f. Small Containers. In some areas, routine attention must be given to artificial
breeding places such as wells, cisterns, bottles, roof gutters, household water
containers, metal cans, coconut shells, road ruts, and shell craters. These may be
screened in, emptied, destroyed, or treated with a larvicide as indicated.
Section V. MOSQUITO-BORNE DISEASES - ARBOVIRUS DISEASES
a. Definition. Arboviruses (arthropod-borne viruses) are those viruses that are
capable of infecting blood-sucking arthropods, proliferating in their tissues, and being
transmitted from vertebrate to vertebrate by arthropods during feeding. The viral agents
transmitted by arthropods now number more than 200, of which 80 are known to cause
b. Basic Cycle of Arbovirus. The perpetuation of an arbovirus in nature is
dependent upon a basic (endemic) cycle involving a vertebrate host and an arthropod
vector in intimate association. This basic cycle has been shown to exist for many
arboviruses, but there are others that has not yet been demonstrated. The intimacy of
the association between host and vector is emphasized because often the viremia (virus
in the blood) is of a transient nature. Human infection is usually incidental to this basic
cycle and is dependent upon the feeding habits of the vector.
c. Transmission of Arbovirus. Sandflies, ticks, and mosquitoes are the only
families of blood-sucking arthropods have been clearly implicated as vectors of viral
agents of disease. Of these, the mosquitoes transmit more than half the known viral
pathogens. Aedes and Culex appear to be the most important genera of mosquitoes in
the transmission of viral agents (Table 5-1).
d. Arbovirus Diseases. Yellow fever, the viral encephalitides, and the dengues
are the best known of the viral diseases transmitted by arthropods. However, it is
becoming increasingly evident that large segments of the world population have had
experience with newly discovered and relatively poorly known viral agents, the clinical
effects of which have been formerly diagnosed as "fever of unknown origin." Exotic
names such as Kyasanur Forest disease, West Nile, and O'nyong-nyong give evidence
of their wide geographical distribution. There is at least one arbovirus disease in
virtually every country where we have military or political commitments.
(1) Viremia. Clinical manifestations of a disease need not accompany
viremia, and indeed there are many avian (bird) and mammalian hosts that are capable
of supporting an intense viremia without clinical symptoms.
(2) Signs/symptoms. In most people who contract infection with one of the
arboviruses, the disease is not clinically apparent. Only a small percentage of those