Chills and headache can be a sign of a flu virus, even if a person doesn't have a fever, according to Healthline. Chills and body aches are often precursors to a fever when flu is the underlying cause. Other symptoms of an onset of the flu virus include fatigue, coughing, sore throat, wheezing and tightness in the chest. Coughing up phlegm or mucus is a warning sign and can cause other complications in people with asthma or other respiratory problems.
Prolonged exposure to a cold environment can cause chills from hypothermia, according to MedicineNet. Hypothermia, which is a condition of a low core body temperature, occurs when the body cannot maintain a temperature of at least 96.08 degrees Fahrenheit. The body's natural ability to regulate temperature can be affected by other chronic illness such as diabetes, malnutrition, hypothyroidism, spinal cord injuries or Parkinson's disease.
Gastroenteritis produces symptoms of chills, headache and body aches with or without a fever, according to the University of Wisconsin-Madison. Gastroenteritis is inflammation of the intestines and stomach lining usually caused by parasites such as salmonella, E. coli, shigella, allergic reactions to foods or irritation from excessive alcohol consumption. The condition can be accompanied by nausea, vomiting, loose stool, and cramping or pain in the abdomen.
When gastroenteritis is caused by bacteria rather than a virus, antibiotics are effective forms of treatment, explains the University of Wisconsin-Madison. Patients should also follow a clear liquid diet in the first 24 to 36 hours of the illness, including water, broth, gelatin, sports drinks and diluted fruit juices.