Table 2. Seasonal drivers of human infectious diseases (continued from Table 1).

Drivers categorized as being related to (a) vector seasonality, (b) seasonality in nonhuman animal host (i.e., livestock, other domestic animals, or wildlife), (c) seasonal climate (e.g., temperature, precipitation, etc.), (f) seasonal exposure and/or behavior and/or contact rate, (g) seasonal biotic environment (e.g., algal density in waterbodies), (h) seasonal flare-up/symptoms and/or remission/latency, (i) observed seasonal incidence with no hypotheses regarding drivers.

Infection/disease	Type	Seasonal driver(s)	Description
Haemophilus influenzae	Acute	i	Slightly elevated incidence in winter (in the US) [29]
Hepatitis A	Acute	f and i	Dry season (in Brazil) [30, 31]
Hepatitis B	Chronic	h	Seasonality is observed with elevated levels in spring and summer and/or autumn in some parts of the world, whereas there is lack of seasonality in other parts of the world [31, 32]
Hepatitis C	Acute and chronic	f	Seasonality observed in some countries and absent in others; spring and/or summer peaks in Egypt, China, and Mexico while there is a winter peak in India [31]
Hepatitis E	Acute	c	Waterborne outbreaks occur during the rainy season or following flooding (in China) [33]
Herpes zoster (shingles)	Acute and chronic	i and h*	Highest in August and lowest in winter (in Japan) [34]
HIV	Chronic	g	There is some evidence to suggest there is seasonal variation in the progression to AIDS; hypothesized to be related to seasonal nutritional deficiencies (study done in Uganda) [35]
Influenza	Acute	c	Winter (in the Northern Hemisphere) [36]
Japanese encephalitis	Acute	a	It is seasonal in the northern part of the tropical zone; outbreaks happen at the end of the rainy season, but there is no seasonal pattern in tropical regions [37]
Lassa fever	Acute	c	Increase in the number of Lassa fever cases during the dry season (in Nigeria) [38]
Legionellosis	Acute	c	Peaks during hot months and particularly during humid periods (in the US) [39]
Leishmania	Chronic	a	Transmitted by sand flies; domestic dogs are the main reservoir, and they are exposed during a discrete transmission season [40]
Leprosy	Chronic	b	Armadillos are the reservoir, and antibody prevalence is seasonal within them [41]
Leptospirosis	Acute	c	Peaks when there is hot weather; usually in a rainy period (on all continents) [42]
Lyme disease	Acute and Chronic	a	Peaks in summer around the time of maximal activity of the nymphal stage of the tick vector (in the US) [43]
Lymphatic filariasis	Chronic	a and c	Transmission is intensified during the rainy season [44]
Malaria	Acute	a	There is a spectrum of seasonal strength; some regions have strong seasonality and no seasonality in others [45]

Since seasonal timing may differ among geographic areas, study location is indicated in parentheses.

*Indicated by author.