This website is not affiliated with the U.S. government or military. All proceeds from the operation of this site are donated to veteran and other charities.

Arthropodborne Diseases

 
  1. Historically, arthropodborne
    diseases have caused more casualties than combat
    injuries. Arthropodborne diseases alone were
    responsible for the loss of 15,576,000 man-days among
    US Armed Forces during World War II.

    1. Today, harmful arthropods
      represent one of the greatest environmental hazard
      to soldiers in the field. The chain of infection for
      arthropodborne diseases involves a pathogenic
      organism in an infected person or animal (the
      reservoir), an arthropod to transmit the disease
      (vector), and a susceptible person (the host).
    2. The significance of vector efficiency in disease
      transmission from reservoir to host is related to
      many factors. Some of the factors are
      species-related such as vector reproductive
      capacity, physiology, morphology, and genetics.
    3. Other factors that affect the vector�s ability
      to transmit disease are physical and related to
      environmental conditions, such as temperature,
      moisture, rainfall, pH, weather, geographical and
      topographical location, photoperiod, and wind.
    4. Soldiers in a field environment must break the
      chain of infection for arthropodborne disease or
      arthropod injury by limiting arthropod pest
      exposures.
  2. Arthropods (insects, ticks, mites,
    spiders, scorpions, and the like) make up over 75
    percent of all animal species. Less than 1 percent of
    the 750,000 species of arthropods are potentially
    dangerous to humans. However, their impact is
    significant due to their high numbers and the negative
    results of their activities. The impact is direct
    injury and disease transmission to man and other
    animals; damage to crops; infestation of stored
    products; and destruction of wooden structures. Still,
    many species are beneficial as pollinators, predators
    of other pests, scavengers of waste, manufacturers of
    food, and a part of the natural balance of nature.
    However, the economic damage and medical disorders
    caused by a few arthropods make some pest management
    practices necessary to control the problem pests.
    Protection of the soldier from arthropods and
    arthropodborne diseases is essential to mission
    accomplishment.

Direct Arthropod
Affects on Human Health

In addition to disease
transmission, arthropods can cause direct injuries to
man. Bites, stings, and allergic reactions are three
major categories of injuries caused by arthropods.
Arthropods also affect man by annoying and disturbing
him. The sound of a single mosquito buzzing around your
head while your are trying to sleep is annoying.
Standing guard with gnats buzzing around your face can
be disturbing. Also, finding cockroaches or other
insects or parts of insects in your food is disturbing.
The problems of arthropod injury and the exaggerated
fear of arthropods can even result in psychiatric
problems.

  1. Biting Arthropods. Arthropods bite
    to feed, probe (taste), or defend themselves. Most
    penetrations of human skin are made by mouthparts that
    are developed for ingesting blood, tissue, and tissue
    fluids of animals or plants. These bites usually
    result in the arthropod injecting salivary fluids or
    regurgitating its digestive tract products into the
    man or animal. Some biting arthropods can also produce
    skin injuries. Each individuals reaction to arthropod
    bites can be very different. Biting arthropods are
    grouped according to the duration of host contact as
    (short-term) or prolonged (long-term).

    1. Short-term host contact.
      Most arthropods that bite man have only short-term
      host contact. Bloodsucking arthropods are frequently
      winged or highly mobile. This accounts for their
      ability to quickly attack and escape capture or
      detection. Some arthropods hide in structures close
      to the host and only feed when the host is nearby.
      Others that bite may not have intended to attack,
      but did so in defense or by mistake. Arthropods can
      bite in several stages of their development; that
      is, adult, larvae, or nymph stages. The mouthparts
      are generally classified into chewing or sucking
      types. Chewing mouthparts are generally not used for
      skin penetration. Usually, injuries of this type are
      not reported, but secondary infections may occur due
      to bacterial contamination. Sucking mouthparts are
      structured for skin penetration.

