And has been incorporated into the Wikipedia entry, which has also been greatly expanded by Dave Souza.
Dave asked me to explain why I thought that it was almost certain that CD Senior died from meningococcal disease. The clues stem from the passage I mentioned earlier:
"About the end of April, Mr. Darwin had employed the greatest part of a day in accurately dissecting the brain of a child which had died of hydrocephalus, and which he had attended during its life. That very evening he was seized with severe head-ach. This, however, did not prevent him from being present in the Medical Society, where he mentioned to Dr. Duncan the dissection he had made, and promised the next day to furnish him with an account of all the circumstances in writing. But the next day, to his headach there supervened other febrile symptoms. And, in a short time, from the hemorrhagies, petechial eruption, and foetid loose stools which occurred,his disease manifested a very putrescent tendency."
The clues are two-fold:
1. meningococcal disease is commonest in childhood and adolescence, so it is one of the likeliest causes of a fatal infection of the brain in a child
2. The petechial haemorrhages are a give-away: as recent clinical guidelines state: "fever plus a petechial rash is meningococcaemia until proven otherwise"
Curiously, I cannot find any other case reports of meningooccal infection acquired from a postmortem examination. This 1995 guidance from the Communicable Disease Report places cadavers with meningococcal disease in an intermediate risk category, whereas this more recent guidance from the HPA is rather more dismissive: "No cases have been reported following post-mortem contact with a case of meningococcal
But all in all, I still conclude that meningococcal disease is by far and away the most likely cause of death here.