Isolation of Borrelia burgdorferi from arthropods collected in Texas.

The Texas Department of Health Laboratory cultured arthropods from November 1988 through December 1989 in an attempt to isolate Borrelia burgdorferi, the etiologic agent of Lyme disease. Spirochetes were isolated from eight of 1,093 pools of arthropods cultured. The spirochetal isolates were from several tick and one flea species, including Amblyomma americanum, A. maculatum, Ixodes scapularis, and Ctenocephalides felis. These 8 isolates reacted specifically when treated with monoclonal antibodies to B. burgdorferi. Polyacrylamide gel electrophoresis of six lysates showed them to be virtually identical with strain B31 of B. burgdorferi.

Rickettsia in Texas.

Since the first reported case in 1941, Rocky Mountain spotted fever in humans has been reported from many areas of Texas, with two major foci, one located in the north-central region and the other in the eastern region of the state. During the period 1979-1988, 421 cases of RMSF were reported, reaching 108 cases in 1983 and declining in subsequent years. Statewide surveillance programs to detect spotted fever group rickettsiae in tick populations were initiated in 1976. In recent years, the SFG infectivity rates in these tick species have included Dermacentor variabilis, 5.2%; Amblyomma americanum, 7.1%; Rhipicephalus sanguineus, 2.9%; and Ixodes scapularis, 10.2%. Further determination of involved rickettsial species and pathogenicity is needed, as many of these specimens are collected from humans and during epidemiological investigations. Various foci of murine typhus occur in Texas. During 1979-1988, 400 human cases were reported. The majority of cases occurred in people who resided in south Texas. Several investigations have shown a possible link between typhus infections and exposure to Ctenocephalides felis. Other rickettsial infections currently reported in Texas include Q fever and ehrlichiosis.

Isolation of Borrelia spirochetes from patients in Texas.

The Texas Department of Health Laboratory began culturing the Lyme disease spirochete Borrelia burgdorferi in 1985. This organism was subsequently isolated from blood, cerebrospinal fluid, joint fluid, skin, bone, and autopsy tissues from humans. Fluorescent-antibody tests with murine monoclonal antibodies confirmed that seven of these isolates were B. burgdorferi and that two others belonged to the genus Borrelia.

Occupational dermatitis associated with straw itch mites (Pyemotes ventricosus).

A 1981 outbreak of dermatitis in Austin, Tex, was traced to occupational exposure to wheat infested with the straw itch mite, Pyemotes ventricosus; the wheat was being sold for decorative purposes by an imported-goods store located on the second floor of a large, modern, shopping mall complex. In addition to an extensive varicelliform skin eruption, one employee also had chills, fever, malaise, diarrhea, and anorexia associated with her exposure to these mites. The straw itch mite has been associated with several large epidemics of dermatitis during the 19th and 20th centuries. This outbreak is the third reported in Texas since 1961. Physicians should consider the possibility of straw itch mite infestations of products brought into the home or places of employment when they observe patients with a varicelliform or chigger-bite-like dermatitis, which may be accompanied by constitutional symptoms.