By: Sidi Andrew
The outbreak of a deadly infectious disease is accompanied by a ripple effect that affects every aspect of human living and existence. From possible economic downturn to pressure on social amenities and a temporary standstill to various activities ranging from business to social and even to the spiritual.
Coupled with all this is fear and worry. Fear for our survival, of the end to life as we know it. We worry about the threat a disease poses to us — not to human lives, but the threat to human life. Our very existence. We ask ‘is this our end’?.
The fear visualizes a large proportion of humans succumbing to the infection, leaving no survivors or so few that the species cannot be sustained.
This is quite understandable, worrying about the end is a fundamental human trait and for most of mankind’s history, epidemics were the existential threat to humanity and there is a good reason for this; they were quite successful at killing people.
In this article, you will understand what epidemics are, their types and transmission modes, why so many of them originate in Asia and Africa, why epidemics cannot be the end of human life and steps that can be taken in preparation to prevent or mitigate any future outbreak.
What are Epidemics
According to the American Center for Disease Control and Prevention, ‘it is the occurrence of more cases of disease, injury or other health condition than expected in a given area or among a specific group of persons during a particular period.’ The cases are usually presumed to have a common cause or underlying factor or to be related to one another in some way.
An epidemic disease may not necessarily be contagious as it was applied to the West Nile fever and the Obesity epidemic by the WHO and other health bodies. Epidemics of infectious diseases are generally caused by several factors which include: increased virulence of an infectious agent, introduction into a novel setting, change in host’s resistance to the infectious agent among others.
Some epidemics occur at certain seasons. For instance, measles produces two epidemics. One in winter and one in March while whooping cough is prevalent in spring. Influenza and other upper respiratory tract infections occur most often in winter. A few cases of a very rare disease may be classified as an epidemic while many cases of a common disease would not be classified as an epidemic such as common cold.
An epidemic may be restricted to one location. However, if it spreads to other countries or continents and affects a substantial number of people, it may be termed a pandemic. Before an epidemic is declared, it requires a good understanding of a ‘baseline rate of incidence’, that is; the normal rate or level at which a particular disease is present or occurs in a community. Once an established baseline is passed, then an epidemic is declared.
Infested food supplies or contaminated drinking water and the migration of certain animal populations such as rats, fleas, mosquitoes or other exotic animals that are new to a community or region act as disease vectors that propagate the spread of infections as they come in contact with humans.
Types of Epidemics
- Common Source Outbreak: The affected individuals had an exposure to a common agent. It can be called a Point Source Outbreak if the exposure is singular and all the affected individuals developed the disease over a single exposure and incubation occurs. It can also be termed a Continuous Outbreak or Intermittent Outbreak respectively if the exposure was continuous or variable.
- Propagated Outbreak: The disease spreads person-to-person in this form. Individuals that have been affected may become independent reservoirs leading to further exposures and transmission. Many epidemics will have the characteristics of both Common Source and Propagated Outbreak, it is sometimes referred to as Mixed Outbreak. For instance, a secondary person-to-person spread may occur after a common source exposure or an environmental vector may spread a zoonotic disease.
Transmission Modes of Epidemics include :
1. Airborne Transmission: Spread of infection by droplet nuclei or dust in the air. Without the active intervention of winds or drafts, the distance over which airborne infection takes place is short as seen in the case of the COVID-19 virus.
2. Arthropod Transmission: An insect propagates this. It could be mechanically through a contaminated proboscis or biologically when there is growth of an organism in the arthropod.
3. Biological Transmission: Involves a biological process and is the opposite of the mechanical process mentioned previously.
4. Contact Transmission: The disease is transferred directly by sucking, chewing, biting or indirectly by drinking contaminated water, travelling in contaminated vehicles or being in contaminated spaces etc.
5. Faecal-Oral Transmission: Infection agent is passed by the infected host in faeces and acquired by the vulnerable host through ingestion of contaminated material.
6. Horizontal Transmission: It involves the lateral spread of the infectious agents to others in the same group at the same time.
