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Concept: Cholera

183

The spatiotemporal evolution of human mobility and the related fluctuations of population density are known to be key drivers of the dynamics of infectious disease outbreaks. These factors are particularly relevant in the case of mass gatherings, which may act as hotspots of disease transmission and spread. Understanding these dynamics, however, is usually limited by the lack of accurate data, especially in developing countries. Mobile phone call data provide a new, first-order source of information that allows the tracking of the evolution of mobility fluxes with high resolution in space and time. Here, we analyze a dataset of mobile phone records of ∼150,000 users in Senegal to extract human mobility fluxes and directly incorporate them into a spatially explicit, dynamic epidemiological framework. Our model, which also takes into account other drivers of disease transmission such as rainfall, is applied to the 2005 cholera outbreak in Senegal, which totaled more than 30,000 reported cases. Our findings highlight the major influence that a mass gathering, which took place during the initial phase of the outbreak, had on the course of the epidemic. Such an effect could not be explained by classic, static approaches describing human mobility. Model results also show how concentrated efforts toward disease control in a transmission hotspot could have an important effect on the large-scale progression of an outbreak.

Concepts: Epidemiology, Disease, Infectious disease, Infectious diseases, Pandemic, Mobile phone, Cholera, Outbreak

180

The global burden of cholera is largely unknown because the majority of cases are not reported. The low reporting can be attributed to limited capacity of epidemiological surveillance and laboratories, as well as social, political, and economic disincentives for reporting. We previously estimated 2.8 million cases and 91,000 deaths annually due to cholera in 51 endemic countries. A major limitation in our previous estimate was that the endemic and non-endemic countries were defined based on the countries' reported cholera cases. We overcame the limitation with the use of a spatial modelling technique in defining endemic countries, and accordingly updated the estimates of the global burden of cholera.

Concepts: Epidemiology, Statistics, Mathematics, Definition, Report, Estimation, Cholera, Aristotle

169

The 2010 Haitian earthquake and consequent Cholera epidemic taxed the already fragile health system. A large number of humanitarian organizations participated in the disaster response and the health communication response was analysed. Health Cluster updates from both periods were analysed for contents with a World Health Organization draft check list for monitoring and evaluating the quality of epidemiological data contained in WHO and Health Cluster emergency reports. The Pan-American Health Organization Emergency Operations Centre reports from the Earthquake had the lowest score with an average score of 2.54/17 and the Health Cluster - Cholera reports had the highest average score of 11/17. There is a wide variety and quality of information published in terms of epidemiological information in emergency reports with a distinct difference found between the earthquake reporting and the cholera event. A comprehensive and modifiable template for emergency reporting could alleviate these differences and allow for improved reporting. Citation: Dhillon P, Annunziata G. The Haitian Health Cluster Experience: A comparative evaluation of the professional communication response to the 2010 earthquake and the subsequent cholera outbreak. PLOS Currents Disasters. 2012 Sep 5. doi: 10.1371/5014b1b407653.

Concepts: Public health, Epidemiology, Evaluation, Pandemic, World Health Organization, Cholera, 2010 Haiti earthquake, John Snow

133

Cholera, caused by infection with toxigenic Vibrio cholerae bacteria of serogroup O1 (>99% of global cases) or O139, is characterized by watery diarrhea that can be severe and rapidly fatal without prompt rehydration. Cholera is endemic in approximately 60 countries and causes epidemics as well. Globally, cholera results in an estimated 2.9 million cases of disease and 95,000 deaths annually (1). Cholera is rare in the United States, and most U.S. cases occur among travelers to countries where cholera is endemic or epidemic. Forty-two U.S. cases were reported in 2011 after a cholera epidemic began in Haiti (2); however, <25 cases per year have been reported in the United States since 2012.

Concepts: Immune system, Epidemiology, Infectious disease, Microbiology, United States, Pandemic, Vibrio cholerae, Cholera

78

In the 19th century, there were several major cholera pandemics in the Indian subcontinent, Europe, and North America. The causes of these outbreaks and the genomic strain identities remain a mystery. We used targeted high-throughput sequencing to reconstruct the Vibrio cholerae genome from the preserved intestine of a victim of the 1849 cholera outbreak in Philadelphia, part of the second cholera pandemic. This O1 biotype strain has 95 to 97% similarity with the classical O395 genome, differing by 203 single-nucleotide polymorphisms (SNPs), lacking three genomic islands, and probably having one or more tandem cholera toxin prophage (CTX) arrays, which potentially affected its virulence. This result highlights archived medical remains as a potential resource for investigations into the genomic origins of past pandemics.

