Epidemiology of Brucellosis in California, 1993-2017: A Continuing Foodborne Disease Risk for Older Latinos.

BACKGROUND: Brucellosis is a severe occupational or foodborne zoonosis throughout much of the world. Although eradicated from domestic cattle in the United States, brucellosis remains a disease risk to people through acquisition and consumption of animal products from endemic countries. METHODS: Cases of human brucellosis reported through the California public health disease surveillance network were reviewed for 1993 to 2017. RESULTS: From 1993 to 2017, 492 cases of brucellosis were reported in California residents. Persons aged >65 years represented less than 20% of cases, but incidence in this age group (0.94 cases per 1 000 000 population per year) was more than twice the incidence in persons aged <19 years (0.44). Incidence was 10 to 20 times greater among Latinos compared with non-Latinos across all age groups and both sexes. Brucella melitensis was identified in 80% of patients for whom cultured Brucella were identified to the species level. Of 187 case patients who reported consuming specifically unpasteurized dairy products, more than 90% reported acquiring these products from outside of the United States, most commonly from Mexico. In the latter half of the study period (2006-2017), 73% of Latino case patients who reported consuming dairy products mentioned specifically Mexican-style soft cheese (queso fresco). CONCLUSIONS: This study underscores the continuing serious health threat of brucellosis for Latinos in California, particularly older men, and the need for targeted public health messaging on preventing the risk presented by importation and consumption of unpasteurized dairy products from outside of the United States, principally Mexico.

Identification and Monitoring of International Travelers During the Initial Phase of an Outbreak of COVID-19 - California, February 3-March 17, 2020.

The threat of introduction of coronavirus disease 2019 (COVID-19) into the United States with the potential for community transmission prompted U.S. federal officials in February 2020 to screen travelers from China, and later Iran, and collect and transmit their demographic and contact information to states for follow-up. During February 5-March 17, 2020, the California Department of Public Health (CDPH) received and transmitted contact information for 11,574 international travelers to 51 of 61 local health jurisdictions at a cost of 1,694 hours of CDPH personnel time. If resources permitted, local health jurisdictions contacted travelers, interviewed them, and oversaw 14 days of quarantine, self-monitoring, or both, based on CDC risk assessment criteria for COVID-19. Challenges encountered during follow-up included errors in the recording of contact information and variation in the availability of resources in local health jurisdictions to address the substantial workload. Among COVID-19 patients reported to CDPH, three matched persons previously reported as travelers to CDPH. Despite intensive effort, the traveler screening system did not effectively prevent introduction of COVID-19 into California. Effectiveness of COVID-19 screening and monitoring in travelers to California was limited by incomplete traveler information received by federal officials and transmitted to states, the number of travelers needing follow-up, and the potential for presymptomatic and asymptomatic transmission. More efficient methods of collecting and transmitting passenger data, including electronic provision of flight manifests by airlines to federal officials and flexible text-messaging tools, would help local health jurisdictions reach out to all at-risk travelers quickly, thereby facilitating timely testing, case identification, and contact investigations. State and local health departments should weigh the resources needed to implement incoming traveler monitoring against community mitigation activities, understanding that the priorities of each might shift during the COVID-19 pandemic.

Francisella tularensis Transmission by Solid Organ Transplantation, 20171.

In July 2017, fever and sepsis developed in 3 recipients of solid organs (1 heart and 2 kidneys) from a common donor in the United States; 1 of the kidney recipients died. Tularemia was suspected only after blood cultures from the surviving kidney recipient grew Francisella species. The organ donor, a middle-aged man from the southwestern United States, had been hospitalized for acute alcohol withdrawal syndrome, pneumonia, and multiorgan failure. F. tularensis subsp. tularensis (clade A2) was cultured from archived spleen tissue from the donor and blood from both kidney recipients. Whole-genome multilocus sequence typing indicated that the isolated strains were indistinguishable. The heart recipient remained seronegative with negative blood cultures but had been receiving antimicrobial drugs for a medical device infection before transplant. Two lagomorph carcasses collected near the donor's residence were positive by PCR for F. tularensis subsp. tularensis (clade A2). This investigation documents F. tularensis transmission by solid organ transplantation.

Novel Focus of Sin Nombre Virus in Peromyscus eremicus Mice, Death Valley National Park, California, USA.

