Many diseases show striking seasonal patterns:
- Influenza – winter
- Gastroenteritis – spring equinox
- Measles – spring
- Heart attacks – spring equinox
- Cancer diagnosis – winter
Influenza
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 show a heavily seasonal pattern.
https://www.cdc.gov/mmwr/preview/mmwrhtml/mm4909a1.htm
The exact season however, varies with latitude and seems to be triggered by sudden changes in the weather (humidity, pressure, rainfall..)
Differences in Influenza Seasonality by Latitude, Northern India – Koul et al
https://wwwnc.cdc.gov/eid/article/20/10/pdfs/14-0431-combined.pdf
Spatial Variation in Humidity and the Onset of Seasonal Influenza Across the Contiguous United States — Serman et al
https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2021GH000469
Norovirus
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
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
Fine grained analysis shows characteristic patterns that depend upon both time of year and latitude. This is similar to influenza, which therefore suggests some sort of geo-magnetic disturbance that is influenced by both season and latitude. See: Influenza and field vortices
“We detected significant seasonality of the Google Trends data in 27 of the 34 countries for which weekly data were available. Each geographic region in our study displayed distinct seasonal patterns of information-seeking behaviour. A strong latitudinal pattern was clearly discernible, with peaks early in the year in the Northern Hemisphere and later in the Southern Hemisphere, corresponding to springtime outbreaks worldwide. These spring peaks agree with the seasonal timing found in historical datasets and previous studies of chicken pox . European countries were mostly unimodal, with a peak in March–May, but some had an additional smaller peak in late December. Several countries in the Southern Hemisphere, including Australia, New Zealand, South Africa, and those countries located in South America, had a single discernible peak at various times of the year. China and Japan had bimodal peaks, which occurred in March–May and December–January, balanced by deep summer troughs occurring in July–August. Other Asian countries had a single peak that occurred in February–March, punctuated by a relatively shallow trough.” – Bakker et al
Cancer
First description of seasonality of birth and diagnosis amongst teenagers and young adults with cancer aged 15–24 years in England, 1996–2005 – van Laar et al
https://bmccancer.biomedcentral.com/articles/10.1186/1471-2407-13-365
The diagnosis of cancer in teenagers and young adults (TYA) shows a seasonal pattern, leading to the authors speculating an ‘infectious’ cause:
“Our novel findings support an infectious aetiological hypothesis for certain subgroups of TYA cancer in England. Further work will examine correlation with specific infections occurring around the time of birth and diagnosis within certain diagnostic groups.“
Seasonal Variations in the Diagnosis of Testicular Germ Cell Tumours: A National Cancer Registry Study in Austria – Tulchiner et al
https://www.mdpi.com/2072-6694/13/21/5377
Herpes
Elevation of ambient temperature is associated with an increased risk of herpes zoster: a time-series analysis – Choi, Lim, Lee, Hong
https://www.nature.com/articles/s41598-019-48673-5
Varicella Vaccination Alters the Chronological Trends of Herpes Zoster and Varicella – Wu, Wu, Choi, Sung
https://www.researchgate.net/publication/258350867_Varicella_Vaccination_Alters_the_Chronological_Trends_of_Herpes_Zoster_and_Varicella
Chart showing herpes zoster and varicella. When one increases, the other decreases. The sum of the two is approximately constant most of the time. Possible diagnostic artefact?
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