FREETOWN (Reuters) - In her free time Isha Turay, an 18-year-old Sierra Leonean student, sells vegetables on Malama Thomas Street in the heart of the bustling capital, Freetown, so that she and her siblings can eat.

But for three days, starting at midnight on Thursday, her stand will be abandoned during a nationwide lockdown aimed at helping Sierra Leone fight an outbreak of Ebola ravaging the country and the region.

"If we don't sell, we cannot eat," Turay said, splashing water over a stack of carrots to keep them fresh in the searing afternoon heat. "We don't know how we can survive in this lockdown. More suffering."

Sierra Leone's government says extreme measures are needed to try to contain the world's worst outbreak of Ebola on record but many fear it will bring more hardship to a nation that is already one of the poorest on earth.

Critics also question whether it will even be effective.

Over 2,600 people have been killed across West Africa, around half the number of people infected. The World Health Organization says the world must act fast to keep the number of cases in the tens of thousands.

Initially a plan to locate the ill, Sierra Leone's lockdown will now seek to make people aware of the risks of Ebola and what to do if a family member falls sick, the government says.

As about 30,000 volunteers train for their dawn-to-dusk information campaign, residents flocked to high-end supermarkets and, between downpours, street stalls to buy food and medicine.

Queues formed along streets as people stocked up on fuel. Banks, already operating at reduced hours to limit infections, overflowed as clients withdrew cash.

Some say a few days hardship is a price worth paying if it contributes to halting the march of Ebola across a nation only a decade into its recovery from an 11-year civil war that killed 50,000 people.

"It's better to stay at home for three days, even 21 days, than to lose thousands of people in a single day," said Freetown resident Mahawa Allieu. "It's very important, necessary and called for."

However, critics argue a public information campaign is not what is needed now, months into a battle against Ebola that most in Sierra Leone are by now aware of.

Barry Andrews, chief executive of Irish aid agency Goal, called the move "an ill-conceived exercise in futility".

"I'm not sure a public information campaign requires the draconian measure of three days locking six million people into their homes," he said. "It puts terrible pressure on vulnerable people. People who live hand to mouth will find it difficult."

Medical charity Medecins Sans Frontieres, which has led international efforts on the ground to fight Ebola, has warned that the lockdown risked further undermining trust in health workers and the hiding of further cases.


HOUSE-TO-HOUSE

This outbreak was initially confirmed in March in Guinea's remote southeastern forest. From there, it spread, slowly at first, across the country and into Liberia and Sierra Leone.

With fragile local health systems overwhelmed and the world slow to react, the disease has in recent months taken hold in towns and cities. Infections are now increasing exponentially.

Hospitals are turning away cases and, in recognition of the scale of the threat, the U.S. government this week pledged to send 3,000 troops to the region to build new treatment centers and train medical personnel.