The 14-time Paralympic champion Dame Sarah Storey has withdrawn from the Great Britain team for the Para-cycling Track World Championships in Rio later this month.
The 40-year-old announced her decision on Thursday, following advice regarding yellow fever vaccination after an outbreak of the disease in Brazil.
Storey gave birth to her son Charlie last year and the four-and-a-half-month-old is breastfed, which means neither mother nor baby can be vaccinated, she said.
“I am obviously disappointed to not be able to compete at the event and miss out on the opportunity to win another rainbow jersey but the health and wellbeing of my family is far more important,” Storey said.
“I am not prepared to risk travelling unvaccinated as contracting the infection results in a high percentage of fatalities.”
Storey won three Paralympic gold medals in Rio in 2016 following the birth in 2013 of daughter Louisa.
The Para-cycling Track World Championships take place from March 22 to 25.