Infectious diseases such as Q-fever and Lyme are caused by animals. Wageningen researchers study how best to respond to these zoonoses. In making an intervention analysis, they include both biological factors and human behaviour. Climate change appears to also have an effect.
How can a zoonosis emerge so rapidly?
In 2008 and 2009, the Netherlands faced a serious Q-fever epidemic. This infectious disease is seen as a risk during the birthing season of goats and sheep. Normally, some fifteen people are infected each year, mostly goat keepers and their relatives. Now, the disease suddenly affected hundreds of people. Q-fever killed 95 people, and many others fell chronically ill.
How can a zoonosis suddenly emerge with such force? And, if you know the answer to that question, will you also be able to predict and influence such occurrences in the future? These are the research questions Wim van der Poel, Wageningen University & Research (WUR) virologist, posed. All related factors were mapped, says the researcher, including those factors that a veterinary researcher might not normally consider. For example, weather factors appeared to influence the Q-fever epidemic of 2008-2009. The outbreak occurred in a period of drought, which positively affected the bacteria’s survival and allowed them to become airborne through dust.
WUR mapped at what points interventions may help prevent future epidemics. Not just for Q-fever but also for rabies and Lyme disease. The latter is caused by pathogenic bacteria transmitted by infected ticks. Due to climate change, the distribution area of Lyme is gradually shifting north. There is no vaccine for Lyme. Possible measures may include reducing ticks in nature reserves by altering the foliage, more frequent checking of visitors and dogs or even closing nature reserves to the public.
Van der Poel says that relatively simple measures, such as public education, may already substantially reduce the number of infections. The general public is increasingly aware of the risk of zoonoses. However, this does not mean that appropriate measures, such as wearing long sleeves or pants, are always taken. However, there is a shift in acceptance. With new emerging diseases, people are generally more receptive to health advice than with diseases that have been around for longer. This is due to social factors that must also be taken into account.
The researchers made a cost-benefit analysis which includes the burden of disease, such as the risk of becoming disabled. There are pesticides available for Lyme, and studies are currently being conducted on their cost and efficacy. The Ministry of Agriculture, Nature and Food Quality (LNV) uses these analyses and has determined that professional goat keepers must vaccinate their animals.
New research is ready to launch. This will help to better predict what pathogens may form a threat in the future. Scientists include not only the abovementioned biological and socioeconomic factors, but also the microbes that are naturally present in humans and animals. The combined system of these microbes is known as the microbiome.
Van der Poel feels that the microbial composition could play a part in explaining why there are differences in individual susceptibility to infectious diseases. The majority of the microbes we carry are harmless. The question is why a small number of pathogens can suddenly gain the upper hand: a new and exciting field of research. By gaining a better understanding of the pallet of micro-organisms, we will be better able to fight the transfer of infectious diseases and resistance to antibiotics.