<prompt> A VDRL reactive mother gave birth to an infant. All of the following would help in determining the risk of transmission to the infant, EXCEPTTPHA test on the serum sample of the motherTPHA test on the serum sample of the infantVDRL on the paired serum sample of the infant and motherTime interval between the treatment of the mother and her delivery  <response>: positive TPHA mother is responsible for transmission of infection to the infant In infants no test even TPHA can show difference between asymptomatic infected and noninfected. VDRL detect antibody titre raised in both infants and mother sugge.ctc the transmission 4 weeks before delivery treatment should be completed so time interval is important factor. 