Ms Cafferkey fell ill hours after she flew back to Scotland from Africa via Heathrow, and the authorities have traced 63 of the 70 people who flew with her from London to Glasgow on Sunday.
Questions are already being asked about the Government's Ebola screening programme because the woman was vetted twice - in Sierra Leone and at Heathrow - without any symptoms being detected.
Dr Deahl said that medical staff in Sierra Leone always wore hazard suits at work but some did not when they went out into the wider community.
A number of the 30 NHS staff out in Sierra Leone, including himself, worshipped at a local church on Christmas Day.
He also said that at Freetown airport in Sierra Leone all the volunteers were "kissing and hugging" as they left the country, including Ms Cafferkey.
All the NHS workers who flew back with Ms Cafferkey must monitor their temperature and call Public Health England every day before Midday with their readings or doctors will be sent.
Pauline Cafferkey in her hazard suit. Photo / Supplied
Dr Deahl said: "I would bet anything that she caught this while out in the community. I went to church myself on Christmas morning and I have no doubt Pauline probably contracted the virus doing something similar.
"We had a rule known as ABC which stood for Absolute no Body Contact but when you are in the community it is difficult to stick to the rules and easy to become complacent. It is also difficult when children come up to you and hug you."
Dr Deahl flew back from Casablanca to London with Ms Cafferkey and said he was "heartbroken" she had fallen ill.
But he criticised Public Health England for poor advice on when those exposed to deadly virus should travel.
He said: "I was sitting next to her on the plane when we flew back on Sunday night and she seemed fine. I am absolutely fine. I am just so shocked and heartbroken to hear that anyone from our team is ill.
"The precautions and checks at the airport were shambolic. They ran out of testing kits and didn't seem to know what they were doing.
"We were told that we were considered high risk but yet were told to make our own way home from Heathrow, either on the Tube, by bus or train or another flight like the one Pauline and others took. I was picked up.
"Public Health England told us we should avoid public transport or crowded places for 21 days, but only after we had got home. It defies common sense and we told them that.
"A group who arrived back on Christmas Eve were all given taxis home but we weren't and one can only conclude this is because Public Health England wanted to save money.
"Now all these people on that flight to Glasgow will be scared witless and it could have been avoided."
This morning she was moved to the Royal Free Hospital in London after being loaded onto a military aircraft in a cocoon by medical staff in protective suits at Glasgow Airport.
There are also fears for passengers and staff who had close contact with the nurse, who flew from Freetown to London via Morocco before reaching Scotland late on Sunday night.
Officials are urgently trying to trace 71 people on her British Airways BA1478 flight from London to Glasgow. They will also be contacting passengers who were sitting near her on her other flights back to the UK via Casablanca - Royal Air Maroc flights AT596 and AT0800.
Ebola nurse's moving diary
Pauline Cafferkey wrote a moving diary of her time working as a volunteer with Save the Children helping Ebola victims in Sierra Leone. She left with 30 other NHS staff in November who all worked at various hospitals in west Africa.
She told how from the moment she stepped off the plane, the smell of chlorine hit her and a thermometer was pointed at her head. She also described the "horrendous" suit she had to wear while treating patients.
She wrote in the Scotsman: "The PPE [personal protective equipment] alien-type suit that I have to wear when going into the positive Red Zone is horrendous. It takes about 20 minutes to dress and 15 minutes to take the suit off at the other end. They would be beneficial on a cold winter's night in Scotland, but working in them in 30-degree heat is uncomfortable to say the least.
"I feel very well protected. I was unaware that I could sweat so much. When I get to the decontamination area and remove the suit and gloves, there are pools of sweat dripping from me and not a dry hair on my head.
"I feel sorry for the poor patients who have these alien-type people caring for them. Especially so for the young children, who are not only very sick but have these strange creatures with only their eyes visible trying to make them drink and take medications."
- Daily Mail
