Home >

Takikng aim at cholera

Monday, 14th of May 2018 Print

The Lancet, Volume 391, No. 10133, p1868–1870, 12 May 2018

Comment

Taking aim at cholera

Eric MintzEmail the author Eric Mintz

Open Access

PlumX Metrics

DOI: https://doi.org/10.1016/S0140-6736(18)30543-9

In 1854, John Snows work on cholera in London immortalised the power of mapping as a tool for disease prevention and control.1 Over 160 years later, a more ambitious effort to map cholera has been reported in The Lancet.2 Forgoing so-called shoe leather epidemiology in favour of big data, Justin Lessler and colleagues2 used 279 cholera datasets covering 2283 locations in 37 countries, and cluster-level maps of access to improved water and sanitation in 41 countries, to map cholera incidence across sub-Saharan Africa at a 20 km × 20 km grid scale. They merged this incidence grid with census data and subnational administrative borders to identify and rank districts by their mean annual cholera incidence. Based on these analyses, they estimate that 151 of 3751 districts (4·0%, 95% credible interval [CrI] 1·7 to 16·8) in sub-Saharan Africa, home to 87·2 million people (95% CrI 60·3 million to 118·9 million), can be classified as high incidence (>1 case per 1000 people), and that targeting just 35·3 million people (95% CrI 26·3 million to 62·0 million) in the highest incidence districts with proven interventions—safe water, sanitation, and cholera vaccination—could reduce mean annual cholera incidence in the entire region by 50%. Alternatively, targeting 50·8 million people (95% CrI 39·7 million to 62·8 million) in just five countries (Somalia, Nigeria, Democratic Republic of the Congo, Sierra Leone, and Ghana) could prevent over 38% of all regional cholera cases.

These encouraging results provide a region-wide geospatial roadmap to guide the actions described in WHO and partners Ending Cholera: a Global Roadmap to 2030,3 released by the Global Task Force on Cholera Control in 2017. Lessler and colleagues2 show that high-burden cholera hot spots to target with interventions can be identified in each affected country. Furthermore, they suggest that this strategy will yield high returns on the resources invested. The latter is particularly important given constraints on the resources needed. Sustainable water supply, sanitation, and hygiene (WaSH) infrastructure is crucial for ending transmission of cholera and other diseases transmitted by the faecal–oral route, and is a Sustainable Development Goal 2030 target in its own right, but its construction is costly and time consuming. Oral cholera vaccines, which are effective at reducing cholera transmission in the short term (3–5 years), remain in short supply relative to global demand despite substantial success in increasing their production and accessibility.4

In sub-Saharan Africa—an area of around 24 million km2 that is home to more than 1 billion people—cholera has been reported to WHO every year since 1971.5 It lags behind other regions in population coverage with improved water and sanitation,6 and populations in many African nations are besieged by other public health threats that increase the risk of cholera transmission and deaths, including drought or flooding;7 terrorism, civil conflict, or war;8 malnutrition;9 and acute economic crises or chronic poverty. Similar conditions afflict cholera-affected areas in the Middle East, Asia, and the Caribbean,10, 11 with refugees from nearby countries sometimes forced to flee to cholera-endemic areas.

Efforts to combat cholera in sub-Saharan Africa in the 21st century have been almost entirely reactive—focused on outbreak response through emergency WaSH measures and the occasional cholera vaccine campaign. Although cholera surveillance, reporting, and diagnostic capacity have benefited from investments in public health preparedness and training, and from a few cholera-specific projects, an overarching strategy to most effectively mobilise efforts and resources for cholera prevention has been sorely lacking.12 As other disease control programmes have shown, the ability to identify and target high-incidence hot spots is a crucial element of successful strategies in resource-constrained environments.

Although essential, disease mapping alone is not sufficient to guarantee the success of a control programme. Continuous iteration will be needed to maintain accurate, reliable, and up-to-date disease maps and modelling. Additionally, disease maps can aid national and local governments, partners, and donors understanding and efforts in targeting interventions. Finally, an absence of dedicated resources for implementation of interventions beyond those available for outbreak response may hinder progress.

The work by Lessler and colleagues is relevant to many parallel efforts. In support of Sustainable Development Goal 6, mapping of WaSH data will be enhanced by 2030 with more information on water quality and an additional institutional focus on schools and health facilities. Also, through its initiative on so-called precision public health, the Institute for Health Metrics and Evaluation is mapping safe water and sanitation coverage at a fine scale and has mapped child death rates in Africa by 5 km2 blocks. Recently, molecular microbiologists published a global history and geography of the seventh pandemic cholera in Africa, and suggested that extensive intercontinental spread has been accompanied by at least 11 introductions of a single expanded lineage from Asia.13 By combining epidemiological, environmental, and genomic information, maps could be generated that are capable of informing future disease prevention efforts in even more powerful ways than are currently possible. In the future, will we identify and intervene readily in high-transmission hot spots, which, like individual super-spreaders within populations, appear to amplify epidemic propagation through their social connectivity or other characteristics? Can cold spots within epidemic zones teach us anything about social behaviours, environmental conditions, or the presence of bacteriophage or other potential inhibitors of toxigenic Vibrio cholerae O1 survival in environmental reservoirs that would confer resistance to epidemic propagation? We inhabit not just a geographical space defined by distances but many different worlds within this space: the worlds of social interactions, behaviours, events, and climate, to name but a few. Disease and risk mapping help us to better understand, learn from, and more successfully navigate those worlds, and are necessary tools as we target an end to cholera.

