Background: Harris County (HC) Public Health (HCPH) received its first travel-related Zika virus (ZIKV) case in November 2015. As of February 15, 2018, HCPH has investigated 1,668 reports of potential ZIKV infection and identified 41 disease cases and 11 infections. During the emergence of ZIKV, surveillance and response have evolved rapidly from initiation to intensification. However, with the drastic reduction of Zika cases in US territories and Latin America, surveillance strategies need to be adjusted accordingly to guide the practice in the field. Objectives: This analysis aims to 1) describe temporal trends of ZIKV cases identified in HC along with the changes of CDC clinical guidelines and testing; 2) describe epidemiological characteristics of cases, and among them, pregnant women with unmeasured ZIKV exposure; 3) describe the county’s rigorous mosquito surveillance and integrated mosquito management; 4) discuss the future direction of ZIKV surveillance and response to contingent local transmission of ZIKV. Methods: Descriptive statistics were used to analyze the surveillance data of ZIKV in HC from November 2015 to present. Results: As of February 15, 2018, through the investigations of 1,668 reports of potential ZIKV infections including negative test results, we identified 41 ZIKV disease cases (symptomatic individuals) and 11 ZIKV infections (asymptomatic individuals with laboratory evidence of ZIKV). There were 4, 40, and 8 disease cases and infections in the years of 2015 to 2017, respectively. The trends of the cases have reflected the evolution of the disease, as well as the changes of CDC clinical recommendations and testing availability. Of the 52 disease cases and infections, 32 (62%) were 18-45 years old, 39 (75%) Hispanic, 17 (33%) pregnant women, and all (100%) had travel history to an area of ZIKV risk. Among disease cases, 36 (90%) reported symptom of rash, and 2 congenital cases were confirmed. Forty-one percent of pregnant cases who were indicated for testing according to CDC guidelines were not tested appropriately, thus their risk of exposure was unmeasured. We have followed up with the mothers and infants, and not found any congenital ZIKV infections. All ZIKV investigations are shared simultaneously with Mosquito and Vector Control Division for prompt mosquito surveillance and control. Conclusion: HC is at high risk for autochthonous Zika infections due to its geography, climate, and large number of international travelers. Although the overall ZIKV infections have decreased remarkably, we should still be vigilant and prepared for local transmission of ZIKV. Routine surveillance, however, should focus on investigating positive test results and educating the community on ZIKV prevention and robust vector surveillance and control. The experience we have accumulated in the past and at present as ZIKV emerged, escalated, and waned may inform the future direction of Zika surveillance and response.

• Background Rocky Mountain Spotted Fever (RMSF) is a tick-borne disease caused by the bacterial pathogen Rickettsia rickettsii (R. rickettsii) and characterized by fever, headache, rash, and thrombocytopenia, and can lead to sepsis, chronic sequelae, and death. From 2009-2014, 752 RMSF cases were reported in Mexicali, a Mexican city that borders Imperial County, California. In this outbreak, 10.5% percent of cases (n=79) were fatal. In 2014, two RMSF cases were identified in Imperial County, including a fatal case who reported travel to Mexicali. Transmission to humans was through the bite of Rhiphicephalus sanguineus, known as the brown dog tick. The California-Baja California border region is a dynamic system where demographic, ecological, and social factors are shared. Because frequent cross-border travel poses a risk to residents for disease spread, the Imperial County Public Health Department conducted seroprevalence surveys in 2016 and 2017 using domestic dogs as sentinels of spotted fever group rickettsiae (SFGR) in the area. • Objectives o Determine seroprevalence of SFGR in domestic dogs in Imperial County, California o Determine exposure factors associated with seropositivity. o Assess relationship between border proximity and seropositivity. • Methods Blood samples were collected from dogs with owners’ consent and tested by Indirect Immunofluorescence Antibody (IFA) for antibodies against R. rickettsii. Seropositivity of R.rickettsii was defined as high (titer ≥1:128), moderate (titer 1:32-1:64), or negative. Owners provided information on dog’s age, residence, exposure risks, health status, and tick prevention. Test results were paired with survey data. Descriptive and bivariate analysis was conducted to assess the association between level of seropositivity, distance from U.S.-Mexico border, and other survey variables. Polychotomous logistic regression with significant variables and model fitting was completed. All analyses were performed with SAS 9.4. • Results High seropositivity was found in 8 (1.1%) dogs; 182 (24.2%) showed moderate seropositivity; and 562 (74.7%) were negative for Rickettsia sp. The odds of moderate seropositivity were significantly higher for dogs residing closest to the border (OR: 2.7, 95% CI: 1.7-4.1). Odds fell to 2.5 (95% CI: 1.6-3.9) for dogs residing mid-level distance. High canine seropositivity was associated with travel to Mexico (OR: 4.4, 95% CI: 1.0-19.3). • Conclusion Results indicate that seropositivity increases with proximity to the U.S.-Mexico border and with travel to Mexico. Therefore, Imperial County could be at risk of transmission of imported SFGR to resident ticks. Adequate tick prevention and continued surveillance of tick-borne pathogens can help prevent the spread of RMSF and other diseases in this dynamic border region.

