A 35-year-old Aboriginal woman living in a remote community presents with exertional dyspnoea and a history of recurrent sore throats in childhood. Echocardiography shows moderate rheumatic mitral regurgitation with no prosthetic valves. She had documented acute rheumatic fever at age 11 but defaulted from follow-up. She now lives >200 km from the nearest regional hospital. According to Australian rheumatic heart disease guidelines, what is the most appropriate secondary prevention strategy?