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Burkholderia pseudomallei, the causative agent of melioidosis, was isolated from abscesses of 2 pet green iguanas in California, USA. The international trade in iguanas may contribute to importation of this pathogen into countries where it is not endemic and put persons exposed to these animals at risk for infection.

Norway rats and their fleas are associated with transmitting diseases, such as murine typhus and plague, to humans. The use of rodenticide baits may increase human exposure to rodent fleas due to loss of their preferred host. Therefore, flea control is an important component of risk reduction. However, the use of insecticide powder or spray can be difficult in certain situations. In this field study we used a feed-through insecticide, imidacloprid, in a grain-based pellet formulation without a rodenticide to determine the effect on the flea index of a well defined, problematic Norway rat focus in a dense urban area of Los Angeles. The flea index was determined to be 12.9 (116 fleas/9 rats) 5 days prior to applying the product. Rats were allowed to feed on the pellets ad libitum for 48 hours, in the presence of previously existing competing food sources. Flea counts were then taken, and again 7 days later, resulting in flea indices of 2.3 (25/11) and 1.5 (23/15), respectively. Since this field trial was conducted in a very dynamic urban area, attempts to survey a concurrent control group were not successful. However, Norway rat surveys conducted in the previous 4 years from the same urban area for the same months, July and August, produced flea indices of 7.4 and 10.1, respectively. In this field trial, we found that a rodent bait formulation containing imidacloprid reduced the flea index of a Norway rat focus from 12.9 to 2.3 (82%) in 48 hours, and to 1.5 (88%) 7 days later.

Hepatitis E virus (HEV) is a major cause of epidemic waterborne and sporadic hepatitis in developing countries. Hepatitis E is caused principally by HEV genotypes 1 and 2 (1). Recently, [...]

Bartonella spp. are vector-borne bacteria associated with -D an increasing array of emerging zoonotic infections in humans and animals (1). Some Bartonella spp. are widely distributed among small mammals in [...]

We investigated the prevalence of Bartonella washoensis in California ground squirrels (Otospermophilus beecheyi) and their fleas from parks and campgrounds located in seven counties of California. Ninety-seven of 140 (69.3%) ground squirrels were culture positive and the infection prevalence by location ranged from 25% to 100%. In fleas, 60 of 194 (30.9%) Oropsylla montana were found to harbor Bartonella spp. when screened using citrate synthase (gltA) specific primers, whereas Bartonella DNA was not found in two other flea species, Hoplopsyllus anomalus (n = 86) and Echidnophaga gallinacea (n = 6). The prevalence of B. washoensis in O. montana by location ranged from 0% to 58.8%. A majority of the gltA sequences (92.0%) recovered from ground squirrels and fleas were closely related (similarity 99.4-100%) to one of two previously described strains isolated from human patients, B. washoensis NVH1 (myocarditis case in Nevada) and B. washoensis 08S-0475 (meningitis case in California). The results from this study support the supposition that O. beecheyi and the flea, O. montana, serve as a vertebrate reservoir and a vector, respectively, of zoonotic B. washoensis in California.

The objective of this study was to advance our knowledge of the epizootiology of Bear Canyon virus and other Tacaribe serocomplex viruses (Arenaviridae) associated with wild rodents in California. Antibody (immunoglobulin G [IgG]) to a Tacaribe serocomplex virus was found in 145 (3.6%) of 3977 neotomine rodents (Cricetidae: Neotominae) captured in six counties in southern California. The majority (122 or 84.1%) of the 145 antibody-positive rodents were big-eared woodrats (Neotoma macrotis) or California mice (Peromyscus californicus). The 23 other antibody-positive rodents included a white-throated woodrat (N. albigula), desert woodrat (N. lepida), Bryant's woodrats (N. bryanti), brush mice (P. boylii), cactus mice (P. eremicus), and deer mice (P. maniculatus). Analyses of viral nucleocapsid protein gene sequence data indicated that Bear Canyon virus is associated with N. macrotis and/or P. californicus in Santa Barbara County, Los Angeles County, Orange County, and western Riverside County. Together, analyses of field data and antibody prevalence data indicated that N. macrotis is the principal host of Bear Canyon virus. Last, the analyses of viral nucleocapsid protein gene sequence data suggested that the Tacaribe serocomplex virus associated with N. albigula and N. lepida in eastern Riverside County represents a novel species (tentatively named "Palo Verde virus") in the genus Arenavirus.

Classic murine typhus, caused by Rickettsia typhi, is endemic in the continental United States in areas of Texas and southern California. We conducted an environmental investigation in an urban area of Los Angeles identified as the probable exposure site for a case of murine typhus. Four Rattus norvegicus heavily infested with Xenopsylla cheopis (average 32.5 fleas per animal, range 20-42) were trapped, and fleas, blood, and tissues were collected. DNAs from all specimens were tested for R. typhi and Rickettsia felis using a TaqMan assay targeting the rickettsial citrate synthase gene. Although rickettsiemia was not detected, DNA of R. felis was detected in at least one tissue from each rat. Tissues from 3 rats were also positive for R. typhi DNA. R. typhi and R. felis DNAs were detected in fleas collected from each animal with average minimal infection rates of 10% and 32.3%, respectively. Although R. typhi still circulates in urban Los Angeles in the classic Oriental flea-rat cycle, R. felis is more prevalent, even in this association.