Any county officer required to act as an officer of the district and perform services for the district by virtue of his office, or any county health officer who becomes the ex officio health officer of the district pursuant to Section 6492.5, shall be entitled to reimbursement from the district for the reasonable and actual expenses incurred by him while acting on behalf of the district, to be paid into the county treasury. The amount of such reimbursement shall not exceed the actual expense which he incurred.