Mortality rate in Wuthering Heights

If there's one thing I got from reading Jane Eyre and Wuthering Heights, it was the appalling mortality rate back then. I suppose the Brontës may have been more sickly than average, but the death rate of natural causes in those books must have been plausible at the time. iirc, the ages and causes of death were as follows:

Name................Age......Cause of death
Mrs Earnshaw......40-55....n/k
Mr Earnshaw.......40-55....n/k
Mrs Linton...........40-55....fever
Mr Linton............40-55....fever
Frances..............20........consumption
Catherine............21........childbirth after she had weakened herself with cold, hunger and self-neglect
Hindley...............30?.......died of injuries resulting from a fight, or murder
Issabella.............36........not stated, probably consumption
Linton Heathcliff..16/17....consumption
Heathcliff...........38.........starvation and exposure

I was puzzled by the fever that carried off Mr and Mrs Linton. Catherine caught a fever after she had stayed out all night in the rain after Heathcliff ran away. The Lintons insisted Catherine convalesce with them, but sadly caught her fever and died. What sort of fever could that be? It was obviously infectious, but Catherine only developed it after she'd stayed out all night in the bad weather.

It's interesting that the Lintons made Catherine stay with them. That happened in "Pride and Prejudice" too. Jane, Elizabeth's sister, gets wet and falls ill while she and Elizabeth are visiting Mr. Bingley and Jane is forced to stay there to convalesce. I cannot imagine anything more horrible than being sick away from home, but that never seems to bother them.

As to the fever, it is so generally described that it makes it impossible to figure out what causes them to actually die. I wonder if it could be strep, which they may not have known about, and which is actually quite serious. It could also be influenza which still causes quite a few deaths each year, despite the flu vaccine.