Dengue, Typhoid and Malaria: Telling Indian Fevers Apart

In the weeks after the monsoon, fever clinics across India fill with people whose symptoms overlap almost completely for the first two or three days. Getting the diagnosis right matters because the treatments are entirely different, and because one of these illnesses can deteriorate suddenly.

Dengue

Spread by Aedes mosquitoes that bite during the day and breed in clean, stagnant water in and around homes.

Typical picture: abrupt high fever, severe headache with pain behind the eyes, intense muscle and joint pain, nausea, and a rash appearing around day three to five. Platelet count falls.

Tests: NS1 antigen is useful in the first five days. IgM antibodies become positive from about day five. A complete blood count showing falling platelets and rising haematocrit supports the diagnosis and, more importantly, tracks severity.

Treatment: supportive only. Paracetamol for fever, and generous oral fluids. NSAIDs and aspirin must be avoided because they increase bleeding risk. There is no antiviral.

The dangerous phase is when the fever falls, usually day four to six. This is when plasma leakage can occur, so this is the moment to watch most closely, not to relax.

Typhoid

A bacterial infection, Salmonella typhi, spread by contaminated food and water.

Typical picture: fever that climbs in a step-ladder pattern over several days rather than spiking abruptly, with headache, abdominal discomfort, loss of appetite and, characteristically, constipation more often than diarrhoea in adults. The pulse is sometimes slower than the fever would suggest.

Tests: blood culture is the reliable test, and is most useful in the first week. The Widal test is widely used in India and widely misinterpreted: it has poor specificity, cross-reacts, and a single positive result in a previously exposed population means little. Treating on a Widal alone leads to a great deal of unnecessary antibiotic use.

Treatment: antibiotics, guided by local resistance patterns, which have changed considerably. Full completion of the prescribed course matters here.

Malaria

Caused by Plasmodium parasites, spread by night-biting Anopheles mosquitoes.

Typical picture: fever with pronounced chills and rigors, often in a cyclical pattern, followed by drenching sweats. Headache, body ache, sometimes anaemia and an enlarged spleen.

Tests: peripheral blood smear or a rapid diagnostic test. Smears may need repeating if the first is negative and suspicion remains.

Treatment: antimalarial drugs chosen according to species and local resistance. P. falciparum can become severe quickly and requires urgent treatment.

What overlaps, and what separates them

In the first 48 hours, all three can present simply as high fever with body ache. Features that help:

• Pain behind the eyes and severe joint pain point toward dengue
• Rigors in distinct cycles point toward malaria
• A gradual step-wise fever with abdominal symptoms and constipation points toward typhoid
• Rash from day three to five suggests dengue

Other causes worth remembering: chikungunya, scrub typhus, leptospirosis after flooding, influenza, urinary infection and COVID-19.

Danger signs that need hospital care immediately

• Severe or persistent abdominal pain
• Persistent vomiting, or inability to keep fluids down
• Bleeding from gums or nose, blood in vomit or stool, or unusual bruising
• Restlessness, drowsiness or confusion
• Cold, clammy skin or a rapid weak pulse
• Passing very little urine
• Difficulty breathing
• A sudden drop in temperature with worsening condition rather than improvement

Prevention

• Empty and scrub water containers, coolers, pots and tyres weekly; Aedes breeds in clean water
• Use repellent and wear covering clothes during the day for dengue, and at night for malaria
• Use bed nets in malaria-endemic areas
• Drink safe water; typhoid vaccination is available and worthwhile in high-risk areas
• Wash hands before eating and avoid uncovered street food during outbreaks

This article is general health information. Any fever lasting more than two to three days in India should be assessed by a doctor, and danger signs need same-day hospital care.