Symptoms of sickness
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Common Symptoms of Sickness: An Overview
Gastrointestinal Infections: Diarrhea, Fever, and Vomiting
Viral infections such as those caused by rotavirus and norovirus primarily manifest through gastrointestinal symptoms. The most common symptoms include diarrhea, fever, and vomiting. Additionally, these infections can lead to nausea, loss of appetite, and stress responses, which are orchestrated by the brain, particularly the hypothalamus.
Sickness Behavior: Anorexia, Fatigue, and Social Withdrawal
Sickness behavior encompasses a range of nonspecific symptoms that occur in response to infection. These symptoms include anorexia, depressed activity, loss of interest in usual activities, and the disappearance of body-care activities. These behaviors are thought to be mediated by cytokines like interleukin 1, which act on the brain to produce these effects. Fever, a common symptom of many infections, is also part of this sickness behavior and is controlled by the central nervous system.
Psychological and Physical Symptoms: Depression, Anxiety, and Fatigue
Chronic illnesses, including those experienced by kidney transplant recipients, often present with a cluster of sickness symptoms such as depressive symptoms, anxiety, and fatigue. These symptoms are interrelated and can significantly impact the quality of life. Fatigue is particularly prevalent, followed by anxiety and depressive symptoms.
Cytokine-Induced Symptoms: Pain, Malaise, and Cognitive Dysfunction
Pro-inflammatory cytokines like interleukin (IL)-1β and IL-6 are closely associated with the manifestation of acute sickness behavior. These cytokines can lead to symptoms such as fever, malaise, pain, fatigue, mood disturbances, and poor concentration. These symptoms are part of the body's defense mechanism to promote recovery .
Behavioral Changes: Sleep Disturbances and Hyperalgesia
Infections can lead to significant changes in behavior, including sleep disturbances, hyperalgesia (increased sensitivity to pain), and cognitive dysfunction. These changes are part of a broader syndrome known as sickness behavior, which is regulated by the brain even though the infections occur outside the brain.
Measurement of Sickness Behavior: The Sickness Questionnaire
The Sickness Questionnaire (SicknessQ) is a tool developed to measure sickness-related symptoms. It has been validated in various populations and contexts, including primary care patients and those with chronic medically unexplained symptoms. The questionnaire assesses both physical and mental symptoms, providing a comprehensive measure of sickness behavior .
Conclusion
Sickness symptoms are a complex interplay of physiological and behavioral responses orchestrated by the brain and mediated by cytokines. These symptoms, ranging from gastrointestinal issues to psychological and behavioral changes, serve as the body's defense mechanism to promote recovery. Tools like the Sickness Questionnaire help in assessing these symptoms, providing valuable insights for better management and treatment strategies.
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