door where mosquitoes might enter. In highly malarious areas, entrances should have
a vestibule with double screen doors at least six feet apart and open outwards. Cracks,
knotholes, and other openings in screened buildings should be filled in. Torn screening
must be repaired promptly. Occupants of each barracks building are responsible for
their own minor repairs. Unit field sanitation teams should make regular inspections of
the facilities and promptly report repair requirements.
Section II. TICK-BORNE DISEASES
Ticks are commonly called insects. Technically, however, they are arachnids--
the class of arthropods that includes spiders, mites and scorpions. Ticks occur
throughout the world, but they are less common in the arctic and subarctic zones. They
are divided into two groups--the hard ticks and the soft ticks. The hard tick has a hard
shield on its back and its mouthparts can be seen from above (figure 5-3 A ). The soft
tick does not have a hard shield on its back and its mouthparts cannot be seen from
above (figure 5-3 B ). The soft tick often has a leather-like appearance.
a. Life Cycle. The life cycle of the tick consists of four stages--egg, larva,
nymph, and adult (figure 5-4). In the larva stage, the tick only has six legs. Ticks in the
larva, nymph, or adult stages will attach to humans, puncture the skin, and consume the
b. Characteristics. Hard ticks and some soft ticks often climb upon grass and
vegetation and then wait for a suitable host to pass by. Should a person brush by the
vegetation, the tick will quickly attach itself to the person's clothing and then take a
blood meal. Soft ticks that transmit relapsing fever usually remain hidden in cracks and
crevices of buildings during the day and feed at night.