From my research, the type of malware used in the text message depends on if you will be able to detect it. If you have a mobile antivirus such as Avast Mobile Security then it may be able to detect the malware once it starts performing its tasks but Avast has yet to release a way block the malware before the infection, i.e. when the MMS video is loaded, but say they are working on it right now.
I believe the reason no android patches and antivirus definitions have been released is due to how deep in the android system the stage fright software resides. Fortunately android is very well protected with its “Sandboxing” and other advanced malware mitigation techniques so it will be difficult for hackers to exploit this vulnerability successfully for quite some time. Hopefully by then patches will have been provided and mobile security apps will be able to protect.
Currently the only way to be sure you are malware free is to factory reset the device. If you suspect you may be infected then the best option is to back up your contacts, photos and any other personal data and reset your device back to factory defaults.