could you tell if you were poisoned

The "pet food poison' has clearly entered the human food chain.
Definitely through animal feed for chickens and pigs raised for human consumption, and quite likely through direct contamination of food additives - gluten and grain/vegetable protein additives

The acute symptoms in cats and dogs are fairly well known, and seem to end in kidney failure and a painful death.

Question is whether melamine, and whatever additional toxins or toxic breakdown products and metabolites may be involved, are causing either acute or chronic illness in humans.

Suspected effects are kidney problems, possible carcinogen (well duh) and fertility problems.

Most worrying short term effect would be kidney failure, or possible increase in kidney stones or urinary tract infections - the latter are "just painful" in most cases; the former is a major cause of death.

And that is the problem, a lot of people die from kidney failure, a lot related to diabetes complications, or age related issues, or infections, at a rate of about 1-2 per 10,000 per year, or about 2% of all deaths.

So about 30-50,000 deaths from kidney failure per year.
That base rate has been climbing, probably mainly because of increased diabetes incidence.

All things being equal, people most likely to be affected are those already ill, old and with pre-existing kidney problems; who might also be eating a lot of enriched processed food. Such as elderly with diabetes in institutional care.
If the death rate from kidney failure increased by 10% because of random toxic food contamination, it would be an extra 3-5,000 deaths per year, nationwide.
But they would be spread randomly around the country, one here, another there. Barely a blip in local statistics. Individual hospitals or doctors would likely not notice, or attribute any change to small number statistics.
It is a public health issue.

National aggregate statistics on causes of death take 1-2 year to be put together by the looks of it, I can't find the '06 tables, and the '05 tables seem to have come out recently. Maybe the CDC has in-house quick look stats to spot short term trends, if they don't, they should.

A 10% increase in kidney failure would probably not be noticable over a single year, or two, it is comparable to the expected base increase from other factors anyway. More obesity, more diabetes, more kidney failure.
You would have to see either "otherwise healthy" people get sick in large numbers, or a very large increase in deaths in the vulnerable population for it to be immediately detectable.

Makes you sick.