• Background Coccidioidomycosis (Valley Fever) is an infection caused by the inhalation of spores of the fungi Coccidioides immitis or Coccidioides posadasii found in soil or dust particles. This respiratory disease is endemic in Southern California, where rates have dramatically increased in recent years. Certain risk factors are associated with coccidioidomycosis, including male sex, African-American or Filipino race, and Hispanic ethnicity. In California, inmate populations have also been found to experience increased rates of coccidioidomycosis. Although 60% of infections are asymptomatic, coccidioidomycosis can present with severe clinical manifestations and dissemination may occur in 1-10% of symptomatic infections. The Border Infectious Disease Surveillance (BIDS) Program of California began conducting enhanced surveillance for coccidioidomycosis in San Diego County on October 1, 2014 to define the epidemiology of the disease in this region. • Objectives This study aimed to describe the characteristics and exposures of patients with coccidioidomycosis in San Diego County, as well as assess the relationship between clinical characteristics and known risk factors. • Methods This cross-sectional study collected information from medical and laboratory records to categorize confirmed cases as acute, chronic, and chronic among inmates. Information regarding demographics, symptoms, and occupational exposures was collected during phone interviews with confirmed cases. Geographical distribution of cases per major statistical area in San Diego County was determined with ArcGIS software. Univariate descriptive statistics were constructed on collected data. Associations between clinical and demographic characteristics were assessed with Pearson’s chi-square or Fisher’s exact tests. SAS 9.4 software was used for analyses. • Results There were a total of 337 enhanced surveillance cases, of which 161 (48%) were acute cases, 80 (24%) were chronic cases among non-inmates, and 96 (28%) were chronic cases among inmates. The majority of cases were male (75%), 24 cases were in African-American patients (8%), and for those with information about ethnicity, 42% were Hispanic. Occupation was largely underreported. White Hispanics were more likely to have visited the emergency room than their non-Hispanic counterparts (p<0.05) and had a higher frequency of pneumonia and hospitalization (n.s.). A rate of 11.9 acute cases per 100,000 people was identified in the South Suburban area versus the overall rate of 4.2 acute cases per 100,000 people in San Diego County. • Conclusion The San Diego County region has environmental factors favorable to the proliferation of Coccidioides, making it a regional public health concern. The results of this enhanced surveillance suggest there may be a disproportionate risk of coccidioidomycosis in certain regions within the county and that Hispanics might be at an increased risk of disease severity. These results can inform targeted campaigns to reach those who are most at risk.

Background: Prompt identification of an influenza outbreak at a senior residential facility helps ensure that infection control measures are quickly implemented to reduce influenza-related morbidity and mortality in a population at increased risk for influenza-related complications. The County of San Diego Health and Human Services Agency (HHSA) implemented an active surveillance approach to identify potential influenza outbreaks at congregate living facilities. Objectives: To describe an active surveillance approach for detecting influenza outbreaks in congregate living facilities (e.g., skilled nursing, assisted living) and to evaluate the impact of this approach on outbreak-associated morbidity and mortality. Methods: Local healthcare providers in San Diego County report individual cases of laboratory-confirmed influenza to HHSA. All case reports, including results received through electronic laboratory reporting interfaces, are entered into a local communicable disease registry. Addresses for confirmed cases are compared to a database of addresses of local senior residential facilities using a SAS-based protocol. Additionally, multiple cases with the same address are flagged. Finally, some influenza cases are reported using a standardized form that includes a box to indicate residence in a long-term care facility. Matches identified by these methods are compiled and reviewed by an epidemiologist. Address matching occurs several times per week during the peak of influenza season, and less frequently when case counts are lower. Depending on the facility type and number of matched cases, detections prompt a call to the facility to determine if an outbreak is occurring and to provide standardized guidance on outbreak control. Outcomes related to these detections during the 2014-15 influenza season through the 2017-18 season to date (2/15/2018) were tracked and characterized with descriptive statistics. Comparisons between outbreaks detected via active surveillance and those reported directly by the facility were made using t-tests and chi-square tests. Results: During the study period, HHSA detected 272 potential influenza outbreaks via active surveillance. Of these, 39% (106) were confirmed as influenza outbreaks following further investigation. Among all confirmed influenza outbreaks in congregate living facilities (191), 56% were initially detected via active surveillance. Outbreaks detected via active surveillance had a mean of 12.4 cases per outbreak compared to 18.5 cases per facility-reported outbreak, a statistically significant difference (p=0.003). At least one death was associated with 40% of facility-reported outbreaks compared to 29% of surveillance-detected outbreaks, though this difference was not statistically significant. Conclusions: More than half of influenza outbreaks in San Diego County were identified via active surveillance; many may not have been detected or reported otherwise. Active surveillance contributes to the prompt identification of outbreaks and rapid implementation of response measures, including antiviral treatment and prophylaxis. Active surveillance can help reduce outbreak-associated morbidity and mortality in these high-risk settings.