A site for medical students - Practical,Theory,Osce Notes

What is chills and rigors?

Chill is a sensation of cold which occurs in most of the fevers.
The normal body temperature is maintained in health by the balance between the heat gain and heat loss by the body that is governed by the Hypothalamus 
Rigor is state of profound chill with piloerection (goose flesh) and is associated with teeth chattering and severe shivering.This shivering is called as rigor
Chills or rigors occur when the thermostat in the hypothalamus, is suddenly reset to a higher temperature due to presence of pyrogens in the body.The body temperature then tends to rise to the newly reset level in the thermostat by conserving heat in the body by the mechanism of cutaneous vasoconstriction and involuntary contraction of skeletal muscles, experienced as chills or rigors. 
When the higher temperature is reached, heat loss starts from the body and the cutaneous vessels dilate to dissipate the heat. Then patient feels hot and sweating starts.
Chills or rigors may be commonly seen with bacterial, rickettsial, protozoal, influenzal infections.

What are the causes of fever with chill and rigor ?
  • Malaria.
  • Urinary tract infection.
  • Pentup pus anywhere in the body (lung abscess, liver abscess etc)
  • Septicaemia or pyaemia.
  • Cholangitis.
  • Subacute bacterial endocarditis.
  • Thrombophlebitis.
  • Acute pyelitis.
  • Acute lobar pneumonia.
  • Intravenous fliud infusion or blood transfusion.
  • Filariasis.