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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.

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 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.

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.

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.

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.

TOC summary: A rare hantavirus outbreak reaffirms the need for control of deer mice and public awareness of the risks posed by contact with them., 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

Tick-borne relapsing fever (TBRF) is endemic in mountainous regions of the western United States. In California, the principal agent is the spirochete Borrelia hermsii, which is transmitted by the argasid tick Ornithodoros hermsi. Humans are at risk of TBRF when infected ticks leave an abandoned rodent nest in quest of a blood meal. Rodents are the primary vertebrate hosts for B. hermsii. Sciurid rodents were collected from 23 sites in California between August, 2006, and September, 2008, and tested for serum antibodies to B. hermsii by immunoblot using a whole-cell sonicate and a specific antigen, glycerophosphodiester phosphodiesterase (GlpQ). Antibodies were detected in 20% of rodents; seroprevalence was highest (36%) in chipmunks (Tamias spp). Seroprevalence in chipmunks was highest in the Sierra Nevada (41%) and Mono (43%) ecoregions and between 1900 and 2300 meters elevation (43%). The serological studies described here are effective in implicating the primary vertebrate hosts involved in the maintenance of the ticks and spirochetes in regions endemic for TBRF.

In response to an outbreak of Rocky Mountain spotted fever (RMSF) in Baja California in early 2009, dogs at two shelters in neighbouring Imperial County, California, were evaluated for ectoparasites. Brown dog ticks (Rhipicephalus sanguineus), a recognized vector for RMSF, were found on 35 (30%) of 116 dogs but all ticks tested negative for Rickettsia rickettsii by PCR.

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.

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.

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°C base). Using a geographic information systems approach, we identified all areas in California sharing these environmental character- istics 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.

Despite more than 25 years' experience with Lyme borreliosis, much remains to be learned about this complex zoonosis. Practicing veterinarians, particularly those in the northeastern and upper midwestern states, where Lyme borreliosis is highly endemic, should be familiar with the ecologic features and typical clinical signs of Lyme borreliosis. Interpretation of signs and serologic test results should be made with consideration of the regional prevalence of Lyme borreliosis and the animal's opportunity for exposure to infected Ixodes spp. The availability of recently marketed topical acaracides is a valuable adjunctive measure in prevention of Lyme borreliosis. A maximally effective prevention strategy should include consideration of environmental modification, activity restrictions, routine examinations for ticks, prompt removal of attached ticks, and vaccination. Technologic advances, such as the C6 EIA and the Osp A recombinant vaccine, offer the promise of additional tools for the clinical management and prevention of this tick-borne zoonosis.

In 1993 Sin Nombre virus was recognized as the cause of hantavirus pulmonary syndrome (HPS) and the deer mouse (Peromyscus maniculatus) was identified as the reservoir host. Surveillance by the Centers for Disease Control and Prevention and state health departments includes investigation to determine the likely site(s) and activities that led to infection, an environmental assessment of the home and workplace, and possibly rodent trappings at these sites. As of December 31, 1998, there were 200 confirmed cases from 30 states (43% case-fatality ratio). The national HPS case registry was examined to determine the incubation period of HPS. Review of 11 case-patients with well-defined and isolated exposure to rodents suggests that the incubation period of HPS is 9 to 33 days, with a median of 14-17 days. Case investigations allow a better understanding of the incubation time of HPS and may define high-risk behaviors that can be targeted for intervention.

Hantavirus pulmonary syndrome (HPS) occurs in most infections with Sin Nombre virus and other North American hantaviruses. We report five cases of acute hantavirus infection that did not fit the HPS case definition. The patients had characteristic prodromal symptoms without severe pulmonary involvement. These cases suggest that surveillance for HPS may need to be expanded.

