Which type(s) of influenza can lead to seasonal epidemics in humans?
The correct answer and explanation is:
The types of influenza that can lead to seasonal epidemics in humans are Influenza A and Influenza B.
Explanation:
Influenza A and Influenza B are the primary strains responsible for seasonal flu outbreaks. These strains typically cause the annual flu season, which often peaks during colder months.
- Influenza A is the most common cause of seasonal epidemics. It has the ability to mutate frequently, allowing it to evade immunity built up from previous infections or vaccinations. Influenza A viruses can infect a wide range of animals, including birds and pigs, which makes it more versatile and prone to reassortment. This can sometimes lead to significant changes in the virus, resulting in new subtypes. The seasonal flu vaccines are updated every year to account for the most common subtypes circulating in the population.
- Influenza B primarily infects humans and is also responsible for seasonal epidemics. Unlike Influenza A, Influenza B does not undergo as much antigenic shift (major genetic changes). However, it still mutates to a degree that can affect immunity. The effects of influenza B infections tend to be less severe than those caused by Influenza A, but they still contribute to a significant number of flu cases during the flu season.
Influenza C does not typically cause seasonal epidemics. It usually results in mild illnesses and is not a major concern in terms of public health. There is also Influenza D, which primarily affects cattle and does not infect humans.
Both Influenza A and B are included in the seasonal flu vaccine, which helps to reduce the impact of the disease and prevent widespread transmission. These vaccines are modified each year to target the strains most likely to cause illness in the upcoming flu season.