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ZOONOTIC DISEASES: The Emerging Public Health Threat in Uganda





KWEEN – In January through March every year, clouds of smoke usually hang over the Mt Elgon forest as part of the national park is burnt to make way for agriculture.


The fires exacerbated by the dry weather across the area, smother in a haze, leaving resident bats, rodents, snails, and other animals whose habitat is a forest with no other option than to run elsewhere for shelter and in search of food, carrying with them deadly Zoonotic diseases.


And not so long after the bats settle in Caves where cattle, sheep, and goats are kept, human beings around them start to fall sick—presumably after eating the bats, goats, and cattle, and taking the milk.

Structural outlook of one of the Zoonotic diseases; Marbug


And in October 2017, two people in Kween district developed a fever, chills, headache, gum bleeding, and vomiting blood.


This was a first known emergence of a strange disease that government epidemiologists confirmed was an outbreak of Marburg hemorrhagic fever case in the eastern district of Kween, which then caused a string of recurrent threats across the sub-region.


While it can be convenient to think of human health and the environment as Silos that are unrelated and operating independently, they are in fact closely related.


The WHO says that Zoonotic diseases — including the Coronavirus — which are transmitted between animals and humans, affect more than two billion people and cause over two million deaths every year.


Some of the animals that can transmit zoonoses include cattle, sheep, horses, pigs, chickens, turkeys, dogs, cats, rodents, bats, and some wild animals, and the mode of transmission is mainly through faeces, urine, saliva, blood, milk, animal bites and contact with the beddings of infected animals.


A paper produced by World Health Forum in July 2022 says Zoonotic pathogens can be bacterial, viral, or parasitic, and can spread to humans by direct contact with domestic, agricultural, or wild animals, or through food and water adding that they can cause many different types of illness in people ranging from mild to serious, and even death.


Epidemiologists and other health experts say the destruction of natural habitats caused by urbanization has increased the risk of Zoonotic diseases due to greater contact between humans and wild animals.


According to the World Health Organisation (WHO), markets selling the meat or by-products of wild animals are especially high risk due to the large numbers of undocumented pathogens known to exist in some animal populations.


A World Health Forum paper on Health and Health Care dated 6 July 2022 says that some of the most dangerous Zoonotic diseases include COVID-19, Marburg and avian flu, salmonellosis, Monkeypox, swine influenza and the Ebola virus.


Dr Muhammed [Mbale regional hospital] says two-thirds of human infectious diseases and the majority of emerging infectious diseases exerting heavy public health and economic burden to the global community originate from animals after the destruction of their habitat, the forest..


He explained that based on their impact and epidemiological characteristics, these Zoonotic diseases have been categorized into the more common endemic zoonoses such as salmonellosis, brucellosis, and leptospirosis which are responsible for more than 2.2 million human deaths and 2.4 billion cases of illness annually


“And the less common epidemic and emerging zoonoses such as anthrax, Rift Valley fever, Ebola, Zika which either occur in sporadic outbreaks in neglected populations or that are new or re-appearing with increased incidence or geographical range,” said Dr Mulongo.


He revealed further that the East African region is endemic with multiple Zoonotic diseases and that it is one of the hotspots for emerging infectious Zoonotic diseases with reported multiple outbreaks of epidemic diseases such as Ebola, Marburg, and Rift Valley Fever adding that some of these diseases in humans include anthrax, rabies, cat scratch disease, Tuberculosis, and brucellosis.


Dr Savino Biryomumaisho, a senior lecturer in the Department of Veterinary Medicine at Makerere University says, “Anyone in direct contact with an infected animal is at risk of acquiring a Zoonotic disease and that there is a higher risk of the disease spreading to other regions if unattended to.


” It is probable that Zoonotic diseases have been an issue for humans ever since man started destroying the environment and then started sharing living space with animals,” said Dr Biryomumaisho.


Dr Emmanuel Othieno, a senior pathologist and consultant at Mulago Hospital says many endemic zoonoses fall into the category of neglected diseases which predominantly affect poor and marginalised populations and which neither attracts the adequate health resources nor the research effort needed for their effective control


He revealed that of the twenty neglected tropical diseases prioritised by the Word Health Organisation (WHO), seven are recognised as neglected Zoonotic diseases (NZD) and that these include rabies and diseases caused by tapeworms such as echinococcosis and taeniasis/cysticercosis, which WHO recently proposed should be targeted for control in order to achieve the sustainable development goals (SDGs).


He explained that these diseases perpetuate poverty by attacking not only people’s health but also their livelihood by reducing livestock productivity.


The World Bank also estimates that the cost to the global economy of six major outbreaks of zoonoses that occurred from 1997–2009 was $80 billion, this cements the fact that Zoonotic diseases are very expensive to our economies.


Dr Richard Pollack of the T.H. Chan School of Public Health at Harvard says forests contain numerous pathogens that have been passed back and forth between  human beings and mammals for ages.


Scientists have repeated the warning for at least two decades: as humans encroach upon forests, their risk of contracting viruses circulating among wild animals increases.


Dr Mulongo [Mbale regional referral] said that communities at the slopes of Mt Elgon have borne the brunt of communicable diseases that have escalated against a backdrop of atmospheric warming.


“With Deforestation, the profound impact of climate change on health cannot be underestimated as we witness a rise in vector-borne diseases that are more resistant to conventional medicine,” said Dr Mulongo.


