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Course:CONS200/2025FL1/Novel Pathogens, Wildlife Trade, and Zoonoses: How Deforestation, Biodiversity Loss, and Wildlife Trade Interact with Disease Emergence

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A tile shop graphic showing the amount of years lost globally in 2019 due to diseases
DALYs, or lost years of life globally due to pathogens, not exclusively zoonoses in 2019 (in millions).

Over the past several decades, there has been a significant uptick in the number of zoonotic disease cases on a regional and global scale[1]. Reported deaths from zoonotic diseases excluding COVID-19 have been increasing by 8.7%±4.7% annually since 1963[1]. Estimates show that approximately 60% of human diseases come from zoonotic origin[2]. Well-known zoonotic diseases include COVID-19, HIV/AIDS, Influenza, Rabies, Dengue, Lassa, Hanta, Ebola, Plague, and MERS[2]. Of these, Dengue and Plague are vector-transmitted, meaning they require animal vectors such as mosquitoes or fleas to be transmitted[2].

The emergence and spread of novel pathogens is a widely recognized issue that is strongly linked to land use change. Forest fragmentation and agricultural development have led to increases in aquatic breeding sites for disease-carrying vectors through irrigation systems [3], and increased density of immunosuppressed livestock can cause outbreaks such as SARS-related coronavirus [3].

In addition to land use change, wildlife trade has also been a major contributor to zoonotic diseases. Unhygienic sanitation standards in wildlife markets and factory farms are connected to increased spread and outbreaks of zoonotic diseases [4]. Several solutions have arisen to mitigate these issues, including monitoring and surveillance of zoonotic pathogens, reducing biodiversity loss and land-use change, stopping illegal wildlife trade, enforcing hygiene restrictions on wildlife trade, meat production, and wet markets, and the gradual phasing out of mink farming and meat production in favor of artificial alternatives. These changes are being implemented, but they require wide-scale efforts from communities and governments to be successful.

Diseases and infection methods

Respiratory diseases spread through water droplets that are expelled when breathing, coughing, or sneezing

Infectious diseases are illnesses caused by pathogens including bacteria, viruses, parasites, and fungi that invade the body and cause harm.[5][6] Pathogens use several vectors to spread from one individual to another.[6][5]

  • Direct contact (transmission by skin, saliva, or bodily fluids, including STIs).[6]
  • Airborne transmission (through droplets or aerosols, common in respiratory infections).[6]
  • Fomite transmission (through contaminated surfaces or objects), and vector-borne transmission (through insects like mosquitoes or ticks) are common vectors.[6]
  • Less common: vertical transmission (from mother to child during pregnancy, birth, or breastfeeding).[6]
  • Less common: fecal-oral transmission (through contaminated food or water, often presenting as diarrhea).[6]

Zoonotic pathogens

Venn diagram of zoonotic diseases and their possibilities to transmit to humans through livestock vs wild animals for zoonotic disease spillovers.

Zoonoses are infections that can be transmitted from vertebrates to humans.[7] Approximately 60% of infectious diseases as well as most novel pathogens come from zoonotic origins.[7]

Many zoonoses are vector-borne. This includes the bubonic plague, West Nile Virus, and Lyme disease, which spread via fleas, mosquitoes, and ticks respectively.[8][9][10] The most virulent zoonoses are typically respiratory, including coronaviruses such as SARS-CoV and MERS-CoV, and are transmitted primarily through water droplets.[7] Other, less common zoonosis transmission methods include direct contact (i.e. HIV/AIDS), and consumption of contaminated food and water(i.e. E. coli).[8]

Regardless of their origin, zoonoses are a prominent public health concern around the world, causing an estimated 2.7 million deaths per year[11].

