Emerging Infectious Diseases: Concepts, Divers, and Implications PDF

Emerging Infectious Diseases: Concepts, divers, and implications Sergio Guerrero-Sanchez, PhD. Research Assistant Professor Centre for One Health Research and Policy Advice Jockey Club College of Veterinary Medicine and Life Sciences About me… Mexic...

Emerging Infectious Diseases: Concepts, divers, and implications Sergio Guerrero-Sanchez, PhD. Research Assistant Professor Centre for One Health Research and Policy Advice Jockey Club College of Veterinary Medicine and Life Sciences About me… Mexico (1998-2012) Malaysian Borneo (2012-2022) TLAOs: Explain the concept of emerging infectious diseases (EID) and explore their impact on humans, animals, and the environment. Examine the strategies for preventing EID in animals and humans and assess their environmental impact. Discuss the importance of the One Health approach in designing actions to address health problems after diseases have established in a population. Parasites in their ecosystem: Just another way of interaction among living beings. Mutualism Commensalism Competition Predation Herbivory Carnivory Parasitism (virus, bacteria, fungi, helminths, acari)  When a microorganism becomes a pathogen Pathogenic microorganisms = pathogens = microorganisms that can cause disease upon colonisation of the host. Opportunistic Facultative pathogen = pathogen = microorganism that Obligate pathogen = microorganism does not ordinarily which can infect microorganism which cause disease but and multiply in a must infect the host to may become host, but it is also survive and multiply pathogenic under capable of certain conditions multiplying in the (e.g. impaired environment immunity). Disease in a nutshell: Pathogens = microorganisms Infectious Diseases = that can cause disease upon diseases caused by colonisation of the host. pathogens (e.g. bacteria, viruses, Communicable diseases = Infection = the invasion prion, parasites or diseases that can be spread and multiplication of fungi). directly or indirectly, pathogens in an from one animal to another (Disease = a disorder of individual or population. (contagious) structure or function in the host that adversely Host = an individual (or cell) impacts the host and is susceptible to being infected by a not simply a result of pathogen. physical injury). Environment = The surroundings or conditions in which an organism lives or operates  Ways of transmission Food-borne = Host is Air-borne = Some infected through being microorganisms are too in contact with food small that can move through contaminated with air from one host to another pathogenic Fomites = Any inanimate microorganisms object or surface where pathogens can survive until infecting a susceptible host Water-borne = Host is Vector-borne = Some infected through being in pathogens require an animal contact with water species to complete its cycle contaminated with before infecting a pathogenic susceptible host microorganisms Ways of transmission Zoonosis = a pathogen that is shared by both humans and non-human animals and can be transmitted from one to the other. Zóon (ζῷoν) = ANIMAL Nóso (νóσoζ) = DISEASE Ways of transmission Over 800 out of 1,400 pathogens identified in humans are shared with animals OIE 2017 The role of parasites in the ecosystem The case of Trichostrongylus tenuis and the Red grouse. This case is a good example of how some parasites contribute to regulating animal populations and, hence, prevent the over-use of resources by the host (food in this case). The role of parasites in the ecosystem Rinderpest in Serengeti While the endemic cycle of rinderpest virus regulated the number of wildebeest in the African savannah, bushfires were part of the natural succession of trees in the ecosystem. Rinderpest eradication campaigns in Africa contributed to the increasing number of wildebeest, which reshaped the savannah and reduced the fire events, producing a cascade of changes in the food web and the dynamics of other wild animals. When do pathogens become a problem? Well, basically when they threat: Our existence (the black plague epidemics in the XIV century killed almost 50% of Europe’s population population) The existence of other animal species (the Christmas Island rat’s extinction due to the introduction of flies and a protozoan parasite is recorded as the first disease- Our food production system and mediated extinction of an animal economic income (the Rinderpest species in history… and it was epidemics in Africa in the late 1800s human-mediated) caused the loss of ~1.02 million USD and millions of deaths due to famine) Humanity has always dealt with diseases: Early times: Thought to be caused by an imbalance of humours, spirits, bad omens, or curse. Humanity has always dealt with diseases: Now we know there is a wide range of causes, from genetic/metabolic disorders (some are correctly named now “conditions” instead of disease) or very tinny bugs (Infectious diseases) Antonie van Leeuwenhoek (1632-1723) Robert Koch (1843-1910) Emerging Infectious Diseases Emerging Infectious disease: a disease that is newly recognised or newly evolved, or that has occurred previously but shows an increase in incidence or expansion in geographical, host or vector range. Re-Emerging Infectious disease: a disease that appears after it has been eradicated or on a significant decline.  