Ms Sarah Bisikwa, the senior environment officer [Manafwa district] says a wide range of activities have resulted in deforestation and that these include colonisation and settlement, trans-migrant programs, logging, agricultural activities to provide for cash crops, mining, hydropower development, and fuel wood collection.


“And each activity influences the prevalence, incidence, and distribution of vector-borne diseases and increase in cases of Zoonotic diseases,” said Ms Bisikwa.


She explained that the people in the rural areas are among the first hit by the environmental negative effect of deforestation which includes climate change, soil degradation reduced biodiversity, Zoonotic diseases, and loss of recreation.


Dr Pauline Byakika, a senior researcher on Malaria at the School of Medicine Makerere University College of Health Sciences says as climate change rises, the higher parts of the mountains which were previously unsuitable for the breeding of disease viruses is becoming favorable.


She said a combination of unusually high temperatures, low rainfall, and humidity encourage malaria and other epidemics to thrive.


Prof Stephen Turner, head of the department of microbiology at Melbourne’s Monash University, says what’s most likely is that a number of viruses are originating from Bats whose habitat has been destroyed by man.


Dr Turner says that before it infected the first humans and spread through the world by living in travelers’ bodies, the novel Coronavirus, officially named SARS-CoV-2, inhabited other hosts in a wild environment — most likely bats.


He explains that when such viruses are isolated and in equilibrium in their habitat, for example, a closed forest, they are not a threat to humans but that the problem arises when this natural reservoir is cut down, destroyed, and occupied.


Scientific studies published before the current pandemic had also already shown a connection between deforestation, the proliferation of bats in the damaged areas, and the family of Coronaviruses, which includes the recent lethal strain.


A paper titled; Ecology of Increasing Diseases: Population Growth and Environmental Degradation 2007 by D Pimentel and others say currently an estimated 40% of world deaths are due to environmental degradation.


“The ecology of increasing diseases has complex factors of environmental degradation, population growth, and the current malnutrition of about 3.7 billion people in the world,” reads the paper in part.


Dr Jonathan Wangisi, the DHO, Mbale district says that forests play a vital role in human health and well-being while offering a wide array of ecosystem services, however, biological diversity and ecosystem goods and services provided by forests are on the decline due to extensive deforestation and degradation.


“And many Virus-carrying rodents will soon be spotted in deforested areas of many forests in the country unless we change our attitude towards conserving our environment and stop cutting down trees,” said Dr Wangisi.


A 2015 study reveals that researchers at Eco-health Alliance, a New York-based non-profit that tracks infectious diseases globally and others found that “nearly one in three outbreaks of new and emerging disease[s] are linked to land-use change like deforestation.


The study reveals further that many viruses exist harmlessly with their host animals in forests, because the animals have co-evolved with them and that humans can become unwitting hosts for pathogens when they venture into or change forest habitat.


An article titled; Wildlife habitat destruction and deforestation will cause more deadly pandemics like Coronavirus, scientists warn,” by Emma Newburg published May 2020 in the Financial Times [CNBC] says the Coronavirus pandemic is the most recent instance of how human degradation of wildlife habitats is linked to the spread of infectious diseases.


Mr Sam Cheptoris, the minister of Water and Environment says for a host of ecological reasons, the loss of forests can act as an incubator for insect-borne and other infectious diseases that afflict humans now.


“Besides mosquitoes, there are other carriers of pathogens from the wild to humans for example bats, primates, and even snails can carry disease, and transmission dynamics change for all of these species following forest clearing,” said Mr Cheptoris.


Uganda’s Forest cover


Environmentalists say that Uganda’s forest cover has been depleted to 8 percent up from 24 percent in the 1990s and the loss is attributed to human encroachment in different activities, including agriculture and tree-cutting for timber and charcoal and other stakeholders.


In the late 1980s, Approx. 75,000 km2 (31.7%) out of 236,040 km2 of the total land in Uganda consisted of forest and woodland. Today, forests and woodlands cover about 15.2% of Uganda’s land surface meaning that Uganda has lost 16.5% of forests and woodland cover.


Suggested solutions


According to Mr Charles Wakube, the Mbale district environment officer, although it is true that the causes of deforestation and forest degradation exist across Mountains, effective solutions need to be developed with a site-specific approach.


Mr Wakube said implementation strategies should be developed for the mountains and hills in Uganda following in-depth consultation with various stakeholders.


He explained that identification of key causes directly linked to deforestation and forest degradation, successful integration of forest stakeholders and policymakers in a common forum, enthusiastic stakeholder participation in various discussions, the establishment of common strategies for field implementation and collaborative development, among stakeholders, of realistic solutions to forest degradation problems should be sought.


He revealed that Pet owners in particular should be conscious of the dangers of disease transmission from the animals to humans and that this requires tough preventive measures in handling animals. You have heard that disease is easier to prevent than treat. “Whoever is in direct contact with an infected animal is at risk,” Mr Wakube said.


He said although prevention methods for Zoonotic diseases differ for each pathogen, several practices are recognized as effective in reducing risk at the community and personal levels.


“Safe and appropriate guidelines for animal care in the agricultural could sector help to reduce the potential for foodborne Zoonotic disease outbreaks through foods such as meat, eggs, dairy or even some vegetables,” Mr Wakube said.


He added that standards for clean drinking water and waste removal, as well as protections for surface water in the natural environment, are also important and effective plus education campaigns to promote hand washing after contact with animals and other behavioral adjustments can reduce community spread of Zoonotic diseases when they occur.


He said Ugandans should also be educated about the importance of conserving the environment in order to be safe from Zoonotic diseases


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