Factors influencing disease emergence

Climate Change

Factors Influencing Zoonosis Emergence

Zoonotic diseases are becoming a major public health threat due to changing ecosystems and people's growing proximity to wild animals.[12][13] Many climate models predict geographic changes in many vector-borne zoonoses.[13] Warmer, wetter, and more variable climates tend to expand mosquito, sand fly, and tick borne diseases,[13] while long, hot, and dry conditions reduce vector populations.[13] Climate models predict a poleward expansion from tropical regions into temperate regions due to these factors.[13]

Biodiversity Loss

Biodiversity refers to the richness and abundance of genes, species and ecosystems.[14] Biodiversity has been decreasing as a result of a growing human population.[14] Species are going extinct 100–1,000 times faster than in the past, and the rate of extinction is expected to multiply up to 100 times over the next 50 years.[14]

Biodiversity loss is one of the main drivers for the increased emergence of zoonotic diseases. Lower biodiversity is known to increase risk of transmission of zoonotic pathogens to humans.[15] Lower biodiversity in an area, especially due to human impacts such as land-use change, can eliminate niches for disease-carrying vectors.[14] These vectors can adapt to a change in their usual hosts by transmitting pathogens to humans instead. One example to illustrate this possibility is the parasite Schistosoma mansoni, which can cause schistosomiasis in humans.[14] It has the capability to alternately infect both humans and snails through free-living infectious stages, and when one of these hosts is not present in the environment, can cause much higher rates of infections in the other.[14] Decreased levels of species diversity can also reduce competition and predation on vectors or hosts, removing barriers to controlling their population.[16] Hunting is also a significant factor in decreasing biodiversity in tropical regions, with these regions having experienced declines of 25-76% of bird populations and 72-90% of mammal populations compared to areas without hunting.[17] Preserving biodiversity is an important step for curbing zoonotic disease emergence.

Land-use Change

Deforestation of the Amazon Rainforest from 1984 to 2018

Land-use change can be defined as the way in which humans alter the Earth’s surface and naturally-occurring ecosystems through processes such as urbanization, deforestation, implementation of irrigation systems, and agricultural practices.[18] Land-use change lessens biodiversity and increases the risk for disease transmission from wildlife. Land-use change has been linked to more than 30% of infectious disease outbreaks worldwide, such as Ebola, HIV, and Zika virus, with 15% of emerging zoonoses being directly tied to agricultural initiatives in tropical rainforest regions.[19] Habitat fragmentation from land-clearing and urbanization pushes wildlife to the margins of their habitats, bringing them into closer contact with people and domesticated livestock animals.[19] Prominent disease-carrying species such as primates and bats are often the ones found more regularly in urbanized landscapes, as they are better able to adapt to ecosystems that have been modified by humans.[20]

Land-use change can also alter the ability of an ecosystem to provide functions and services that naturally mitigate the pervasiveness of zoonoses. This can include provisioning of freshwater, which is necessary for sanitation to limit transmission of diseases between humans.[19] As many as 1 in 5 households around the world lack access to a clean and secure source of freshwater, putting them at significant risk for contracting infectious diseases.[19] The spread of coronaviruses such as COVID-19 is greatly reduced by frequent washing with clean water.[19] Overexploitation and degradation of natural freshwater systems, especially due to crop irrigation and eutrophication from agricultural run-off, depletes an ecosystem’s ability to provide water to communities, increasing pathogen contamination risk.[19]

Wildlife Trade

Unsanitary wet market in Hong Kong, China. Meat from many different animlals is hanging with no apparent temperature control or protective covers, which increases the risk of contamination with dust, insects, people, and zoonoses. Workers are not wearing protective equipment or close-toed shoes.

Wildlife trade refers to the trade of organisms of any kind, like fungi, animals and plants, obtained from the wild.[21] International wildlife trade is regulated by the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES).[22][23] Wildlife trade can be legal as well as illegal, and due to the relatively low risk in comparison to the possible rewards, the amount of illegal wildlife trade continues to be significant.[21] The wildlife trade market has a high economic value globally, with just commercial fishing valued at $180 billion, timber valued at $227 billion and fashion valued at $2.5 billion.[21] Illegal wildlife trade is mostly unquantified,[24] but it has been estimated to be worth over 20 billion USD annually, making it an illegal activity with profits comparable to weapons trading and drug trafficking.[23] The growth in the economy of historically poor countries such as China[24] has increased the global demand for items sourced through wildlife trade, such as for certain meats, pets, medicines, and ornamental uses.[21]

