Scientific data representation

As a graduate student, one is asked to read and interpret quite a few research and review papers every week. Usually, most of the articles represent data in the form of mundane tables and histograms, which can get tedious. Recently, I read this nature review article on zoonotic diseases (diseases spread between humans and animals, for example, malaria, west nile virus infection, ebola, H1N1 flu, etc) and was really impressed by the unique and creative way the data is represented in it.

NOTE: All images and image captions copyrighted to – Bean AG, Baker ML, Stewart CR, Cowled C, Deffrasnes C, Wang LF, Lowenthal JW. Studying immunity to zoonotic diseases in the natural host – keeping it real. Nature Reviews Immunology. Published online 25 October 2013. doi: 10.1038/nri3551

Figure 1: Emergence of zoonoses. / Tombstones representing number of deaths!

Over the past century, humanity has witnessed the emergence of numerous zoonotic  infections that have resulted in varying numbers of human fatalities. Influenza viruses that originate from birds account for  an important proportion of these deaths, and recently many new zoonotic viruses that originate in bats, such as Hendra  virus, Nipah virus and severe acute respiratory syndrome (SARS) coronavirus, have caused outbreaks with high mortality  rates. Hyperlinks to World Health Organization disease report updates are provided in BOX 1. MERS, Middle East  respiratory syndrome coronavirus.
Over the past century, humanity has witnessed the emergence of numerous zoonotic
infections that have resulted in varying numbers of human fatalities. Influenza viruses that originate from birds account for an important proportion of these deaths, and recently many new zoonotic viruses that originate in bats, such as Hendra virus, Nipah virus and severe acute respiratory syndrome (SARS) coronavirus, have caused outbreaks with high mortality rates.

Figure 2: The severity of emerging infectious diseases is influenced by the host-pathogen interaction. / Organisms in the innermost circle (bats) show no sign of symptoms at all and the signs increase as one moves to the organisms in the outer circle (humans) – leading to high mortality rates. Mainly, animals in the inner blue circle are the transmission hosts. Read ‘The curious case of MERS-CoV‘ for more on MERS transmission hosts.

Many  zoonotic agents cause little or no signs of disease in their natural hosts, such as wild birds and bats, but transmission hosts  might present with disease symptoms ranging from moderate (for example, pigs infected with avian influenza virus) to  severe (for example, horses infected with Hendra virus). The terminal or spillover host can present with severe symptoms  and high mortality rates (for example, in the case of humans infected with H5N1 influenza and Hendra virus). For some of  the most recently identified emerging infectious diseases, such as H7N9 influenza and Middle East respiratory syndrome  (MERS) coronavirus, natural and transmission hosts have not been conclusively identified (indicated by a question mark).  SARS, severe acute respiratory syndrome.
Many zoonotic agents cause little or no signs of disease in their natural hosts, such as wild birds and bats, but transmission hosts might present with disease symptoms ranging from moderate (for example, pigs infected with avian influenza virus) to severe (for example, horses infected with Hendra virus). The terminal or spillover host can present with severe symptoms and high mortality rates (for example, in the case of humans infected with H5N1 influenza and Hendra virus). For some of the most recently identified emerging infectious diseases, such as H7N9 influenza and Middle East respiratory syndrome (MERS) coronavirus, natural and transmission hosts have not been conclusively identified (indicated by a question mark). SARS, severe acute respiratory syndrome.

Figure 3: The host immune response to an infection influences the disease outcome. / The difference in immune response to H5N1 in different spillover hosts.

Infection with H5N1 influenza  virus can cause very different disease outcomes in different reservoir and spillover host species. Waterfowl, such as wild  ducks, are the natural host for this virus and develop a limited inflammatory response that is associated with low levels of  cytokine expression. Intermediate hosts, including mice, pigs and ferrets, are often used to study this infection and display  mild to severe disease symptoms (depending on the H5N1 virus strain used) that are associated with increased levels of  pro-inflammatory cytokines. By contrast, spillover hosts such as chickens and humans display a rapid and strong  inflammatory response, often referred to as hypercytokinaemia (or cytokine storm) and the infection becomes systemic,  causing severe disease symptoms and high mortality rates.
Infection with H5N1 influenza virus can cause very different disease outcomes in different reservoir and spillover host species. Waterfowl, such as wild ducks, are the natural host for this virus and develop a limited inflammatory response that is associated with low levels of cytokine expression. Intermediate hosts, including mice, pigs and ferrets, are often used to study this infection and display mild to severe disease symptoms (depending on the H5N1 virus strain used) that are associated with increased levels of pro-inflammatory cytokines. By contrast, spillover hosts such as chickens and humans display a rapid and strong inflammatory response, often referred to as hypercytokinaemia (or cytokine storm) and the infection becomes systemic, causing severe disease symptoms and high mortality rates.

I think it is really important to represent scientific data in a simple, straightforward and an efficient fashion. Many researchers disregard this fact and don’t acknowledge it well enough.  A really good diagram or data representation is one which contains all important facts or information required to infer the purpose of the diagram itself. One must be able to simply look at it to make interpretations and get the general idea without having to go too much into the depth of long procedures and discussions in the paper. (Sometimes exceptions exists w.r.t. the kind of paper & data, of course.)

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