propose a cholera model with hyperinfectious and hypoinfectious vibrios, in which both human-to-human and environment-to-human transmissions are considered. By analyzing the characteristic equations, the local stability of disease-free and endemic equilibria is established. By using Lyapunov functionals and LaSalle's invariance principle, it is verified that the global threshold dynamics of the model can be completely determined by the basic reproduction number. Numerical simulations are carried out to illustrate the corresponding theoretical results and describe the cholera outbreak in Haiti. The study of optimal control helps us seek cost-effective solutions of time-dependent control strategies against cholera outbreaks, which shows that control strategies, such as vaccination and sanitation, should be taken at the very beginning of the outbreak and become less necessary after a certain period.

PMID: 31499665 [PubMed - indexed for MEDLINE]

Oral Defense: How Oral Rehydration Solutions Revolutionized the Treatment of Toxigenic Diarrhea.

July 23, 2020
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Oral Defense: How Oral Rehydration Solutions Revolutionized the Treatment of Toxigenic Diarrhea.

Dig Dis Sci. 2020 02;65(2):345-348

Authors: Kaunitz JD

PMID: 31900719 [PubMed - indexed for MEDLINE]

Cholera in travellers: a systematic review.

July 23, 2020
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Cholera in travellers: a systematic review.

J Travel Med. 2019 Dec 23;26(8):

Authors: Connor BA, Dawood R, Riddle MS, Hamer DH

Abstract
Exposure to cholera is a risk for individuals and groups travelling to endemic areas, and the bacteria can be imported to cholera-free countries by returning travellers. This systematic review of the literature describes the circumstances in which cholera infection can occur in travellers and considers the possible value of the cholera vaccine for prevention in travellers. PubMed and EMBASE were searched for case reports of cholera or diarrhoea among travellers, with date limits of 1 January 1990-30 April 2018. Search results were screened to exclude the following articles: diarrhoea not caused by cholera, cholera in animals, intentional cholera infection in humans, non-English articles and publications on epidemics that did not report clinical details of individual cases and publications of cases pre-dating 1990. Articles were reviewed through descriptive analytic methods and information summarized. We identified 156 cases of cholera imported as a consequence of travel, and these were reviewed for type of traveller, source country, serogroup of cholera, treatment and outcomes. The case reports retrieved in the search did not report consistent levels of detail, making it difficult to synthesize data across reports and draw firm conclusions from the data. This clinical review sheds light on the paucity of actionable published data regarding the risk of cholera in travellers and identifies a number of gaps that should drive additional effort. Further information is needed to better inform evidence-based disease prevention strategies, including vaccination for travellers visiting areas of cholera risk. Modifications to current vaccination recommendations to include or exclude current or additional traveller populations may be considered as additional risk data become available. The protocol for this systematic review is registered with PROSPERO (registration number: 122797).

PMID: 31804684 [PubMed - indexed for MEDLINE]

Climate, Infectious Disease and Health: An Interdisciplinary Perspective: A colloquium was convened by the American Academy of Microbiology to discuss research issues relating to the effects of climate on the incidence and distribution of infectious...

July 21, 2020

Climate, Infectious Disease and Health: An Interdisciplinary Perspective: A colloquium was convened by the American Academy of Microbiology to discuss research issues relating to the effects of climate on the incidence and distribution of infectious disease. The colloquium was held in Montego Bay, Jamaica, June 20–22, 1997.

