As Sierra Leoneans endure a lockdown to contain the virus, Monica Mark reports from Freetown on her own anxiety visiting hospitals and villages, and the key role of charities in fighting the epidemic

Hospital waiting rooms are miserable places at the best of times, but in the middle of an Ebola outbreak Freetown's Princess Christian Maternal Hospital is suffocating. Corridors that would normally bustle with children and harried parents are sepulchral. Nurses whisper in forlorn huddles in empty rooms. Then a shriek of joy shatters the silence. "Jessica! You're back from America!", a tiny elderly woman cries, rushing towards me with open arms. Before I have time to react, she throws her arms around me in a vice-like embrace.

What would ordinarily be brushed off as a case of mistaken identity takes me 21 days – the incubation time of the Ebola virus – to get over.

In a country where more than 500 have died after six months of Ebola – which is spread through direct contact with bodily fluids – the "no touching" rule has become the norm. At the beginning of my 10-day trip to Sierra Leone, I went to shake a friend's hand. He threw himself back against the wall with a panic that would have been comical if not for the fear on his face. Such reactions soon became as routine as having my temperature taken at road checkpoints and washing my hands in buckets of chlorinated water found everywhere.

I had only one more lapse. On my third day I was at the Médecins Sans Frontières treatment centre with my sister Katie, a documentary film-maker who was accompanying me, when I reached out to tuck a wisp of her hair that had come loose. The act was so natural, I didn't even think about it. Suddenly a medic yelled across the field hospital: "No touching!"

The paranoia that seized me then didn't leave until I returned home. Unlike other hostile situations I've covered over five years in west Africa – riots, wars and natural disasters – in this case people I cared about were the enemy. Ebola makes you a risk even to yourself: touching your eyes, nose or mouth can infect you. Now a stranger in a hospital was hugging me.

"I'm so happy you came, Jessica. My daughter gave birth!", this wizened woman declared, beaming up at me. "Come and see," she said. At some point, as Mariatu marched me past deserted rooms – "so is your husband back in America now?" she asked, to which I replied, "He's in Nigeria, where we live"– she must have realised I was neither Jessica nor from America. Even then, she kept going. When she handed me the newborn swaddled in a pink blanket, I understood why. In a country where births can prompt neighbourhood festivities, only me, Mariatu and her daughter were there to celebrate. Everyone else she knew was too scared of catching Ebola to come to the hospital.

To me, this incident defines what it is like living through an Ebola epidemic. It is both underwhelming and terrifying. It turned out the most exhausting part was my own paranoia. Some, like Mariatu, have defeated their paranoia. Logically, I knew the risk of contagion was low and I understood how to protect myself. But throughout my time in Sierra Leone I was plunged into a state of hyper-awareness about my own body and that of every person around me. One health worker who had identified dozens of cases told me many patients had reddened eyes in the early stages. Suddenly I noticed an awful lot of people in Sierra Leone seemed to have bloodshot eyes.

The World Health Organisation has warned that huge resources need to be poured into Sierra Leone, Guinea and Liberia, which account for all but a handful of the 2,500 deaths, in order to keep them from spiralling into the tens of thousands by the year's end.

To travel to Kailahun, where lush forest sprawls across the interior regions of Sierra Leone, Liberia and Guinea, is to understand how Ebola exploded here, and how it was swept under the carpet for so long. I spent every childhood summer at my paternal grandfather's house in rural Nigeria, yet the remoteness of the affected villages shocked me. Roads burrowed tunnels through vegetation that looked as if it had paused for breath before engulfing us all again.

"Around here you don't know if you're in Guinea, Liberia or Sierra Leone. You'd never say 'I'm going to Guinea'; you'd just say 'I'm going to the next village'," said Nickson, our cheerful driver, explaining why the disease has cast such a wide net over the three countries' porous interior regions. Nickson wore a surgical mask most of the time – "I don't want to die, I have a son," he kept saying – brought his own tinned food from Freetown and whipped out a bottle of chlorinated spray whenever someone touched the car.

I watched a team of young Sierra Leonean burial volunteers in anti-contamination suits descend in this environment of straw-topped huts, towering forests and mud-lined streams. It was surreal, almost frightening.

But for all that traditional practices and suspicion of outsiders has fuelled the outbreak – last week villagers in the remote Guinean village of Womey killed eight members of an education team – what lies at the heart of many people's denial and inability to adapt is an all-too-common fear of illness and death. One doctor seconded to the country told me he had dealt with similar reactions when diagnosing patients in the US with HIV.

I was surprised to discover how hard it is to change your behaviour, even when your life is at risk. In every village we visited, several people would bound up to the car before I'd even got out and lean cheerfully against the window. Sweat and spit would sometimes fly in – you notice this when you're hyper-aware. But always, as with the hospital situation with Mariatu in the hospital, I didn't want to be rude and turn away from them.

Habits go much deeper than that, of course. Most experts believe many unrecorded Ebola outbreaks may have died out naturally as locals adapted at their own pace. For example, by the tail-end of the 2000 outbreak in northern Uganda, the Acholi turned to long-trusted measures for two gemo –roughly translating into "an illness borne by evil winds" – which had been applied during flareups of other infectious diseases, like measles and smallpox, medical anthropologist Barry Hewlett discovered. Alongside spirit-chasing rituals, infected people were treated in homes where sticks of elephant grass signalled that only previous survivors could enter.

Such measures can't solve an outbreak of this magnitude, which has jumped to urban areas, too. The help of western nations is desperately needed, but for me the great tragedy of this outbreak has been the revelation of just how abjectly west African governments have failed to invest in their own citizens' healthcare, education and infrastructure – all of which might have nipped the epidemic in the bud.

Only four ambulances serve Kailahun, a district of nearly half a million people. Entire families sometimes cram into one car to accompany Ebola-sick relatives to the centre, so those who weren't ill before become infected. Unsurprisingly, that feeds a cycle of mistrust.

Dozens continue to die in conditions that are unimaginable in the west. The only reason things aren't even worse is down to the incredible efforts of international medical charities, who can't safely expand without more experts on the ground.

One afternoon a group of women at the MSF centre dragged themselves to a small outside area fenced off with orange plastic mesh. It was impossible to guess their ages – they had been hollowed out by illness, and could barely acknowledge anything beyond their pain. One woman turned to glance at me with what was clearly enormous effort. I understood I was witnessing physical agony too private to be shared.

"It's sad in there. We see people who have diarrhoea, who have vomited on themselves; sometimes they fall on the ground and cannot move," said Moussa Kefa, a volunteer hygienist who was getting ready to enter the isolation tent. "Sometimes we see 10 people die in one day. It's a hard job, but we're doing it for our people."

The morning after the nine-hour ride back to Freetown, Cheikh, who had driven me back, called to say he wasn't feeling very well. He had a headache, he couldn't eat and – his voice wavered slightly – he had a temperature. All the classic symptoms of Ebola. I told him to head to the nearest clinic for a check-up.

My voice was calm but when I hung up, my hands were shaking. I couldn't disentangle my panic from what was real. I was acutely aware of every twinge or ache in my body.

Was I feeling this hot before I spoke to him, or was it the onset of fever? Had my neck really been so sore from sleeping badly last night or was it muscle aches?

I turned out to be okay, as did Cheikh. But each time I hear of fresh Ebola deaths, I picture those women sitting in a tent in the tropical heat, too weak to raise their heads.