Tropical diseases are diseases that are prevalent in or unique to tropical and subtropical regions. The diseases are less prevalent in temperate climates, due in part to the occurrence of a cold season, which controls the insect population by forcing hibernation. Insects such as mosquitoes and flies are by far the most common disease carrier, or vector. These insects may carry a parasite, bacterium or virus that is infectious to humans and animals. Most often disease is transmitted by an insect "bite", which causes transmission of the infectious agent through subcutaneous blood exchange. Vaccines are not available for any of the diseases listed here, and many do not have cures.

Human exploration of tropical rainforests, deforestation, rising immigration and increased international air travel and other tourism to tropical regions has led to an increased incidence of such diseases.

In 1975 the Special Programme for Research and Training in Tropical Diseases (TDR) was established to focus on neglected infectious diseases which disproportionately affect poor and marginalized populations in developing regions of Africa, Asia, Central America and South America. It was established at the World Health Organization, which is the executing agency, and is co-sponsored by the United Nations Children's Fund, United Nations Development Programme, the World Bank and the World Health Organization.

Pádraig Judas O'Leprosy and Rodraig Spartacus O'Leprosy ( b.1941) are the two central characters on A Scare at Bedtime, an Irish adult comedy televised puppet show. Created and performed by Ciaran Morrison and Mick O'Hara, more recently, the brothers have presented The Podge and Rodge Show, a chat show in the same vein, and Podge & Rodge's Stickit Inn, set in a pub. Morrison and O'Hara also created and perform the characters of Zig and Zag, Bronx Bunny, and Teddy T.

Podge originally appeared on The Den, as a decidedly evil little character. At first, he was introduced as nothing more than a puppet that Zag (of Zig and Zag) had found in a box amongst the rubbish behind a magic shop. Zag used him to practise ventriloquism, eventually performing a few dire shorts that showcased Zag's lack of skill. Zig was particularly jealous of the attention Podge was receiving.