Concepts: Bioinformatics, Epidemiology, Microbiology, Pandemic, Vibrio cholerae, Cholera, 19th century, El Tor

47

After more than a decade of steadily declining notifications, the number of reported cholera cases has recently increased in Vietnam. We conducted a matched case-control study to investigate transmission of cholera during an outbreak in Ben Tre, southern Vietnam, and to explore the associated risk factors.

Concepts: Epidemiology, Coffee, Case-control study, Tea, Cholera, Iced tea, Lipton, Sweet tea

45

Leptospirosis, a spirochaetal zoonosis, occurs in diverse epidemiological settings and affects vulnerable populations, such as rural subsistence farmers and urban slum dwellers. Although leptospirosis is a life-threatening disease and recognized as an important cause of pulmonary haemorrhage syndrome, the lack of global estimates for morbidity and mortality has contributed to its neglected disease status.

Concepts: Epidemiology, Diseases and disorders, Poverty, Demography, Population, Slum, Cholera, Leptospirosis

39

Pseudomonas aeruginosa has three type VI secretion systems (T6SSs), H1-, H2-, and H3-T6SS, each belonging to a distinct group. The two T6SS components, TssB/VipA and TssC/VipB, assemble to form tubules that conserve structural/functional homology with tail sheaths of contractile bacteriophages and pyocins. Here, we used cryoelectron microscopy to solve the structure of the H1-T6SS P. aeruginosa TssB1C1 sheath at 3.3 Å resolution. Our structure allowed us to resolve some features of the T6SS sheath that were not resolved in the Vibrio cholerae VipAB and Francisella tularensis IglAB structures. Comparison with sheath structures from other contractile machines, including T4 phage and R-type pyocins, provides a better understanding of how these systems have conserved similar functions/mechanisms despite evolution. We used the P. aeruginosa R2 pyocin as a structural template to build an atomic model of the TssB1C1 sheath in its extended conformation, allowing us to propose a coiled-spring-like mechanism for T6SS sheath contraction.

Concepts: Bacteria, Microbiology, Secretion, Structure, Pseudomonas aeruginosa, Model theory, System, Cholera

32

Background In October 2010, nearly 10 months after a devastating earthquake, Haiti was stricken by epidemic cholera. Within days after detection, the Ministry of Public Health and Population established a National Cholera Surveillance System (NCSS). Methods The NCSS used a modified World Health Organization case definition for cholera that included acute watery diarrhea, with or without vomiting, in persons of all ages residing in an area in which at least one case of Vibrio cholerae O1 infection had been confirmed by culture. Results Within 29 days after the first report, cases of V. cholerae O1 (serotype Ogawa, biotype El Tor) were confirmed in all 10 administrative departments (similar to states or provinces) in Haiti. Through October 20, 2012, the public health ministry reported 604,634 cases of infection, 329,697 hospitalizations, and 7436 deaths from cholera and isolated V. cholerae O1 from 1675 of 2703 stool specimens tested (62.0%). The cumulative attack rate was 5.1% at the end of the first year and 6.1% at the end of the second year. The cumulative case fatality rate consistently trended downward, reaching 1.2% at the close of year 2, with departmental cumulative rates ranging from 0.6% to 4.6% (median, 1.4%). Within 3 months after the start of the epidemic, the rolling 14-day case fatality rate was 1.0% and remained at or below this level with few, brief exceptions. Overall, the cholera epidemic in Haiti accounted for 57% of all cholera cases and 53% of all cholera deaths reported to the World Health Organization in 2010 and 58% of all cholera cases and 37% of all cholera deaths in 2011. Conclusions A review of NCSS data shows that during the first 2 years of the cholera epidemic in Haiti, the cumulative attack rate was 6.1%, with cases reported in all 10 departments. Within 3 months after the first case was reported, there was a downward trend in mortality, with a 14-day case fatality rate of 1.0% or less in most areas.

Concepts: Epidemiology, Pandemic, World Health Organization, Vibrio cholerae, Cholera, Serotype, Robert Koch, El Tor

28

Introduction of Vibrio cholerae to Haiti during the deployment of United Nations (UN) peacekeepers in 2010 resulted in one of the largest cholera epidemics of the modern era. Following the outbreak, a UN-commissioned independent panel recommended three pre-deployment intervention strategies to minimize the risk of cholera introduction in future peacekeeping operations: screening for V. cholerae carriage, administering prophylactic antimicrobial chemotherapies, or immunizing with oral cholera vaccines. However, uncertainty regarding the effectiveness of these approaches has forestalled their implementation by the UN. We assessed how the interventions would have impacted the likelihood of the Haiti cholera epidemic.

Concepts: Epidemiology, Microbiology, Vibrio cholerae, United Nations, Cholera, Vibrio, Peacekeeping, United Nations Security Council