def detectionLimit(self):
        """
        Detection limit for parasitaemia
        Limit above which a human's infection is reported as patent
        https://github.com/SwissTPH/openmalaria/wiki/GeneratedSchema32Doc#detection-limit-for-parasitaemia
        """
        surveys_elem = self.et.find("surveys")
        if surveys_elem is None:
            return None

        try:
            detectionLimit = float(surveys_elem.attrib["detectionLimit"])
        except KeyError:
            detectionLimit = None
        return detectionLimit