While attending a protein expression and purification workshop, one of the technicians mentioned a book he had been reading about the first outbreak of Ebola virus, ‘The Hot Zone’ by Richard Preston. His brief description piqued my interest, and it was not long before I had a copy of my own. I am familiar with viruses, having studied them during my undergraduate studies, and my current research is on a protein from the Hepatitis C virus.
Laboratories are classified according to the risk they present to people within the facility and the containment procedures they must follow in a series of levels (1-4) also known as PC (physical containment) facilities. In a PC1 laboratory, you can only work with microorganisms that do not cause disease in humans, plants, or animals. In PC2 laboratories, such as the one I work in, the microorganisms may cause mild to moderate disease in individuals exposed but would have a limited impact on the community. PC3 contains microorganisms who can cause serious disease in exposed individuals and spread throughout the community. PC4 laboratories contain the worst of the worst, microorganisms that can cause lethal infections, are highly contagious, and often no treatments or vaccines are available. To put this in perspective, HIV is only considered a level 3 agent. I had the opportunity to visit the high-security emerging diseases laboratory (Australian Animal Health Laboratory) in Geelong, Victoria, the only Level 4 laboratory in Australia. Level 4 workers use fully enclosed bio-space suits. Air is pumped into the suit using attachable tubes or a battery-powered device, and forces air out of the suit, preventing backwards flow and exposure. The laboratory is completely sealed off from the outside world; it is a biologically ‘hot’ zone. Unfortunately, not all hot zones exist in controlled environments.
Humans interact with the surrounding environment and are exposed to millions of microorganisms everyday. Thankfully, most of the microorganisms are harmless or are recognised by the body’s immune system and destroyed. Occasionally, in this arms race of evolution, there emerges a pathogenic microorganism unlike anything our immune system has been exposed to and ravages the body.
Viruses, unlike bacteria, are not alive in the traditional sense. They cannot reproduce with a host cell. They consist of strands of genetic information, the blueprint of the virus, surrounded by a protein shell. To copy itself, it needs tools and resources not found in the environment. Upon viral entry, it can hijack a cell, and turn it into a virus spawning factory, and as the new viruses infect adjacent cells the cycle repeats. Viruses are zombies. Isolated outside a cell, a virus remains unchanged, it is by all appearances dead, but can be revived in an instant. Some viruses cannot exist outside of a host, however, due to exposure to humidity, sunlight, and temperature changes.
Viruses have different types of hosts:
- Primary Host – the main species the virus infects and replicates within
- Vector – a species which transmits the virus to other hosts
- Reservoir – a species which is typically unaffected by the virus but provides it with a safe environment to replicate, mutate, and persist (e.g. bats). Some reservoir species are also vectors.
Viruses are tiny, millions can fit on the dot of this i, yet they are powerful enough to subdue the strongest and most complex creatures. Their simplicity is beautiful but deadly, and few others are as deadly as Ebola. Shaped as a thin worm, Ebola belongs to the Filoviridae family of viruses known as filoviruses. Bats are most likely the reservoir of the virus, and it causes diseases in primates. Humans exposed to bodily fluids from an Ebola-infected monkey can become infected. It replicates so quickly that it can kill a human in days from the earliest detectable symptom, turning internal organs, the brain, and blood vessels into a sludge. Some forms of the virus have 50-90% mortality rates. It is generally not considered to be airborne but is still highly contagious, and can remain dormant in a dead body, waiting to be reanimated by an unsuspecting mourner.
The Hot Zone documents the initial outbreak of the virus and related strains, in the jungles of West Africa, in the 60’s and 70’s and the discovery of Ebola infected monkeys in a storage house outside Washington D.C in 1980. It follows the lives of the scientists and veterinarians as they fought to contain a potential wildfire of infection in Africa and the U.S.A. The numerous close-calls and tragic deaths are terrifying, even Stephen King said that it was “one of the most horrifying things I’ve ever read”. Although they were successful in eliminating the virus in the U.S.A., the virus retreated back into the African jungle to strike again in the subsequent decades.
West Africa is currently experiencing the worst outbreak of Ebola in recorded history, with over five thousand suspected cases and 2,630 deaths as of September 16. Although more is known about the virus since this book was written, scientist have yet to find and implement an effective vaccine and treatment. Unlike the well funded teams in Washington D.C., healthcare workers in West Africa are unprepared for the severity and infectivity of Ebola. People are scared to admit they have Ebola-like symptoms, many of which are unspecific, lest they be quarantined with infected patients.
The virus has yet to establish itself outside of Africa’s shores but the potential for an international pandemic is real. WHO and the CDC have responded with a significant amount of resources, personnel, and funding to prevent the spread of the virus. Entrepreneurs, such as Bill Gates, have donated millions to assist in the efforts. Although West Africa’s healthcare system is not as developed, no country is prepared for an infective agent of this ferocity. We are all living in a potential hot zone. Only with coordinated efforts by governments, healthcare workers, civilians, and the military can we contain Ebola and other viruses we are yet to have the misfortune of encountering.
Ebola is not evil in the sense that the virus has a sinister purpose or design. It is a product of natural interactions between species, the struggle for existence between primates with dexterity, memory, cognition, language, mobility and what seems to be simply a nucleic acid wrapped in a protein envelope. But must not forget that all living things were once no more than a few pieces of nucleic acid in an envelope. Both humans and Ebola speak the most ancient language of them all: DNA. The struggle for existence continues between planet Earth, with its complex environments, weather, ecosystems, geology, and biology, and some nucleic acid within proteins within membranes within humans. We are an infection living at the expense of our host, and Earth is the ultimate hot zone in the solar system. Like Ebola, we are striving to spread among the stars in the universe. I only hope that the consequences will not be as deadly.
Patheology 