Living in Bozeman, Montana is great: mountains, blue skies, happy dogs, outdoor sports and SCIENCE! Yesterday evening I had the opportunity to attend a talk by respected author David Quammen at Montana State University. David Quammen, a Bozeman resident since 1984, is deeply involved in reporting and educating the world about the ongoing Ebola outbreak in Eastern Africa. Author of Spillover: Animal Infections and the Next Human Pandemic published in 2012, Quammen has since written Ebola: The Natural and Human History of a Deadly Virus, and most recently The Chimp and the River: How AIDS Emerged from an African Forest.
In his talk Thursday night titled, Ebola and Beyond: Scary Viruses in a Globalized World Quammen talked about emerging diseases. As reported Ebola cases from the current outbreak total 24,907 (as of 3/25/14[i]), his timely writings and inspired presentations help the public to better understand this and other diseases to decrease fear and inspire prevention.
Ebola is one of many zoonotic diseases (diseases in which an animal infects a human). These diseases live in reservoir hosts—animals which carry the disease and transmit it to humans. The reservoir host for Ebola is suspected to be an Angolan Free-tailed Bat but samples are still being analyzed, so at present the reservoir host for Ebola is unknown. Spillover refers to what happens when a disease carried by a reservoir host first infects a human. The more interaction there is between reservoir hosts and humans, the more opportunity there is for spillover to occur. Disruption of natural environments by humans (such as expanding urban areas) leads to more instances of interaction, and therefore more opportunity for spillover and outbreaks of zoonotic disease. Finally, it is connectivity that allows diseases to spread around the globe. As Quammen noted, “a disease can travel at the speed of an airplane.”
These factors are what set in motion the current Ebola crisis—the local outbreak (small cluster of cases) resulted from spillover of a zoonotic disease from its reservoir host to a human. The connectivity of people led the outbreak that originated in Guinea to expand to an epidemic (national scale outbreak) that crossed international borders and eventually a pandemic (global scale outbreak) that has global implications. A similar scenario exists for what is believed to have been the initial spillover of AIDS (find the detailed story in The Chimp and the River: How AIDS Emerged from an African Forest). The point is, by understanding how these diseases emerge and spread, we have a better chance to determine and implement the necessary precautions to avoid large outbreaks of other zoonotic diseases.
Quammen went on to discuss the implications of disease epidemics on populations. Human population has surpassed 7 billion. The science of population ecology indicates that when a population gets too large conditions are conducive for diseases to emerge and cause potentially catastrophic population decrease. At least this has been observed in populations where individuals have little capacity to make educated decisions and perform actions to change their fate. Individual humans do have the capability to take action and make changes. Thus, to work toward avoiding a population crash for our own species, it is important that we understand how these diseases work and how we can prevent and control their spread.
To learn more about Ebola, the science of disease spread and prevention please check out David Quammen’s books and visit the links below.
Reliable source for current Ebola information