The deer mouse (Peromyscus maniculatus) is the primary reservoir for Sin Nombre virus (SNV) in the western United States. Rodent surveillance for hantavirus in Death Valley National Park, California, USA, revealed cactus mice (P. eremicus) as a possible focal reservoir for SNV in this location. We identified SNV antibodies in 40% of cactus mice sampled.

Tickborne relapsing fever - United States, 1990-2011.

Tickborne relapsing fever (TBRF) is a zoonosis caused by spirochetes of the genus Borrelia and transmitted to humans by ticks of the genus Ornithodoros. TBRF is endemic in the western United States, predominately in mountainous regions. Clinical illness is characterized by recurrent bouts of fever, headache, and malaise. Although TBRF is usually a mild illness, severe sequelae and death can occur. This report summarizes the epidemiology of 504 TBRF cases reported from 12 western states during 1990-2011. Cases occurred most commonly among males and among persons aged 10‒14 and 40‒44 years. Most reported infections occurred among nonresident visitors to areas where TBRF is endemic. Clinicians and public health practitioners need to be familiar with current epidemiology and features of TBRF to adequately diagnose and treat patients and recognize that any TBRF case might indicate an ongoing source of potential exposure that needs to be investigated and eliminated.

Hantavirus infections among overnight visitors to Yosemite National Park, California, USA, 2012.

In summer 2012, an outbreak of hantavirus infections occurred among overnight visitors to Yosemite National Park in California, USA. An investigation encompassing clinical, epidemiologic, laboratory, and environmental factors identified 10 cases among residents of 3 states. Eight case-patients experienced hantavirus pulmonary syndrome, of whom 5 required intensive care with ventilatory support and 3 died. Staying overnight in a signature tent cabin (9 case-patients) was significantly associated with becoming infected with hantavirus (p<0.001). Rodent nests and tunnels were observed in the foam insulation of the cabin walls. Rodent trapping in the implicated area resulted in high trap success rate (51%), and antibodies reactive to Sin Nombre virus were detected in 10 (14%) of 73 captured deer mice. All signature tent cabins were closed and subsequently dismantled. Continuous public awareness and rodent control and exclusion are key measures in minimizing the risk for hantavirus infection in areas inhabited by deer mice.

Clinical and epidemiologic features of persons accessing emergency departments for dog and cat bite injuries in California (2005-2019).

OBJECTIVE: To describe the clinical and epidemiologic features of persons with dog and cat bite injuries who presented to emergency departments. SAMPLE: Records of 648,492 dog and cat bite-related emergency department visits in California from 2005 to 2019. PROCEDURES: Visits were selected by standardized International Classification of Diseases, Ninth or Tenth Revision, Clinical Modification codes that indicated a bite as an external cause of injury in the medical record. Incidence rates were calculated for patient demographics, location and month of bite incident, characteristics of bite injury, infection, patient outcome/disposition, and expected source of payment. Cross-sectional descriptive analysis was performed. RESULTS: The average annual incidence of dog bites was highest in children aged < 10 years and males, while that of cat bites was highest in adults aged ≥ 80 years and females. Bites were more likely to occur in rural settings, in private residences, and during the summer. The median household income for zip codes in which animal bite patients resided was lower than the statewide median household income. Both dog and cat bite injuries were more likely to occur to upper limbs. Bacteria were isolated from 3% of dog bite injuries and 21.5% of cat bite injuries at initial presentation. CLINICAL RELEVANCE: Epidemiologic findings about persons presenting to emergency departments for animal bite injuries can inform bite prevention efforts by identifying at-risk populations. Effective animal bite prevention demands an ongoing multisectoral program of veterinarians and other health professionals, collaborating with community and governmental organizations, to develop and implement integrated strategies within the context of other socially contributory factors.

Racial/Ethnic Disparities In COVID-19 Exposure Risk, Testing, And Cases At The Subcounty Level In California.

With a population of forty million and substantial geographic variation in sociodemographics and health services, California is an important setting in which to study disparities. Its population (37.5 percent White, 39.1 percent Latino, 5.3 percent Black, and 14.4 percent Asian) experienced 59,258 COVID-19 deaths through April 14, 2021-the most of any state. We analyzed California's racial/ethnic disparities in COVID-19 exposure risks, testing rates, test positivity, and case rates through October 2020, combining data from 15.4 million SARS-CoV-2 tests with subcounty exposure risk estimates from the American Community Survey. We defined "high-exposure-risk" households as those with one or more essential workers and fewer rooms than inhabitants. Latino people in California are 8.1 times more likely to live in high-exposure-risk households than White people (23.6 percent versus 2.9 percent), are overrepresented in cumulative cases (3,784 versus 1,112 per 100,000 people), and are underrepresented in cumulative testing (35,635 versus 48,930 per 100,000 people). These risks and outcomes were worse for Latino people than for members of other racial/ethnic minority groups. Subcounty disparity analyses can inform targeting of interventions and resources, including community-based testing and vaccine access measures. Tracking COVID-19 disparities and developing equity-focused public health programming that mitigates the effects of systemic racism can help improve health outcomes among California's populations of color.