7. Vertical Transmission: Transmission from one generation to the next, i.e. some retroviruses’ genetic material are integrated into the DNA of either the ovum or sperm, thereby going from one generation to the next.
Focus on Asia and Africa
Most epidemics in the last two decades have at least one thing in common: They originate from Asia or Africa. The reasons are quite simple and might surprise you.
Increasing Population and Urban Migration
Both of these continents have experienced a population explosion and corresponding changes in urban landscape as people migrate into surrounding urban areas from smaller towns and villages. A recent survey found 60% of the world’s population to be living in Asia and the Pacific region and this has led to rapid urbanization in these regions.
Migration and urbanization leads to large scale deforestation to create residential areas. Wild animals displaced are forced to move closer to cities and towns, inevitably they encounter domestic animals and the human population.
Wild animals are often vectors that harbour viruses; bats for instance, can harbour hundreds of them. When a virus jumps from one species to another through mingling and migration, humans eventually get infected.
Loss of habitat ultimately kills off predators, not excluding those that feed off rodents and with the predators gone or their numbers sharply diminished, the rodent population explodes. Extensive studies have shown that this population explosion contributes greatly to the risk of zoonotic diseases in Africa as the case of the Ebola virus has shown and the situation is likely to get worse as urbanization continues.
Subsistence Agriculture and Animal Markets
Tropical regions rich in host biodiversity hold a large pool of pathogens, greatly increasing the chance of emergence of a novel pathogen.
Many families depend on subsistence farming in both continents and a small supply of livestock. Disease control, feed supplementation and housings for the animals are limited. Consequently, chickens, cattle, pigs and other domestic animals which can carry endemic diseases are often housed together and in close contact with each other, other non-domestic animals and humans.
Live animal markets are also commonplace throughout Asia and Africa, these places are often crowded and there is little or no sanitation supervision involved and an unavoidable mixing of species including humans. It was confirmed that the COVID-19 virus was transmitted in such a market in China.
Bushmeat hunting which is widespread in sub-Saharan Africa threatens the very existence of some animal species and as a result, there is a change in ecosystems bringing people and wild animals together. Bushmeat hunting presents a clear path for the transmission of zoonotic diseases.
Traditional Chinese Medicine which claims to provide cure for a number of conditions such as epilepsy, arthritis, erectile dysfunction, infertility etc. uses some animal parts such as tigers, bears, pangolins, bats, elephants, monkeys and a host of other poached animals as ingredients in making these medicines even though no concrete scientific evidence supports this claims. This is a major contributor to animal-human interactions which may inadvertently cause the transmission of zoonotic disease. Asia no doubt is an enormous consumer of traditional Chinese medicine products and demand for some of these medicines are likely to go up as online marketing keeps increasing with the steady economic growth of Asia.
Epidemics and The Fear of Extinction
As far back as the 6th century, the Plague of Justinian killed an estimated 17 percent of the world’s population then, the Black Death in the 14th century decimated a third of Europe after leaving so many dead in Asia, the 1918-1920 influenza pandemic killed off about 5 percent of the world’s population, the AIDS pandemic and epidemic that started since 1981 till present day has claimed an estimated 35 million lives since it was first identified, malaria has killed off millions and the swine flu pandemic of 2009-2010 that originated in Mexico before spreading to the rest of the world infected as many as 1.4 billion people across the globe in one year and killed about 575,400 people according to the Center for Disease Control and Prevention in Atlanta; the West African Ebola epidemic ravaged the whole of West Africa between 2014 and 2016 with tens of thousands dead and no cure in sight and of course the COVID-19 pandemic that started in China that has left more than 400,000 dead in its wake and still counting.
These are large and terrifying numbers of fatalities and the viruses involved and the diseases they caused were deadly but yet, humanity has continued to flourish during and after each of these outbreaks.
The human species’ recent boom in lifespan can almost be attributed to the control of infectious disease through sanitation, vaccination and antimicrobial therapies.
Therefore, the question now is: what would it take for a disease to wipe out humanity ?
For any particular disease to be able to wipe out humanity, it must possess a very special combination of two attributes.
