Saw a show yesterday with the bug guy "Dr. Mike" - he was featuring the most dangerous bugs and reptiles of Mexico. The two at the top of the list surprised me - because I had never heard of them before. The first was not dengue mosquitoes, or rattle snakes, but the 'kissing bug', which can spread a disease called "Chagas Disease".
http://en.wikipedia.org/wiki/Chagas_disease He said that over twenty million people had this in Latin America, which the Wiki confirms as:
"Chagas disease affects 16–18 million people as of 2008, with some 100 million (25% of the Latin American population) at risk of acquiring the disease, killing around 20,000 people annually."
This bug can sense C02 and you do not feel it on your skin. Dr. Mike lied on the ground and sure enough a bug found him within a few minutes. You are usualy bitten around your mouth or nostrils. The Chagas does not affect pets and other mammals. It is suspected that Charles Darwin died of this disease.
The second most deadly is the "beaded lizard" which he easily found in small park in Mexico City. It has a vice like grip which slowly pumps venom as it grips. Not thought to be deadly, but extremely painful.