Asthma occurs in adults and children, and usually starts in childhood.
According to a 2018 Global Asthma Report, "Asthma kills around 1000 people every day and affects as many as 339 million people - and prevalence is rising. Low- and middle-income countries disproportionally suffer the most severe cases. We have the tools to counter the devastating personal and economic impact of untreated and poorly managed asthma."
Asthma is more common in boys and is seen predominantly in children who are allergic or come from allergic families. It tends to run in families, as do related allergic conditions, such as hay fever and eczema.
Approximately 50% of childhood asthma, particularly if it’s mild, goes into remission during the teenage years. However, as many as 30% of teenagers in asthma remission go on to re-develop asthma during adulthood.
Asthma usually persists if contracted during adulthood.
For decades, it was accepted that allergic diseases were infrequent amongst black people and in people who live in rural communities. Recent studies have confirmed that black people with asthma are much less likely to have parents or older siblings who suffer from asthma (family history) than other asthma sufferers.
However, if a black person does have a positive family history of asthma, they are much more likely to have asthma than black people without a family history, and even people from other races with a family history. In patients who have moved from rural to urban areas, either the early exposure to foreign allergens from the newly adopted Western lifestyle or the loss of protection from the rural lifestyle, contributes to a higher degree of allergic sensitisation recorded amongst African infants than in other races. These factors account for the increased number of black children who have asthma.