I declare no competing interests. The views in this Comment are those of the author and do not necessarily represent the official position of the Centers for Disease Control and Prevention.

References

  1. Snow, J. On the mode of communication of cholera. 2nd edn. John Churchill, London; 1855

  1. Lessler, J, Moore, SM, Luquero, FJ et al. Mapping the burden of cholera in sub-Saharan Africa and implications for control: an analysis of data across geographical scales. (published online March 1.)Lancet. 2018;

http://dx.doi.org/10.1016/S0140-6736(17)33050-7

 

 

 

 

 | 

  1. Global Task Force on Cholera Control. Ending cholera: a global roadmap to 2030. ((accessed Dec 3, 2017).)

http://www.who.int/cholera/publications/global-roadmap/en/

  1. Pezzoli, L and on behalf of the Oral Cholera Vaccine Working Group of the Global Task Force.Deployments from the oral cholera vaccine stockpile, 2013–2017. Wkly Epidemiol Rec. 2017; 92: 437–442

 | 

  1. WHO. Global Health Observatory data. Number of reported cholera cases. ((accessed Dec 3, 2017).)

http://www.who.int/gho/epidemic_diseases/cholera/cases/en/

  1. UNICEF and WHO. Progress on sanitation and drinking water: 2015 update and MDG assessment.((accessed Dec 3, 2017).)

https://www.unicef.org/publications/index_82419.html

  1. Moore, SN, Azman, AS, Zaitchik, BF et al. El Niño and the shifting geography of cholera in Africa.Proc Natl Acad Sci USA. 2017; 114: 4436–4441

 

 

 | 

  1. Kelly-Hope, LA. Conflict and emerging infectious diseases. Emerg Infect Dis. 2008; 14: 1004–1005

 | 

  1. Ververs, M and Narra, R. Treating cholera in severely malnourished children in the Horn of Africa and Yemen. Lancet. 2017; 390: 1945–1946

 

 

 

 

 | 

10.  Qadri, F, Islam, T, and Clemens, D. Cholera in Yemen—an old foe rearing its ugly head. N Engl J Med. 2017; 377: 2005–2007

 

 

 | 

11.  Ivers, LC. Eliminating cholera transmission in Haiti. N Engl J Med. 2017; 376: 101–103

 

 

 | 

12.  Mintz, ED and Tauxe, RV. Cholera in Africa: a closer look and a time for action. J Infect Dis. 2013;208: S4–S7

 

 

 | 

13.  Weill, FX, Domman, D, Njamkepo, E et al. Genomic history of the seventh pandemic of cholera in Africa. Science. 2017; 358: 785–789

 

 

 | 

Previous

Comment

Contemporary cardiovascular risk prediction

 

Next

Comment

Can improving access to care help to eliminate malaria?

 

Access this article on

 

ScienceDirect

Article Options

Linked Articles

  • ARTICLES

Mapping the burden of cholera in sub-Saharan Africa and implications for control: an analysis of data across geographical scales

Open Access

Popular Articles

 

Most read in The Lancet within the past 30 days.

Top of Form

  • ARTICLES

Risk thresholds for alcohol consumption: combined analysis of individual-participant data for 599 912 current drinkers in 83 prospective studies

Vol. 391, No. 10129

Published: April 14, 2018

Open Access

  • ARTICLES

Comparative efficacy and acceptability of 21 antidepressant drugs for the acute treatment of adults with major depressive disorder: a systematic review and network meta-analysis

Vol. 391, No. 10128

Published: February 21, 2018

Open Access

  • ARTICLES

Associations of fats and carbohydrate intake with cardiovascular disease and mortality in 18 countries from five continents (PURE): a prospective cohort study

Vol. 390, No. 10107

Published: August 29, 2017

  • ARTICLES

Development and validation of a Hospital Frailty Risk Score focusing on older people in acute care settings using electronic hospital records: an observational study

Vol. 391, No. 10132

Published: April 26, 2018

Open Access

  • COMMENT

Thresholds for safer alcohol use might need lowering

Vol. 391, No. 10129

Published: April 14, 2018

Open Access

Bottom of Form

The Lancet Choice

The Lancet Choice is a new payment option that gives you the freedom and flexibility to access any 5 premium articles of your choice from across The Lancet family of journals - all for a one-off payment of $49.00 USD.

Simply purchase your Lancet Choice pass from the Summary or Full Text page of an article you wish to access. This will count as the first of 5 article credits, or Allowances, and you can use your 4 remaining Allowances to access other articles from any of The Lancet journals.

Find out more about The Lancet Choice

The Lancet Journals

Information & Support

Subscription

Copyright © 2018 Elsevier Limited except certain content provided by third parties.

The Lancet is a trade mark of Elsevier Limited.

The Lancet.com website is operated by Elsevier Inc. The content on this site is intended for health professionals.

Cookies are set by this site. To decline them or learn more, visit our Cookies page.

The Lancet demonstrates its commitment to accessibility by enabling access and optimising the experience for individuals with disabilities and impairments.

 

Download PDF

Taking aim at cholera - The Lancet

 

(C) All Rights Reserved - Child Survival.net