Wildlife trade is a significant contributor to the spread of zoonotic pathogens, providing a direct point of contact between wildlife and humans as well as providing pathways for transmission throughout the world as species are shipped internationally.[25] All activities related to hunting, transporting, and selling bushmeat risk human contact with infected animals, but butchering the highest risk of zoonotic spillover due to direct animal fluids-to-blood contact.[23] Due to this, wildlife trade has been the source of many significant outbreaks and pandemics that affected large numbers of people’s health.[25]

Case study of factors influencing the spread of COVID-19

The novel COVID-19 caused a healthcare crisis, economic crisis, and significant public fears,[23] caused over 775 million cases and over 7 million deaths globally.[25] There is ongoing debate between different hypotheses on the origin of SARS-CoV-2, the coronavirus strain responsible for the pandemic, but the scientific consensus agrees the strain began in 2019 from a zoonotic spillover from a bat carrying the virus in a wet market in Wuhan.[23][25][26] The World Health Organization notes that despite their requests, China has not shared genetic sequences from individuals affected by the virus early in the pandemic,[26] so it is hard to disprove other hypotheses on the pandemic's origin. Scientists[23] studied the pandemic and found four key takeaways.

Surveillance and research

All members of the coronavirus (Coronaviridae) family have been associated with animal hosts, with birds and mammals being hosts for Orthocoronavirinae, the subfamily containing SARS-CoV-2 and all other strains pathogenic to humans,[23] and all but two genera originating from bat species.[23] In a paper published in March 2019, researchers[27] accurately predicted that “is highly likely that future SARS- or MERS-like coronavirus outbreaks will originate from bats, and there is an increased probability that this will occur in China”.[23][27] Screening animals and understanding risk factors is critical to predicting and preventing future outbreaks, so scientists urge researching and funding the long-term surveillance of pathogens in wild animals, especially bats, birds, and marine mammals.[23] Wild, domestic, and livestock viruses should be systematically assessed and sequenced to identify possible intermediate hosts.[23]

Illegal wildlife trade and wet markets

American Minks are farmed for their soft fur. They are also major carriers of SARS-CoV-2.
A fur coat made from mink fur

Wild animals involved in wildlife trade are often not tested for pathogens or conditions of transport (especially in illegal trade), which increases risk of pathogen transmission.[23] To reduce risks of spillover, all wildlife species involved in illegal trade should be identified and screened for the pathogens they may carry, and their transmissibility to humans.[23] Additionally, regulations around sanitary standards, transport conditions, wet markets, and wildlife trade in general must be stronger and better enforced.[23]

Mink farming and fur production

Minks are farmed for their desirable fur. Minks and mustelids carry very high viral loads when infected with coronaviruses.[23] This made them important catalysts to the spread of COVID-19.[23] On top of regular surveillance, researchers recommend developing and deploying vaccines against SARS-CoV-2 for minks if fur farming continues.[23] This would greatly reduce spillover and culling needs.[23] However, phasing down mink farming entirely is the best long-term solution that lowers risks of accelerating zoonotic transmission of coronaviruses.[23]

Meat production

Livestock was not a major contributor to the spread of COVID-19, but researchers continue to stress the importance of preventing novel zoonoses from emerging.[23] Maintaining and reinforcing strict hygiene protocols in conventional livestock production is critical to limiting zoonoses and protecting food security.[23] Researchers also recommend shifting focus to cultured (lab-grown) meats as a long-term alternative to livestock.[23] HPAI A(H5N1) can be spread to humans through poultry and beef if proper preparation methods are not used.[28] In April, 2024 the CDC confirmed one human in Texas caught HPAI A(H5N1) from a cattle farm in May of the same year more cases were reported after people came in contact with infected cattle.[28]

Zoonotic origins of HIV from SIV

The African green monkey (source of SIV; left), the sooty mangabey (source of HIV-2; middle), and the chimpanzee (source of HIV-1; right)

Human Immunodeficiency Virus (HIV) has the third highest deaths of any disease since its emergence in the 1980s, having killed an estimated 44.1 million people.[29] It is transmitted directly through the exchange of bodily fluids including blood, genital secretions, and breast milk.[29]

