Once DDT had established a reputation as 'the atomic bomb of the insect world', public health officials adopted the weapon with an unquestioning fervour. By the mid 1960s when the World Health Organisation's anti-malarial campaign peaked, 76 000 tons of DDT fell on 76 countries. Although the chemical intitially killed anopheles with clinical efficiency, it soon bred a stronger and more resistant adversary. At least 57 breeds of mosquitos can now swim in DDT and other pesticides without suffering any ill effects. Gallons of DDT sprayed randomly also produced a myriad of unforeseen health problems.
A typical case of good intentions gone awry occurred in Sarawak, part of Borneo. Here the spraying of homes with DDT not only killed mosquitos but cockroaches. Cats returned to the sprayed homes, ate the poisoned cockroaches and died. Free of predators, the Malaysian field rat, a carrier of plague and typhus, overran the mosquito free villages. Fearing an outbreak of the plague , the World Health Organisation eventually asked the Royal Air Force to drop cats by parachutes over the isolated villages. Fortunately for Sarawak's villagers, 'Operation Cat Drop' helped avert an epidemic of plague that DDT and malarial control had invited in to their villages.