The World Health Organization’s global surveillance system currently picks up ~7000 public health threat signals every month Species richness and hosts Taxonomic groups with more (host) species generally hold more potentially zoonotic pathogens. Although worldwide distributed, the tropics hold the largest number of zoonotic pathogens  Rodents Species richness and hosts Primates Chiroptera Carnivore Soricomorpha Artiodactyla  The probability of finding a zoonotic virus increases with the number of virus types held by the species host (e.g., rodents, bats and primates are the taxonomic group with the larger number of viruses recorded and, hence, could have the larger number of viruses with zoonotic potential. Contrary to rabbits or even birds. Mollentze and Streiker, 2019)  Image Note aside… No bats, MORE MOSQUITOES! No Bats, NO DURIAN! No Bats, NO TEQUILA! Image  Reasons of (re)emergence Change in the population dynamic of Change in pathogen host range characteristics Population growth/High density Mutation Urbanisation Drifting Hunting/farming practices Trade/Travels Change in the environment Lack in the application of control Lack of biodiversity measures Climate change Lack of surveillance Deforestation  Reasons of (re)emergence Biodiversity loss Climate change Land use change  Biodiversity loss The case of Lyme Disease (and other Rickettsioses). Disruption of the food web Disruption of the forest resilience Dilution effect The lower the diversity, the higher the risk of being infected The most common host species dominates the animal community Amplification effect The risk of infection increases when the diversity increases Some pathogens can infect different host species. i.e., if we include the dogs in the figure, they may play an important role in amplifying the transmission Climate change The case of Dengue virus. ®Chris Sharp Increased vector abundance and feeding activity Increased geographical range Increased human activities during warmer times Land use change, parasites, and public health: Adaptation of Plasmodium knowlesi from macaques to humans. Fornace et al., 2019 Land use change, parasites, and public health: Echinostomatids in oil palm plantations. The abundance of generalist animal species increases the abundance of multi-host parasites in agricultural landscapes, increasing the risk of infection to humans (i.e., fishermen, crop workers, and farmers). A generalist is a species that adapts and persists in different environments, including man-made ecosystems. Frias et al. (Parasitology, 2024) Interspecies interactions and spillovers SPILLOVER Pathogen transmission from a reservoir to a novel species produces disease. Stochastic Zoonotic and No Zoonotic OHHLEP, 2023  Interspecies interactions and spillovers ©Health at the Edge Project TRAFFIC, 2020 Interspecies interactions and spillovers The case of SARS-CoV2 Interspecies interactions and spillovers The case of SARS-CoV2 Interspecies interactions and spillovers The case of SARS-CoV2 A map of the world with yellow planes Description automatically generated Interspecies interactions and spillovers The case of SARS-CoV2  Interspecies interactions and spillovers Canine Distemper in Africa Reduction of populations Species introduction Virus introduction Local extinctions Roelke-Parker et al., 1996 Interspecies interactions and spillovers The case of the Bornean felids Interspecies interactions and spillovers The case of the Bornean felids Interspecies interactions and spillovers The case of the Bornean felids Guerrero-Sanchez et al., 2022 Impacts on the ecosystem Rinderpest in the Serengeti Impacts on the ecosystem Rinderpest in the Serengeti A disease that, after being introduced, regulated the wildebeest population… and with it, the dynamics of the whole ecosystem Impacts on the ecosystem Rinderpest in the Serengeti Outbreak in domestic cattle in Africa (late 1800’s) ~1.02 Billion USD Not a zoonosis… Millions of deaths caused by famine Impacts on the ecosystem Rinderpest in the Serengeti Outbreak in domestic cattle in Africa (late 1800’s) ~1.02 Billion USD Not a zoonosis… Millions of deaths caused by famine Vaccination started in 1960 Eradication in 2011 Impacts on the ecosystem Rinderpest in the Serengeti Holdo et al., 2009 What regulates the population? Impacts on the ecosystem Rinderpest in the Serengeti Holdo et al., 2009 What regulates the population? Beyond the impact on the ecosystem: Nipah Virus outbreak in Malaysia (1998) Flying foxes are natural reservoirs of the virus. Habitat encroachment and agricultural expansion modified flying foxes' distribution. Lack of biosecurity in the farms and overlapping of feeding sites 265 human cases 105 deaths > 1 million pigs culled Looi and Chua, 2007 Beyond the impact on the ecosystem: African Swine Fever in Asia (2018- ) First reported in 2018 16 countries