“Summer flu” is a common term for viral illnesses that cause flu-like symptoms during the warmer months, but the name is often misleading. These infections are typically not caused by the influenza virus, which peaks during winter. This article clarifies the true causes behind this seasonal sickness, details the typical symptoms, and provides practical advice for management and prevention.
What Causes Summer Flu
The true culprits behind most summer flu cases are non-polio Enteroviruses, a large group of viruses that thrive in late summer and early autumn. This makes “summer flu” largely a misnomer, as true influenza is a different virus altogether. Enteroviruses, such as Coxsackievirus, are responsible for a significant number of these infections, with an estimated 10 to 15 million Americans contracting them each year.
These viruses are resilient and can survive in the environment longer than many other respiratory viruses. Transmission frequently occurs through the fecal-oral route, often linked to contaminated water or poor hygiene. Enteroviruses also spread through respiratory droplets (saliva, nasal mucus, or cough) or by touching contaminated surfaces.
The seasonality of Enteroviruses is often tied to people spending more time in close contact, such as in daycare centers or at public swimming pools. Unlike influenza, Enteroviruses are active when temperatures rise. Most adults have developed immunity from prior exposures, which is why these summer illnesses are most common in children, teenagers, and infants.
Identifying the Symptoms
The symptoms of a summer viral infection can mimic the abrupt onset of influenza, including fever, headache, and body or muscle aches. However, the overall illness is often milder and shorter in duration than a severe case of influenza. A runny nose, coughing, and a sore throat are also common presentations, similar to a typical cold.
A distinguishing feature of these summer Enterovirus infections is the higher likelihood of gastrointestinal symptoms, such as nausea, vomiting, or diarrhea. These are less common in adult influenza but frequently associated with these summer bugs. Certain Enterovirus strains, like Coxsackievirus, can also cause specific manifestations rarely seen with influenza. These include hand-foot-and-mouth disease (a rash or blisters in the mouth and on the extremities) or viral conjunctivitis (pink eye).
Treatment and Prevention Strategies
Since the cause of summer flu is viral, antibiotics are ineffective and should not be used. Treatment is primarily supportive, focusing on managing symptoms until the body’s immune system clears the virus. Rest is helpful, as the body requires energy to fight the infection.
Maintaining adequate hydration is important, particularly if vomiting or diarrhea is present. Electrolyte-replacement drinks can help hydrate more quickly than plain water. Over-the-counter medications, such as acetaminophen or ibuprofen, can reduce fever and alleviate body aches. Most healthy people will recover fully within a few days to a week.
Prevention centers on disrupting the common transmission routes of Enteroviruses, especially the fecal-oral route. Rigorous handwashing with soap and water for at least 20 seconds is the most effective action. This is particularly important after using the toilet, changing diapers, or before preparing and eating food. General hygiene practices, such as avoiding close contact with sick individuals and cleaning frequently touched surfaces, also limit the spread of these viruses.