Skip to content
Spiral Staircase
Buy the book
Menu

Glossary

Sickness behavior

Defined in topic 20

The lethargy, low mood and lost appetite that travel with fever, argued in 1988 to be an organized strategy rather than debilitation. Mice have neurons that control fever and appetite together.

Published Updated

Where this comes from

In the reference topic that owns this term

Reference topic 20, The Fever and the Old Enemies, states the mismatch as a card: what the system evolved to expect, what it gets instead, and what happens in the gap.

Mismatch card

What it expects

Infection as the commonest threat, care from others while sick, and bands too small for crowd diseases.

What it gets

Crowd and herd diseases, fever treated as the enemy, work while sick, antibiotics overused and vaccines refused.

What happens in the gap

Fever phobia and contagious presenteeism; returning measles; resistant bacteria; old genetic trade-offs meeting new viruses.

The full card, and the topic behind it

What that chapter recommends

3 of the 6 graded recommendations in Reference topic 20, strongest evidence first. How the grades work.

  1. Treat the person, not the thermometer

    StrongEvidence grade: Strong. Multiple randomized controlled trials, or consistent large cohort studies with a well-understood mechanism.

    Use paracetamol (acetaminophen) or ibuprofen when fever makes you or your child miserable, not to hit a number. For children, give one drug at a time, not both together.

    Read it in full

  2. Know the red flags, and call a clinician when in doubt

    StrongEvidence grade: Strong. Multiple randomized controlled trials, or consistent large cohort studies with a well-understood mechanism.

    Get prompt medical help for a baby under 3 months with 38°C (100.4°F) or more, or 3 to 6 months with 39°C (102.2°F) or more.

    Read it in full

  3. Vaccinate on schedule

    StrongEvidence grade: Strong. Multiple randomized controlled trials, or consistent large cohort studies with a well-understood mechanism.

    Follow your national schedule for children and adults; if you are pregnant or have a weakened immune system, ask about live vaccines.

    Read it in full

The argument behind this term, its studies and its notes are in Reference topic 20 of the reference library. The book gives the practical version. Get the book.