Pneumonic plague is more serious and less common than bubonic plague. The outbreak was in the form of bubonic and pneumonic plague. Most of the infections in Peru were bubonic plague, with four cases of pneumonic plague. Madagascar has experienced two notable outbreaks of bubonic and pneumonic plague in the 21st century. Unusually most of the cases were pneumonic rather than bubonic. There are three types of plague&colon; bubonic, pneumonic and septicemic. It causes the disease plague, which takes three main forms&colon; pneumonic, septicemic, and bubonic. Almost all cases were bubonic, with only a very small percentage changing to pneumonic plague. Aerosolized pneumonic plague remains the most significant threat. Less common causes include aspergilloma, bronchiectasis, coccidioidomycosis, pulmonary embolism, pneumonic plague, and cystic fibrosis. The pneumonic form of plague arises from infection of the lungs. Left untreated, pneumonic plague is nearly always fatal. Treatment of pneumonic plague is with antibiotics. Pneumonic plague is a very aggressive infection requiring early treatment. Australia's only outbreak of pneumonic plague occurred in Maryborough in 1905.