I'm not sure on the implemented status of diseases and weather these disease are even fully implemented. That being said I still spotted this, so I might be in error here but, inside

scripts\4_World\classes\playermodifiers\modifiers\diseases\salmonella.c

the trigger conditions for the disease check the cholera value for its activation

	override protected bool ActivateCondition(PlayerBase player)
	{
		if(player.GetSingleAgentCount(eAgents.CHOLERA) > SALMONELLA_AGENT_THRESHOLD_ACTIVATE) 
		{
			return true;
		}
		else 
		{
			return false;
		}
	}

Where I would have thought it should be checking eAgents.SALMONELLA and not eAgents.CHOLERA. Otherwise having cholera will also trigger salmonella.