The said Board of Health shall not contract any debt or incur any expense of any kind beyond the amount of the appropriation made for its use by the Council, except that whenever any epidemic of any contagious or infectious disease exists or is threatened or any special need arises for the protection of the public health, and in the judgment of the Board the expenditure of a sum greater than that already appropriated to the Board for the current year is necessary, the Board shall so certify to the Council; thereupon, the Council may appropriate such sum as the Board may certify to be necessary and, if required, the Council may borrow the sum on the credit of the municipality, in accordance with N.J.R.S. 26:3-44, as amended and supplemented.