Mosquito Militancy

Growing up in the Midwest, I constantly dealt with the onslaught of mosquitoes in the summer. They were, however, no more than a pest, as we engaged in slapping them away and suffered at best, little itchy bumps on our skin for a day or so. When I moved to Virginia, a few decades ago, I feared that mosquitoes would be a greater nuisance down here, but was relieved to find fewer of those pesky critters than I had expected.

My experience with these biting insects has been nothing, however, compared to most of humanity's battles. A recent article in the New Yorker (“Buzz Off,” by Brooke Jarvis) chronicles the horrors that mosquitoes have brought to humans. In fact, some researchers have estimated that over 50 billion humans have died from mosquito attacks—about half of all people who ever were born! Think about that: more deaths from a tiny insect than all the wars we've ever engaged in.

Mosquitoes are very efficient vectors of disease. They bite a person or animal infected with various maladies, ingest the harmful bacteria, and then pass them on. In the deep past, mosquitoes did their greatest damage when people traveled from one region to another—bringing the diseases with them. That's still true today, but travel by airplane is ever so much farther and faster.

The victors of many past wars were determined by diseases carried by these insects. Roman army advances on the English island were halted by strains of malaria native to Scotland. As a result, Rome set its northern frontier at Hadrian's Wall—roughly the border between Scotland and England today. Hannibal's troops and Genghis Khan's forces were stymied by the mosquito. Napoleon's army in Haiti was decimated by yellow fever.

A late major 17^th century major attempt by Scottish colonists to settle in Panama, in order to control traffic between the Pacific and Atlantic, was defeated by yellow fever and malaria. As a result, a debilitated Scotland yielded to England, to forge Great Britain. Prehistoric Africa was an ideal breeding ground for malaria (it still is), resulting in an evolutionary adaptation in Africans' red blood cells: acquiring a sickle shape that resisted the disease.

For millennia people did not understand that the mosquito—giving a free ride to malaria bacteria—was the cause of diseases. Since it was encountered primarily in warm, wet climes, it was thought to be caused by something in the stinky air of marshlands. Thus the Italian term mala aria: “bad air.”

When Columbus sailed to America, the mosquitoes there carried no diseases, but they quickly began transporting the maladies brought by the Europeans. Within a short time, some 95% of American Indians, which had previously numbered some 100 million souls, succumbed to the new diseases. As invading Europeans pushed into the interior of the New World, they came to believe that the continent was largely uninhabited. It became their “Manifest Destiny” to occupy the land.

Centuries later we continue to struggle against malaria and other mosquito-borne diseases. Despite the insecticides our technology has created, the mosquito evolves and adapts new forms of resistance. Now global warming brings new dangers, as these insects move north into new territory. The arms race continues. It raises the question: Are mosquitoes our worst enemy ever, or are we ourselves?