Rickettsia 364D: a newly recognized cause of eschar-associated illness in California.

BACKGROUND: Four spotted fever group rickettsiae (SFGR) are known to infect humans in the United States. A member of the SFGR designated 364D and detected in Dermacentor occidentalis ticks has not previously been identified as a human pathogen. METHODS: An 80-year-old man from a rural northern California community presented with an eschar on his forearm. A skin punch biopsy of the lesion was evaluated by immunohistochemistry and molecular analysis. Serum specimens obtained from the patient and 3 other area residents with similar illnesses were tested by immunofluorescence and Western immunoblot for antibodies to SFGR. Ticks were collected near the patient's residence and tested for SFGR. RESULTS: Abundant intracellular rickettsiae and fragmented rickettsial antigens were observed in the mononuclear inflammatory infiltrates of the biopsy. Nucleotide sequences of DNA fragments amplified from the biopsy were identical to those of 364D. Convalescent sera from all four patients exhibited high immunoglobulin G titers to Rickettsia rickettsii, Rickettsia rhipicephali, and 364D antigens. Three adult D. occidentalis were positive for 364D, R. rhipicephali, and an unidentified Rickettsia species. CONCLUSIONS: This is the first confirmation of human disease associated with the SFGR 364D, which was likely transmitted by D. occidentalis. Although the patients described here presented with a single cutaneous eschar as the principal manifestation, the full spectrum of illness associated with 364D has yet to be determined. Possible infection with 364D or other SFGR should be confirmed through molecular techniques in patients who present with "spotless" Rocky Mountain spotted fever or have serum antibodies to R. rickettsii with group-specific assays.

Meningitis due to a "Bartonella washoensis"-like human pathogen.

We report the second human case of infection caused by an organism identified as the proposed Bartonella species, "B. washoensis." The organism was isolated from a blood sample from a patient presenting with meningitis and early sepsis. Oropsylla montana fleas were implicated as the vector for disease transmission in this case.

Spatial analysis of plague in California: niche modeling predictions of the current distribution and potential response to climate change.

BACKGROUND: Plague, caused by the bacterium Yersinia pestis, is a public and wildlife health concern in California and the western United States. This study explores the spatial characteristics of positive plague samples in California and tests Maxent, a machine-learning method that can be used to develop niche-based models from presence-only data, for mapping the potential distribution of plague foci. Maxent models were constructed using geocoded seroprevalence data from surveillance of California ground squirrels (Spermophilus beecheyi) as case points and Worldclim bioclimatic data as predictor variables, and compared and validated using area under the receiver operating curve (AUC) statistics. Additionally, model results were compared to locations of positive and negative coyote (Canis latrans) samples, in order to determine the correlation between Maxent model predictions and areas of plague risk as determined via wild carnivore surveillance. RESULTS: Models of plague activity in California ground squirrels, based on recent climate conditions, accurately identified case locations (AUC of 0.913 to 0.948) and were significantly correlated with coyote samples. The final models were used to identify potential plague risk areas based on an ensemble of six future climate scenarios. These models suggest that by 2050, climate conditions may reduce plague risk in the southern parts of California and increase risk along the northern coast and Sierras. CONCLUSION: Because different modeling approaches can yield substantially different results, care should be taken when interpreting future model predictions. Nonetheless, niche modeling can be a useful tool for exploring and mapping the potential response of plague activity to climate change. The final models in this study were used to identify potential plague risk areas based on an ensemble of six future climate scenarios, which can help public managers decide where to allocate surveillance resources. In addition, Maxent model results were significantly correlated with coyote samples, indicating that carnivore surveillance programs will continue to be important for tracking the response of plague to future climate conditions.

Emerging tick-borne diseases.