Book. 1998

Authors: Colwell RR, Patz JA

Abstract
A colloquium was convened by the American Academy of Microbiology to discuss research issues relating to the effects of climate on the incidence and distribution of infectious disease. The colloquium was held in Montego Bay, Jamaica, June 20–22, 1997. The principal findings of the colloquium are summarized below. The global infectious disease burden exceeds several hundred million cases each year, and infectious diseases are estimated to account for one-third of annual human mortality. For many infectious diseases, principally those that are vectorborne, there is a significant amount of data relating diseases incidence to climate or weather factors. With the increasing accumulation of satellite data, a better understanding is emerging of the complex interrelations among weather and climate conditions and the survival and spread of pathogenic microorganisms and disease vectors and hosts. Annual rainfall and temperature averages are important parameters in the demarcation of bioclimate envelopes within which the occurrence of many infectious diseases is concentrated. These factors also have significant effects on variables, such as vector population size, which are related to disease outbreaks and epidemics. Although more is known about the effects of weather and climate conditions on the prevalence of vectorborne disease, there are important links between these factors and the occurrence of waterborne, airborne, soilborne, and foodborne diseases. Large-scale weather disturbances like El Niño can have a dramatic impact on the incidence of many infectious diseases, such as malaria and Rift Valley fever. Scientists have discovered numerous connections between the 1991–1995 El Niño and increases in the incidence of diseases, including cholera and hantavirus pulmonary syndrome. El Niño-related increases in sea-surface temperature and sea-surface height in the Bay of Bengal have been associated with a rise in the number of cholera cases in Bangladesh. Recent findings from the 1997–98 El Niño are providing corroborating evidence for a causal relationship between extreme weather events and disease outbreaks. Better quality and more comprehensive data sets are needed to improve the current understanding of how weather and climate affect the prevalence and occur-rence of infectious disease. This information is essential for developing accurate predictive models of disease outbreaks. Research on climate-disease links is interdisciplinary in scope and includes microbiology, epidemiology, ecology, oceanography, climatology, atmospheric sciences, and marine biology. Progress needs to be made in making data sets more accessible to researchers in these and other disciplines.


PMID: 32687286

Assessment of Bone Turnover Biomarkers in Lead-Battery Workers with Long-Term Exposure to Lead.

July 20, 2020

Assessment of Bone Turnover Biomarkers in Lead-Battery Workers with Long-Term Exposure to Lead.

Int J Occup Environ Med. 2020 07;11(3):140-147

Authors: Kalahasthi R, Barman T, Bagepally BS

Abstract
BACKGROUND: The major portion of lead in the body resides in skeletal system. The bone turnover affects the release of lead into the circulation from bones. The bone turnover biomarkers (BTM) in lead-battery workers with long-term exposure to lead have not been explored yet.
OBJECTIVE: To evaluate the BTM (formation and resorption) in lead-battery workers with long-term exposure to lead in lead-battery manufacturing plant.
METHODS: 176 male lead-exposed workers and 80 matched comparison group were studied. All participants were examined for blood lead levels (BLLs), bone formation biomarkers- serum osteocalcin (OC), alkaline phosphatase (ALP), bone-specific alkaline phosphatase (BALP)-and bone resorption biomarkers-serum pyridinoline (PYD), deoxypyridinoline (DPYD), tartarate-resistant acid phosphatase-5b (TRACP-5b), and urinary hydroxyproline (UHYP).
RESULTS: We found a significantly higher bone formation biomarkers such as BALP (p=0.007) and bone resorption biomarkers, eg, PYD (p=0.048), TRCAP-5b (p=0.001), and UHYP (p=0.001) in lead-exposed workers. A significant (p=0.041) negative correlation (ρ ‑0.128) was noted between BLLs and OC. A significant positive correlation was noted between BLLs and TRACP-5b (ρ 0.176, p=0.005) and UHYP (ρ 0.258, p=0.004). Serum OC (p=0.040) and UHYP (p=0.015) levels changed significantly with BLL level. Bone resorption biomarkers levels- PYD, TRACP-5b, and BALP-were higher among those with higher BLLs levels. The duration of exposure was significantly associated with BALP (p=0.037), DPYD (p=0.016), TRACP-5b (p=0.001), and UHYP (p=0.002) levels.
CONCLUSION: Long-term lead exposure affects the bone turnover.

PMID: 32683426 [PubMed - as supplied by publisher]

Toxigenic Vibrio cholerae evolution and establishment of reservoirs in aquatic ecosystems.

July 17, 2020
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Toxigenic Vibrio cholerae evolution and establishment of reservoirs in aquatic ecosystems.

