For each multiple county or city-county health department, a joint health department fund shall be created either in the treasurer’s office where the principal office of the health department is located or in the office of the city treasurer of a city within the health department’s jurisdiction, as determined by the local board of health. The treasurer of each county and city participating in the health department shall annually pay or cause to be paid into the fund the share of the county or city. This fund shall be expended by the treasurer in whose office the fund is kept in the manner prescribed by the local board of health pursuant to properly authenticated vouchers of the health department signed by the local health officer.