Ticks are capable of transmitting numerous pathogens to both humans and their pets. The risks of tick-borne disease risks vary geographically and are determined by the climate, environment, the presence of rodents and other mammal reservoirs, and the species of ticks parasitizing wild and domestic animals. Zoonoses such as Lyme borreliosis, tularemia, and tick-borne rickettsioses can emerge in previously nonendemic areas when circumstances favorable to their maintenance and transmission arise. Tick-borne zoonosis can be prevented by implementation and adoption of an integrated program to reduce the likelihood of tick bites on pets and their owners.

Occupational risk of exposure to rodent-borne hantavirus at US forest service facilities in California.

Hantavirus cardiopulmonary syndrome (HCPS) is a frequently fatal viral disease transmitted through rodent secretions and excretions. Working around deer mice can increase risk of infection. This study assessed potential risk of HCPS at facilities occupied by the US Forest Service (USFS) in California. In 2004-2005, 18 USFS facilities in eight National Forests in California were evaluated for evidence of rodent infestation and circulation of hantavirus. Structural deficiencies and evidence of rodent infestation were observed at 18 facilities. Serum antibodies to hantavirus were detected in 50 of 255 deer mice collected from 15 facilities. Seroprevalence was higher at elevations > 1,600 m (22%). Employees at 14 facilities had received training in rodent-borne disease prevention. Risk of HCPS among USFS employees should motivate inclusion of disease prevention information into employee safety training.

Effect of conveyance pipe dimension and orientation on mosquito oviposition in a simulated stormwater management device.

Simulated stormwater management devices baited with alfalfa infusion were constructed to test conveyance pipe dimension and orientation as a potential deterrent to mosquito oviposition. Various configurations of pipe diameter, length, and orientation were evaluated based on egg raft counts. Field trials tested pipes of 1.3-, 5-, and 10-cm diam and 0-, 90-, or 270-cm lengths, in both horizontal and vertical orientations. Additional trials of 10-cm-diam horizontal pipe evaluated the effects of a 90 degrees bend, single or dual entry points, and lengths greater than 270 cm. Significantly fewer egg rafts were collected in pipes of smaller diameter and longer length in both horizontal and vertical orientations. A 90 degrees bend or removal of an entry point to pipes of fixed length had no significant effect on oviposition. A maximum tested length of 24.4 m did not preclude oviposition. The results of this study suggest that manipulating diameter and length of conveyance pipe in stormwater management devices may not be an effective strategy to deter oviposition. The need for integrating improved, novel, nonchemical mosquito control measures into designing and operating stormwater management structures is discussed.

Mosquito production in stormwater treatment devices in the Lake Tahoe Basin, California.

In response to increasing evidence of mosquito production in structural stormwater Best Management Practices (BMPs), a collaborative project was developed to document the occurrence, species composition, and seasonal abundance of mosquitoes from selected urban and highway BMPs in the Lake Tahoe Basin, California. Structural and environmental factors associated with mosquito production in highway BMPs were identified and analyzed. Ten species of mosquitoes were collected from 47 BMPs, including Culex tarsalis, Culiseta incidens, Cs. inornata, and 7 species of Aedes. In and around South Lake Tahoe, immatures were most abundant in urban BMPs during the warmer summer and fall months, whereas natural water sources in the surrounding area harbored mosquitoes more often during the colder months of early spring. In BMPs installed along Lake Tahoe's perimeter highways, mosquitoes were observed in 11% of site visits conducted during a single season. Larval presence in highway BMPs was positively associated with water temperature and negatively associated with precipitation, sand, and unspecified organic matter. The significance of mosquito production in BMPs of the Tahoe Basin and the potential for increased transmission of mosquito-borne disease are discussed.

Development time of Culex mosquitoes in stormwater management structures in California.

A widely recommended strategy to minimize mosquito production in structural stormwater Best Management Practices (BMPs) is to ensure they hold captured water for no more than 72 h. However, this standard may be overly conservative for many mosquito species found in urban environments and may impede or prevent the capacity of BMPs to fulfill more stringent water quality standards in environmentally sensitive areas. Egg-to-pupa development of Culex tarsalis, Cx. pipiens, and Cx. quinquefasciatus were examined during July, August, and September 2006 in stormwater management basins and in water collected from these basins in 3 climatically distinct regions of California: the Lake Tahoe Basin, Sacramento Valley, and Los Angeles Basin. The observed minimum times to pupal development were 6 days for Cx. tarsalis and Cx. quinquefasciatus and 8 days for Cx. pipiens. Multiple linear regression models were used to estimate minimum predicted development times under optimal conditions for each region. The results suggest that water residence times of up to 96 h will not significantly increase the potential for Culex mosquito production in stormwater BMPs in the 3 regions included in this study.