reported with the disease The virus spread to farmed pigs and wild pigs, too. Over 5 Million pigs have been culled It represents a direct cost of 55 – 130 Billion US Dollars. Asian Development Bank, 2020 Beyond the impact on the ecosystem: African Swine Fever in Asia (2018- ) 11 wild pig species (endemic to Asia) are at risk. 3 species belonging to Sulawesi and one to Sumatra are of major concern. Impact on rural families in the region whose income and protein source depend on wild boars. Impact on the forest dynamics and the food web in the region. Luskin et al., 2020 Some ways to prevent or control infectious diseases Biosecurity, personal protection: hand washing, masks Immunisation (vaccination) Isolation (quarantine), culling Treatment with antibiotics, antivirals  Biosecurity Biosecurity consists of the implementation of measures to prevent or restrict the spread of a pathogen through the use of protective equipment and the sanitation and disinfection of tissues, surfaces and physical surroundings. It is as simple as washing hands and covering the mouth when coughing or sneezing.  Immunisation It is the process through which the body develops a memory of the immunity system to answer to the next external aggression. Infection of a naïve host Immunisation of the Infection of an immune = sickness host host = no sickness Unvaccinated population Patient Zero Vaccinated population (herd immunity) Patient Zero Isolation (quarantine/culling/population control) The implementation of the measures depends on different factors, such as: Characteristics of the pathogen Animal species and their value Social and cultural context Economics and politics Isolation (quarantine/culling/population control) Rabies The import of pets from a country where rabies is endemic into a free-rabies country requires the pet to be vaccinated and to spend between 30 and 120 days in isolation. Vaccination of the dog and cat population in the country/region Population control of free-ranging cats and dogs. Culling vs Neutering Isolation (quarantine/culling/population control) Avian influenza (Once the outbreak is detected) Elimination of infected birds Reduction of the population on the farm. Active surveillance in the surroundings. Immunisation of susceptible birds Isolation (quarantine/culling/population control) African Swine Fever (Once the outbreak occurs) No Vaccine No treatment Elimination of all the infected and suspected pigs in the farm. Remember COVID-19 Some drivers we MUST consider… >70 % of terrestrial habitats have been converted to agriculture Changes in wildlife distribution and behaviour Intensive food production ~ $26 billion per year in profits Civilizations have been raised as part of a bi-directional adaptation of humans and the environment. Humans and animals have co-existed, sharing and being part of the ecosystem for millennia. Technology has improved quickly after the Industrial Revolution… to satisfy the needs and wants of a growing population ~8 billion people currently living in the world Density = ~60 people / km2 Our World in Data ~8 billion people currently living in the world Density = ~60 people / km2 Our World in Data But all comes at a price. The production of goods and commodities requires a substantial amount of natural resources. Fancy a chocolate?  © Edward Burtynsky, 2017 The backstage of (over) consumption © Edward Burtynsky, 2016 © Edward Burtynsky, 2016 Conflict, war, inequity, and disinformation War and conflicts Deterioration of health systems Pause of vaccination campaigns Migration to safe places. e.g. the “Spanish” Influenza pandemic in 1918 spread from the USA into Europe (and the world) during WWI. Conflict, war, inequity, and disinformation Inequity Poverty and hunger Unaffordable health care Access to vaccines and treatments Migration for a “better life” Limited or inexistent access to health care for immigrants (especially illegal). For example, the 2019 polio outbreak in Malaysia was linked to a strain circulating in the Philippines.  Disinformation (Fake news) Nowadays, we have access to loads of Conflict, war, inequity, information through the www. and disinformation Our way of life requires us to get such information quick and clear Filtering such an amount of information is critical but also difficult. It's important to note that fear also plays a significant role in the spread of disinformation. This is why critical thinking is now more important than ever. E.g., the anti-vaxxer movement and the resurgence of measles.  Food for thought… How do we re-think our relationship with the world concerning: Health and nutrition? Wellbeing and mental health? Our decisions matter, either as a person or as a professional. Simple solutions are not always the most efficient… Simple solutions are not always the most efficient… Fairies are Ogres Well… now Fairies are become a good for the we need to now a pest! figure out environment; pest! Release the who will let’s release Release the ogres! control the them! dragons! dragons… Simple solutions are not always the most efficient… But let Remy explain it to us… Next week…