The pandemic-causing HIV-1 strain originated from wild chimpanzees infected with simian immunodeficiency virus (SIVcpz) in Cameroon.[30] Other less common strains of HIV-1 and HIV-2 originated from primates with different strains of SIV. SIV was zoonotically transmitted through direct blood-to-blood contact, likely when a hunter's or butcher's skin had open cuts that came into contact with the chimpanzee's blood.[30][31] SIVcpz was likely transmitted to humans at low frequencies for thousands of years, but three factors of colonial activities are theorized to have drastically increased the risk of a pandemic.[31]

  1. Increased exposure due to colonial authorities conscripting people to forced labor in the forest, making many people rely on bushmeat.[31]
  2. Increased viral transmission due to massive influxes of people into major cities, making previously isolated towns no longer isolated.[31]
  3. Increased viral adaptation due to unsanitary arm-to-arm inoculation of smallpox that re-used needles, transmitting blood from one individual to another and selecting for more virulent HIV strains.[31]

Global and Community Impacts

Zoonotic diseases do not impact all groups of people equally. Rural communities and marginalized groups, especially those in the Global South, are disproportionately affected by zoonoses.[11] In developing countries, around 68% of rural households keep livestock, depending on them for food, income, and other economic services such as insurance guarantees.[11] As a result, the probability of coming into contact with infected animals is significantly higher for people in these areas.

27% of livestock in these countries show signs of having been infected with bacterial food-borne disease, a major source of food contamination and illness in people.[11] Cases of Q fever and trypanosomiasis virus in livestock are found in greater numbers near areas of forested land accessed by rural communities. In general, wildlife trade is also much more prevalent among impoverished groups of people, whose livelihoods are maintained by continuous interactions with potentially diseased animals.[32]

Not only are impoverished communities more likely to be exposed to vectors that carry zoonotic diseases, they are also at much higher risk of experiencing severe symptoms due to improper sanitation, access to preventative measures such as vaccines, low quality of available medical treatment options, and lack of education and information on zoonoses.[33] In Paraguay,11.7% of dairy farmers interviewed were illiterate, 64% had never heard of various diseases that could be transmitted to humans by cows, and 73.3% did not know how to prevent such diseases in their herds.[33] This insufficiency of awareness for the dangers that zoonotic diseases pose is one of the most crucial aspects of their persistence in rural areas.

Solutions for Mitigation

Several factors that can be addressed to mitigate the impact of zoonotic disease. The simplest methods to mitigate zoonotic disease is to maintain a high standard of sanitary habits as well as avoiding coming in contact with dead animals

Urbanization and wildlife encroachment are two key factors in the rise in zoonotic spillovers.[1][13][34] Human encroachment on wildlife habitat increases contact, increasing the probability of cross-species transmission.[34] Focusing on urban planning in partnership with restoring ecosystems and habitats.[34] Mitigating zoonotic diseases can be achieved by implementing measures such as these to minimize human to wildlife contact.[34] Another step towards mitigation is vaccination against zoonotic diseases. Keeping up to date vaccinations reduces the risk of spread through the model of ‘herd immunity’.[35] This model stems from the idea that the more a population is immune, the safer it becomes for everyone, including those not vaccinated against the diseases.[35] When SARS-CoV-2 started its global spread the vaccinations prevented and decreased the severity of illness.[23]

A less widespread method for disease prevention is sentinel animals which are animals placed in specific locations and monitored for signs of disease (eg. poultry being monitored for West Nile virus).[35] The zoonosis data is monitored by national organizations and partnered with international organizations including the World Health Organization and United Nations,[35] e.g. the Global Early Warning System was established in 2006 to improve detection of diseases and to communicate information to prevent pandemics. This system declined in 2018.[35] Global surveillance of zoonotic diseases is one of the major components in mitigating these diseases.[36] Having systems in place that identify, report and send a response to an outbreak greatly reduces the risk of exposure and spread.[36] Recently, advancements in early detection, treatments, prevention and control, were improved.[36] The use of polymerase chain reaction (PCR) technology, such as in SARS-CoV-2 tests, has reworked the detection of zoonotic viruses e.g. Ebola, SARS-CoV-2 and Zika.[36]