- it would have to be so unfamiliar that no existing therapy or vaccine could be applied to it and secondly, it would need to have a high and stealthy transmissibility before symptoms occur.
The first is absolutely essential because any microbe from a known class of pathogens would have family members that could serve as models for containment and countermeasures
- It would allow such a hypothetical disease to spread without being detected by even the most astute of clinicians.
HIV, Ebola and Influenza are infectious diseases most likely to be considered extinction level threats in the world today but even they do not meet the two requirements stated earlier.
HIV for instance, which has killed more than 35 million people over several decades is limited due to some factors. Most importantly, it depends on blood and fluid for transmission which requires intimate human-to-human contact and this limits the risk of contagion. Simple prevention strategies like needle exchange for injection drug users and barrier contraceptives can curtail transmission risk when made available and followed. Potent antiviral therapies have also allowed most people to live normally with the disease.
Similarly, Ebola for many of the same reasons as HIV as well as some others also falls short of the mark in causing human extinction. It is especially due to the fact that it spreads almost exclusively through people with easily recognizable symptoms plus its mortality rate can be tamed by simple supportive care.
Despite influenza’s ability to kill on a large scale, it’s contagiousness and ability to shift and drift away from vaccines, humans have become attuned to its risks. In this modern era, effective antiviral therapies and vaccine strategies and preparedness exist to combat it.
One of the reasons for the failure of a disease to wipe out human existence is due to the resilience of our immune system which is one of the most complex on the planet and it is always finding ways to adapt even without the benefits of vaccines or the help of antimicrobial drugs. Coupled with this is the genetic variation among humans which leaves different adaptability features in each individual that ensures that almost any infectious disease onslaught can be repelled.
Preventing Future Epidemics
While it may not be entirely possible to mitigate every risk, there are strategies that countries can singularly and or collectively adapt to prevent and mitigate future epidemics.
Here is a look at some ways we can be prepared and stay prepared for a potential future epidemic.
1. Investment in Research and Preparation
Extensive research should be done to look at new and emerging pathogens to see how we can best be prepared for any disease they might bring. This will involve holistic information sharing among countries and research organizations.
2. Vaccine Program Funding and Implementation
Generally, large scale vaccination programs are effective at minimizing the rates of diseases while making sure that health systems do not become overwhelmed. Focus can remain on understanding and containing emerging diseases with a good vaccination program.
3. Strengthening and Improving Health Systems
Governments should make adequate efforts to strengthen and improve their health systems by expanding capacity and obtaining necessary equipment coupled with adequately trained staff and personnel needed to provide quality care.
4. Food Safety Education
People should be sensitized on the need for food safety from the production and harvesting of food, to its processing and distribution and preparation until it is eventually consumed. There should be quality assurance and inspection strategies at each stage of these processes to ensure food safety.
5. Early Warning Systems for Emerging Pathogens
Various mechanisms can be put in place with the efforts of scientists and relevant personnel to detect newly emerging pathogens, so they can warn and provide detailed information for further research and analysis.
6. Better Biosecurity in Wildlife and Animal Markets
To prevent future emergence of epidemics, the animal market’s biosecurity needs to be improved regarding hygiene, sanitation and processing facilities and the source of animals traded at the market. Regulatory bodies could be established to monitor these activities and laws passed to regulate hunting of animals especially exotic animals.
7. Fast and Flexible Epidemic Control Strategies
Mobile treatment units and mobile field laboratories will help to provide care in remote and rural areas and to conduct tests without wasting valuable time in trying to move infected patients to the cities for treatment. Potential outbreaks could be easily contained at the point of infection and a wider spread of such infection averted.
The threat posed by infectious diseases is great and ever present, but if governments and various institutions rally together and implement some of these strategies and other relevant ones, the threat of epidemics is greatly diminished and potential outbreaks are easily contained and managed.
Humanity’s strength lies in its being able to pick up the pieces and rebuild again after every outbreak. Perhaps we love life too much to just simply give up living.
No doubt humanity will continue to live to fight another day as we have been doing for millennials.
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