H1N1 virus is sometimes mentioned in the news with reference towhich one of the following diseases?

1. A

   AIDS

   AIDS is caused by HIV, a retrovirus, not by H1N1. This option is not the key.

2. B

   Bird flu

   Bird flu is typically associated with avian influenza strains such as H5N1, not H1N1 as ‘bird flu’. This option is therefore wrong.

3. C

   Dengue

   Dengue is a flavivirus transmitted by Aedes mosquitoes, not an influenza H1N1 disease. This option is not the key.

4. D

   Swine flu

   H1N1 influenza virus is the agent of swine flu (the 2009 pandemic strain was influenza A(H1N1)pdm09). This option is the official key.

Summary. Official key is (d) Swine flu. H1N1 is an influenza A subtype circulating in pigs and in humans after zoonotic events; the 2009 pandemic popularised the ‘swine flu’ name. HIV, H5N1-type bird flu and dengue viruses are different pathogens. Haemagglutinin (H) and neuraminidase (N) numbering identifies influenza subtypes. Only (d) matches H1N1.