Looking Forward

Zoonotic diseases are becoming a major threat to public health due to rising global temperatures, population growth and increasing population density, land use change, and wildlife trade.[13] The increasing commonality of epidemics has led to the gathering of information and pattern recognition through the use of available methodological tools,[37] as well as the quantification of changes to the environment such as the aforementioned land use change and biodiversity loss.[37] Current research is now focused on how diseases affecting wildlife or domestic animals will evolve in the future to affect humans due to changing environmental conditions,[37] as well as how we can prepare. In order to do this succesfully, a system created with the purpose of detecting the transmission of zoonotic viruses emerging from animals to humans early enough in the disease emergence process so that methods of decreasing the risk of transmission to the populations most exposed to animal contact can be implemented.[38]

Regulations around sanitary standards and transport conditions in wet markets and wildlife trade must be stronger and better enforced.[23] However, even though there is room for improvement of enforcing wildlife trade regulations, many countries appear to be over-reliant on regulation, which means that other methods of intervention are not being put into effect.[39] This leads to insufficient control over trade of wildlife, and as such additional interventions besides improving and enforcing regulation are needed.[39] Regulation places the cost on the developing countries that source the wildlife products, and avoids placing responsibility on developed countries who are the market for wildlife trade.[39]

References

 This conservation resource was created by Course:CONS200.
  1. ↑ 1.0 1.1 1.2 Meadows, A. J., Stephenson, N., Madhav, N. K., & Oppenheim, B. (2023). "Historical trends demonstrate a pattern of increasingly frequent and severe spillover events of high-consequence zoonotic viruses". BMJ Global Health, 8(11), e012026.
  2. ↑ 2.0 2.1 2.2 Weiss, R. A., & Sankaran, N. (2022). "Emergence of epidemic diseases: zoonoses and other origins. Faculty Reviews", 11(2).
  3. ↑ 3.0 3.1 Rulli, M. C., D’Odorico, P., Galli, N., & Hayman, D. T. S. (2021). "Land-use change and the livestock revolution increase the risk of zoonotic coronavirus transmission from rhinolophid bats". Nature Food, 2(6), 409–416.
  4. ↑ Wikipedia Contributors. (2025, October 25). "Wildlife trade and zoonoses. Wikipedia; Wikimedia Foundation". Wikipedia
  5. ↑ 5.0 5.1 Burrows, William (Oct. 30, 2025). "Disease". Britannica. Check date values in: |date= (help)
  6. ↑ 6.0 6.1 6.2 6.3 6.4 6.5 6.6 van Seventer, Jean Maguire; Hochberg, Natasha S (2017). "Principles of Infectious Diseases: Transmission, Diagnosis, Prevention, and Control". International Encyclopedia of Public Health. doi:10.1016/B978-0-12-803678-5.00516-6. Retrieved 2025-DEC-07. Check date values in: |access-date= (help)
  7. ↑ 7.0 7.1 7.2 Rahman, MT; Sobur, MA; Islam, MS; Ievy, S; Hossain, MJ; El Zowalaty, ME; Rahman, AT; Ashour, HM (2020 Sep 12). "Zoonotic Diseases: Etiology, Impact, and Control". Microorganisms. Check date values in: |date= (help)
  8. ↑ 8.0 8.1 Kulkarni, MA; Berrang-Ford, L; Buck, BA; Drebot, MA; Lindsay, LR; Ogden, NH (2015 Jun 10). "Major emerging vector-borne zoonotic diseases of public health importance in Canada". Emerging Microbes & Infections. 4. Check date values in: |date= (help)
