species discussed in this publication. Arthropods are grouped into classes, two of
which are important here.
a. Class Insecta. This class contains the true insects. Adult insects have three
distinct body regions: head, thorax, and abdomen. The thorax has three pairs of jointed
legs attached to it. Many species also have either one or two pairs of wings attached to
the thorax. Insects of military importance in disease transmission include mosquitoes,
fleas, flies, and lice.
INSECTS (Class Insecta) of Military Importance in
Transmission of Disease
Mosquitoes
Fleas
Flies
Lice
b. Class Arachnida. Adult arachnids have two distinct body regions:
cephalothorax and abdomen. The cephalothorax has four pairs of legs attached to it.
The arachnids include spiders, mites, and ticks. Mites and ticks are the only arachnids
that transmit disease organisms. Arachnids are sometimes incorrectly called insects.
ARACHNIDS (Class Arachnida) of Military Importance in
Transmission of Disease
Mites
Lice
c. Sub classification of the Classes. Each class of arthropods is further
divided into orders, families, and genera, and each genus is divided into the various
species. The species division is usually a true biological grouping, in that the members
have common characteristics and do not mate with members of any other species.
5-3.
HOW ARTHROPODS AFFECT MAN'S HEALTH
Aside from the fact that arthropods are responsible for transmitting some of the
deadliest known diseases, arthropods affect man's health in a number of ways.
a. Direct Injury. Arthropods are often capable of inflicting painful injuries to
man through their bites. They also frequently cause injury to the sense organs, such as
the eye, the ear, and the nose.
b. Envenomization. Many arthropods are capable of injecting toxins or venoms
into or on the skin, causing a wide variety of symptoms. Examples include wasps,
scorpions, spiders (particularly the black widow and the brown recluse), blister beetles,
centipedes, bees, and countless others.
MD0152
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