1. Biological vectors. These are animals in whose
bodies the infecting organism develops or multiplies
For detail information on pathogens and
before it can infect the recipient animal.
toxins, you should refer to NSTM, chapter 470.
"Shipboard BW/CW Defense and
2. Mechanical vectors. These are animals that
transmit infective organisms from one host to another
but, in themselves, are not essential to the life cycle of
EFFECTS OF BW AGENTS
BW agents may be selected to produce various
Mosquitoes that transmit malaria and yellow fever
strategic or tactical goals. These goals range from brief
are biological vectors. The black horsefly, which
but crippling diseases to widespread serious illnesses
transmits anthrax, and many insects that transmit plant
with many deaths. The effects of biological agents vary
diseases are mechanical vectors. Higher animals, and
widely, depending upon the agent or agents selected.
man himself, sometimes act as vectors. Swine are host
The mere presence of a disease-producing organism
to trichine, which produces trichinosis in man when he
on or in the body of a host does not guarantee infection
eats inadequately cooked, infected pork. Dogs, cats,
or illness. In fact, pathogenic organisms are frequently
skunks, foxes, and some other animals transmit rabies.
present and cause no harm in the human body for long
periods of time. The factors that determine whether
PESTS.-- The meaning of the term pest as used
infection will result from contact between a pathogen
here is restricted to certain animals (excluding
and a host are not completely understood; however,
microorganisms) that interfere with the health of other
some important factors are as follows:
organisms. These pests live on or within the animals, or
they are associated with them in other injurious ways.
· The general state of health of the individual
Pests are known as parasites when they obtain their
· The immunity of the particular individual to the
food from living host cells. The presence of a large
number of parasites on the surface of the body of the
host, producing only mechanical effects, is known as
· T h e n u m b e r o f o rga n i s m s t o w h i c h t h e
infestation. Invasion of the tissues of the body of the
individual is exposed
host by parasites, producing injury followed by host
· The ability of the organisms to cause disease
reaction, is known as infection. Living organisms that
consume or destroy food, clothing, and forest products
Remember that the effects of pathogens are always
also are characterized as pests.
delayed. There is always an incubation period between
A l t h o u g h m a ny i n s e c t s a r e b e n e fi c i a l t o
the time organisms enter the body and the time that
agriculture, great losses are caused by plant-feeding
symptoms of disease are observed. This period may
vary from several hours to several weeks.
insects and by insect-borne plant diseases. Other
serious losses result from the destruction of stored
To some extent, the effects of pathogens are
food, clothing, and forest products by such pests as rats
determined by the route that the infecting organisms
and moths. Some pests affecting the animal kingdom
use to enter the body. Many organisms require a
are mites, ticks, spiders, scorpions, chiggers, lice,
specific portal of entry to produce infection or disease.
bedbugs, and flies. Some pests affecting plants are the
Other organisms can cause disease when they enter by
Japanese beetle, snails, corn earworm, boll weevil, and
any route. The usual ways in which pathogenic
the elm leaf beetle. Other pests that take a toll on man's
organisms enter the body are by inhalation, by
products and have potential value as BW agents are
swallowing, by direct contact, and by injection.
rats, mice, groundhogs, starlings, and crows.
Injection includes insect and animal bites.
Toxins are poisonous products of living organisms
BW agents may be spread in various ways. They
that when inhaled or swallowed or injected into a man
may be used as fillings in bombs, shells, or aerial or
or animal will cause illness or death. Some toxins used
surface spray tanks. Biological agents may be released
as BW agents are produced synthetically. Because they
from munitions such as aerosols. The aerosols are
have similar characateristics, toxins are disseminated
cloudlike formations of solid or liquid particles in
in the same manner as chemical agents.
which the biological agents are held suspended.