Use of a chitin synthesis inhibitor to control fleas on wild rodents important in the maintenance of plague, Yersinia pestis, in California.

A study was designed to test the insect development inhibitors fluazuron and lufenuron for the control of fleas on sylvatic rodents as an adjunct to the control of plague. Historical data of flea burden from 15 prior years of study at Chuchupate Campground, Ventura County, CA, were compared to six years of treatment period data to determine if fluazuron and lufenuron were effective in controlling flea densities. The insect development inhibitors, delivered systemically via a feed cube, reduced flea loads effectively on California ground squirrels (Spermophilus beecheyi), long-eared woodrats (Neotoma macrotis), and mice (Peromyscus spp.) but not on Merriam's chipmunks (Tamias merriami).

Spatial patterns of Lyme disease risk in California based on disease incidence data and modeling of vector-tick exposure.

Ixodes pacificus, particularly the nymphal life stage, is the primary vector to humans of the Lyme disease agent Borrelia burgdorferi in California. During 2004, we collected I. pacificus nymphs from 78 woodland sites in ecologically diverse Mendocino County, which has a moderately high incidence of Lyme disease. Within this county, nymphal density was elevated in forested areas with a growing degree day range of 2,600-3,000 (10 degrees C base). Using a geographic information systems approach, we identified all areas in California sharing these environmental characteristics and thus projected to pose high acarologic risk of exposure to host-seeking nymphal ticks. Such areas were most commonly detected in the northwestern part of the state and along the Sierra Nevada foothills in the northeast, but the analysis also identified isolated areas with high acarologic risk in southern California. This mirrors the spatial distribution of endemic Lyme disease during 1993-2005; most cases occurred in counties to the northwest (58%) or northeast (26%), whereas fewer cases were reported from southern California (16%). Southern zip-codes from which Lyme disease cases had been reported were commonly located in close proximity to areas with high projected acarologic risk. Overall, Lyme disease incidence in zip code areas containing habitat with high projected acarologic risk was 10-fold higher than in zip code areas lacking such habitat and 27 times higher than for zip code areas without this habitat type within 50 km. A comparison of spatial Lyme disease incidence patterns based on county versus zip code units showed that calculating and displaying disease incidence at the zip code scale is a useful method to detect small, isolated areas with elevated disease risk that otherwise may go undetected.

Clinical, epidemiologic, and environmental surveillance for ehrlichiosis and anaplasmosis in an endemic area of northern California.

Two forms of tick-borne leukocytotropic rickettsioses have been recognized in California since the mid-1990s: human monocytic ehrlichiosis (HME) caused by Ehrlichia chaffeensis and human granulocytic anaplasmosis (HGA) caused by Anaplasma phagocytophilum. Between 1997 and 1999, two cases of HME and four cases of HGA were diagnosed in residents of southern Humboldt County, California. Environmental followup at case-patients' residences revealed dense populations of Ixodes pacificus ticks, particularly in grassy roadside areas. PCR evidence of A. phagocytophilum was detected in approximately 2.0% of I. pacificus; E. chaffeensis was not detected in any of 625 ticks tested. Serologic antibody to A. phagocytophilum was detected in two of 54 participants in a community epidemiologic study; one of these also had antibody to E. chaffeensis. Over 85% of study participants reported finding a tick on themselves in the preceding 12 mo. Residents of southern Humboldt County are at significant risk of tick bites and should take appropriate prevention measures to avoid infection with rickettsia and other tick-transmitted pathogens.

The epidemiology of tick-borne relapsing fever in the United States.

Each year, many residents of and visitors to endemic regions of the western United States are exposed to the vector of tick-borne relapsing fever (TBRF), an underrecognized and underreported disease. Through review of report forms and literature review, we identified 450 cases of TBRF acquired in the United States in 11 western states (and in British Columbia by a U.S. resident) from January 1977 to January 2000. Exposure sites were in forested areas, at varying elevations, in mountainous regions (Cascade, Rocky Mountain, San Bernardino, and Sierra Nevada ranges) of the United States and Canada and in limestone caves in central Texas. Only 13 counties accounted for approximately 50% of all cases. Forty percent of the cases were not residents of the state where TBRF exposure occurred, including 7% from 11 states where TBRF is not endemic. TBRF is endemic in the United States and is a disease affecting travelers, who may return home with the disease to areas where physicians are not familiar with it.