A seroprevalence and risk factor study of emerging tickborne infectious diseases (Lyme disease, ehrlichiosis, and babesiosis) was conducted among 230 residents of a semirural community in Sonoma County, California. Over 50% of residents reported finding a tick on themselves in the preceding 12 months. Samples from 51 (23%) residents were seroreactive to antigens from one or more tickborne disease agents: 1.4% to Borrelia burgdorferi, 0.4% to Ehrlichia equi, 4.6% to Ehrlichia chaffeensis, and 17.8% to the Babesia-like piroplasm WA1. Only 14 (27%) of these seroreactive residents reported one or more symptoms compatible with these diseases. Seroreactivity was significantly associated with younger age (o16 years), longer residence in the community (11 ‐ 20 years), and having had a physician’s diagnosis of Lyme disease. In northern California, the risk of infection with these emerging tickborne diseases, particularly in children, may be greater than previously recognized.

A sample of 244 persons in northern California who provided care for individuals with possible or probable Alzheimer's disease was studied to examine the effect of association with companion animals on three indices of psychological health. 124 caregivers had regular contact with pets; 120 caregivers did not. Men who were attached to dogs scored better on some measures of psychological health than did men who had no pets. Women less than 40 years old who were attached to cats scored better on some measures of psychological health than did the same-age women who had no pets. Women aged 40 to 59 years who were attached to dogs scored worse on measures of life satisfaction and depression than did the same-age women who had no pets. The data suggested a positive indirect effect on caregivers' mental health through interaction between the pet and the patient, but small strata numbers precluded definitive conclusions. Association with pets appeared to temper some of the psychological stress associated with caring for a cognitively impaired adult among young female and male caregivers but not among middle-aged female caregivers.

In September 1994, in response to a reported epidemic of plague in India, the Centers for Disease Control and Prevention (CDC) enhanced surveillance in the United States for imported pneumonic plague. Plague information materials were rapidly developed and distributed to U.S. public health officials by electronic mail, facsimile, and expedited publication. Information was also provided to medical practitioners and the public by recorded telephone messages and facsimile transmission. Existing quarantine protocols were modified to effect active surveillance for imported plague cases at U.S. airports. Private physicians and state and local health departments were relied on in a passive surveillance system to identify travelers with suspected plague not detected at airports. From September 27 to October 27, the surveillance system identified 13 persons with suspected plague; no case was confirmed. This coordinated response to an international health emergency may serve as a model for detecting other emerging diseases and preventing their importation.

Interactions with companion animals have been shown to have socializing and calming effects for Alzheimer's patients in an institutional setting. Sixty-four Alzheimer's patients living in the private home were studied, through medical records and information provided by caregivers, to determine what effect association with a companion animal had on the progression of cognitive decline and the manifestation of concomitant noncognitive symptoms. Prevalence of episodes of verbal aggression and anxiety was reported less frequently in 34 patients who were exposed to companion animals compared with patients who were not exposed. Significantly fewer mood disorders were reported in patients who were attached to their pets compared with patients who were not attached. There was no significant difference in the rate of cognitive decline between pet-exposed and nonexposed patients as measured by three standard indices. This study lends preliminary support to the belief that interaction with pets can aid in tempering feelings of agitation and aggression in Alzheimer's patients.

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.

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.

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). Journal of Vector Ecology 33 (2): 278-284. 2008.

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.

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.

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.

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.

Relapsing fever, caused by the spirochete Borrelia hermsii and transmitted by the soft tick Ornithodoros hermsi , is endemic in many rural mountainous areas of California. Between 1996 and 1998, 12 cases of relapsing fever associated with two exposure sites in northern California were investigated. Follow-up at exposure sites included collection of soft ticks and serum specimens from sylvatic rodents. Attempts to cultivate spirochetes were made through inoculation of patient blood into mice and by feeding Ornithodoros ticks on mice. Three isolates of B. hermsii were recovered from two blood specimens and one pool of ticks. The protein and plasmid profiles of the three isolates were comparable to those of previous B. hermsii isolates from the western United States. Western immunoblotting of patient sera demonstrated an expanding immunologic response to antigens within four distinct molecular weight regions by 3 to 4 weeks postonset. Antibody to B. hermsii was detected in sera from 4 of 11 yellow-pine chipmunks ( Tamias amoenus ); no other rodent species collected were seropositive.

