A Planet of Viruses
Author: Carl Zimmer
This relatively small, but surprisingly comprehensive, book paints a complete picture of the viruses which have become a defining feature of our lives. It gives excellent insights into the abundance of viruses, both inside and outside our bodies, showing how ‘just about wherever scientists look…they are discovering viruses faster than they can make sense of them’ (page 5). Whilst emphasising the collective impact of viruses on humans, the book also appraised the unique features of the most influential of them. The author’s perspective on human-virus interactions provides a window into how this co-existence determines, not only our health, but our development. He stressed the enormous threat we face from viruses when he said that ‘despite all the vaccines, antiviral drugs, and public health strategies at our disposal, viruses still manage to escape annihilation‘ (pages 104-107 and 89).
The main goal of the book was to raise awareness about viruses, and the author did this in a balanced way. He rightly highlighted the threat of the rarer but aggressive viruses, but also explored the common and relatively benign ones. In this regard, the book did not ignore ‘mundane’ viruses such as the rhinovirus, the cause of the common cold, a very ancient virus which, with only 10 genes, has managed to ‘outwit’ our immune systems and remain incurable (pages 13-15). In a similarly engaging way, the book explored the relatively newer and more virulent viruses such as HIV, the cause of the devastating AIDS epidemic that infected about sixty million people, killing about half of them. In line with the author’s comprehensive approach, he depicted the full profile of HIV, for example describing how it leaped across species from its African simian origins; HIV-1 from chimpanzees, and HIV-2 from sooty mangabey monkeys (pages 61-67).
Perhaps the most remarkable theme of the book is the intimate genetic relationship we have with viruses. The author highlighted this when he pointed out that 8 percent of human DNA is derived from viruses, and ‘each of us carries almost a hundred thousand fragments of endogenous retrovirus DNA in our genome‘ (pages 55-57). He underscored the essential evolutionary advantages of this curious phenomenon, without which, he argues, ‘none of us today would have been born‘ (page 57). The book also stressed that we derive similar wide-ranging benefits from viruses living outside our genomes, citing examples of how rhinoviruses ‘help train our immune systems not to overreact to minor triggers’, and how bacteriophages help us to fight bacterial infections (pages 17 and 38-39). To further illustrate our dependence on viruses, the author highlighted the critical roles marine viruses play such as in protecting us against cholera epidemics, and in producing ‘a lot of the world’s oxygen‘ by contributing to photosynthesis (pages 49-51).
The book described several historical viral epidemics, and in each case it extracted relevant lessons for our future engagement with viruses. An example is its review of the 1918 Spanish influenza pandemic which affected 500 million people, and killed about 50 million. The author discussed several important features of this epochal catastrophe, for example how the elderly were relatively spared because they harboured protective antibodies from a similar pandemic in 1889 (pages 19-21). Another historical virus was the 2009 H1N1 swine flu, remarkable for its ability to evade detection by using reassortment, the process which enables different viral strains to combine their genes (pages 22-23). The author stressed the very high risk of future viral pandemics by pointing out the ease and rapidity by which animal viruses mutate and evolve into human pathogens; to minimise the risks of future epidemics, he argued that surveillance of wild animals will be critical in detecting when their viruses start to develop risky genetic mutations (pages 23-24 and 87).
An extension of the book’s historical approach is the frequent reference to the scientists who resolved the mysteries of viruses. For example, it traced the first discovery of viruses to Adolph Meyer and Martinus Beijerinck, pioneers who recognised that an organism smaller than bacteria, and which is resistant to heat, alcohol, and desiccation, was the cause of tobacco mosaic disease (pages 5-6). The account of the crystallisation studies carried out by Wendell Stanley is equally fascinating because it described the groundbreaking experiments which enabled the visualisation of viruses for the very first time (page 7). Other key figures in the viral saga include Felix d’Herelle who first identified bacteriophages when studying shigella dysentery; Francis Peyton Rous who predicted that viruses were responsible for cancer in rabbits; and Herald zur Hausen who discovered that HPV, human papillomavirus, causes cervical cancer (pages 38-39 and 28-29).
The range of virus-related concepts this small book covers is truly breathtaking. Its discussion of vaccination, for example, is quite thorough. It covered several vaccine breakthroughs, such as the successful eradication of smallpox, a disease which ‘may have killed more people than any other disease on Earth’ (pages 90-93). It narrated the significant breakthrough of HPV vaccination against cervical cancer, noting however that the vaccine is only effective against two of the about 15 cancer-causing strains of the virus (pages 32-33). The author however stressed that, despite some high profile successful vaccination strategies, there are still significant obstacles to stopping viral diseases; to illustrate this, he cited the example of poliomyelitis which has so far ‘withstood eradication thanks to the disruptions of war and poverty‘ (pages 94-95).
This relatively small book is an excellent primer on viruses because it is both detailed and focused. It explores the diversity of viruses and their far-reaching impact on the earth and its inhabitants. The author, a highly informed health journalist, illustrated the ubiquity of viruses, and the diverse diseases they engender. In doing this, he explored the genetic and environmental factors that favour the development of viral epidemics and pandemics. The book however also points out the equally beneficial effect of viruses on our health and environment.
This is a very comprehensive book which is very thorough in its approach to the the topic of viruses. It reviews, in very simple language, the relationship between viruses and humans, pointing out both beneficial and detrimental outcomes. It very helpfully highlights the continual threat of viruses, but points out the practical approaches to containing the threat. It is a very well-written and highly informative book, and I recommend it to all doctors.
Publisher, Place, Year: University of Chicago Press, Chicago, 2011
Number of chapters: 11
Number of pages: 122
Star rating: 5