      1. Bloodsucking (hematophagous)
        arthropods.
        Blood,
        normally from warmblooded animals (including man),
        is used both for life support and growth and/or
        egg development. The mouthparts of sucking
        arthropods vary greatly in structure from
        arthropod-to-arthropod. For example, adults of the
        order Diptera (two-winged insects) have the most
        diverse mouthparts. Only the females of the
        mosquitoes, black flies, biting midges,
        horseflies, and deer flies are bloodsuckers, while
        both males and females of tsetse flies and stable
        flies are bloodsuckers. The mouthparts are
        different within each of these families of Diptera,
        but the goal of a blood meal is the same. Other
        examples of arthropods that are short-term are
        fleas, true bugs (conenose bugs and bedbugs), and
        soft ticks.
      2. Nonbloodsucking (nonhematophagous)
        arthropods.
        Some plant-feeding arthropods and
        some arthropod predators have piercing/sucking
        mouthparts, which are capable of penetrating the
        human skin. Bites from these arthropods can be as
        painful as bloodsuckers, if not more so. Bites
        from these arthropods are usually an act of
        defense.
    2. Long-term host contact.
      Some biting arthropods require a considerable time
      on the host to complete a normal life cycle. Since a
      continuous food supply is available on one host, the
      search for another host is reduced. Most of these
      arthropods are categorized as parasites. They are
      classified as either ectoparasites or endoparasites.
      Ectoparasites (those living outside the host body)
      may be flat (fleas) or thin (lice) which allows them
      to travel easily through a hairy environment. Their
      feet are specialized for holding on to hair. The
      mouthparts of ticks and mites are designed to anchor
      their bodies to the host. Endoparasites (those
      living inside the host body) are usually soft-bodied
      (fly larvae, mites) without legs or with very short
      legs; their bodies usually have specially arranged
      spines or hairs.
  2. Stinging Arthropods.
    Some arthropods affect man by injecting venom (insect
    toxins) through stingers, fangs, modified front legs,
    or spines. An arthropod�s injection of poison is in
    defense or to kill prey. Usually, man is envenomized
    by arthropods in defense of themselves and their nest
    or eggs.

    1. Venoms from bites.
      Spiders and centipedes are arthropods in the
      category that uses mouthparts for envenomization.
      Most spiders use venom to kill prey. Man is not part
      of a spider�s diet. The fangs of many spiders cannot
      penetrate the human skin. Some species have venom
      that is more poisonous than other venomous animals,
      including snakes. Fortunately, most spiders are not
      aggressive, but will defend themselves and their
      eggs and/or webs. Antivenom has been developed for
      the venom of some species of spiders, but they may
      not be immediately available for use. Some of the
      more toxic spiders are night hunters, and by day,
      they hide in clothing and boots that were left on
      the floor or in tents on the ground. Less common are
      the bites of centipedes that are also night hunters.
      In the tropics, some species of centipedes reach 25
      centimeters in length; a bite by such a large
      specimen could be serious.
    2. Venoms from stings. The number of soldiers
      seeking medical assistance because of arthropod
      bites is far fewer than those seeking aid because of
      bee, wasp, hornet, or ant stings. Stings from these
      arthropods are frequently the result of defensive
      action. A single sting to an allergic person can be
      fatal. Even to a person who is not strongly
      allergic, medical complications due to swelling can
      occur with stings to the face, neck, or throat.
      Stings usually occur during daylight hours. However,
      night maneuvers can result in individuals running
      into paper wasp nests and being stung by wasps
      trying to protect their nests; or an individual may
      stand on an anthill and receive numerous stings from
      the ants trying to protect their nest. Therefore,
      individuals who are highly sensitive or have severe
      reactions to stings should carry an emergency first
      aid kit for stings as prescribed by a physician.
      Obviously, high-risk persons should use extreme
      caution in tropical areas. Another venomous
      arthropod with a potent sting is the scorpion.
      Scorpions are active at night. During the day
      scorpions are usually well-hidden from the light;
      they hide under rocks or in piles of debris outside
      and in clothing, cabinets, boxes, and footwear
      indoors. Stings often are the result of individuals
      walking barefoot or in stocking feet, or because
      they use their hand to move the object where the
      scorpion is hiding. Also, stings occur when
      individuals put on clothing or footgear without
      first shaking the item to make sure that it is free
      of unwanted arthropods. Some scorpion venoms are
      very painful or they may be deadly, while others are
      not. The absence of initial pain is not always an
      indication of no problem. The lack of or the
      nonavailability of antivenom and the possible

