Typhoid symptoms: the fever pattern, the danger signs, and which test to trust

Typhoid fever is an infection with the bacteria Salmonella Typhi. It spreads through food or water contaminated with the bacteria, usually from the stool of someone who has it or carries it. Once swallowed, the bacteria multiply and spread into the bloodstream.

It's common where clean water and sanitation are limited, in parts of Asia, Africa, and Central and South America. An estimated 9 million people get sick with typhoid each year, and about 110,000 die.

Paratyphoid fever is a similar illness caused by Salmonella Paratyphi, and is tested for and treated in much the same way.

Carriers: some people keep the bacteria in their body after the symptoms go, sometimes for months or years, and can pass it on without feeling ill.

Symptoms usually start 6 to 30 days after infection, often slowly:

• a fever that rises a little each day, reaching 39 to 40°C (103 to 104°F) by the third or fourth day, and lasting more than 3 days
• headache, weakness and tiredness
• chills and body aches
• a dry cough
• poor appetite, feeling sick
• tummy pain, and constipation or diarrhoea, which often come after the other symptoms
• sometimes a rash of flat, light-pink (rose-coloured) spots, usually on the chest or tummy

Without treatment, typhoid can last a month or more. With the right antibiotics, most people make a full recovery.

Serious complications happen in about 10 to 15% of people in hospital with typhoid, usually after 2 to 3 weeks of illness:

• bleeding in the gut
• a hole in the bowel (intestinal perforation), which can cause a severe infection of the tummy lining (peritonitis)
• confusion or drowsiness

Get emergency help now for:

• sudden tummy pain that keeps getting worse
• black or dark red poo
• vomiting blood, or vomit that looks like coffee grounds

Relapse: up to 10% of people get symptoms again, usually 1 to 3 weeks after recovering. See your doctor if the fever comes back after you finish treatment.

Carriers: about 1 to 4% of treated people still carry the bacteria a year later. A doctor may check your stool before you go back to work with food, in healthcare or with young children.

• Blood culture is the preferred test: the lab grows the bacteria from a blood sample. One culture finds it in about 50% of cases, so doctors sometimes take more than one, ideally before antibiotics are started.
• Bone marrow culture finds about 80%, but it's an invasive test used only sometimes.
• Stool culture is usually negative in the first week.

The Widal test is unreliable. It's widely used because it's cheap, but it can be positive in people who don't have typhoid (for example after past infection or vaccination) and negative in people who do. A Widal result on its own shouldn't decide whether you have typhoid or which antibiotic you need. Quick rapid tests aren't very accurate either.

Doctors also check a complete blood count (CBC) and, where they're common, test for malaria and dengue. Our dengue guide explains how that fever differs.

Typhoid is treated with antibiotics, which shorten the illness and lower the risk of complications and death. Which antibiotic is used depends on where the infection was caught, because resistance to antibiotics is increasing, including extensively drug-resistant typhoid. Your doctor may order tests to choose the right one.

• Take the antibiotics exactly as prescribed, and finish the course, even when you feel better. Stopping early can let the illness return and helps resistance spread.
• Don't buy antibiotics without a prescription or use leftover ones: the wrong antibiotic can delay proper treatment.
• The fever may last about 5 days after starting treatment. If it isn't settling by then, or you feel worse, see your doctor again.
• Rest, drink plenty of fluids, and eat small, simple meals when you can. Paracetamol can help with the fever; follow the pack or ask a pharmacist, and ask a doctor for a child.
• Severe typhoid is treated in hospital.

Protect others: wash your hands well with soap after using the toilet and before touching food, and don't prepare food for other people until your doctor says it's safe. Which medicine, and how much, is your doctor's decision.

• Safe water: drink bottled or boiled water, or water that's been disinfected. Avoid ice unless it's made from safe water.
• Safe food: eat food that's been cooked thoroughly and is still hot. Avoid raw milk. Wash fruit and vegetables in safe water, or peel them yourself.
• Wash your hands with soap and water, especially after the toilet and before eating or cooking.
• Vaccines: WHO recommends a typhoid conjugate vaccine, a single injection, for children from 6 months of age and adults in countries where typhoid is common. Travellers can get a typhoid vaccine too, ideally a few weeks before leaving; ask a doctor or travel clinic which one and when. No vaccine protects completely, so food and water care still matters.