A woman may be in for a $5.2m (£4.2m) payout after she allegedly contracted a sexually transmitted infection while having sex in a car.

The US woman, identified in court files as ‘MO’, said she caught the human papillomavirus (HPV) from having sex with her then-partner in his car.

This week, the Missouri Court of Appeals upheld a judgment that awarded MO a hefty settlement – to be paid by Geico, which insured the vehicle.

Geico is contesting the decision.

According to court documents, MO said she learned she was infected with HPV in 2018, and claimed her former partner knew he had virus but did not disclose his condition, leaving her with “past and future medical expenses” and “mental and physical pain and suffering”.

In February 2021, the Jackson County woman told Geico, known in the US for its popular green gecko mascot, that she intended to seek damages of $1m following the sexual interaction in her then-partner’s Hyundai Genesis, asserting that the insurance firm’s policy covered her injuries.

The insurance company denied coverage and refused her settlement offer, court documents show.

MO and her former partner entered arbitration. The arbitrator sided with MO.

The arbitrator determined “there was sexual activity in [insured’s] automobile” that “directly caused, or directly contributed to cause” the woman to be infected with HPV, despite the man’s existing knowledge of his positive HPV diagnosis.

HPV infections can often be asymptomatic, although some types can cause warts that may appear on a person’s hand, foot, genitals or inside the mouth. High-risk types of HPV can cause abnormal tissue growth which can lead to cancers.

In May 2021, the arbitrator awarded MO $5.2m in damages, to be paid by Geico. Jackson County Circuit Court later confirmed the award.

Geico appealed the judgement. But on Tuesday, a three-judge panel confirmed the lower court’s ruling and said the insurance company failed to defend its own interests by entering a defense of the insured man.

“Geico did not take advantage of this opportunity, and instead denied coverage and refused to defend Insured,” the opinion said.

In a statement to CBS MoneyWatch the US automobile insurance company said: “The question of whether there is coverage for this will be determined”, by a federal lawsuit filed in the US District Court for the Western District of Missouri.