South Africa is well into the 2019 influenza season. Influenza virus infections cause significant morbidity and mortality on an annual basis resulting in up to five million cases of severe illness and 650 000 deaths globally each year. There have been media reports that refer to outbreaks of “swine flu”, the name incorrectly given to the circulating H1N1 strain that was introduced into the population in 2009. However, the National Institute for Communicable Diseases (NICD) has reported that more than 90% of all influenza A samples tested this season are subtype H3N2, not H1N1. It is important to note that both H1N1 and H3N2 co-circulate, and together with influenza B are normal seasonal influenza strains, cause disease of the same severity and should be managed in the same way.

An influenza infection typically presents with sudden onset of fever, myalgia (muscular aches and pains), cough, sore throat, rhinitis (runny or congested nose) and headache. In the majority of people, it will clear over the course of a few days, but influenza may progress to pneumonia, secondary bacterial or viral infections, and even multi-organ failure especially in individuals at high risk for severe disease.

High-risk individuals include:

• pregnant women;

• immunocompromised individuals (like HIV positive patients, diabetics, cancer patients or patients on chemotherapy;

• persons with chronic diseases such as congestive heart failure or COPD;

• persons who are morbidly obese; • persons over the age of 65 years;

• children under the age of 2 years.

Routine testing of uncomplicated cases is not recommended as it is unlikely to alter the management of the patient. During peak influenza season, someone presenting with flu-like symptoms is likely to have influenza. If oseltamivir (Tamiflu®) is to be used, it should be initiated within 48 to 72 hours of the onset of symptoms and thus one should not wait for the result of testing before initiating treatment. Testing is recommended in high-risk individuals and those ill enough to require hospitalisation as it confirms the diagnosis, directs the use of oseltamivir and assists with infection control. Testing involves a swab done in the nose or throat. Turnaround time is 24hours.

References Blumberg L et al. Influenza: NICD recommendations for the diagnosis, prevention, management and public health response. Available at http://www.nicd.ac.za/ wp-content/uploads/2017/03/Influenza-guidelines-final_24_05_2017.pdf, accessed 19 June 2019 http://www.nicd.ac.za/no-influenza-outbreak-in-south-africa/, accessed 19 June 2019

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