Marking World Zoonoses Day 2015
Ebola, bird flu, mad cow disease, rabies…what do all these diseases have in common? They can all infect both animals and humans and are frequently transmitted between the two. This type of disease is called a zoonosis and today, on the 6th of July every year, we acknowledge these diseases with World Zoonoses Day.
Approximately 60% of infectious diseases are zoonotic, yet many are poorly understood or relatively unheard of. Over the last year the Ebola epidemic in West Africa has highlighted the devastating impact zoonotic diseases can have on society. The animal reservoir for Ebola is unclear; however, it is thought that humans initially became infected with the Ebola virus following exposure to bats. There have been several outbreaks across Central Africa since the virus was discovered in 1976. However the 2014/15 epidemic has been the largest to date; it has taken the lives of over 11,000 people with over 26,000 people thought to be still infected with the virus. The unprecedented scale of the epidemic was, in part, due to the limited healthcare infrastructure and resources available to identify and treat Ebola cases and prevent further infection.
Not all zoonoses result in high death rates. Consequently, many are low on the global health agenda, often with limited resources dedicated to their elimination. However, these diseases can be a major cause of ill health in low- and middle-income countries (LMICs). Food borne trematodiasis is one such disease; around 56 million people are thought to be infected with this parasitic worm, yet many go untreated. In chronic cases, this can lead to severe liver and lung complications. Often, a major risk factor for these infections is poor sanitation and a lack of a clean, running water supply. Good hygiene and sanitation practices are simple solutions to preventing many infections of this kind; however, in many LMICs these facilities are not readily available.
Zoonotic diseases can also impact on animal productivity. In rural areas, animals are particularly relied upon for transport, food, crop production and clothing and there is potential for agricultural loss. This can have a major impact on the local economy.
Whilst many zoonoses can remain endemic in a population, others can be dormant in the surrounding environment in animal reservoirs until such a time when new human contact occurs. Outbreaks may arise when human-animal contact is facilitated through human or animal migration, expansion of human dwellings into new territory, contact through animal markets or a change in environmental conditions (e.g. an increase in rainfall).
As shown by the recent Ebola epidemic, appropriate planning is crucial to controlling, preventing and containing outbreaks. If left unchecked, zoonotic diseases can have serious and detrimental repercussions for human and animal health, with serious consequences at the individual, community, national and even international level.
World Zoonoses Day is an important way of increasing awareness of the risks of these diseases and the reasons why we must support research, health policy and planning for the prevention, control and management of zoonotic infections worldwide.
- Centers for Disease Control and Prevention. 2014 Ebola Outbreak in West Africa – Case Counts Atlanta, USA2015 [cited 2015 23 June]. Available from: http://www.cdc.gov/vhf/ebola/outbreaks/2014-west-africa/case-counts.html.
- Mari Saez A, Weiss S, Nowak K, Lapeyre V, Zimmermann F, Dux A, et al. Investigating the zoonotic origin of the West African Ebola epidemic. EMBO molecular medicine. 2015;7(1):17-23.
- World Health Organization. Neglected zoonotic diseases [6 May 2015]. Available from: http://www.who.int/neglected_diseases/zoonoses/en/.
- World Health Organization. Foodborne trematode infections [cited 2015 23 June ]. Available from: http://www.who.int/foodborne_trematode_infections/infections_more/en/.
- World Health Organization. Foodborne trematode infections [cited 2015 23 June]. Available from: http://www.who.int/foodborne_trematode_infections/en/.
- World Health Organization. Research Priorities for Zoonoses and Marginalized Infections. 2012.
- World Health Organization. Ebola Virus Disease Fact Sheet 2015 [cited 2015 23 June]. Available from: http://www.who.int/mediacentre/factsheets/fs103/en/.