A lack of diagnostic tools and skills in Tanzanian health facilities are blamed for widespread malaria misdiagnosis, which fails the patient's need, wastes precious resources and contributes to drug resistance. As many as 45% of arboviral infections in the country are misdiagnosed as malaria. Automatically updated local estimates of the relative transmission risk of malaria and arboviral infections, delivered via mobile phone text messages to rural health workers, will help to better inform clinical diagnoses.