Focus on behaviour in zoonosis “hotspots”
Posted: May 31st, 2010 - 9:32am
Source: Emerging Health Threats
Behaviour change should be top of the agenda for mitigating pandemics, say researchers
Efforts to stop the next pandemic in its tracks would be bolstered by public health programmes designed to change the habits of people living in emerging infectious disease “hot spots”, say researchers online this month in Clinical Infectious Diseases. Experts see merit in the strategy but highlight the scale and difficulties of the task.
Zoonotic disease hotspots lie in parts of the world where the behaviour of local people may put them at risk of catching diseases that normally affect animals. Such habits include raising food animals inside homes, a risk factor for infection with new influenza viruses, and hunting for bushmeat in forests, which provides the opportunity for other animal viruses to infect humans.
“In situations where humans and animals are in close contact, behavioural change approaches may be a preventative step to reducing the risk of zoonotic transmission,” write Brian Pike, from the Global Viral Forecasting Initiative in California, USA, and colleagues. They reviewed evidence available in published scientific literature about how new zoonotic diseases emerge in people, and highlight the importance of the human-animal interface — where people come in close contact with the wild or domestic animals in their environment.
It is now widely accepted that the hunting and butchering of non-human primates caused the simian immunodeficiency virus to jump the species barrier to infect humans, say the authors. This gave rise to the modern-day human immunodeficiency virus (HIV) that has resulted in more than 25 million deaths worldwide since the 1980s.
As more people come into closer contact with animals because of growing human and animal populations and a loss of natural habitats, scientists predict that future pandemics are likely to emerge in a similar way. There is no global surveillance system in place to monitor any potential zoonoses, explain Pike and colleagues. Currently, emerging infectious disease control programmes focus “almost exclusively” on responding to pandemics after they have spread globally, they say.
Failings in the response to the spread of HIV have shown that the “wait-and-respond approach” is not sufficient, argue the authors. In the 25 years since HIV emerged, scientists still have not developed a vaccine against the virus and this, they say, highlights the difficulties of keeping disease in check once it has emerged.
Ideally, a global monitoring system should be established to identify new pathogens early and help stop them from spreading, according to Pike and colleagues. But the global health community is far from having such a tool within reach. For this reason they suggest that in the interim period, programmes aimed at changing risky behaviour in people living in disease-emergence hotspots could help to prevent the spread of diseases picked up from animals.
The authors have worked with bushmeat hunters in the forests of Cameroon, aiming to reduce their risk of animal diseases. With “healthy hunter” sessions the team teach them about the safest way to hunt and butcher meat so they can limit exposure to animal blood and body fluids.
“Behavioural change is key to preventing pandemics,” says Mark Woolhouse, from the University of Edinburgh, UK. Apart from the “exotic” issue of butchering bush meat raised by Pike and colleagues, there are more everyday practices that are potentially very important in reducing the spread of disease in an epidemic. These include hand washing and encouraging people to stay at home from work if they have the flu, he explains.
Targeting areas where pathogens are more likely to ‘jump’ between animals and humans “makes absolute sense”, according to Calum Macpherson of St George’s University in Grenada. “The threat of new zoonotic infections can evolve anywhere but targeting the most likely hotspots will divert our limited human and financial resources to the most likely sources,” he explains.
Steve Luby, from the International Centre for Diarrheal Disease Research in Dhaka, Bangladesh, also supports this targeting strategy. But he warns that scientists should not underestimate how much interaction between animals and humans occurs every day worldwide — and how much behaviour there is to modify.
Bangladesh is a hotspot country, notes Luby, particularly for the emergence of deadly new strains of flu. Around 40 million people living in rural parts of Bangladesh raise poultry inside their homes, which puts them at risk of the avian influenza virus H5N1, he says. “Focused behaviour change makes sense, but changing the behaviour of 40 million people is not a small focused undertaking.”
Many behaviour change campaigns designed to help make drinking water safe in poor areas have also failed to see lasting changes in people’s habits. Woolhouse admits that changing people’s behaviour over the long term may not be easy. “[In the UK] it has proven difficult to get hospital workers to adhere to new hand washing recommendations, or even to get vaccinated against swine flu,” he says.
But Macpherson believes it is possible to change people’s behaviour, and cites successful public health campaigns against parasitic diseases including trichinellosis in sub Saharan Africa and opisthorchis in Thailand. However, measuring the public health impact of behaviour change on the prevention of viral zoonotic diseases is very difficult, he adds.
“Involving the communities will be the cornerstone to a successful sustainable outcome [of behaviour change projects],” says Macpherson. People will only change their behaviour if they find the new habits culturally acceptable and financially viable, he explains, so this approach will only have an impact if communities take ownership of the public health projects and participate actively in decision making.
Macpherson adds that communities have to see the need for the desired changes and deem them important. “The public health team should be aware that behaviour change will not ever be acceptable or implemented by all members of the community.” It will be important to work with and monitor the people who do not participate, he explains.
Macpherson and Luby say that changing people’s habits effectively relies on scientists understanding why people behave in ways that put them at risk in the first place.
Writing in the review, Pike and colleagues note that poor people are more likely to be exposed to disease-causing pathogens. Luby explains that for disadvantaged people disease risk may be a reasonable trade-off that enables them to earn enough money to feed themselves and their families.
“Simply telling poor people to keep their chickens in a separate living area from their house, when they cannot afford it, will not produce meaningful behaviour change,” adds Luby. He says that public health campaigns are most successful at changing behaviour when the local environment is improved at the same time. In the USA, for example, laws restricting smoking in public places and mandating the inclusion of seatbelts in cars have complemented behaviour change campaigns, he explains.
When it comes to emerging infectious diseases, Luby knows of no similar success stories. But he notes that this way of approaching disease prevention is new, and so there are few examples of these efforts. Pulling together a reasonable strategy targeting behaviour change and implementing it requires a “substantial investment” of time and expertise, he says.
“For all the concern expressed in wealthy countries about the global risk of emerging infectious diseases, this has not been matched by a commitment to activities that would lessen the risk in the highest need communities,” says Luby.