Ask any epidemiologist if a disease is deadly, and they will likely respond with a statement whereby the word deadly is defined. For example, is chicken pox deadly? If the intent is to say that it can kill people who contract it, then the answer is that, yes, chicken pox is deadly. (CDC): "In the prevaccine era, approximately 11,000 persons with varicella required hospitalization each year. Hospitalization rates were approximately 2 to 3 per 1,000 cases among healthy children and 8 per 1,000 cases among adults. Death occurred in approximately 1 in 60,000 cases. From 1990 through 1996, an average of 103 deaths from varicella were reported each year. Most deaths occur in immunocompetent children and adults. Since 1996, hospitalizations and deaths from varicella have declined more than 70% and 88% respectively."
Now, if there is some arbitrary threshold with regards to number of dead before something can be called deadly, that is a whole other discussion outside of the scope of this blog. However, , and this week was not very different. A reader contacted us to complain that we were "demonizing" chicken pox, and their evidence was their own personal experience. They claim that they were not scarred by chicken pox and that "none of the other children who had the disease when [they] did were in any way disfigured." We were then warned that we would "pay a price" for "pushing [our] agenda" by "misleading" the public.
If we are misleading the public, then we are not alone in doing so. You read what CDC had to say about chicken pox in the United States: children have died from it. : "We examined varicella deaths in the United States during the 25 years before vaccine licensure and identified 2262 people who died with varicella as the underlying cause of death. From 1970 to 1994, varicella mortality declined, followed by an increase. Mortality rates were highest among children; however, adult varicella deaths more than doubled in number, proportion, and rate per million population. Despite declining fatality rates, in 1990–1994, adults had a risk 25 times greater and infants had a risk 4 times greater of dying from varicella than did children 1–4 years old, and most people who died of varicella were previously healthy. Varicella deaths are now preventable by vaccine. Investigation and reporting of all varicella deaths in the United States is needed to accurately document deaths due to varicella, to improve prevention efforts, and to evaluate the vaccine's impact on mortality."
It's not just deaths directly attributed to chicken pox that make it deadly, however. Combined with social inequities and in developing nations with high indices of poverty and lack of access to care (and the vaccine), chicken pox can be the disease that tips a child or adult into dying. : "Average annual mortality rates for varicella in Brazil between 1996 and 2011 ranged from 0.88 cases/100,000 population aged < 1 year to 0.02 cases/100,000 population aged 15–19 years (Fig. 9). In total over this period, 2334 varicella-associated deaths were reported; the authors note that this represents almost one death every 2 days.
A study of varicella-related mortality in children aged < 7 years attending municipal daycare centers in the city of São Paulo, Brazil, reported 12 deaths in the period 1996–1999, a rate of 0.240/100,000. By comparison, the rate of varicella-related death rates for all children in the county was 0.105/100,000.
The fatality rate was 2% among Brazilian inpatients with varicella (N = 255) in the period 2004–2005; causes of death included pneumonia-associated encephalitis, hemorrhagic varicella associated with septicemia, and immunosuppression.
An analysis of varicella cases leading to death by the Ministerio de Salud in Argentina showed that deaths from this cause occurred in all age groups (Fig. 10)."
Thus, to a person like the reader who emailed us, chicken pox is not a deadly disease because they and their peers survived it unscathed. To the parents of one of the children who have died from chicken pox, the disease is undeniably and unimaginably deadly. To me, as an epidemiologist, the numbers say that it is deadly. Is it as deadly as other childhood diseases? Of course not, but that doesn't take away the "deadly" adjective from it, in my opinion.
Furthermore, my opinion is also guided by my own experience. I grew up in northern Mexico, spending summers and holidays with my relatives in a small town that -- at the time -- lacked full access to preventative care and proper sanitation. I saw many families bury children my age. I never saw some of the friends I made as a child because they died from meningitis, measles, diphtheria and diarrheal diseases. However, I was lucky to live in a big city on the border with the United States; we had access to vaccines, medical care and potable water.
Many of the debates we are having today on scientific matters are not really "scientific" in the true sense of the word. They are more "philosophical" or "social" debates. The Earth is flat. The climate is changing. Germ theory explains the transmission patterns of infectious disease. It is our point of view and our social values that lead us to have debates about concepts whose foundations are set. Unfortunately, those debates sometimes end up being contentious, uncivilized or downright violent. Scientific discussions for the advancement of science and discovery should be better than that. We should be better than that.