Summer is a time for sun-drenched fun. From relaxed days outdoors to packed festival fields and meals under open skies. But with the joy of the season comes an overlooked downside: a heightened risk of infection.
Author
- Manal Mohammed
Senior Lecturer, Medical Microbiology, University of Westminster
Warmer weather, increased social interaction and more frequent contact with unfamiliar environments all make it easier for germs to spread. That's why handwashing becomes especially important during the summer months. It might not be glamorous, but clean hands are your first line of defence against the microbes that love to crash summer plans.
Microbes thrive in warmth and moisture, and the activities we enjoy in summer often bring us into closer contact with the surfaces, food and water sources that help them spread.
1. Public restrooms and shared toilets
Outdoor festivals, service stations, beaches and campsites all rely on public toilet facilities. These high-traffic areas can become breeding grounds for bacteria like E coli, salmonella and Staphylococcus aureus. Viruses such as norovirus and flu also spread easily via contaminated surfaces. Even coronavirus can persist in poorly ventilated or inadequately cleaned environments.
Washing your hands thoroughly after using public toilets is essential - and hand sanitiser may not be enough if your hands are visibly dirty.
Worryingly, even in places where hygiene is critical, like hospitals, people often skip this basic step. A 2025 study found that nearly half of hospital visitors failed to wash their hands after using the toilet, despite clear reminders. If so many people skip handwashing in hospitals, where the risks are obvious and facilities readily available, how many more are failing to do so at summer events, where soap and water can be scarce?
2. Outdoor eating and food preparation
Barbecues and picnics are summer staples - but they come with a side of risk. Foodborne pathogens like salmonella, E coli, Bacillus cereus and Staphylococcus aureus thrive in warm temperatures. Undercooked meat, poor hand hygiene and leaving food out in the sun can easily turn a festive gathering into a bout of food poisoning.
Even fungi such as Aspergillus can grow on food and produce mycotoxins: toxic compounds that can cause nausea, organ damage or even long-term harm when ingested.
Wash hands before and after handling food, especially raw meat and after touching shared surfaces like picnic tables, barbecue tools and cool boxes.
3. Swimming and water play
Lakes, rivers, swimming pools and oceans can all harbour harmful germs. Parasites like cryptosporidium and giardia can cause gastrointestinal illness - and they're often resistant to chlorine. Beach sand and seawater can also carry faecal bacteria.
Whether you're swimming, paddling or just building sandcastles, make sure to wash or sanitise your hands before eating or touching your face.
4. Camps, playgrounds and festivals
Children are particularly vulnerable to infection in summer thanks to group settings like summer camps, soft play centres and playgrounds.
A US study reported 229 youth camp-associated outbreaks of gastroenteritis over seven years. Common culprits included norovirus, salmonella and Shiga toxin-producing E coli, a particularly dangerous strain of E coli that can cause severe illness and even kidney failure.
In one incident, 20 campers became ill, and three were hospitalised, after eating undercooked beef cooked over a campfire . Shared toilet facilities, communal food preparation and tight sleeping arrangements all increase the importance of hand hygiene.
But isn't it good to 'get a bit dirty'?
Some people believe that letting children get dirty helps build their immune system. While early exposure to natural microbes from soil, animals or the environment can support immune development, this is not the same as skipping handwashing after using the toilet or before meals.
Leaving hands unwashed doesn't strengthen the immune system - it increases the risk of illness. No credible studies show that poor hygiene is good for you. On the contrary, unwashed hands are a leading cause of preventable infections worldwide. This risk is especially serious for young children, older adults and people with weakened immune systems.
Hand hygiene is simple, cheap and effective - and never more important than in summer. As the hospital toilet study shows, we can't assume that people are washing their hands properly, even in places designed to protect health. Add in the chaos of a campsite or the distractions of a music festival, and it becomes even easier to forget.
So, whether you're hiking, camping or dancing in a field, you should wash your hands with soap and clean running water for at least 20 seconds and then dry them properly as damp hands spread germs more easily. Use hand sanitiser (at least 60% alcohol) if soap and water aren't available and ideally keep some in your bag in case you can't rely on public facilities.
Manal Mohammed does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.
