No member of the board of county commissioners or other officer or employee of a county which has adopted any form of county managership, and no person receiving a salary or compensation from funds appropriated by the county, shall be interested, directly or indirectly, in any contract to which the county is a party, either as principal, surety, or otherwise. No such officer or employee or an officer’s or employee’s partner, agent, servant, employee, or the firm of which the officer or employee is a member, shall purchase from or sell to the county any real or personal property, nor shall an officer or employee be interested, directly or indirectly, in any work or service to be performed for the county or in its behalf. Any contract made in violation of the provisions of this section shall be void.