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Dr William Lucas said a pulmonary embolism caused the death of Brenda Buckley, 43, a tourist who was on a cross-Canada train trip.
The death provoked a health scare after other passengers reported being ill, including one who was taken by air ambulance to a hospital. Authorities quarantined the train for several hours in the northern Ontario town of Foleyet, about 500 miles (800 kilometres) northwest of Toronto. They announced later that day that there was no infectious disease outbreak.
Clot caused by deep vein thrombosis
The train, carrying 269 passengers and 30 crew members, was allowed to leave Foleyet late that night and arrived in Toronto several hours late.
Lucas declined to provide details of Buckley's autopsy, saying such information could only be disclosed to her family, but he speculated that the fatal blood clot may have been caused by deep-vein thrombosis (DVT), an ailment that can afflict long-distance travellers.
This again highlights the dangers of deep-vein thrombosis (DVT). Last year, Afrikaans blues-rocker Valiant Swart was also a victim DVT.
What is DVT?
Disturbing new research results were released by the World Health Organisation. Preliminary findings show that the risk of so-called venous thromboembolism doubles after travel lasting four hours or more.
The two most common manifestations of venous thromboembolism (VTE) are deep-vein thrombosis (DVT) and pulmonary embolism. Symptoms of DVT are principally pain, tenderness and swelling.
Swart, who was on a flight from London to South Africa, became aware of pain in his lower right leg during the night. "I told myself that it's probably just a muscle spasm or hypochondria," he told Beeld.
When his plane touched down, he didn't pay much attention to his leg. But the pain persisted until he finally went for a medical check-up two days later. "The doctor told me that I indeed had thrombosis and that there were two blood clots in my one vein. I must admit that I got quite a fright," Swart said.
Few travellers affected
Although VTE is a dangerous – and potentially fatal condition – the good news is that it affects only a relatively small number of travellers. The absolute risk, if seated and immobile for more than four hours, is about 1 in 6 000.
According to the World Health Organisation, the condition becomes life-threatening when a blood clot in a leg vein breaks off and travels through the body to the lungs where it becomes lodged and blocks blood flow. Symptoms of so-called pulmonary embolism include chest pain and breathing difficulties.
The study showed that plane, train, bus or automobile passengers are at higher risk of VTE when they remain seated and immobile on journeys of more than four hours. This is due to a stagnation of blood in the veins caused by prolonged immobility, which can promote blood clot formation in the veins.
Multiple flights increase risk
People taking multiple flights over a short period of time are also at greater risk. This is because the risk of VTE does not go away completely after a flight is over. The risk remains elevated for about four weeks.
A number of other factors also increase the risk of VTE during travel. These include obesity, being very tall or very short (taller than 1,9m or shorter than 1,6m), use of oral contraceptives, and inherited blood disorders leading to increased clotting tendency.
Exercising the calf muscles with up-and-down movements of the feet and not wearing tight clothing during travel can help to prevent the dangerous condition.
Air pollution could also cause DVT
A recent study has also linked air pollution which is heavy in small particles to DVT. They claim such pollution may cause blood clots in the legs.
Dr Andrea Baccarelli of the Harvard School of Public Health in Boston and colleagues said they found the link after looking at 870 people in Italy who had developed deep vein thrombosis between 1995 and 2005.
Previously, particulate pollution had not been linked to blood clots in the veins. The findings introduce a new and common risk for deep vein thrombosis, the researchers said, and "give further substance to the call for tighter standards and continued efforts aimed at reducing the impact of urban air pollutants on human health."
(WHO, Beeld, Sapa, May 2008)
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