Many diseases show striking seasonal patterns:
- Influenza – winter
- Gastroenteritis – spring equinox
- Norovirus – adenovirus
- Measles – spring
- Heart attacks – spring equinox
Influenza admissions according to the CDC demonstrate a precise peak about 10 days before winter solstice. Why?
Admissions precede the shortest day and cannot therefore be caused by any occurrence on that day.
https://www.cdc.gov/mmwr/preview/mmwrhtml/mm4909a1.htm
Deaths from influenza peak at winter solstice. Deaths usually occur after some days or weeks of sickness so these patients did not just drop dead but contracted flu in advance so as to create a peak at midwinter. How?
https://www.cdc.gov/mmwr/preview/mmwrhtml/mm4909a1.htm
Norovirus is supposedly a transmissible disease but nevertheless seems to know what time of year it is. Peaks at winter solstice, zero at midsummer.
Estimated hospitalizations attributed to norovirus and rotavirus infection in Canada, 2006–2010 – Morton et al
https://www.researchgate.net/publication/277085418_Estimated_hospitalizations_attributed_to_norovirus_and_rotavirus_infection_in_Canada_2006-2010
Gastroenteritis, a ‘stomach bug’ peaks around spring equinox!
Very interesting Children peak at a different time to adults and display an intriguing biennial pattern.
Estimated hospitalizations attributed to norovirus and rotavirus infection in Canada, 2006–2010 – Morton et al
https://www.researchgate.net/publication/277085418_Estimated_hospitalizations_attributed_to_norovirus_and_rotavirus_infection_in_Canada_2006-2010
Heart attacks again are seasonal. Here we see the pattern for heart attacks within hospitals so we can’t really blame physical exertion or excessive cold.
Outside of hospitals, the phenomenon was found to be more common in temperate climates.
Seasonal Variation in the Incidence of In-Hospital Cardiac Arrest – Ashraf et al
https://www.jacc.org/doi/full/10.1016/j.jacep.2023.04.012
This chart of Australian data shows heart attacks peaking close to the spring equinox. The seasonal pattern was found for both acute and chronic heart disease.
Provisional Mortality Statistics – Australian Bureau of Statistics
https://www.abs.gov.au/statistics/health/causes-death/provisional-mortality-statistics/jan-dec-2022
Seasonal variations in cardiovascular disease – Stewart et al
(Most predominant in temperate climates)
https://www.nature.com/articles/nrcardio.2017.76
Winter Cardiovascular Diseases Phenomenon – Auda Fares
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3662093/
Strokes – midwinter:
An analysis of recent stroke cases in South Africa: Trend, seasonality and predictors – Ranganai, Matizirofa
https://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0256-95742020000200007
Kawasaki disease and Adenovirus, again winter seasonality.
Calculating the fraction of Kawasaki disease potentially attributable to seasonal pathogens: a time series analysis – Valtuille et al
https://www.thelancet.com/journals/eclinm/article/PIIS2589-5370%2823%2900255-9/fulltext
Pertussis (whooping cough) is again winter-seasonal
Monitoring Pertussis Infections Using Internet Search Queries – Zhang et al
https://www.nature.com/articles/s41598-017-11195-z
Measles is heavily seasonal in late winter / early spring
In this paper they try to model the seasonal pattern of measles by a modified infection model. But if the main feature is seasonality all you need to predict the number of cases is to look at the calendar!
Modelling seasonal measles transmission in China – Bai, Liu
https://www.sciencedirect.com/science/article/abs/pii/S1007570415000088
Measles again, this time from the WHO – peaking in spring
https://vaxopedia.org/2019/07/08/when-is-measles-season/
Chickenpox
Digital epidemiology reveals global childhood disease seasonality – PNAS
https://www.pnas.org/doi/10.1073/pnas.1523941113
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