Author: Frank Ryan


The author of this book set out to explain what viruses are, and to explore the great influence they have had, and continue to have, on our history (page 5). Whilst he focuses on the established facts about viruses, he also discussed the uncertainties that still surround them; these range from the unresolved issue of whether they are living beings at all, to the conflicting theories about their origin (page 223). The book’s coverage is quite extensive, ranging from the familiar viruses, such as influenza and norovirus, to the strange megaviruses, such as mimivirus and pandoravirus (pages 46-51 and 163-165). The author, a physician, was particularly interested in viral ecologies, and the book illustrates the ubiquitous presence of viruses in nature, and the diverse ways they interact with their human and animal hosts. Of practical relevance, the book relives the great viral pandemics of history to extract lessons on how to predict and contain the emerging viruses that regularly threaten us.

By Photo Credit: Cynthia GoldsmithContent Providers(s): CDC/ Dr. Erskine. L. Palmer; Dr. M. L. Martin Link

The threat of viral epidemics is, as expected, a major theme of this book, and the author took a helpful historical perspective to put the subject in context. In this regard, he discussed several epochal pandemic events; the Spanish influenza of 1918 for example received prominent attention, being ‘the most lethal influenza epidemic in history, infecting half a billion people worldwide and killing an estimated 20 to 50 million victims’ (pages 101-102). The book’s assessment of the relatively more recent, but very impactful, HIV epidemic was also particularly detailed, highlighting, amongst other things, its simian origins from chimpanzees and sooty mangabay monkeys, and how its ‘ferocious capacity for mutation‘ confers each victim with ‘his or her own strain of the virus’ (pages 208-211). The author applied the same detailed approach in reviewing emerging viral epidemics, appraising such deadly viruses as SARS CoV, a coronavirusbecause the virions are crowned with thorny projections‘ (page 104). Many of the other viruses the book reviews are rather less epidemic but also carry a heavy toll in terms of morbidity and mortality. These include the ‘mercurial’ Zika virus, the ‘Machiavellian’ rabies virus, with its ‘sinister modus operandi’, measles, rubella, herpes, yellow fever, and chikungunya (pages 33-40, 85-87, 111-116, and 135-138).

By Photo Credit: C. GoldsmithContent Providers: CDC/ C. Goldsmith, P. Feorino, E. L. Palmer, W. R. McManus – This media comes from the Centers for Disease Control and Prevention‘s Public Health Image Library (PHIL), with identification number #10000, Link

A recurring subject throughout the book is the symbiotic relationship and co-evolution of viruses with their hosts (page 242). It explored how this intriguing concept of viral symbiosis affects humans and animals, and how it fashions our atmosphere by its occurrence in the oceans and in soil. The booked resolved the seeming paradox of how a virus which is deadly to humans, for example Ebola, remarkably shows ‘a striking lack of aggression in relation to its long-established zoonotic host‘ (pages 83 and 113). It goes further to explain how new viral epidemics emerge, attributing this to the disruption of established virus-host associations by rapidly expanding human populations (page 132). Citing experts such as Lyn Margulis, Joshua Lederberg, and Luis Villareal, the author explores how the delicate balance of viral-host relationships influences the ecology of both parties (pages 82-83).

Ebola viral particle. NIAID on Flickr.

Surprisingly, the most influential role viruses play in human life is to perform essential functions. The book reviews many of these roles, and perhaps the most compelling relates to the endogenous retroviruses (ERVs); by becoming part of our genome, ERVs influenced human evolution over the ages, and today play critical roles in such vital processes as placentation and reproduction (pages 213-219). The author also discussed how viruses such as herpes simplex and herpes zoster, make up our so-called virosphere. These viruses colonise almost all our body parts and ‘seem to stick with us for life‘, but they also have diverse beneficial effects on our health; cytomegalovirus (CMV), for example, ‘may actually improve our immune response to other infectious agents’ (pages 204 and 94).

By Thomas Splettstoesser ( – Own work, CC BY-SA 4.0, Link

The author dedicated a major part of the book to the prospects of preventing future viral epidemics. One of the most promising measures he reviewed is how to predict epidemics by understanding the ‘patterns of viral diversity in wildlife’ (page 132). The likely targets of this approach may include the many lethal viral species that use bats as zoonotic hosts; indeed, the author noted, bats are ‘more likely to harbour viruses that could cross to humans than any other wild animal group’ (pages 132-133). He also discussed how the surveillance of new mutations in wild animals may help to predict the emergence of flu pandemics, supporting his arguments with the work of scientists such as Nancy Cox (pages 103-109). He also reviewed other intriguing approaches to containing viruses, for example the introduction of Wolbachia bacteria to infect their mosquito vectors (pages 141-142).

Aedes mosquito. NIAID on Flickr.

Central to the book’s narrative are the key scientists that have played significant roles in the discovery of viruses, and in increasing our understanding of their influence. For example, the author cited the breakthrough achieved by Felix d’Herelle, considered the father of virology, who showed that bacteriophage viruses infect and kill bacteria (pages 26-31). He noted the achievements of Michael Epstein and Yvonne Barr in discovering EBV, the virus that bears their names, and which causes Burkitt lymphoma, infectious mononucleosis, and nasopharyngeal cancer (pages 95-97). We also learn about the contributions of Nobel prize winners Baruch Blumberg, who identified hepatitis B virus (HBV), and Harald zur Hausen, who proposed that cervical cancer was caused by human papillomavirus (HPV), the virus that also causes genital warts (pages 148 and 156). More generally, the book acknowledged the impact of the global collaboration of scientists in rapidly identifying, classifying, and containing deadly viral epidemics such as Marburg in the 1970’s (pages 123-133).


By NaransonOwn work, CC BY-SA 3.0, Link


This book provides a helpful context in which to understand viruses and their wide-ranging impacts. With relevant examples of historical and emerging epidemics, the book paints a picture of viruses that reflects both their detrimental and advantageous influences. Applying cutting edge information, the author reveals the advances in our understanding of viral ecologies, and how these are defining how we predict and contain future epidemics. The introduction and early chapters of the book were not as focused as the latter chapters, and the author tended to overuse some words such as ‘quintessential’. These minor points notwithstanding, the book is well-written, and its exploration of the diversity of viruses is very detailed.

Overall assessment

This is an insightful perspective on viruses which discusses a subject that is contemporarily relevant. The author’s approach, by clarifying details of the diversity and ecology of viruses, simplifies what would otherwise be a complex subject. His discussion of the beneficial effects of viruses on human health and evolution is revealing, and alters the general perception of viruses as totally malevolent organisms. The contents of the book are pertinent to healthcare, exploring as it does, how to anticipate and prevent emerging viral epidemics. I recommend it to all doctors.

Book details

Publisher, Place, Year: William 2019
Number of chapters: 23
Number of pages: 278
ISBN: 0-00-829667-4
Star rating: 4
Price: £8.19

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