Views from the London School of Hygiene & Tropical Medicine

Haiti cholera map

Mapping the spread of cholera to aid the MSF response in Haiti

Our free exhibition, Cartographies of Life & Death, opened last week to mark the bicentenary of John Snow – an iconic figure in public health, the forefather of epidemiology, and the man who first proved cholera was water-borne by tracking an outbreak to a water pump in Soho.

The exhibition features historical treasures, newly commissioned artworks and disease maps showing how scientists track deadly outbreaks around the world. One of items on display is a series of maps by Médecins Sans Frontières (MSF), produced following the 2010 Haiti earthquake in the hope of tracking how a cholera outbreak was spreading.

Lindsey Bryson, Ludovic Dupuis and Ruby Siddiqui from MSF discuss their work…

Haiti Cholera Map, 2013, MSFThe chaotic conditions that followed the 2010 earthquake in Haiti as well as the pre-existing poor water and sanitation situation, crowded conditions in urban slums and a population with no previous cholera experience contributed to the large cholera outbreak that started in late October 2010.

With over 200,000 cholera patients in three months, the country’s health system was utterly overwhelmed. International agencies’ capacity was stretched to the limit, and one of the challenges was rational deployment of resources. Mapping tools were utilised to convert patient registers into animated maps in Google Earth® with dots sized according to daily numbers of cases from each neighbourhood. Water point mapping was performed with graduated colours corresponding to chlorination levels.

As John Snow demonstrated in London in 1854, a spatiotemporal correlation between water system breakdowns and increased cholera cases was demonstrated in Carrefour, Haiti. This was successfully used to advocate for improved water system maintenance. Cholera hotspots were easily visualised, as were incidence trends in neighbourhoods. However earlier and more widespread implementation of such mapping analysis might have led to an improved medical response through targeted outreach, water chlorination and timelier advocacy.

Amongst the 650,000 cases reported by the Ministry of Public Health and Population up to February 15, 2013, MSF treated nearly 200,000 for a total cost of approximately $60 million and with a mortality rate of less than 1%.  During 2011, MSF handed over to the Haitian health authorities all the cholera treatment centers located outside the quake-affected area but continues to run four emergency surgical hospitals in Port-au-Prince, Carrefour and Leogane (in 2012 alone MSF treated more than 23,000 cholera patients, more than half of the total caseload).

In recent evaluations of public health facilities in four Haitian departments — Artibonite, Nippes, Southeast and North—MSF found that the quality of cholera treatment declined significantly in the last year due to funding shortfalls. With the next rainy season (and cholera season) due in May, the Haitian government and international donors need to ensure that existing treatment sites are equipped and staffed in time.

(Images: Haiti cholera maps. Credit: MSF)

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