Control and Prevention of Anthrax, Texas, USA, 2019.

The zoonotic disease anthrax is endemic to most continents. It is a disease of herbivores that incidentally infects humans through contact with animals that are ill or have died from anthrax or through contact with Bacillus anthracis-contaminated byproducts. In the United States, human risk is primarily associated with handling carcasses of hoofstock that have died of anthrax; the primary risk for herbivores is ingestion of B. anthracis spores, which can persist in suitable alkaline soils in a corridor from Texas through Montana. The last known naturally occurring human case of cutaneous anthrax associated with livestock exposure in the United States was reported from South Dakota in 2002. Texas experienced an increase of animal cases in 2019 and consequently higher than usual human risk. We describe the animal outbreak that occurred in southwest Texas beginning in June 2019 and an associated human case. Primary prevention in humans is achieved through control of animal anthrax.

Rickettsia parkeri (Rickettsiales: Rickettsiaceae) in the Sky Islands of West Texas.

Rickettsia parkeri, a tick-borne pathogen distributed throughout several countries of the Americas, causes a mild to moderately severe, eschar-associated spotted fever rickettsiosis. Although most U.S. cases of R. parkeri rickettsiosis are reported from southeastern states, some have been reported recently from remote regions of southern Arizona. These cases are linked to R. parkeri-infected ticks of the Amblyomma maculatum (Acari: Ixodidae) group found in several isolated mountain ranges of southern Arizona and New Mexico, referred to as 'sky islands'. Archival records also document ticks of the A. maculatum group collected from domestic and wild animals in West Texas. We surveyed sites in two sky island chains of Jeff Davis and Brewster counties to document the off-host occurrence of these ticks and identify the presence of R. parkeri in the Trans-Pecos region of Texas. During August 2019, 43 adult A. maculatum group ticks were flagged from vegetation or removed from a road-killed, female mule deer. Of 39 samples evaluated by PCR, eight contained a partial sca0 sequence with complete identity to R. parkeri and two with complete identity to 'Candidatus Rickettsia andeanae', a species of undetermined pathogenicity. Four isolates of R. parkeri were obtained using cell culture. Persons at risk for R. parkeri rickettsiosis include those who work or recreate in these mountains, such as hikers, backpackers, research scientists, foresters, and border enforcement personnel. Additional investigations are needed to define the distribution of these medically important arthropods in other parts of the southwestern United States and northern Mexico.

Trypanosome species, including Trypanosoma cruzi, in sylvatic and peridomestic bats of Texas, USA.

In contrast to other mammalian reservoirs, many bat species migrate long-distances and have the potential to introduce exotic pathogens to new areas. Bats have long been associated with blood-borne protozoal trypanosomes of the Schizotrypanum subgenus, which includes the zoonotic parasite Trypanosoma cruzi, agent of Chagas disease. Another member of the subgenus, Trypanosoma dionisii, infects bats of Europe and South America, and genetic similarities between strains from the two continents suggest transcontinental movement of this parasite via bats. Despite the known presence of diverse trypanosomes in bats of Central and South America, and the presence of T. cruzi-infected vectors and wildlife in the US, the role of bats in maintaining and dispersing trypanosomes in the US has not yet been reported. We collected hearts and blood from 8 species of insectivorous bats from 30 counties across Texas. Using PCR and DNA sequencing, we tested 593 bats for trypanosomes and found 1 bat positive for T. cruzi (0.17%), 9 for T. dionisii (1.5%), and 5 for Blastocrithidia spp. (0.8%), a group of insect trypanosomes. The T. cruzi-infected bat was carrying TcI, the strain type associated with human disease in the US. In the T. dionisii-infected bats, we detected three unique variants associated with the three infected bat species. These findings represent the first report of T. cruzi in a bat in the US, of T. dionisii in North America, and of Blastocrithidia spp. in mammals, and underscore the importance of bats in the maintenance of trypanosomes, including agents of human and animal disease, across broad geographic locales.

Use of serology and bacterial culture to determine prevalence of Brucella spp. In feral Swine (sus scrofa) in proximity to a beef cattle herd positive for Brucella suis and Brucella abortus.

Using serology and bacterial culture, we determined the prevalence of Brucella spp. and the antibody to Brucella spp. in a feral swine (Sus scrofa) population in proximity to a cattle herd that was culture positive for Brucella abortus and Brucella suis in north-central Texas, USA. During a prospective cross-sectional quantitative study in April 2005, we collected blood and tissue samples from 40 feral swine within a 30-km radius of the infected herd. Serum samples were tested by the Rose Bengal test, particle concentration fluorescence immunoassay, and fluorescence polarization assay. In addition, tissue samples were cultured, and the Brucella species and biovar determined. Four feral swine were Brucella positive by serology, and two were culture positive for B. suis biovar 1. Of the culture-positive swine, one was concurrently antibody and culture positive, and one was culture positive only. The presumptive source of the B. suis infection in the index cattle herd was likely the surrounding feral swine population. Because B. abortus was not cultured from the feral swine, it is unlikely that the source of the B. abortus infection in the index herd originated from the feral swine. Endemic diseases in feral swine populations can pose a disease threat to livestock and a zoonotic risk to humans.

Maintaining a vigilance for foreign animal diseases.

The incursion of foot-and-mouth disease (FMD) into the United Kingdom in February 2001 served as a wakeup call for North American agriculture. As the livestock health crisis in the United Kingdom progressed, it became increasingly evident that the United States, Canada, and Mexico were also susceptible to an incursion of a foreign animal disease. The terrorist attacks of September 11, 2001, and the subsequent anthrax mailings reaffirmed the fact that the United States is vulnerable to an infectious assault, regardless of whether it is intentional or accidental.