Several insect species are notorious carriers of diseases and, in the past, have
been responsible for epidemics that have decimated human populations. Many of
them continue to cause major problems in some parts of the world.
The Common House Fly is the world’s most dangerous bug. They travel continuously
between human food, rubbish, and both human and animal excrement. Each fly can
carry as many as six million bacteria on its feet. The list of diseases they
spread includes many of the worst killers of humankind: typhoid, cholera,
gangrene, tuberculosis, gonorrhoea, bubonic plague, leprosy, hepatitis,
diphtheria, scarlet fever, anthrax, amoebic dysentery and poliomyelitis.
Flies not only transmit diseases, but also the eggs of parasitic worms to our
mouths. Most of these infecting organisms thrive in the warm, moist,
nutrient-rich environments of our digestive systems, multiply rapidly and may
invade other parts of our bodies.
Mosquitoes are responsible for the deaths of 2.7 million people each year. They
are able to spread a huge range of diseases including malaria and dengue fever.
In Australia, mosquitoes carry a range of parasites and viruses such as
encephalitis, dengue fever and Ross River fever. Only female mosquitoes suck
blood, which is necessary for the development of their eggs. It is also only
female mosquitoes that make a buzzing sound as they fly.
Lice were among the most dangerous of all insects until the mid-twentieth
century. They were transmitters of typhusa debilitating and deadly
disease that was particularly prevalent in Europe. Lice epidemics plagued high
density human populations, such as in prisons and armies. During World Wars I
and II, lice were responsible for the deaths of over 6 million people. The last
typhus epidemic occurred in Naples in 1944 and was eventually controlled by
dusting three million people with insecticides.
In 1347, Oriental Rat Fleas, carried by Black Rats, introduced the bubonic
plague into Europe. Called ‘The Black Death’, this was one of the worst human
disasters in history. The disease struck and killed with incredible speed. It
ravaged the cities, caused widespread hysteria and ultimately claimed 25
million livesone third of the population of Europe.