Question

Infectious diseases can emerge through genetic, social and behavioural changes in the host and/or pathogen.

Provide: (a) two examples of genetic changes, and (b) two examples of social or behavioural changes that have enabled new infectious diseases or new strains to emerge.

In all four examples that you give, name the pathogens and explain how the changes led
to disease emergence. Mandatory word limit: Write no more than 200 words in total.

Answer 1

Infectious diseases that emerge through genetic changes in the host and/or pathogen are

• Nosocomial infection caused by Methicillin-resistant Staphylococcus aureus (MRSA). The drug resistance is acquired by genetic changes caused in pathogen by introduction of antibiotic resistance gene via plasmid e.g. (NDM-1 i.e. New Delhi β-lactamases).
• Influenza virus: due to antigenic drift shown by the influenza virus, it is another example of genetic changes in pathogen.
• Brazilian purpuric fever caused by clonal variant of Haemophilus influenzae type b bacteria

Infectious diseases that emerge through social / behavioural changes in the host.

• AIDS/HIV, emergence has occurred mainly due to irresponsible sexual behaviour of humans, and intravenous drug abuse.
• Cholera due to Vibrio cholerae: emergence in South America and Africa has occurred mainly due international travel and commerce via Asia .(through contaminated water)