A day earlier, two passengers on a British Airways flight from Miami to Heathrow died, including one from suspected viral meningitis.
The Virgin Atlantic passenger, who was not identified, died on flight VS006 shortly before landing, a spokeswoman for the carrier said. She said crew had tried to revive her and a doctor had come forward to help, but the woman was pronounced dead on arrival at Heathrow, west of London.
Police said the cause of death was unknown but added that an autopsy would be performed.
On Sunday, a female passenger fell ill on British Airways flight BA208 from Miami to Heathrow and the aircraft was diverted to Nova Scotia, Canada so she could receive emergency treatment, a spokeswoman for BA said. The woman died but it was unclear whether she died in the hospital or on the aircraft, she said.
A male passenger became ill after the flight resumed and died shortly before arriving at Heathrow, the spokeswoman said. She did not give either passenger's age or nationality or the suspected cause of death, but said the deaths weren't linked.
Hillingdon Borough, which oversees the Health Control Unit at Heathrow, said the male BA passenger was British and died of suspected viral meningitis. A spokesman for the local authority, Ian Macey, said he believed the female BA passenger had suffered a suspected heart attack.
Macey said health authorities would inform all passengers on the BA flight of the dead man's autopsy results, although he stressed that viral meningitis is only contagious in very close contact.
He did not have information on the death of the Virgin Atlantic passenger.
Meningitis involves inflammation of the tissues that cover the brain and spinal cord. It can be caused by a virus, bacteria or fungus.
Viral meningitis, which can be caused by many different viruses, is debilitating but rarely fatal in people with normal immune systems. Usually, the symptoms last from 7 to 10 days and the person recovers completely.
Bacterial meningitis is an infection of the membranes surrounding the spinal cord and the brain. Symptoms include severe headache, fever, nausea, stiff neck, and sometimes a rash. The incubation period is generally two to six days. According to the federal Centers for Disease Control and Prevention, up to 15 percent of meningitis cases are fatal.
Vaccinations exist for some forms of bacterial meningitis, and the disease can often be controlled with antibiotics if identified at an early stage.
Meningitis killed 727 Americans in 2001, according to government statistics