[El Cid]

We all suspect the reason, but the article doesn't provide any info (other than the young child died suddenly). And as other people commented, Australia is full of poisonous critters - so perhaps she got bitten by one of those - but that should have been a 'known cause' (e.g., 'bitten by one our many poisonous spiders. Or poisonous snakes. Or venomous rabbits ...').
'Died Suddenly of Unknown causes' makes us suspect the one thing that must not be mentioned.

[gnarledmaw]

Hard to say, its either Miracle Whip or that weird glaze that some people put on their breadcrumb filled playdough meatloaf.