BACKGROUND: A premature infant in California developed respiratory distress associated with infection with a protozoal parasite, Babesia. The infant had received two blood transfusions, one from the father and one from an anonymous donor (Donor A). This study describes the follow-up required to identify the source and species of Babesia that infected the infant. STUDY DESIGN AND METHODS: At the time of the infant's illness, whole blood from the infant, father, and mother was evaluated for Babesia infection. Similar evaluation of whole blood from Donor A was performed 2 months after the suspected donation to the infant. Samples were tested using blood smear examination, serology, PCR, and hamster inoculation. Identity of the recovered Babesia parasites was confirmed by DNA amplification by PCR, genetic sequencing of the 18S gene, and phylogenetic analysis. RESULTS: WA1-type Babesia was recovered from the infant. Neither parent was the source of infection. Serology and hamster inoculation confirmed WA1-type Babesia infection in Donor A. DNA sequences of the 18S gene from the infant and donor isolates were 100% identical. CONCLUSION: WA1-type Babesia infections may be difficult to detect among blood donors because such infections can be subclinical. This is the second WA1-type Babesia transmission via blood transfusion and the first in an infant. Physicians in the western United States should consider Babesia as a possible cause of nonspecific febrile illness after a blood transfusion.

Persons who have frequent contact with rodents as part of their occupation may be at increased risk of exposure to rodent-borne viruses such as Sin Nombre virus (SNV), the agent of hantavirus pulmonary syndrome, and Whitewater Arroyo virus (WWA), a New World arena-virus. Eighty-one persons with possible occupational exposure to rodents completed questionnaires and provided specimens for serologic testing. Seventy-two participants reported handling rodents as part of their job. The mean total number of rodents handled during participants' careers was approximately 2200. IgG antibody to lymphocytic choriomeningitis virus was detected in serum from one (1.2%) participant. IgG antibody to SNV, WWA, and Amapari viruses was not detected in any of the serum specimens. Despite considerable exposure to rodents, participants did not have significant serological evidence of exposure to rodent-borne viruses.

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.

A 27-year-old woman presented to a hospital with symptoms resembling pyelonephritis; respiratory distress did not develop until nearly a day after admission and she subsequently died. The Unexplained Deaths and Critical Illnesses Project of the Centers for Disease Control and Prevention confirmed Sin Nombre virus infection by the results of serological testing and sequencing of the viral genome; staining of Sin Nombre virus antigen in the pulmonary capillaries was relatively weak.

Exposure to cats infected with Yersinia pestis is a recently recognized risk for human plague in the US. Twenty-three cases of cat-associated human plague (5 of which were fatal) occurred in 8 western states from 1977 through 1998, which represent 7.7% of the total 297 cases reported in that period. Bites, scratches, or other contact with infectious materials while handling infected cats resulted in 17 cases of bubonic plague, 1 case of primary septicemic plague, and 5 cases of primary pneumonic plague. The 5 fatal cases were associated with misdiagnosis or delays in seeking treatment, which resulted in overwhelming infection and various manifestations of the systemic inflammatory response syndrome. Unlike infections acquired by flea bites, the occurrence of cat-associated human plague did not increase significantly during summer months. Plague epizootics in rodents also were observed less frequently at exposure sites for cases of cat-associated human plague than at exposure sites for other cases. The risk of cat-associated human plague is likely to increase as residential development continues in areas where plague foci exist in the western US. Enhanced awareness is needed for prompt diagnosis and treatment. Plague is a bacterial zoonosis caused by infection with Yersinia pestis, a gram-negative coccobacillus. Active foci exist in wild rodent and flea populations in many regions of the world, including the western US (where the disease probably was first introduced in 1899‐1900 by rat- and flea-infested ships) [1‐3]. To date, surveillance programs have identified evidence of Y. pestis infection in mammal or flea samples collected from 17 western states (K.L.G., Plague Section, Centers for Disease Control and Prevention [CDC], unpublished data). A total of 297 human cases of plague were identified in 13 of these states from 1977 through 1998.