      medical problems associated with the use of
      antivenoms, even if they were on hand, are
      additional reasons for avoiding scorpion stings.
  3. Allergy. Allergic reactions are
    caused by both the bites and stings of arthropods.
    Additionally, arthropod parts (live or dead) and their
    body fluids can cause allergic reactions. Allergic
    reactions are extremely variable in different people
    ranging from very mild to severe reactions. Highly
    sensitive persons should be prepared to deal with
    their problems in case they are bitten, stung, or
    exposed to other arthropod allergens.

Arthropodborne
Diseases

Diseases transmitted to
man by arthropods are some of the most serious known to
man. Uncontrolled, these illnesses can cripple or
destroy military forces. The effect of these diseases on
man can range from a very mild illness to death. For
examples of arthropodborne diseases and their vectors
see Table 2-1. House flies and other flying insects that
are attracted to human wastes or other organic material
can spread disease organisms to food and water. The
disease organisms or parasites of humans are carried
from diseased humans or animals (reservoirs) by
arthropods (vectors) to other humans or animals (hosts).
By employing individual PMM, soldiers can stop
arthropodborne diseases from being a factor in their
lives and in their units mission accomplishment. The
most common arthropodborne diseases that affect combat
troops are discussed below.

   



DISEASE


VECTOR

  MALARIA

  MOSQUITO

  CHAGAS’
DISEASE

  KISSING BUG (REDUVIID)

  LEISHMANIASIS

  SAND FLY (PHLEBOTOMINE)

  YELLOW FEVER

  MOSQUITO

  DENGUE FEVER

  MOSQUITO

  ENCEPHALITIS

  MOSQUITO

  SANOFLY FEVER
OR PHLEBOTOMUS FEVER

  SAND FLY (PHLEBOTOMINE)

  TYPHUS FEVER
(EPIDEMIC)

  BODY LOUSE

  TYPHUS FEVER
(MURINE)

  FLEA

  SCRUB TYPHUS

  LARVAL MITE
(CHIGGER)

  BUBONIC
PLAGUE

  FLEA

  DYSENTERY

  FILTH FLIES
(PARTICULARLY THE HOUSE FLY)

  TYPHOID FEVER

  FLIES AND
COCKROACHES (BY FOOD CONTAMINATION)

  SPOTTED FEVER

  TICK

  FILARIASIS
(ELEPHANTIASIS)

  MOSQUITO

 
ONCHOCERCIASIS

  BLACK FLY

  1. Malaria. Malaria is a serious disease
    occurring most commonly in tropical and semitropical
    regions. It is caused by a microscopic parasite
    carried by the Anopheles mosquito. This parasite
    destroys blood cells and causes chills, fever,
    weakness, and anemia. If untreated, malaria can cause
    death.
  2. Yellow Fever. Yellow fever is a viral
    disease transmitted by the Aedes mosquito. It occurs
    in tropical Africa, Central America, and tropical
    South America. Symptoms are fever, headache, backache,
    jaundice, and internal bleeding. If untreated, yellow
    fever can result in death.
  3. Dengue Fever. Dengue viruses of multiple
    types are now endemic throughout most tropical areas
    of the world and are highly endemic in Southeast Asia,
    the Philippines, West Africa, and northern Australia.
    Like yellow fever, it is transmitted by the Aedes
    mosquito. Symptoms are fever (lasting about 5 days),
    intense headaches, skin rash, and muscle pain which
    can be severe; for this reason, another name for
    dengue fever is �breakbone� fever. The disease seldom
    results in death, but the recovery time is usually
    long and the victim may be fatigued and depressed.