Mayaro Virus Disease

Mayaro virus (MAYV) is an alphavirus related to chikungunya, transmitted by Haemagogus mosquitoes in forested areas of South and Central America (Brazil, Peru, Bolivia, Colombia, Venezuela, Guyana, Panama).

• Primates are the reservoir. Occurs in forest workers, hunters, and travellers; urban transmission by Aedes aegypti is possible.
• Incubation 3 to 12 days. Epidemics in the Amazon basin occur sporadically.
• Mortality is rare. Chronic arthralgia is common.

• Fever, headache, retro orbital pain, myalgia, rash (maculopapular), and nausea.
• Prominent arthralgia or arthritis of wrists, ankles, fingers, and toes, with swelling, often lasting weeks to months (50% persist beyond 3 months).
• Lymphopenia, mild thrombocytopenia, and raised liver enzymes.
• Rare: haemorrhagic features, myocarditis, and neurological involvement.

• RT-PCR (first 5 to 7 days of illness) and virus isolation; IgM ELISA with confirmation by plaque reduction neutralisation (cross reaction with chikungunya).
• Travel and exposure history (forest areas).
• Exclude chikungunya, dengue, Zika, Oropouche, malaria, leptospirosis, yellow fever, and rheumatic disease.
• Blood count, liver tests, and CRP.

• Supportive therapy: rest, hydration, paracetamol for fever and pain.
• NSAIDs (naproxen 500 mg twice daily) for arthralgia once dengue excluded.
• Chronic arthritis: short course prednisolone 10 to 20 mg daily tapered over weeks, hydroxychloroquine 200 mg twice daily, or methotrexate for persistent inflammatory arthritis (extrapolated from chikungunya).
• Physiotherapy for joint stiffness.
• No licensed antiviral or vaccine.
• Prevention: repellents, long clothing, avoiding forest exposure at dawn and dusk, and notification of cases.