Distribution and Occurrence of Amblyomma maculatum sensu lato (Acari: Ixodidae) and Rickettsia parkeri (Rickettsiales: Rickettsiaceae), Arizona and New Mexico, 2017-2019.

Amblyomma maculatum Koch sensu lato (s.l.) ticks are the vector of Rickettsia parkeri in Arizona, where nine cases of R. parkeri rickettsiosis have been identified since the initial case in 2014. The current study sought to better define the geographic ranges of the vector and pathogen and to assess the potential public health risk posed by R. parkeri in this region of the southwestern United States. A total of 275 A. maculatum s.l. ticks were collected from 34 locations in four counties in Arizona and one county in New Mexico and screened for DNA of Rickettsia species. Rickettsia parkeri was detected in 20.4% of the ticks, including one specimen collected from New Mexico, the first report of R. parkeri in A. maculatum s.l. from this state. This work demonstrates a broader distribution of A. maculatum s.l. ticks and R. parkeri in the southwestern United States than appreciated previously to suggest that R. parkeri rickettsiosis is underrecognized in this region.

Dengue Knowledge, Attitudes, and Practices Among Arizona Health Care Providers, 2014-2015.

Background: Detection of local dengue transmission requires an aware and engaged medical community, as health care providers are the front line of public health surveillance. To assess the knowledge, attitude, and practice about dengue, an online survey was distributed among Arizona health care providers during 2014 and 2015. Materials and Methods: The survey consisted of a total of 10 knowledge, attitude, and practice questions divided as follows: 5 knowledge questions, 2 attitude questions, and 3 practice questions. The link to the Qualtrics survey was distributed through the Arizona Health Alert Network to a total of 4582 e-mail addresses, of which 335 participants opened the survey, and 196 completed and submitted their responses. Results: Less than half the respondents reported choosing the right dengue diagnostic test (40.4%) or understanding the epidemiology of dengue in Arizona (40.9%). Slightly more than half the respondents reported frequently asking for travel history (59%), and three-fourth of them would notify the local health department on suspicion of a dengue patient (76.1%). Survey score was associated with providers specialized in infectious diseases (1.88, 95% CI: 0.42-3.33, p = 0.01), medical doctors or doctors of osteopathic medicine (1.82, 95% CI: 0.98-2.65, p < 0.0001), and respondents who reported to have heard about the increase in dengue cases in Sonora (Mexico) in fall 2014 (1.51, 95% CI: 0.67-2.34, p = 0.0005), indicating better survey performance. Conclusions: These results indicate that education for health care providers on dengue should be improved particularly among general practice noninfectious disease providers who might be the first point of care for dengue patients. Findings suggest that additional training on clinical management, asking travel history, and notifying the local health department on suspicion of a dengue patient are needed.

Serologic assessment for exposure to spotted fever group rickettsiae in dogs in the Arizona-Sonora border region.

Rocky Mountain spotted fever (RMSF) is a severe tick-borne rickettsial illness. In the south-western United States and Mexico, RMSF displays unique epidemiologic and ecologic characteristics, including Rhipicephalus sanguineus sensu lato (brown dog tick) as the primary vector. Expansion and spread of the disease from hyperendemic regions of Arizona or Mexico to new areas is a key public health concern. Dogs are thought to play an important role in the emergence and circulation of R. rickettsii in these regions and are often one of earliest indicators of RMSF presence. A canine serosurvey was conducted in 2015 among owned and stray dogs at rabies clinic and animal shelters in three southern Arizona counties where RMSF had not previously been identified. Of the 217 dogs sampled, 11 (5.1%) tested positive for spotted fever group rickettsia (SFGR) IgG antibodies, with seropositivity ranging from 2.9% to 12.2% across the three counties. Large dogs were significantly more likely than small dogs to have positive titres reactive with R. rickettsii; no additional statistically significant relationships were observed between seropositivity of canine age, sex, neuter or ownership status. In addition, 17 (7.8%) dogs had ticks attached at the time of sampling, and stray dogs were significantly more likely to have ticks present than owned dogs (p < 0.001). All 57 ticks collected were identified as Rh. sanguineus s.l., and four (7%) had DNA evidence of genera-wide Rickettsia species. The results of this project demonstrated canine seroprevalence levels lower than those previously reported from dogs in highly endemic areas, indicating a low risk of SFGR transmission to humans in the southern Arizona border region at this time. Continued surveillance is critical to identify SFGR emergence in new geographic regions and to inform prevention efforts for humans and dogs in those areas.

Fatal Rocky Mountain Spotted Fever along the United States-Mexico Border, 2013-2016.

Rocky Mountain spotted fever (RMSF) is an emerging public health concern near the US-Mexico border, where it has resulted in thousands of cases and hundreds of deaths in the past decade. We identified 4 patients who had acquired RMSF in northern Mexico and subsequently died at US healthcare facilities. Two patients sought care in Mexico before being admitted to US-based hospitals. All patients initially had several nonspecific signs and symptoms, including fever, headache, nausea, vomiting, or myalgia, but deteriorated rapidly without receipt of a tetracycline-class antimicrobial drug. Each patient experienced respiratory failure late in illness. Although transborder cases are not common, early recognition and prompt initiation of appropriate treatment are vital for averting severe illness and death. Clinicians on both sides of the US-Mexico border should consider a diagnosis of RMSF for patients with rapidly progressing febrile illness and recent exposure in northern Mexico.