Influenza Seasonality: Underlying Causes and Modeling Theories

Please cite this paper as: Adhin et al. (2012) Trends of Influenza infection in Suriname. Influenza and Other Respiratory Viruses DOI: 10.1111/irv.12037.The trends of influenza infection in Suriname were assessed from February 2010 through February 2011. Testing of 393 patients with symptoms of acute respiratory infection (ARI) revealed 15·3% Influenza B and 18·6% could be identified as influenza A positive, consisting of 56% influenza A(H1N1)pdm09 and 44% seasonal A(H3N2). Influenza infection occurred throughout the year, and all three influenza types affected young children as the primary population. The annual incidence of A(H1N1)pdm09 was 6·88 per 100 000 inhabitants [CI] 4·87–9·45. The spread of influenza could neither be linked to tourist flow from the Netherlands nor to contact rates related to school schedules.

Section: Discussioncontrasting

confidence: 68%

Trends of influenza infection in Suriname

Adhin

Grunberg²,

Labadie-Bracho³

2012

“…Recent research suggests a connection to weather, particularly cold and/or dry (low humidity) air 3. Possible explanations for this relationship includes factors related to virus characteristics,4, 5 drying of nasal mucous membranes,6 enhanced airborne transmission,7 and human behavioral factors 8…”

Section: Introductionmentioning

confidence: 99%

Cold, dry air is associated with influenza and pneumonia mortality in Auckland, New Zealand

Davis

Dougherty

McArthur

et al. 2016

The relationship between weather and influenza and pneumonia mortality was examined retrospectively using daily data from 1980 to 2009 in Auckland, New Zealand, a humid, subtropical location. Mortality events, defined when mortality exceeded 0·95 standard deviation above the mean, followed periods of anomalously cold air (t a.m. = −4·1, P < 0·01; t p.m. = −4·2, P < 0·01) and/or anomalously dry air (t a.m. = −4·1, P < 0·01; t p.m. = −3·8, P < 0·01) by up to 19 days. These results suggest that respiratory infection is enhanced during unusually cold conditions and during conditions with unusually low humidity, even in a subtropical location where humidity is typically high.

“…In temperate regions, influenza epidemics exhibit clear seasonality with peaks during winter months3, 4 suggestive of an association with climatic factors. In these regions, lower temperature and lower specific humidity have been shown to be significantly associated with increased influenza activity 5, 6. In contrast, influenza seasonal characteristics are less predictable in tropical and subtropical regions which are characterized by semiannual epidemics or year‐round influenza activity 5, 7, 8, 9, 10.…”

Section: Introductionmentioning

confidence: 99%

Influenza activity in Kenya, 2007–2013: timing, association with climatic factors, and implications for vaccination campaigns

Emukule

Mott

Spreeuwenberg

et al. 2016

BackgroundInformation on the timing of influenza circulation remains scarce in Tropical regions of Africa.ObjectivesWe assessed the relationship between influenza activity and several meteorological factors (temperature, specific humidity, precipitation) and characterized the timing of influenza circulation and its implications to vaccination strategies in Kenya.MethodsWe analyzed virologically confirmed influenza data for outpatient influenza‐like illness (ILI), hospitalized for severe acute respiratory infections (SARI), and cases of severe pneumonia over the period 2007–2013. Using logistic and negative binomial regression methods, we assessed the independent association between climatic variables (lagged up to 4 weeks) and influenza activity.ResultsThere were multiple influenza epidemics occurring each year and lasting a median duration of 2–4 months. On average, there were two epidemics occurring each year in most of the regions in Kenya, with the first epidemic occurring between the months of February and March and the second one between July and November. Specific humidity was independently and negatively associated with influenza activity. Combinations of low temperature (<18°C) and low specific humidity (<11 g/kg) were significantly associated with increased influenza activity.ConclusionsOur study broadens understanding of the relationships between seasonal influenza activity and meteorological factors in the Kenyan context. While rainfall is frequently thought to be associated with influenza circulation in the tropics, the present findings suggest low humidity is more important in Kenya. If annual vaccination were a component of a vaccination strategy in Kenya, the months of April to June are proposed as optimal for associated campaigns.