Why you’re feeling so feverish? Understanding acute febrile illness, its causes, treatment and more
Acute Febrile Illness (AFI) is a sudden onset of fever lasting less than two weeks with unclear cause at presentation. It may result from bacterial, viral, parasitic, or systemic infections. Careful evaluation of clinical signs, history, and investigations helps identify causes like sepsis, meningitis, malaria, or viral infections for appropriate management.
Overview of acute febrile illness Sudden onset of fever that usually lasts for less than two weeks, for which the cause cannot be determined clearly when the person presents is often referred to as acute febrile illness. It can occur because of multiple reasons, which could be bacterial, viral, or even parasitic. (Image: Canva)
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Bacterial sepsis and fever Bacterial sepsis is one reason why a person may experience acute febrile illness. There will usually be a sudden onset of fever, along with an increased heart rate and altered sensorium. Early intervention with broad-spectrum antibiotics is usually necessary. Finding and controlling the focus or source of infection can help curb it soon. (Image: Canva)
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Lower respiratory tract infections There are many infections that affect the lower respiratory tract, which consists of the trachea, bronchi, bronchioles, and alveoli. The person often complains of fever with cough and difficulty in breathing, along with pain sensation in the chest. A chest X-ray with blood cultures usually points toward the diagnosis. (Image: Canva)
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Urinary tract and kidney infections There are infections that affect the urinary tract (UTI) and the kidneys (pyelonephritis). These may clinically present as fever with pain in the loin area, pain during micturition, an alteration in the frequency of micturition, and a sepsis-like picture. It is more common in the elderly and in children. (Image: Canva)
Meningitis and encephalitis infections The outer coverings of the brain, known as the meninges, may also get infected (meningitis). Some pathogens have the ability to affect the brain parenchyma as well (encephalitis). The affected individual experiences an acute onset of fever with headache and neck stiffness. Altered mental status may also be seen. (Image: Canva)
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Common viral infections causing fever Viral infections (like dengue, influenza) are quite common, and can affect all age groups. Classic symptoms include high-grade fever, systemic manifestations, and pain in the muscles. The severity can be mild to life-threatening, and it depends on the organs affected as well. Viral infections often have a self-limiting course. (Image: Canva)
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Fever with rash conditions There are some kinds of fever that present with a rash. This can occur because of conditions like measles, meningococcemia, scarlet fever, and drug reactions. It is necessary to find the underlying cause by assessing the pattern and timing of fever. Some pathognomonic signs like Koplik spots (seen in measles) can help cinch the diagnosis. (Image: Canva)
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Tropical and vector-borne diseases There exist many tropical and vector-borne infections like malaria, chikungunya, leishmaniasis, etc. that occur while travelling to a different state or country. Such infections can cause periodic fever and a reduction in the platelets of the body (thrombocytopenia). Abdominal problems like an enlarged liver can be associated with such infections. (Image: Canva)
Infective endocarditis of the heart The heart is not spared of infections either. The chambers of the heart are lined on the inside by the endocardium, and inflammation of the endocardium is referred to as endocarditis. It can present with changes in the heart sounds (murmurs). Such inflammation is common in IV drug abusers and those with prosthetic valves. (Image: Canva)
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Fever of unknown origin Fever of unknown origin (FUO) requires an extensive evaluation with detailed history, physical examination, and cultures. A stepwise approach is necessary to identify the pathology, which may be infectious, malignant, or autoimmune. (Image: Canva) Disclaimer: This article, including health and fitness advice, only provides generic information. Don’t treat it as a substitute for qualified medical opinion. Always consult a specialist for specific health diagnosis
Rajeshwaari Kalla is a freelance health and wellness writer
