This value set includes codes based on the following rules:

• Include these codes as defined in http://snomed.info/sct version http://snomed.info/sct/731000124108/version/20200901

  Code	Display
  409700000	Animal to human transmission
  416086007	Food-borne transmission
  409699001	Person to Person
  418375005	Indeterminate disease transmission mode
  418117003	Water-borne transmission

• Include these codes as defined in urn:oid:2.16.840.1.114222.4.5.274 version 20200526

  Code	Display
  PHC1238	Environmental contamination other than food/water

• Include these codes as defined in http://terminology.hl7.org/CodeSystem/v3-NullFlavor version 20090501

  Code	Display
  OTH	Other
  UNK	Unknown