AN old belief assumed that crop and stock farmers in Zimbabwe did not need to be literate.
However, in this age of information revolution, climate change and its attendant pests and animal diseases, literacy and knowledge are crucial for all professional agricultural workers.
A book titled Zoonoses: Animal Diseases and Man by Dr Jan H. Du Preez and Dr Gert P. Du Preez will enlighten and educate the new farmer on the unseen dangers and diseases that come with the professions of farming, wildlife conservation, veterinary practice, abattoir management and even wildlife tourism, especially in Southern Africa.
The book examines the complex, fluid and interactive interdependence of people, livestock and diseases as well as discusses how veterinary medicine and agricultural livestock production and human health and welfare are inevitably linked.
Given the growth of the agricultural sector, which is key to Zimbabwe’s future development, (and according to the US Department of Agriculture where I was on attachment – ‘…agriculture is the foundation of manufacture and commerce’), I urge farmers to read this book.
What is Zoonoses?
According to Dr Jan Du Preez: “A zoonosis is any disease or infection naturally transmissible from vertebrate animals to humans and vice versa. Humans are often an incidental host that acquire disease through close contact with an infected animal that may or may not be symptomatic”.
Dr Du Preez posits that more than 200 zoonoses of various types are recognised worldwide.
They can be caused by a range of disease-causing agents such as viruses, bacteria and many more. Of 1 415 disease-causing agents known to infect humans, 61 percent are zoonotic.
Statistical data indicate that 15 percent or more of the human population will pick up a zoonotic infection at some stage of their lives.
With obligate zoonotic diseases, such as anthrax and rabies, transmission occurs only from animal to human, whereas in facultative zoonoses, infections are mostly transmitted among humans.
Some zoonotic viruses have limited host ranges; others may infect a wide range of vertebrates, both human and animal.
Some viral zoonoses have been recognised since ancient times while others have become public health problems in recent times.
Both new and old viral zoonoses are especially important in emerging and re-emerging virus diseases. Human infection may vary from unapparent to fatal disease.
Although hundreds of viruses are zoonotic, the importance of many of these viruses has not yet been established.
Both new and old viral zoonoses are especially important in emerging and re-emerging virus diseases.
Transmission of zoonotic viruses may occur by a variety of routes. These include: ‘direct’ (rabies) or ‘indirect’ (hantavirus) contact; ‘nosocomial’ (arenavirus and filovirus); ‘aerosol transmission’ (SARS coronavirus); ‘vertical’ (in utero), (arenaviruses); and ‘vector or arthropod-borne’ (yellow fever – YF).
Zoonoses represent a major public health problem around the world due to our close relationship with animals in agriculture, as companions and in the natural environment.
Zoonotic pathogens may be bacterial, viral or parasitic, or may involve unconventional agents and can spread to humans through direct contact or through food, water or the environment.
Zoonoses can also cause disruptions in the production and trade of animal products for food and other uses.
Zoonotic diseases comprise a large percentage of all newly identified infectious diseases as well as many existing ones.
Some diseases, such as HIV, began as a zoonosis but later mutated into human-only strains.
Other zoonoses can cause recurring disease outbreaks, such as Ebola virus disease and salmonellosis.
Still others, such as the novel coronavirus that causes COVID-19, have the potential to cause global pandemics as we witnessed in recent years in Zimbabwe and elsewhere.
Medical prevention methods for zoonotic diseases differ for each pathogen; however, several practices are recognised as effective in reducing risk at community and personal levels.
In Zimbabwe and the rest of Southern Africa, safe and appropriate guidelines for animal care in the agricultural sectors help to reduce the potential for zoonotic disease outbreaks.
Hygienic standards for clean drinking water and waste removal, as well as protection for surface water in the natural environment, are also important and effective in the prevention of zoonotic diseases in the agro-sectors.
Widespread education campaigns in rural farming communities to promote handwashing after contact with animals and other behavioural adjustments can reduce community spread of zoonotic diseases when they occur.
Due to their proximity to animals on farms, men are more commonly infected by Zoonoses than women. Zoonotic pathogens can spread to humans through any contact point with domestic, agricultural or wild animals.
The selling of meat or by-products of wild animals are particularly high risk due to the large number of new or undocumented pathogens known to exist in some wild animal populations.
People living adjacent to wilderness areas or in semi-urban areas with higher numbers of wild animals are at risk of disease from animals such as rats, wild dogs, bat-eared foxes, genets and cerval cats.
The destruction of natural habitats and urbanisation increase the risk of zoonotic diseases by increasing contact between humans and wild animals.
WHO works to develop capacity and promote practical, evidence-based and cost-effective tools and mechanisms for zoonoses prevention, surveillance and detection through reporting, epidemiological and laboratory investigation, risk assessment and control, as well as assisting countries in their implementation.
As part of the One Health approach, WHO collaborates with the Food and Agriculture Organization of the United Nations (FAO) and the World Organisation for Animal Health (OIE) on the Global Early Warning System for Major Animal Diseases (GLEWS).
This joint system builds on the added value of combining and co-ordinating alert mechanisms of the three agencies to assist in early warning, prevention and control of animal disease threats, including zoonoses, through data sharing and risk assessment.
Zoonoses also undermine the health, productivity and reproductivity of livestock on which humans rely for their food, fibre, labour and transport.
Worldwide monetary losses due to diseases, such as tuberculosis, brucellosis and rabies in cattle can amount to multi-billion dollars annually.
The relationship between people and animals offers important mutual benefits.
It is, therefore, imperative that the health of such pets and animals is invulnerable and full proof to protect us against zoonotic infections.
Research shows that most emerging infectious diseases in humans have animal origins, either originating in domestic animals or wildlife.
On the other hand, neglected and endemic zoonoses continuously transmitted between livestock and humans are a significant burden to public health and livelihoods.
According to Drs Jan H du Preez and Gert P du Preez: “Zoonoses can be prevented and controlled through the necessary knowledge and information. There is no reason to fear animals or avoid them to protect oneself from zoonoses and this book, the result of collaboration between experts in veterinary and human medicine, presents the message very clearly: continue to enjoy your relationships with companion and other animals, the pleasure of watching and interacting with wildlife, fishing, working with animals and eating whatever your favourite food may be, as long as you are aware of possible risks. Take the appropriate hygienic precautions in terms of their health and yours to avoid infection.”
As Zimbabwe rapidly develops its wildlife tourism, agricultural sectors, livestock farmers, agronomists, veterinary personnel, agricultural scholars and farm workers involved in animal husbandry may do well to understand farm health and safety measures during this era of viruses and zoonotic diseases.
Dr Tony M. Monda BSc, DVM, is currently conducting veterinary epidemiology, agronomy and food security and agro-economic research in Zimbabwe. He also holds a PhD. and a DBA in Post-Colonial Heritage Studies. E-mail: tonym.MONDA@gmail.com
