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Transboundary threats to food and nutrition security in Southern Africa. Issue 2. October - December 2017

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ZOONOTIC THREATS

ANIMAL DISEASES THAT ALSO AFFECT HUMANS

Zoonoses are diseases that are naturally transmissible between animals and humans. It is estimated that about 60 percent of known human infectious diseases originate from animals, and that 75 percent of newly emerging diseases affecting humans are zoonotic, with most coming from wildlife. Zoonoses can cause severe and potentially fatal illness in animals and humans, as well as serious epidemics and pandemics.

These diseases negatively impact on the health and productivity of animals and undermine the ability of humans to live healthy and productive lives and on livelihoods.

Important zoonoses that have newly emerged in various parts of the world the last decade include Highly Pathogenic Avian Influenza (HPAI) viruses H5N1, H1N1 (swine flu), severe acute respiratory syndrome (SARS) and Middle East Respiratory coronavirus (MERS-CoV). Human Immunodeficiency Virus (HIV), the virus that causes acquired immunodeficiency syndrome (AIDS) and Ebola virus disease (EBOV) are other examples of serious human diseases with animal origins.

Some zoonotic diseases are of global importance, affecting many countries in many regions of the world and have the potential to cause global pandemics. Others have a more limited geographical distribution but with the potential to expand to other regions. There are a number of zoonoses of importance in Southern Africa that cause the following diseases:

BOVINE TUBERCULOSIS (bTB)

Zoonotic tuberculosis (TB) is a form of tuberculosis in people caused by Mycobacterium bovis, which belongs to the M. tuberculosis complex. It often affects sites other than the lungs (extrapulmonary), but in many cases is clinically indistinguishable from TB caused by M. tuberculosis. Within animal populations, M. bovis is the causative agent of Bovine tuberculosis (bTB). The disease mainly affects cattle, which are the most important animal reservoir, and can become established in wildlife (buffalo, kudu, lion and elephant), as seen at the wildlife/livestock interfaces in South Africa (Kruger National Park) and Zimbabwe (Gonarezhou and Hwange National Parks). The epidemiological situation of bTB in livestock and human populations in Southern Africa is highly variable, with reports of up to 50 percent prevalence at herd level, in some cattle populations. The disease has also been reported in cattle populations in Mozambique, Tanzania and Zambia. It results in significant economic losses and trade barriers with a major impact on the livelihoods of poor and marginalized communities.

While the most common route of transmission of M. bovis to humans is through contaminated food (mainly untreated dairy products or, less commonly, untreated meat products), airborne transmission also poses an occupational risk. The high prevalence of HIV in some Southern African rural populations is also an important additional risk factor for bTB.

Despite the apparent public health concern about bTB in the region, little has been done to highlight the zoonotic importance of the disease and to raise awareness of the community to prevent it. Furthermore, the presence of multiple hosts, inefficient diagnostic techniques, absence of defined national controls and eradication programs also hamper its control.

Preventing and controlling bTB at its animal source is crucial to avoid its transmission to humans, improve food safety and protect the livelihood of many rural communities.

Find more information about zoonotic TB here - http://www.fao.org/news/ story/en/item/1043345/icode/