How to beat Pandemic II:
First of all choose your virus and play mode. - If you have time choose realistic ;)
Next you can choose your disease class. The parasite games took a bit longer than the others, but the probability to win is much higher.

It is also helpfull, if there's an harbour in the country your disease come from.

The fist thing you should do when te game starts: Sell all the diseases so you get an lower visibility. Remember: You want to infect every country and don't kill the people (in the beginning). - Because if someone dies, they'll close the borders.

Since Madagasca is the hardest country to infect you should set your priorities to infect Madagascar:
So you should buy resistance against Heat and Drugs.
But first buy the Transmition "airborne".
Now buy heat I + II and Drug I + II

Now buy "rodents" and later "Insects".
Remember: "Waterborne" requires Moisture II so buy it later. If you have bought the other transmitions and Heat III + Drug III. You should buy resistance against cold and Moisture, too.
You need the drug resistance so the hospitals can't cure your disease.

Since your disease travels all over the world you should buy "Cold" too, so your disease won't die.
Be carefull that there are not too many infectet persons in the country, where your disease come from.
In case in a country are too many infectet persons they'll close the borders. So be careful!

If you click on "World" you can see all the infected and clean countrys.

You shouldn't buy any Symptoms before every Country is infected. To be shure they can't cure the disease buy "Drug IIII"
Now buy diseases that will kill all the persons in no time. Now it doesn't matter anymore whether your disease is visible.

You don't have to follow this walktrough exact. The most important thing is to sell all the diseases in the beginning.

good luck ;)

If you have suggestions please review it ;)