The author is Sonia Shah and the subtitle is How Malaria has Ruled Humankind for 500,000 Years. Excerpt:
The mosquito's immune system instinctively attacks the parasite, encapsulating the intruder in scabs and bombarding it with toxic chemicals. To survive, the parasite must unleash armies of progeny in such massive numbers that fighting it off becomes more trouble than it's worth. Male and female forms of the parasite, called gametocytes, then fuse, and the resulting parasites create cysts that cling to the walls of the bug's gut. (The spasmodic waving of the male gametocyte's long tail, which precedes the act of fusing with the female — yes, this microbe reproduces sexually as well as asexually — is called exflagellation.) Tens of thousands of slithering threads explode from the cysts and swarm up to the mosquito's salivary gland. This is the form of parasite must take to infect human beings. Malariologists call it the sporozoite. When a mosquito starts a blood feed, some two dozen slivery sporozoites will escape into their next host.
It's an excellent book. There is a short review and excerpt here.