Superinfection is when a second infectious disease is grafted onto one infectious disease. While virologists use the term “superinfection” only when this second disease is caused by a very similar pathogen – for example, in the case of hepatitis B followed by hepatitis D – the term is often used when the first disease is caused by viruses and the second by bacteria (as in the case of “disseminated bronchitis“).
Use of the term “superinfection”
Actually, the technical term for this is secondary infection. The term superinfection is also used when the initial illness is not caused by an infectious agent at all, but by another cause of illness, such as diabetes or atopic dermatitis, and bacteria then come into play.
Where can a superinfection occur?
The best-known superinfection is disseminated bronchitis. This refers to a flu-like infection triggered by viruses, which first leads to a sore throat, cough, cold and bronchitis, and then develops into purulent bronchitis in a second phase. Due to the viruses, the mucous membranes of the nose and bronchial tubes are already sore and irritated, making it easier for bacteria to take hold and multiply.
Signs of superinfection
Often, after only a few days, you can feel whether your immune system is handling the cold viruses well and the cough and cold quickly go away – or whether the cold becomes tough, the feeling of being sick intensifies again, and coughing up becomes exhausting and perhaps productive: These are all signs of a bacterial superinfection.
Other superinfections are not quite as common, but they can take a dramatic course. For example, long-standing diabetes leads to poor blood flow to the body’s periphery and nerve endings. This can develop into a diabetic foot, where skin lesions heal very slowly because of poor circulation.
Consequences of superinfelction
If a diabetic skin lesion becomes infected with bacteria, the healing process can be so severely disrupted and the infection can spread so massively that surgery or, in the worst case, amputation may even be required. The skin environment is also disturbed in atopic dermatitis, and especially in acute episodes, scratched, weeping skin areas are susceptible to colonization with pathogenic bacteria or fungi. Fortunately, the “real” superinfections occur less frequently.
In order to contract hepatitis D, one must have previously been infected with hepatitis B viruses – only then can hepatitis D viruses survive and multiply in the body.
In the case of infection with HIV, superinfection occurs when a patient who has been infected with HIV type A, for example, later becomes infected with HIV type B as well.
