Knee osteoarthritis

Disease Description (Causes and Symptoms)

Chikungunya fever is an acute viral febrile illness caused by being bitten by an infected Aedes mosquito (mainly the Asian tiger mosquito and tropical forest mosquito) carrying the chikungunya virus (an alphavirus). The incubation period is usually 2–12 days (typically 2–7 days). The main pathophysiology involves the virus invading the peripheral bloodstream and tissues around the joints, triggering an inflammatory response that causes high fever and severe joint and muscle pain.

Main symptoms

• Sudden high fever (often 39–40℃)
• Severe joint pain (often symmetrically affecting small and medium-sized joints such as the wrists, knees, and ankles)
• Muscle pain, headache, malaise, nausea and vomiting
• Erythematous rash (on the arms, legs, and trunk)
• In some cases, chronic joint pain and fatigue may persist for weeks to months after the fever subsides

Diagnostic features: During the acute phase, detection of the virus in the blood (PCR) or viral culture is possible, and a specific IgM antibody test can assist diagnosis several days after disease onset. Because the symptoms clinically resemble those of other mosquito-borne diseases such as dengue fever, differential diagnosis through testing is necessary.

Summary of complications and prognosis: Most people recover spontaneously and the mortality rate is low, but neurological complications (meningitis and Guillain–Barré syndrome), myocarditis, hepatitis, and other complications may rarely occur. Chronic joint symptoms are particularly likely to persist for a long time in older adults and people with underlying conditions.

Treatment

No specific antiviral medication has currently been approved, so treatment is focused on supportive care and symptom relief.

Treatment during the acute phase

• Fever and pain relief: Acetaminophen (such as Tylenol) is recommended.
• Nonsteroidal anti-inflammatory drugs (NSAIDs) and aspirin: Avoid these during the early phase when dengue fever has not been ruled out because of the risk of bleeding. They may be used under a doctor's direction after dengue has been excluded.
• Adequate hydration, rest, and nutritional support.
• Hospitalization and intravenous fluid replacement in cases of severe dehydration or electrolyte abnormalities.

Chronic or persistent joint pain

• Physical therapy (to restore joint function and strengthen muscles)
• Short-term steroids may be helpful, but long-term use should be decided cautiously.
• If chronic inflammatory arthritis-like symptoms persist, evaluation by a rheumatologist is needed; antimalarial drugs (e.g., hydroxychloroquine) or immunomodulators (such as methotrexate) may be used in a small number of patients (as determined by a specialist).

Follow-up and complication management

• Immediate emergency evaluation is needed if neurological symptoms (limb paralysis, impaired consciousness, severe headache, or seizures), chest pain or shortness of breath, or a sudden tendency to bleed develops.
• Electrocardiography, liver function tests, urinalysis, complete blood count (CBC), and other monitoring may be performed as needed.

Prevention and other information

• Medical isolation of infected people is not required, but preventing transmission by avoiding mosquito exposure (taking measures to prevent mosquito bites) is important.

Checklist Before an Outpatient Visit (Including Sample Questions)

Items to bring and information to record in advance

• Travel destinations (country/region/city) within the past 2 weeks and the possibility of mosquito exposure
• Date symptoms began (including the date fever started) and a timeline of symptom progression (temperature log and changes in pain severity)
• A list of all medications currently being taken (including prescription medications, OTC medications, and supplements)
• Medical history: chronic conditions (heart disease, liver or kidney disease, autoimmune disease, etc.) and whether you are pregnant (or could be pregnant)
• Previous test results (blood tests, imaging tests, etc.) or a medical certificate from another healthcare institution, if available
• History of allergies (medications, foods, etc.)

Symptoms to check when visiting an outpatient clinic

• Signs of bleeding (nosebleeds, bleeding gums, petechial rash, bloody stool, etc.)
• Signs of severe dehydration (decreased urine output, dizziness, clouded consciousness)
• Neurological abnormalities (decreased sensation, paralysis, speech or visual disturbances)
• Chest pain, shortness of breath, or decreased consciousness

Sample questions (to prepare in advance)

• When did the symptoms begin? (Exact date/time)
• What was the fever pattern, and how did you respond after taking fever-reducing medication?
• What are the location and characteristics of the joint pain (symmetry, presence of morning stiffness, etc.)?
• Have you recently had a blood transfusion, injury, surgery, pregnancy, childbirth, or breastfeeding?

General Sample Questions to Ask the Doctor

• What tests are needed to make an accurate diagnosis of this illness? (PCR, IgM/IgG, etc.)
• Which medications should I take to relieve the symptoms, and for how long? What are the side effects?
• How likely are complications to occur, and what symptoms should I watch for?
• When can I return to work or school? To what extent should I limit my activities?
• I am pregnant or breastfeeding. Is there any risk to the fetus or newborn?

Disease-Specific Sample Questions

• If joint pain persists for more than several weeks, what treatment options (medication, physical therapy, and specialist care) are available, and when should I be referred to rheumatology?
• I recently traveled to an area where an outbreak is occurring. If infection occurs during pregnancy, what should be done regarding fetal risks (the possibility of vertical transmission) and delivery-related management (including transfusion and mode of delivery)?

Additional Useful Information (Brief Summary)

• Diagnosis: PCR during the acute phase (viral genetic material in the blood) and, as supportive evidence, a positive IgM antibody test within several days after disease onset. Blood tests may show leukopenia and, occasionally, mild thrombocytopenia and elevated liver enzymes.
• Prevention: Use mosquito repellent, wear long sleeves and long pants, use screens and mosquito nets, and remove standing water. Take precautions when visiting areas with outbreaks.
• Emergency symptoms: Visit the emergency department if severe bleeding, shortness of breath, changes in consciousness, acute paralysis or visual disturbances, or persistent high fever and signs of dehydration occur.