24 Feb 2016
Targeting the household contacts of cholera patients – who are themselves at high risk of contracting the disease – could dramatically cut the spread of cholera, a clinical trial run in Dhaka by icddr,b scientists and international collaborators has shown
The World Health Organization (WHO) estimates that cholera causes up to 142,000 deaths worldwide each year. It is most usually transmitted through contaminated water and poor hygiene practices. Previous icddr,b research has shown that family members and household contacts are at more than 100 times higher risk of contracting cholera in the one-week period after a patient seeks hospital care. This may be because they acquire cholera from the patient, or are exposed to the same source of contamination that caused the initial infection.
Currently, when cholera patients are discharged from hospital, they are provided with oral rehydration solution (ORS) packets.
However, there is also an opportunity to communicate the importance of good water sanitation and hygiene (WASH) practice to all members of the family points out Dr MunirulAlam, Senior Scientist and Principal Investigator from icddr,b, who coordinated the trial in Bangladesh. “We took advantage of the time patients and accompanying family members spent in our hospital during a severe diarrheal episode to deliver information about water sanitation and hygiene (WASH) behaviour change and introduce the cholera prevention package when patients and their accompanying family members spend time at our hospital facility,” said Dr Alam. “No standard of care exists for household contacts of these patients despite their very high risk for cholera,” he continued.
Dr Christine Marie George, the Johns Hopkins University Principal Investigator of the trial and lead author, worked closely with Dr Alam’s team at icddrb to develop, pilot, and evaluate a simple intervention to promote good WASH practice in cholera-affected households. In the Cholera-Hospital Based-Intervention-for-7-Days (CHoBI7) intervention, health promoters showed cholera patients and their accompanying family members a pictorial guide of how cholera is spread and how transmission can be prevented. They were also given a cholera prevention package, consisting of a 3-month supply of chlorine tablets for water treatment, soapy water bottles, a hand-washing station, and a sealed water vessel to ensure safe water storage. These messages were reinforced during daily visits to the household during the week-long period of the intervention.
The CHoBI7 intervention was assessed in a randomised controlled trial carried out at icddr,b’s Dhaka Hospital, which compared the new approach with the usual standard of care (ORS packets given to patients). Some 219 intervention household contacts of 82 cholera patients received the CHoBI7 intervention, and 220 control contacts of 83 cholera patients received the usual standard of care.
The trial demonstrated major advantages of the CHoBI7 intervention. Families receiving the intervention had significantly reduced symptomatic cholera infections compared to those receiving the usual standard of care. Furthermore, a follow-up study of trial participants 6-12 months later found that CHoBI7 families were much more likely to be maintaining good hygiene and have improved water quality than control families – suggesting that the intervention had achieved sustained changes in behaviour. For example, during an observation period in their homes, household members who had received the CHoBI7 intervention were four times more likely to wash their hands with soap. Dr. Alam emphasises that ‘Although people around the world clean their hands with water, very few use soap to wash their hands that removes germs effectively. Hygiene practice and safe drinking water would prevent transmitting not only cholera but other infectious diseases – thus contributing to the enhancement of global health ’.
The intervention may be particularly effective because it targets families when concerns about cholera are foremost in their minds – when a family member is seriously ill. Furthermore, by concentrating efforts on those most at risk, rather than the population at large, the intervention is likely to be cost-effective. However, a larger study is required to confirm the benefits of the CHoBI7intervention, and whether it is also effective without home visits, which would make it easier to scale up to more general use.
Dr Mohammad Yunus, former Senior Scientist and currently Emeritus Scientist of icddr,b and an expert on cholera control and prevention said,
“The findings of the study have strong public health importance as the intervention strategy has the potential to be implemented and scaled up in hospital settings and thus can benefit communities in reducing cholera transmission not only in Bangladesh but also in many other countries where cholera is still a public health problem causing death.”
The CHoBI7 trial was funded by the Center for Global Health at Johns Hopkins University and the National Institute of Allergy and Infectious Diseases, National Institutes of Health, USA. Initial results from the CHoBI7 trial were published in the journal Emerging Infectious Diseases and the follow-up study was published in the American Journal of Tropical Medicine and Hygiene.
Dr George, Johns Hopkins University Principal Investigator, and Dr Alam, icddrb Principal Investigator, have recently received a US$1.5 million United States Agency for International Development grant to test strategies to take their CHoBI7 intervention to scale.