Combating Zoonoses Using the Example of Rift Valley Fever
A guest post by Dr. Bernard Bett, Senior Scientist, Animal and Human Health, at the International Livestock Research Institute ( ILRI, Kenya) and Team Leader of the One Health Research, Education and Outreach Centre in Africa (OHRECA).
One Health is an integrated, unifying approach that aims to sustainably balance and optimize the health of people, animals and ecosystems. It recognizes that the health of humans, domestic and wild animals, plants and the wider environment (including ecosystems) are closely linked and interdependent (source: The One Health High Level Panel). These approaches are being used to address antimicrobial resistance, food safety and emerging and neglected zoonotic diseases that are considered as the most important and complex health challenges of the 21st century. Similar health problems caused by malnutrition, environmental pollution and other neglected tropical diseases are slowly being incorporated under the One Health umbrella.
In practice, the implementation procedures of the One Health approach can be adapted to specific situations or health challenges. In this context, collaboration between different actors concerned with the health of people, animals and the shared environment is central. Studies show that it is more efficient to combat zoonotic diseases at the animal level before they spread to humans. In this context, consistent implementation of the One Health approach enables early detection and control of the disease as well as efficient use of resources, helping to develop effective solutions for epidemic control. We describe ways in which One Health approach can be used to control Rift Valley fever (RVF).
Finding individual cases to prevent epidemics: Better surveillance through interdisciplinary teams
Continuous systematic observation, analysis, interpretation, and reporting of health and epidemiological data (surveillance) of the RVF virus is the basic requirement for early detection of isolated cases of the disease in humans or animals. The surveillance protocols that have been developed for RVF throughout the sub-Saharan region are largely founded on One Health principles.
RVF forecasting tools utilize climate data that have been processed by climate scientists. They highlight seasons and geographical regions with a heightened risk of outbreaks. Information generated from these tools can be used by public and animal health professionals to sensitize local communities to report RVF-like syndromes based on pre-defined case definition. The case definition includes a list of clinical signs like stormy abortion in livestock, or fever and jaundice in people.
When symptoms such as these or cases are reported, surveillance teams respond and involve laboratories to confirm diagnoses. One Health enhances communication, coordination and integration of information on the disease to facilitate early
detection and control.
For a better prediction of RVF, experts from other disciplines that are not currently involved in surveillance, such as ecology or land-use, should be engaged. Research has shown that land-use change, such as the conversion of rangelands into crop irrigation schemes and the development of dams, increases the risk of RVF by providing standing water masses for mosquito development.
Controlling outbreaks and mitigating their consequences
RVF can be controlled using multiple interventions, including mosquito control, livestock vaccination, and quarantine. Livestock vaccination has been found to be the most effective control measure compared to the others. Still, a successful containment of the disease requires integrated approaches that incorporate non-pharmaceutical interventions such as risk communication. None of the available control measures can be successful on their own. Again, the One Health approach supports coordination, collaboration, and communication among sectors, professionals, and stakeholders to ensure that control strategies are targeted and resources used efficiently. For example, veterinarians implementing livestock vaccination, will need the support of livestock owners and traders to take up vaccines, avail animals for vaccination and implement quarantine measures that are imposed to prevent the disease from being disseminated in various locations. Moreover, vaccination of livestock will minimize RVF risk in humans, sustain livestock production and safeguard livelihoods of a large number of livestock owners and traders.
However, more needs to be done to effectively prevent epidemics in the future. For example, Communication agents should step in to sensitize people on the preventative measures that should be used to limit human exposure. Policy makers play an important role in all these stages by setting up regulations and contingency funds that are needed to support interventions. Like other zoonotic diseases, RVF outbreaks cause a lot of anxiety given the huge health and socio-economic burden they cause. Interventions that are usually implemented should also include those that manage uncertainty and livelihood losses. Therefore, in addition to containing the outbreak, measures should always be taken to mitigate economic uncertainty and help manage the psychological stresses associated with the disease.
Rift Valley Fever (RVF)
RVF is caused by a virus transmitted by many species of mosquitoes and can affect humans as well as livestock and wildlife. First discovered in the early 20th century in Kenya’s “Rift Valley” in Kenya, it has since spread throughout sub-Saharan Africa.
People become infected through mosquito bites, or when they come into contact with infected blood during the slaughter of sick animals, for example. Consumption of infected animal products can also lead to infection. The disease causes flu-like symptoms, and in rare cases there is a fatal inflammation of the meninges. So far, there are no therapeutic options.
RVF is particularly problematic for animal herds; in young animals, the disease is fatal in about 70 percent of the animals, and miscarriages frequently occur. Epidemics of RVF occur in certain ecosystems after prolonged rains and floods, where mosquitoes multiply to high populations, increasing transmission of the virus.
Improve cross-sector research, foster institutional collaboration
To find new insights into the origins of the disease, its risk factors, and its health and socioeconomic impacts, and to develop new technologies to monitor and control the disease, it is particularly important that research on RVF also involves experts and stakeholders from different sectors and disciplines. A wide range of professionals should be engaged in research partnerships given the complex transmission patterns of the disease. Key among these are entomologists, virologists, epidemiologists, agricultural economists, gender scientists, meteorologists, and ecologists.
More work is needed to address institutional or disciplinary barriers that prevent establishment of practicable One Health partnerships. A common problem, for example, is that the different stakeholders do not have joined budgets but must work with their separate budgets, which makes partnerships on an equal footing difficult. It is therefore particularly important to also demonstrate the financial benefits for the various stakeholders. It would also be helpful to evaluate existing One Health measures to highlight the benefits of these partnerships. In this way, the insights gained could help stakeholders to strengthen their collaboration or identify gaps that should be closed.