TICK-BORNE DISEASES: VECTOR SURVEILLANCE AND CONTROL

cloth; nymphs of southern I. scapularis rarely, if ever, bite people and are rarely collected with
drag cloths; most hard ticks acquired by persons in the south-central and southeastern states in
the winter months are of this species; in one study, they were most often collected questing at
around 20°C, but were collected on days as cold as 6.9°C
Brown Dog Tick
Rhipicephalus sanguineus (Latreille)
Medical Importance: Recently reported to transmit the agent of RMSF; in southern Europe and
Africa, known vector of Rickettsia conorii, the causative agent of boutonneuse fever
Description: Light to dark brown in color, with no white markings on the dorsum; basis capituli
hexagonal in outline; festoons and eyes both present
Distribution: Probably the most widely distributed of all ticks, being found almost worldwide;
in the Western Hemisphere, records from most of U.S. and southeastern and southwestern parts
of Canada; reported from most of Mexico, Argentina, Venezuela, Colombia, Brazil, Nicaragua,
Panama, Uruguay, Paraguay, Galapagos Islands, Surinam, Guyana, French Guiana, Peru, Costa
Rica, Caribbean islands of Cuba, Jamaica, and Bahamas; also widely distributed throughout
Eurasia, Africa, and the Australian region
Hosts: The dog is the principal host, although in immature stages may attack numerous other
animals; humans historically only occasionally bitten in U.S.; could be becoming more
anthropophilic
Seasonality: May be active in the warmer parts of its range year-round; however, in temperate
zones adults and immatures primarily active from late spring to early fall
Remarks: Most often found indoors in and around pet bedding areas; strong tendency to crawl
upward and often seen climbing the walls of infested houses; associated with homes and yards of
pet owners and seldom found out in the middle of a forest or uninhabited area; unfed larvae may
survive as long as 8.5 months, nymphs 6 months, and adults 19 months; females usually lay 2000
to 4000 eggs
3. Diseases Transmitted by Ticks in the United States
a. Babesiosis (CHPPM Fact Sheet)
Causative agent and distribution. Human babesiosis is an uncommon infection caused by
several species of intraerythrocytic, malaria-like protozoans in the genus Babesia that
collectively are known as piroplasms because of their pear-shaped appearance within infected
red blood cells. Over 100 species of Babesia have been described to date and virtually all are
transmitted from ixodid ticks to vertebrate hosts (one report identifies the argasid Ornithodoros
erraticus as a reservoir of B. meri). The disease is found mainly in temperate regions of the
Northern Hemisphere and was first recognized in humans in 1957, with the report of a case in a
splenectomized farmer from the former Yugoslavia. The first American case was described in a
Californian in 1968. In the United States, babesiosis occurs chiefly along the northeast coast and
in the upper Midwest, where the agent is B. microti, a rodent-borne piroplasm. Additional types
of Babesia that are associated with human disease in limited areas of the United States include B.