David Strettle, Iain Balshaw and Nick Wood have all flown home early due to illness and injury, leaving the tourists in a chronically patched-up state.
Even Brown, England's 6ft 7in lineout leader, failed to avoid effects of the stomach virus that has laid low so many players since arriving in South Africa two weeks ago.
He said: "There is no real comparison between how I feel now and last week.
"On the Friday before the first Test I was on a drip because I had lost so much fluid, but I am now feeling 100% better.
"After the game in Bloemfontein, I felt a bit rough because it was an intense game, but I managed to get over that and I am finally back on the straight and narrow.
"With the altitude and everything else it does make a difference, so sickness doesn't help."
Despite England's record 58-10 defeat against the Springboks at Vodacom Park, their set-piece game operated efficiently, with scrum and lineout holding up well in the face of a fierce challenge from South Africa's front-row and their revered second-row operator Victor Matfield.
And Brown knows it will take a repeat performance if the tourists are not to travel home reeling from another landslide loss.
He added: "The set-pieces were okay. Our scrum went well and the lineout was okay.
"Last week's game reminded me a little bit of the Guinness Premiership final when Gloucester played Leicester three weeks ago.
"The result was fairly similar, and like Leicester, South Africa were more physical on the day than we were, but I don't think it is something we should be intimidated by.
"Their size has got some faults with it. They are not as mobile as we are, and we are going to look to run them around.
"I think if we are critical, then our backs want quality ball, and while we gave them possession, it wasn't top quality.
"Matfield and his boys are pretty formidable. They are at the top end of world rugby, so to come away with as much possession as we did from our lineouts and scrums was pretty pleasing, considering all the events that happened during the build-up.
"I actually enjoy studying the opposition and the mental challenge of it. You have got to have a passion for it.
"Matfield has got the all-round game. He has the lineout skills, there there is his ball-carrying and his defensive work. He runs the lineout particularly well."
A towering display by Brown in the face of adversity this weekend would undoubtedly assist his World Cup cause - Ashton is due to name a training squad later this month - although a first victory in England colours looks certain to remain on hold.
Brown's previous two England appearances have seen him finish on the wrong end of emphatic defeats against Australia and South Africa, but the 28-year-old - like his colleagues - is determined to make a mark before heading home.
He said: "We didn't do ourselves justice last Saturday - we turned the ball over so many times.
"We looked at the video on Monday, and it was just frustrating for us because we had the ball in good positions and just gave it away.
"When we gave it away, South Africa seemed to score. We need to tidy up and improve our reaction when the ball is turned over.
"Defensively, we weren't that out of place, it was the turnovers which is something we must all take blame for. We've got to eradicate that and have a better run of it this weekend."