Tag Archives: health impact assessment

Haiti: disease model predicts more cholera and potential impact of clean water

The number of Haitians infected with cholera may reach 779,000 by the end of November 2011, nearly twice as many as UN estimates, according to a new study [1].

The UN estimate is “essentially a guess, based on no data, and ignoring the dynamics of cholera epidemics” co-author Dr. Jason Andrews told SciDev.Net.

Using a mathematical model of the epidemic, the study projects 779 000 cases of cholera and 11,100 deaths between March 1 and November 30, 2011, if there are no new interventions to curb transmission and treat victims.

The researchers estimate that 170,000 cases of cholera and 3,400 deaths could be averted by a combination of clean water, vaccination and greater distribution of antibiotics.

A 1% per week reduction in consumption of contaminated water would the greatest effect by averting 105,000 cholera cases and 1,500 deaths. Vaccination of 10% of the population would avert 63,000 cases and 900 deaths. The extension of the use of antibiotics to all patients with severe dehydration and half of patients with moderate dehydration would avert 9,000 cases and 1,300 deaths.

Andrews told SciDev.Net that the interventions could be achieved if the international community was willing to invest in them.

But Marcos Espinal, head of health surveillance, disease prevention and control at the Pan American Health Organization (PAHO), defended the UN’s approach. He told SciDev.Net that “the model used up to now is consistent with reality. We have seen just over 250,000 people with cholera in six months”.

A cholera epidemic broke out in Haiti in late October 2010, in the wake of the earthquake in January of the same year. The latest UN figures for the epidemic, published on 31 March 2011, are 267,224 cases, 4,749 deaths and a mortality rate of 1,8%.

[1] Andrews, J.R. and Basu, S. (2011). Transmission dynamics and control of cholera in Haiti : an epidemic model. The Lancet, 16 March 2011 (Article in Press). DOI: (free registration is required to view this article)

Source: María Elena Hurtado, SciDev.Net, 28 March 2011

Effect of water quality, hygiene and sanitation in preventing diarrhoea deaths

Researchers propose diarrhoea risk reductions of 48, 17 and 36%, associated respectively, with handwashing with soap, improved water quality and excreta disposal as the estimates of effect for the Lives Saved Tool (LiST) model [1].

LiST is a new computer-based planning tool to help estimate the impact of scaling-up maternal, newborn and child health interventions. LiST was developed by a consortium of academic and international organizations, led by Institute of International Programs at the Johns Hopkins Bloomberg School.

Researchers led by Prof. Sandy Cairncross of the London School of Hygiene & Tropical Medicine, drew on three systematic reviews, two of them for the Cochrane Collaboration, to determine the estimated effect on diarrhoea mortality of the three interventions.

The striking effect of handwashing with soap (48% reduction) was found to be consistent across various study designs and pathogens, though it depended on access to water. The effect of (household) water treatment appeared similarly large, but was not found in few blinded studies, suggesting that it might be partly due to the placebo effect. The researchers found very little rigorous evidence for the health benefit of sanitation; four intervention studies were eventually identified, though they were all quasi-randomized, had morbidity as the outcome, and were in Chinese.

While most of the evidence was found to be of poor quality and more trials were required, the evidence was nonetheless strong enough to support the provision of water supply, sanitation and hygiene for all.

[1] Cairncross, S., Hunt, C., Boisson, S., Bostoen, K., Curtis, V., Fung, I.C. and Schmidt, W.P. (2010). Water, sanitation and hygiene for the prevention of diarrhoea. International journal of epidemiology ; vol. 39 (Suppl. 1) ; p. i193-i205. DOI:10.1093/ije/dyq035

The complete issue of the April 2010 supplement of the International journal of epidemiology is devoted to the development and use of the Lives Saved Tool (LiST). Other articles deal with rotavirus vaccine, zinc treatment for diarrhoea, antibiotics for dysentery, and oral rehydration solution. All articles are free to download.

India: BORDA introduces Health Impact Assessment and -Monitoring for all Community Based Sanitation Projects

BORDA and its 16 network partners in India are implementing sanitation projects including the construction of DEWATS [Decentralized Waste Water Treatment] in slums and poor peri-urban settlements for the last 8 years. Due to time and resources constraints, a systematic evaluation of the achieved impacts on the health and hygiene condition of the direct beneficiaries/users could not be done until this year.

In spring 2008, BORDA together with 5 partner organizations developed a tool allowing the evaluation of already realized impacts and an on-going health and hygiene impact monitoring.

Read more: Meike Zinn-Meinken, BORDA, 01 July 2008