Proc Natl Acad Sci U S A. 2020 04 07;117(14):7897-7904

Authors: Mavian C, Paisie TK, Alam MT, Browne C, Beau De Rochars VM, Nembrini S, Cash MN, Nelson EJ, Azarian T, Ali A, Morris JG, Salemi M

Abstract
The spread of cholera in the midst of an epidemic is largely driven by direct transmission from person to person, although it is well-recognized that Vibrio cholerae is also capable of growth and long-term survival in aquatic ecosystems. While prior studies have shown that aquatic reservoirs are important in the persistence of the disease on the Indian subcontinent, an epidemiological view postulating that locally evolving environmental V. cholerae contributes to outbreaks outside Asia remains debated. The single-source introduction of toxigenic V. cholerae O1 in Haiti, one of the largest outbreaks occurring this century, with 812,586 suspected cases and 9,606 deaths reported through July 2018, provided a unique opportunity to evaluate the role of aquatic reservoirs and assess bacterial transmission dynamics across environmental boundaries. To this end, we investigated the phylogeography of both clinical and aquatic toxigenic V. cholerae O1 isolates and show robust evidence of the establishment of aquatic reservoirs as well as ongoing evolution of V. cholerae isolates from aquatic sites. Novel environmental lineages emerged from sequential population bottlenecks, carrying mutations potentially involved in adaptation to the aquatic ecosystem. Based on such empirical data, we developed a mixed-transmission dynamic model of V. cholerae, where aquatic reservoirs actively contribute to genetic diversification and epidemic emergence, which underscores the complexity of transmission pathways in epidemics and endemic settings and the need for long-term investments in cholera control at both human and environmental levels.

PMID: 32229557 [PubMed - indexed for MEDLINE]

Sheltering in Place in a Xenophobic Climate: COVID-19 and Children in Immigrant Families.

July 16, 2020
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Sheltering in Place in a Xenophobic Climate: COVID-19 and Children in Immigrant Families.

Pediatrics. 2020 07;146(1):

Authors: Cholera R, Falusi OO, Linton JM

PMID: 32345687 [PubMed - indexed for MEDLINE]

Spatial dynamics and the basic reproduction number of the 1991-1997 Cholera epidemic in Peru.

July 15, 2020
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Spatial dynamics and the basic reproduction number of the 1991-1997 Cholera epidemic in Peru.

PLoS Negl Trop Dis. 2020 Jul;14(7):e0008045

Authors: Smirnova A, Sterrett N, Mujica OJ, Munayco C, Suárez L, Viboud C, Chowell G

Abstract
After being cholera free for over 100 years, Peru experienced an unprecedented epidemic of Vibrio cholerae O1 that began in 1991 and generated multiple waves of disease over several years. We developed a mechanistic transmission model that accounts for seasonal variation in temperature to estimate spatial variability in the basic reproduction number ([Formula: see text]), the initial concentration of vibrios in the environment, and cholera reporting rates. From 1991-1997, cholera spread following a multi-wave pattern, with weekly incidence concentrated during warm seasons. The epidemic first hit the coastal departments of Peru and subsequently spread through the highlands and jungle regions. The correlation between model predictions and observations was high (range in R2: 58% to 97%). Department-level population size and elevation explained significant variation in spatial-temporal transmission patterns. The overall R0 across departments was estimated at 2.1 (95% CI: 0.8,7.3), high enough for sustained transmission. Geographic-region level [Formula: see text] varied substantially from 2.4 (95% CI: 1.1, 7.3) for the coastal region, 1.9 (0.7, 6.4) for the jungle region, and 1.5 (0.9, 2.2) for the highlands region. At the department level, mean [Formula: see text] ranged from 0.8 to 6.9. Department-level [Formula: see text] were correlated with overall observed attack rates (Spearman ρ = 0.59, P = 0.002), elevation (ρ = -0.4, P = 0.04), and longitude (ρ = -0.6, P = 0.004). We find that both [Formula: see text] and the initial concentration of vibrios were higher in coastal departments than other departments. Reporting rates were low, consistent with a substantial fraction of asymptomatic or mild cases associated with the El Tor cholera biotype. Our results suggest that cholera vibrios, autochthonous to plankton in the natural aquatic environment, may have triggered outbreaks in multiple coastal locations along the Pacific coast of Peru. Our methodology could be useful to investigate multi-wave epidemics of cholera and could be extended to conduct near real-time forecasts and investigate the impact of vaccination strategies.

