1. The word "employer" as used in this chapter shall be construed to mean:
(1) Every person, partnership, association, corporation, limited liability partnership or company, trustee, receiver, the legal representatives of a deceased employer, and every other person, including any person or corporation operating a railroad and any public service corporation, using the service of another for pay;
(2) The state, county, municipal corporation, township, school or road, drainage, swamp and levee districts, or school boards, board of education, regents, curators, managers or control commission, board or any other political subdivision, corporation, or quasi-corporation, or cities under special charter, or under the commission form of government;
(3) Any of the above-defined employers must have five or more employees to be deemed an employer for the purposes of this chapter unless election is made to become subject to the provisions of this chapter as provided in subsection 2 of section 287.090, except that construction industry employers who erect, demolish, alter or repair improvements shall be deemed an employer for the purposes of this chapter if they have one or more employees. An employee who is a member of the employer's family within the third degree of affinity or consanguinity shall be counted in determining the total number of employees of such employer.
2. Any reference to the employer shall also include his or her insurer or group self-insurer.