Science: Life in the time of cholera: a new fear of flying

The international flight, the seafood salad and Vibrio cholerae. Bernard Dixon tells a cautionary tale

In January 1991, for the first time this century, a cholera epidemic erupted in South America. Within a year, it had spread to 11 different countries, affected 400,000 people and killed more than 4,000 of them. The disease is still raging in that region.Butthebacterium responsible for cholera is a capable traveller, especially through water. That is why this month's Epidemiology and Infection contains a disturbing report of an outbreak of the disease contracted from food served on a passenger flight between Lima, Peru, and Los Angeles. Written by Richard Besser, of the University of California, and his colleagues, it describes the largest airline-associated epidemic of cholera ever recorded.

Most people infected by Vibrio cholerae do not become ill, especially if they are well-nourished and in good health. Nevertheless, the disease is understandably feared. It is a vile infection, largely attributable to a poison produced by V. cholerae, which causes diarrhoea so bad it can lead to death within hours. V. cholerae is invariably spread through contaminated water or food, only rarely passing from person to person.

The South American epidemic began in January 1991, when a Chinese grain boat brought the bacterium into Lima. Paradoxically, it was able to proliferate and spread there because the authorities had suspended chlorination of some of the city's wells. Their motive for doing so was to combat a far less tangible hazard associated with chemicals which may be formed when chlorine reacts with other substances in soil and water.

The recent incident came to lightwhentheLAhealth department received reports that bacteriologists had found V. cholerae in stools from five people who had been admitted to hospital with severe diarrhoea. One of the patients, a 70-year-old man, had died. All five had been passengers on a flight five days earlier, which had arrived in LA from Buenos Aires, calling at Lima en route.

Investigators set out to trace the other 331 people on the flight. They managed to locate 189 of them. Including the five who had been hospitalised, 100 of the passengers proved to be infected with V. cholerae. Seventy- five of them had also suffered from diarrhoea since arriving in the US. Ten had cholera and were treated accordingly.

All but one item of the food and drink consumed during the flight - including potentially suspect iced drinks and chicken sandwiches - were at most very weakly associated with infection. The exception was a seafood salad. It had been chosen by 87 per cent of the passengers whose stools contained V. cholerae, but only by 36 per cent of those who were free of the bacterium.

A caterer in Lima had prepared the salad, but how it becamecontaminatedis unclear. The most likely explanation is that the shrimps it contained were caught in waters containing V. cholerae and the bacterium had not been killed when they were cooked.

Before this incident, the biggest outbreak of cholera associated with airline travel occurred in 1972, when 47 passengers developed the disease after a flight from London to Sydney. Cold hors d'oeuvres, taken on board in a cholera-affected country, were the source of infection. The latest incident clearly demonstrates the risk associated with eating cold foods prepared in a place where cholera is raging.

Richard Besser and his co-authors strongly recommend that one conventional piece of advice, often given to travellers inareaswithinadequate hygiene and sanitation, should also be followed on flights originating from, or stopping in, such countries. This is to eat only foods that have been thoroughly cooked and are still hot.

"It is unlikely that the epidemic in Latin America will end soon," they conclude. "With thousands of airline passengers dispersing daily from cholera-affected countries, cholera outbreaks could easily occur in the US or other countries unaffected by the current pandemic." Indeed, one of the most disquieting aspects of the LA outbreak is that it attracted attention only because of its size and severity. Smaller outbreaks may have occurred, yet remained undetected. No doubt there will be others.

Suggested Topics
Start your day with The Independent, sign up for daily news emails
PROMOTED VIDEO
ebooks
ebooksA special investigation by Andy McSmith
Latest stories from i100
Have you tried new the Independent Digital Edition apps?
Independent Dating
and  

By clicking 'Search' you
are agreeing to our
Terms of Use.

iJobs Job Widget
iJobs General

Tradewind Recruitment: Phase Co-ordinator for Foundation and Key Stage 1

Negotiable: Tradewind Recruitment: Phase Co-ordinator for Foundation and Key S...

Tradewind Recruitment: SEN Teacher

Negotiable: Tradewind Recruitment: SEN Teacher We have a fantastic special n...

Tradewind Recruitment: History Teacher

Negotiable: Tradewind Recruitment: My client is an 11-18 all ability co-educat...

Tradewind Recruitment: Year 6 Teacher

£100 - £150 per day: Tradewind Recruitment: Year 6 Teacher Birmingham Jan 2015...

Day In a Page

Isis hostage crisis: The prisoner swap has only one purpose for the militants - recognition its Islamic State exists and that foreign nations acknowledge its power

Isis hostage crisis

The prisoner swap has only one purpose for the militants - recognition its Islamic State exists and that foreign nations acknowledge its power, says Robert Fisk
Missing salvage expert who found $50m of sunken treasure before disappearing, tracked down at last

The runaway buccaneers and the ship full of gold

Salvage expert Tommy Thompson found sunken treasure worth millions. Then he vanished... until now
Homeless Veterans appeal: ‘If you’re hard on the world you are hard on yourself’

Homeless Veterans appeal: ‘If you’re hard on the world you are hard on yourself’

Maverick artist Grayson Perry backs our campaign
Assisted Dying Bill: I want to be able to decide about my own death - I want to have control of my life

Assisted Dying Bill: 'I want control of my life'

This week the Assisted Dying Bill is debated in the Lords. Virginia Ironside, who has already made plans for her own self-deliverance, argues that it's time we allowed people a humane, compassionate death
Move over, kale - cabbage is the new rising star

Cabbage is king again

Sophie Morris banishes thoughts of soggy school dinners and turns over a new leaf
11 best winter skin treats

Give your moisturiser a helping hand: 11 best winter skin treats

Get an extra boost of nourishment from one of these hard-working products
Paul Scholes column: The more Jose Mourinho attempts to influence match officials, the more they are likely to ignore him

Paul Scholes column

The more Jose Mourinho attempts to influence match officials, the more they are likely to ignore him
Frank Warren column: No cigar, but pots of money: here come the Cubans

Frank Warren's Ringside

No cigar, but pots of money: here come the Cubans
Isis hostage crisis: Militant group stands strong as its numerous enemies fail to find a common plan to defeat it

Isis stands strong as its numerous enemies fail to find a common plan to defeat it

The jihadis are being squeezed militarily and economically, but there is no sign of an implosion, says Patrick Cockburn
Virtual reality thrusts viewers into the frontline of global events - and puts film-goers at the heart of the action

Virtual reality: Seeing is believing

Virtual reality thrusts viewers into the frontline of global events - and puts film-goers at the heart of the action
Homeless Veterans appeal: MP says Coalition ‘not doing enough’

Homeless Veterans appeal

MP says Coalition ‘not doing enough’ to help
Larry David, Steve Coogan and other comedians share stories of depression in new documentary

Comedians share stories of depression

The director of the new documentary, Kevin Pollak, tells Jessica Barrett how he got them to talk
Has The Archers lost the plot with it's spicy storylines?

Has The Archers lost the plot?

A growing number of listeners are voicing their discontent over the rural soap's spicy storylines; so loudly that even the BBC's director-general seems worried, says Simon Kelner
English Heritage adds 14 post-war office buildings to its protected lists

14 office buildings added to protected lists

Christopher Beanland explores the underrated appeal of these palaces of pen-pushing
Human skull discovery in Israel proves humans lived side-by-side with Neanderthals

Human skull discovery in Israel proves humans lived side-by-side with Neanderthals

Scientists unearthed the cranial fragments from Manot Cave in West Galilee