PMID: 32663235 [PubMed - as supplied by publisher]

A cholera transmission model incorporating the impact of medical resources.

July 14, 2020
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A cholera transmission model incorporating the impact of medical resources.

Math Biosci Eng. 2019 06 06;16(5):5226-5246

Authors: Yang CY, Wang J

Abstract
We propose a mathematical model for the transmission dynamics of cholera under the impact of available medical resources. The model describes the interaction between the human hosts and the pathogenic bacteria and incorporates both the environment-to-human and human-to-human transmission routes. We conduct a rigorous equilibrium analysis to the model and establish the global asymptotic stability of the disease-free equilibrium when R0 ≤ 1 and that of the endemic equilibrium when R0 > 1. As a realistic case study, we apply our model to the Yemen cholera outbreak during 2017-2018. By fitting our simulation results to the epidemic data published by the World Health Organization, we find that different levels of disease prevalence and severity are linked to different geographical regions in this country and that cholera prevention and intervention efforts should be implemented strategically with respect to these regions in Yemen.

PMID: 31499710 [PubMed - indexed for MEDLINE]

Surgeons, plague, and leadership: A historical mantle to carry forward.

July 7, 2020
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Surgeons, plague, and leadership: A historical mantle to carry forward.

Am J Surg. 2020 08;220(2):298-299

Authors: Barr J, Hwang ES, Shortell CK

PMID: 32386712 [PubMed - indexed for MEDLINE]

Deciphering the possible role of ctxB7 allele on higher production of cholera toxin by Haitian variant Vibrio cholerae O1.

July 7, 2020
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Deciphering the possible role of ctxB7 allele on higher production of cholera toxin by Haitian variant Vibrio cholerae O1.

PLoS Negl Trop Dis. 2020 04;14(4):e0008128

Authors: Naha A, Mandal RS, Samanta P, Saha RN, Shaw S, Ghosh A, Chatterjee NS, Dutta P, Okamoto K, Dutta S, Mukhopadhyay AK

Abstract
Cholera continues to be an important public health concern in developing countries where proper hygiene and sanitation are compromised. This severe diarrheal disease is caused by the Gram-negative pathogen Vibrio cholerae belonging to serogroups O1 and O139. Cholera toxin (CT) is the prime virulence factor and is directly responsible for the disease manifestation. The ctxB gene encodes cholera toxin B subunit (CTB) whereas the A subunit (CTA) is the product of ctxA gene. Enzymatic action of CT depends on binding of B pentamers to the lipid-based receptor ganglioside GM1. In recent years, emergence of V. cholerae Haitian variant strains with ctxB7 allele and their rapid spread throughout the globe has been linked to various cholera outbreaks in Africa and Asia. These strains produce classical type (WT) CTB except for an additional mutation in the signal sequence region where an asparagine (N) residue replaces a histidine (H) at the 20th amino acid position (H20N) of CTB precursor (pre-CTB). Here we report that Haitian variant V. cholerae O1 strains isolated in Kolkata produced higher amount of CT compared to contemporary O1 El Tor variant strains under in vitro virulence inducing conditions. We observed that the ctxB7 allele, itself plays a pivotal role in higher CT production. Based on our in silico analysis, we hypothesized that higher accumulation of toxin subunits from ctxB7 allele might be attributed to the structural alteration at the CTB signal peptide region of pre-H20N CTB. Overall, this study provides plausible explanation regarding the hypertoxigenic phenotype of the Haitian variant strains which have spread globally, possibly through positive selection for increased pathogenic traits.

PMID: 32236098 [PubMed - indexed for MEDLINE]

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