Differential Diagnosis

The patient's symptoms and epidemiological history suggest a range of possible diagnoses. Here's a categorized differential diagnosis:

• Single Most Likely Diagnosis

  • Tick-borne encephalitis: meningitis: The patient's recent visit to the mountains 5 days before the onset of illness increases the likelihood of tick exposure, which is a common vector for tick-borne encephalitis. Symptoms such as high fever, headache, weakness, nausea, vomiting, and signs of meningismus (e.g., rigidity of the occipital muscles, positive Kernig's symptom) are consistent with this diagnosis.

• Other Likely Diagnoses

  • Meningococcal infection: meningitis: The acute onset of high fever, headache, weakness, and signs of meningitis (such as neck stiffness and positive Kernig's symptom) could suggest meningococcal meningitis. However, the epidemiological link to the mountains is less typical for this diagnosis.
  • Enterovirus infection: meningitis: Enteroviruses can cause aseptic meningitis, presenting with fever, headache, and signs of meningitis. This diagnosis is possible but less directly linked to the patient's recent mountain visit.

• Do Not Miss Diagnoses

  • Herpesvirus infection: meningitis: Although less common, herpesvirus infections (like HSV-2) can cause meningitis, often presenting with similar symptoms. Missing this diagnosis could lead to severe consequences, including neurological damage, if not promptly treated with antiviral therapy.
  • Meningococcal infection: meningitis: Given its potential for severe outcomes and the need for immediate antibiotic treatment, meningococcal meningitis should not be missed, despite being categorized under "Other Likely Diagnoses" due to its severity and public health implications.

• Rare Diagnoses

  • Extra-intestinal amoebiasis: meningitis: This condition is rare and typically associated with amoebic infections spreading from the intestines to the brain, causing meningitis. The patient's symptoms and history do not strongly suggest this diagnosis, making it less likely.
  • Other viral or bacterial meningitides: There are numerous other pathogens that can cause meningitis, each with different epidemiological and clinical characteristics. While they are part of the broad differential diagnosis, they are not as directly suggested by the patient's presentation and history as the aforementioned options.