Related Experiment Video
Updated: Feb 6, 2026

A Method of Trigonometric Modelling of Seasonal Variation Demonstrated with Multiple Sclerosis Relapse Data
Published on: December 9, 2015
Seasonal Variation in Human Adenovirus Conjunctivitis: A 30-Year Observational Study
Jennifer Lee1, Richard A Bilonick1,2, Eric G Romanowski1,3
1a Department of Ophthalmology and Visual Sciences , University of Pittsburgh Medical Center , Pittsburgh , Pennsylvania , USA.
Purpose:
The aim of this study is to measure the seasonal trends of adenovirus conjunctivitis.
Methods:
A total of 926 positive cases of HAdV conjunctivitis were reviewed at the University of Pittsburgh Medical Center (UPMC) in Pittsburgh (Allegheny County, Pennsylvania, USA) from 11th March 1987 to 15th December 2016. To determine seasonal variation, daily counts were adjusted for yearly changes in Allegheny County population size, modelled as a function of long-term trend using Basis-spline (B-spline), and analysed for seasonal trend by quarter (1Q = January to March, 2Q = April to June, 3Q = July to September, 4Q = October to December).
Results:
The number of adenovirus conjunctivitis cases in 3Q was 45% higher than that of 2Q (95% confidence interval [CI] 1.21-1.74, P = 0.0001). When 3Q is compared to 1Q and 4Q, it was not statistically significant (95% CI 0.96-1.42, P = 0.1209 and 95% CI 0.96-1.41, P = 0.1180, respectively).
Conclusion:
To the best of our knowledge, this is the first report and the longest time-series evaluating the potential seasonality of adenovirus conjunctivitis in the USA. We observed the highest number of cases from July to September and the lowest number of cases from April to June in our study population. Knowledge of seasonality can be used to guide outbreak expectations, limit antibiotic over-prescription, and enhance disease prevention.
Related Concept Videos
Observational Studies
There are three types of observational studies – Prospective, retrospective, and cross-sectional.
Prospective Study
Prospective studies, also known as longitudinal or cohort studies, are carried out by collecting future data from groups sharing similar characteristics. One...
Seasoning of Wood
Achieving equilibrium moisture content is the goal of seasoning; this is the point where the wood's moisture content stabilizes to align with the moisture levels of the surrounding environment. Proper...
What is Variation?
The range, standard deviation, standard error, and variance are the different measures of variation.
Range: The range is the difference between its maximum and...
Biological Clocks and Seasonal Responses
Conservative Site-specific Recombination and Phase Variation
The recognition sites for Cre recombinase called LoxP...
Variation
When independent and dependent variables are plotted on a scatter plot, the slope of a line is a value that describes the rate of change between the two...

