Typhoid, Viral Fever or Something Else? Reading a Fever Pattern
In much of South Asia, Africa and Latin America, a fever lasting more than a few days has a recognisable differential. Getting the right diagnosis matters because the treatments are entirely different and some of these illnesses deteriorate quickly.
Ordinary viral fever
- Fever usually 3 to 5 days, often settling by day 5 to 7
- Body ache, headache, sore throat, runny nose, cough
- Mild to moderate fever that responds to paracetamol
- No specific treatment; fluids, rest, paracetamol
Most short fevers are this. Antibiotics do nothing.
Dengue
- Abrupt high fever, often 39 to 40°C
- Severe headache, classically behind the eyes
- Intense muscle and joint pain
- Rash, often appearing as fever subsides
- Falling platelets and white cells
- The dangerous phase starts as the fever falls, days 3 to 7
- No NSAIDs; paracetamol only
Typhoid, enteric fever
- Fever that rises in a stepwise pattern over several days rather than spiking immediately
- Fever often persists and climbs through the first week, frequently higher in the evening
- Headache, marked fatigue, abdominal discomfort
- Constipation is more common than diarrhoea in adults, which surprises people
- Loss of appetite, coated tongue
- Relative bradycardia: the pulse is slower than expected for the degree of fever
- Enlarged spleen, sometimes faint rose-coloured spots on the trunk
- Transmitted through contaminated food and water
Untreated typhoid can cause intestinal perforation and bleeding in the third week. It needs antibiotics, and drug-resistant strains are an increasing problem, so culture-guided treatment is preferable where possible.
Malaria
- Fever often with distinct chills and rigors, then sweating
- Classic periodicity every 48 or 72 hours in established infection, though often absent early
- Headache, body ache, vomiting
- Enlarged spleen, anaemia, jaundice in some
- Falciparum malaria can deteriorate rapidly
Any fever in or after travel to a malaria area needs malaria excluded, repeatedly if necessary.
Scrub typhus and other rickettsial infections
Often missed, and important because they respond rapidly to doxycycline.
- Fever, severe headache, muscle pain
- An eschar: a painless black scab with a red rim, often in a skin fold, the armpit, groin, waistband area or behind the knee. Easily missed unless specifically looked for
- Rash, enlarged lymph nodes
- Can progress to multi-organ failure if untreated
- Common after exposure to scrub vegetation, farming and outdoor activity
If you have an unexplained fever, ask the doctor to look for an eschar.
Keep reading
The rest of this guide is free. Watch a short ad to unlock it and support independent health writing.
Preparing your ad…
Leptospirosis
- Fever, severe calf muscle pain, red eyes without discharge, jaundice, kidney involvement
- Associated with exposure to floodwater, sewage, or water contaminated by animal urine
Tuberculosis
Worth considering with fever lasting weeks rather than days, particularly with evening fever, night sweats, weight loss and cough.
Testing: what is reliable
Full blood count. Low platelets and low white cells suggest dengue. A normal or low white count with fever suggests typhoid rather than a pyogenic bacterial infection.
Dengue NS1 from day 1 to 5; dengue IgM from day 5.
Malaria: rapid diagnostic test plus a peripheral blood smear, repeated if negative and suspicion remains.
Blood culture is the reference standard for typhoid. Yield is highest in the first week, and falls once antibiotics have been started, which is a strong argument against taking antibiotics before testing.
Scrub typhus IgM ELISA, plus the clinical search for an eschar.
The test to be cautious about
The Widal test for typhoid is still widely performed and widely misinterpreted.
Its problems are well documented: cross-reactivity with other infections including malaria and dengue; false positives in people previously exposed or vaccinated in endemic areas; false negatives early in illness; and no agreed cut-off across laboratories.
A single Widal test, particularly early in the illness, is not a reliable basis for diagnosing typhoid, yet it drives a great deal of unnecessary antibiotic use. Where available, blood culture is the test to ask for.
When to seek care urgently
- Fever lasting more than five to seven days without diagnosis
- Fever above 40°C not responding to paracetamol
- Confusion, drowsiness, difficulty waking, seizure
- Stiff neck with headache and light sensitivity
- Difficulty breathing or chest pain
- Any bleeding: gums, nose, vomit, black stools
- Severe abdominal pain
- Reduced urine output
- Cold hands and feet with a rapid pulse
- Rash that does not fade under pressure
- Jaundice
- Any fever in a baby under three months
- Fever in pregnancy, in someone on chemotherapy, or anyone immunosuppressed
General management while waiting
- Paracetamol, within the daily maximum
- Avoid NSAIDs until dengue is excluded
- Fluids, including oral rehydration solution, with urine output as the practical guide
- Rest
- Do not start antibiotics on your own
- Keep a simple record of temperature, timing and symptoms
Prevention
- Typhoid vaccines are available and recommended for endemic areas and travellers
- Safe water and food: boiled or bottled water, avoiding raw salads and cut fruit from street vendors, and hand hygiene
- Mosquito control for dengue and malaria
- Covered footwear and avoiding floodwater for leptospirosis
- Protective clothing and repellent in scrub areas
The short version
A stepwise rising fever with constipation suggests typhoid; abrupt high fever with eye pain and falling platelets suggests dengue; chills and rigors suggest malaria; and a painless black scab somewhere hidden suggests scrub typhus. Ask for blood culture rather than relying on Widal, avoid NSAIDs until dengue is ruled out, and do not start antibiotics before the tests are taken.