  9. ↑ CDC (May 15, 2024). "How Plague Spreads". Center for Disease Control.
  10. ↑ Fearon, Margaret (12, Dec. 2011). "West Nile story: the transfusion medicine chapter". Future Virology. 6: 1. Check date values in: |date= (help)
  11. ↑ 11.0 11.1 11.2 11.3 Grace, Delia; Mutua, Florence; Ochungo, Pamela; Kruska, Russ; Jones, Kate; Brierly, Liam; Lapar, Lucy; Said, Mohamed; Herrero, Mario (2012). "Mapping of poverty and likely zoonoses hotspots". International Livestock Research Institute; Nairobi, Kenya: 6.
  12. ↑ Andersen-Ranberg, Emilie, Ingebjørg H Nymo, Pikka Jokelainen, Anastasia Emelyanova, Solveig Jore, Brian Laird, Rebecca K Davidson, et al. (2024). “Environmental Stressors and Zoonoses in the Arctic: Learning from the Past to Prepare for the Future.” Science of the Total Environment 957: 176869. https://doi.org/10.1016/j.scitotenv.2024.176869.
  13. ↑ 13.0 13.1 13.2 13.3 13.4 13.5 13.6 Rupasinghe, Ruwini; Chomel, Bruno B.; Martínez-López, Beatriz (Nov. 20, 2021). "Climate change and zoonoses: A review of the current status, knowledge gaps, and future trends". Acta Tropica. 226 – via Elsevier. Check date values in: |date= (help)
  14. ↑ 14.0 14.1 14.2 14.3 14.4 14.5 Keesing, Felicia; Belden, Lisa K.; Daszak, Peter; Dobson, Andrew; Harvell, C. Drew; Holt, Robert D.; Hudson, Peter; Jolles, Anna; Jones, Kate E. (01 December 2010). "Impacts of biodiversity on the emergence and transmission of infectious diseases". Nature. 468: 648–649. Check date values in: |date= (help)
  15. ↑ Wolfe, Nathan D., Peter Daszak, A. Marm Kilpatrick, and Donald S. Burke (2005). “Bushmeat Hunting, Deforestation, and Prediction of Zoonotic Disease.” Emerging Infectious Diseases 11 (12): 1822–27. https://doi.org/10.3201/eid1112.040789
  16. ↑ Wilkinson, David A.; Marhsall, Jonathan C.; French, Nigel P.; Hayman, David T. S. (2018). "Habitat fragmentation, biodiversity loss and the risk of novel infectious disease emergence". Journal of the Royal Society Interface. 15: 6.
  17. ↑ Benítez-López, A., R. Alkemade, A. M. Schipper, D. J. Ingram, P. A. Verweij, J. A. J. Eikelboom, and M. A. J. Huijbregts. (2017). “The Impact of Hunting on Tropical Mammal and Bird Populations.” Science 356 (6334): 180–83. https://doi.org/10.1126/science.aaj1891.
  18. ↑ Rulli, M. Cristina; D'Odorico, Paolo; Galli, Nikolas; John, Reju S.; Muylaert, Renata L.; Santini, Monia; Hayman, David T. S. (31 May 2025). "Land Use Change and Infectious Disease Emergence". Reviews of Geophysics. 63: 1–3.
  19. ↑ 19.0 19.1 19.2 19.3 19.4 19.5 Everard, Mark; Johnston, Paul; Santillo, David; Staddon, Chad (September 2020). "The role of ecosystems in mitigation and management of Covid-19 and other zoonoses". Environmental Science & Policy. 111: 8–10.
  20. ↑ Johnson, Christine K.; Hitchens, Peta L.; Pandit, Pranav S.; Rushmore, Julie; Smiley Evans, Tierra; C. W. Young, Cristin; Doyle, Megan M. (08 April 2020). "Global shifts in mammalian population trends reveal key predictors of virus spillover risk". Proceedings of the Royal Society B. 287: 8. Check date values in: |date= (help)
  21. ↑ 21.0 21.1 21.2 21.3 Hughes, Alice C. 2021. “Wildlife Trade.” Current Biology 31 (19): R1218–24. https://doi.org/10.1016/j.cub.2021.08.056.
  22. ↑ Convention on International Trade in Endangered Species. "CITES".
  23. ↑ 23.00 23.01 23.02 23.03 23.04 23.05 23.06 23.07 23.08 23.09 23.10 23.11 23.12 23.13 23.14 23.15 23.16 23.17 23.18 23.19 23.20 23.21 23.22 23.23 Halabowshi, Dariusz; Rzymski, Piotr (Dec. 28, 2020). "Taking a lesson from the COVID-19 pandemic: Preventing the future outbreaks of viral zoonoses through a multi-faceted approach". Science of the Total Environment. 757 – via Elsevier. Check date values in: |date= (help)
