Shigellosis (shigella infection): symptoms, treatment and prevention in the UK

Shigellosis is the name doctors give to infection of the bowel with shigella bacteria. NHS inform explains that shigella is found most commonly in faeces and that it is usually caused by food contamination, although it can also pass directly from one person to another. Anyone can catch it, but NHS inform notes that it is most common in young children.

The infection is one of the recognised causes of dysentery, the general term the NHS uses for an infection that gives you diarrhoea with blood in it. Many people with shigella never see blood, and the picture ranges from a day or two of loose stools to a more severe illness with fever and cramping. Because the bacteria are shed in the stool, the practical focus of care is rehydration, careful hygiene and preventing spread to others.

Shigella is also one of several germs that can cause what people loosely call food poisoning. The NHS names campylobacter, salmonella, E. coli and norovirus as the usual causes of food poisoning in the UK, and the same general advice on fluids and when to seek help applies to many of these infections.

According to NHS inform, most people with shigella have mild symptoms that settle within a few days. Symptoms usually begin 1 to 3 days after infection and can last up to a week. The pattern can be mild in one person and much more severe in another, which is why the advice depends on how you are, not simply on the diagnosis.

• Watery diarrhoea, which in severe cases may contain blood, mucus or pus.

• Feeling sick or being sick.

• Tummy (abdominal) pain.

• A high temperature, listed by NHS inform as a fever over 38 degrees Celsius.

• Feeling low or generally unwell.

NHS inform advises contacting your GP practice if you have symptoms of shigella, if your diarrhoea contains blood or if you are worried. If you think the infection was passed on during sex, it advises contacting a local sexual health service.

The NHS page on dysentery says to ask for an urgent GP appointment or get help from NHS 111 if you or your child have bloody diarrhoea, and to mention any recent travel abroad. The NHS food poisoning page adds that you should call 111 if you are worried about a baby under 12 months, if a child stops feeding, if signs of dehydration persist after using oral rehydration sachets, if you keep being sick and cannot keep fluid down, or if diarrhoea lasts more than 7 days or vomiting more than 2 days.

Call 999 or go to A&E, according to the NHS, if you or your child vomit blood or something that looks like ground coffee, have a stiff neck and pain looking at bright lights, have a sudden severe headache or severe tummy ache, have blue, grey, pale or blotchy skin, lips or tongue, have severe difficulty breathing or are confused or not responding as usual.

NHS inform says shigella passes from person to person through poor hygiene, for example not washing hands thoroughly after using the toilet. In Scotland, it notes that most cases are passed on within families and in settings where people are in close contact, such as schools and nurseries. It is mostly caused by contaminated food but can also be passed on sexually, and sex that may involve contact with faeces is the route: anal sex, oral sex that involves licking the anus, fisting, touching a condom or sex toy used for anal sex and having oral sex after anal sex. NHS inform says you could be at higher risk if you are a man who has sex with men.

The NHS dysentery page lists eating food or drink handled by someone with the infection, drinking unclean water, especially when travelling abroad, and oral or anal sex with an infected person as the main routes. NHS inform advises against drinking tap water in countries with poor sanitation systems.

NHS inform also states that shigella occurs more often in people living with HIV, and that if you have shigella that may have been passed on through sex you should be offered an HIV test. Early diagnosis helps treatment and also helps prevent passing HIV on.

When you see a GP or nurse they will talk through your symptoms and ask about recent travel. You should also say if you think you picked up the infection through sex. NHS inform says further tests may be recommended to confirm the infection, and that testing involves sending a sample to a laboratory.

The two main ways of collecting a sample, according to NHS inform, are a stool sample and a swab, where a small cotton bud is gently wiped over an area that might be infected, such as inside the anus. The NHS dysentery page explains that you will need to give a poo sample to find out the cause, because the choice of treatment depends on what is causing the illness.

NHS inform says shigella infection usually clears up on its own without treatment, and that a GP may prescribe antibiotics if symptoms are severe or continue after 1 week. The NHS says people with severe dysentery may need treatment in hospital.

The most important self-care step is to avoid dehydration. The NHS advises drinking plenty of fluids, particularly water, so that you pee regularly and do not feel thirsty, using oral rehydration sachets mixed with water, and eating when you feel able to. It also says you do not need to avoid any foods. For dysentery, the NHS specifically says not to use anti-diarrhoea medicines. This is different from advice for milder food poisoning, so ask a pharmacist or GP if you are unsure which applies.

Hand washing with soap and water is the central measure: regularly, before preparing food and eating, and after using the toilet. NHS inform adds washing hands after sex, especially after touching someone's anus or handling used condoms or sex toys, using condoms for anal sex and dental dams for rimming.

When travelling in places without a clean water supply the NHS suggests drinking only bottled or boiled water, cleaning your teeth with bottled or boiled water, avoiding ice in drinks and ice cream, and avoiding uncooked fruit and vegetables, including salads, unless you have washed them in bottled or boiled water and prepared them yourself.

Most people with a suspected bowel infection are assessed by their GP or NHS 111 and have stool samples processed through NHS laboratories, without charge for the test. Sexual health services provide free, confidential testing and treatment for infections passed on through sex, including HIV testing.

Some people choose to see a private GP or use a private laboratory for faster access to a stool test, for example before travel or when symptoms persist. The underlying tests are the same as those used in the NHS. Whichever route you use, keep to the hygiene rules above until at least 48 hours after symptoms stop, and tell the clinician about travel and any possible sexual exposure so the right tests are chosen.