The incidence of Lyme disease in most endemic areas is unknown but will be an important factor in determining the cost-effectiveness of Lyme disease vaccines in those areas. The authors developed a deterministic model with nine components to estimate the frequency of Ixodes scapularis tick bites and the resulting incidence of Lyme disease in residents of endemic areas. For each component, best point estimates and plausible ranges of values were based on the published literature, unpublished data, expert opinion, or a combination of the above. By using the mean, crude, annual total of 3,827 Lyme disease cases reported from the endemic county of Westchester, New York, in 1991-1994, a mean of 178,889 scapularis bites (20.4 per 100 person-years) and a mean of 10,632 incident Lyme disease cases (1.2 per 100 person-years) were estimated to have occurred per year. Results of a sensitivity analysis that used two different methods suggested that this deterministic model is reasonably robust. In conclusion, according to this model, the incidence of Lyme disease in Westchester County is several-fold higher than suggested by the current passive reporting system. Am J Epidemiol 1998;148:1018-26.

HGE and HME have been recognized as distinct clinical conditions for only 5 and 10 years, respectively, and much information regarding their ecology and epidemiology remains uncertain. The nonspecific character of the illness complicates this incomplete knowledge, as an unknown percentage of infections are likely misdiagnosed. Ehrlichiosis should be considered in any patient presenting with flu-like illness and history of a tick bite. Although expanding, diagnostic support for human ehrlichioses is currently limited to a few regional academic and public health laboratories. Healthcare providers should educate themselves regarding the clinical presentation of ehrlichioses and the availability of diagnostic resources in their area.

Author(s): Fritz, Curtis L.; Kramer, Vicki L.; Enge, Barryett; Sun, Benjamin | Abstract: Hantavirus Pulmonary Syndrome (HPS), a severe and frequently fatal respiratory disease, was first recognized in 1993 during an outbreak of acute illness in the Four Comers area of the southwestern United States. The etiologic agent, Sin Nombre virus (SNV), was identified as a previously unrecognized member of the Hantavirus genus transmitted by rodents, especially members of the genus Peromyscus, which shed SNV in urine and feces. Since 1993, 16 California residents have been diagnosed with HPS, four of these were identified retrospectively with onset prior to 1993. The median age of case-patients was 42 years, 10 were male, and 8 died. Sites of likely exposure for these cases tended to cluster in the eastern Sierra Nevada range. Serologic surveillance of rodents has been conducted prospectively in California since 1993 and retrospectively for specimens collected back to 1975. To date, serologic evidence of infection with SNV has been recognized in 473 (6.6%) of 7,191 rodents from 18 genera, and in 426 (9.6%) of 4,489 Peromyscus spp. At least one seroreactive Peromyscus sp. specimen has been identified in 40 of 46 counties surveyed.

This study was conducted to assess whether three scales commonly used in psychological research of Alzheimer's disease caregivers—Caregiver Burden Interview, Life Satisfaction Index-Z, and Geriatric Depression Scale—measure similar or different aspects of mental health. Responses from 244 nonprofessional caregivers were used to estimate factor structure, intercorrelation, and independent variables associated with the three scales. Self-rated health was the only variable significantly associated with scores on all three scales. Financial concern and number of weekly telephone calls were associated with total scores on the Satisfaction and Depression scales. Factor models of five, three, and six factors were fitted for the Burden, Satisfaction, and Depression scales, respectively. Correlations of factor scores and canonical variables among the scales did not yield strong associations between subsets of items. Although a few common aspects of caregiving influence scores of all three techniques, the facets of caregivers' psychology assessed by the three scales appear to be different.