  24. ↑ 24.0 24.1 “Rough Trade.” 2013. BioScience 63 (12): 928–38. https://doi.org/10.1525/bio.2013.63.12.6.
  25. ↑ 25.0 25.1 25.2 25.3 Latinne, Alice, and Pawin Padungtod. 2025. “Wildlife Pathogens and Zoonotic Disease Risk Assessment in Vietnam: A Wildlife Trade Hotspot.” Transboundary and Emerging Diseases 2025 (1): 4926262–62. https://doi.org/10.1155/tbed/4926262.
  26. ↑ 26.0 26.1 World Health Organization (Jun. 27, 2025). "WHO Scientific advisory group issues report on origins of COVID-19". Check date values in: |date= (help)
  27. ↑ 27.0 27.1 Fan, Yi; Zhao, Kai; Shi, Zheng-Li; Zhou, Peng (2 March 2019). "Bat Coronaviruses in China". Viruses and Bats 2019. 11 (3) – via MDPI.
  28. ↑ 28.0 28.1 CDC. 2025. “Current Situation: Bird Flu in Dairy Cows.” Avian Influenza (Bird Flu). July 23, 2025. https://www.cdc.gov/bird-flu/situation-summary/mammals.html. ‌
  29. ↑ 29.0 29.1 World Health Organization (Jul. 15, 2025). "HIV and AIDS". World Health Organization. Check date values in: |date= (help)
  30. ↑ 30.0 30.1 Sharp, Paul M.; Hahn, Beatrice H. (Aug. 27, 2010). "The evolution of HIV-1 and the origin of AIDS". Philosophical Transactions B. 365: 2487–2494 – via The Royal Society. Check date values in: |date= (help)
  31. ↑ 31.0 31.1 31.2 31.3 31.4 Chitnis, A; Rawls, D; Moore, J (Jan. 1, 2000). "Origin of HIV type 1 in colonial French Equatorial Africa?". Aids research and human retroviruses. 16: 5–8 – via PubMed. Check date values in: |date= (help)
  32. ↑ Dzingirai, Vupenyu; Bukachi, Salome; Leach, Melissa; Mangwanya, Lindiwe; Scoones, Ian; Wilkinson, Annie (2017). "Structural Drivers of Vulnerability to Zoonotic Disease in Africa". Philosophical Transactions: Biological Sciences: 2–3.
  33. ↑ 33.0 33.1 Noguera Zayas, Liz Paola; Rüegg, Simon; Torgerson, Paul (November 2, 2021). "The burden of zoonoses in Paraguay: A systematic review". Neglected Tropical Diseases: 6.
  34. ↑ 34.0 34.1 34.2 34.3 Anupama, K.; Kumar Paul, Saikat (22 July 2025). "Nature-Based Solutions for Mitigating Zoonotic Disease Spillover Risk in Urban Areas". Urban Sustainability: 209–229 – via Link Springer.
  35. ↑ 35.0 35.1 35.2 35.3 35.4 Vourc’h, Gwenaël; Moutou, François; Morand, Serge; Jourdain, Elsa (1 Feb 2022). "PREVENTING AND LIVING WITH ZOONOSES". NIH.
  36. ↑ 36.0 36.1 36.2 36.3 Elsohaby, Ibrahim; Villa, Luca (October 3, 2023). "Zoonotic diseases: understanding the risks and mitigating the threats". “BMC Veterinary Research”. 19 – via National Library of Medicine.
  37. ↑ 37.0 37.1 37.2 SLINGENBERGH, J., M. GILBERT, K. BALOGH de, and W. WINT. 2004. “Ecological Sources of Zoonotic Diseases.” Revue Scientifique et Technique de L’OIE 23 (2): 467–84. https://doi.org/10.20506/rst.23.2.1492.
  38. ↑ Pike, Brian L., Karen E. Saylors, Joseph N. Fair, Matthew LeBreton, Ubald Tamoufe, Cyrille F. Djoko, Anne W. Rimoin, and Nathan D. Wolfe. 2010. “The Origin and Prevention of Pandemics.” Clinical Infectious Diseases 50 (12): 1636–40. https://doi.org/10.1086/652860. ‌
  39. ↑ 39.0 39.1 39.2 Challender, Daniel W.S., Stuart R. Harrop, and Douglas C. MacMillan. 2015. “Towards Informed and Multi-Faceted Wildlife Trade Interventions.” Global Ecology and Conservation 3 (January): 129–48. https://doi.org/10.1016/j.gecco.2014.11.010. ‌
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