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In Europe, two species of hantaviruses, Puumala orthohantavirus (PUUV) and Dobrava orthohantavirus (DOBV), cause hemorrhagic fever with renal syndrome in humans. The rodent reservoirs for these viruses are common throughout Ukraine, and hence, the goal of this study was to identify the species and strains of hantaviruses circulating in this region. We conducted surveillance of small rodent populations in a rural region in northwestern Ukraine approximately 30 km from Poland. From the 424 small mammals captured, we identified nine species, of which the most abundant were Myodes glareolus , the bank vole (45%); Apodemus flavicollis , the yellow-necked mouse (29%); and Apodemus agrarius , the striped field mouse (14.6%) Using an indirect immunofluorescence assay, 15.7%, 20.5%, and 33.9% of the sera from M. glareolus , A. glareolus , and A. flavicollis were positive for hantaviral antibodies, respectively. Additionally, we detected antibodies to the hantaviral antigen in one Microtus arvalis , one Mus musculus , and one Sorex minutus . We screened the lung tissue for hantaviral RNA using next-generation sequencing and identified PUUV sequences in 25 small mammals, including 23 M. glareolus , 1 M. musculus , and 1 A. flavicollis, but we were unable to detect DOBV sequences in any of our A. agrarius specimens. The percent identity matrix and Bayesian phylogenetic analyses of the S-segment of PUUV from 14 M. glareolus lungs suggest the highest similarity (92-95% nucleotide or 99-100% amino acid) with the Latvian lineage. This new genetic information will contribute to future molecular surveillance of human cases in Ukraine.

Norway rats (Rattus norvegicus) carry several zoonotic pathogens and because rats and humans live in close proximity in urban environments, there exists potential for transmission. To identify zoonotic agents carried by rats in Baltimore, Maryland, USA, we live-trapped 201 rats during 2005-2006 and screened them for a panel of viruses, bacteria, and parasites. Antibodies against Seoul virus (57.7%), hepatitis E virus (HEV, 73.5%), Leptospira interrogans (65.3%), Bartonella elizabethae (34.1%), and Rickettsia typhi (7.0%) were detected in Norway rats. Endoparasites, including Calodium hepatica (87.9%) and Hymenolepis sp. (34.4%), and ectoparasites (13.9%, primarily Laelaps echidninus) also were present. The risk of human exposure to these pathogens is a significant public health concern. Because these pathogens cause non-specific and often self-limiting symptoms in humans, infection in human populations is probably underdiagnosed.

The primary vector of Borrelia burgdorferi in North America, Ixodes scapularis, feeds on various mammalian, avian, and reptilian hosts. Several small mammal hosts; Peromyscus leucopus, Tamias striatus, Microtus pennsylvanicus, and Blarina spp. can serve as reservoirs in an enzootic cycle of Lyme disease. The primary reservoir in the northeast United States is the white-footed mouse, P. leucopus. The infection prevalence of this reservoir as well as the roles of potential secondary reservoirs has not been established in southern Maryland, a region of low to moderate Borrelia infection in humans. Intensive trapping at 96 locations throughout the western Coastal Plains of Maryland was conducted and we found that 31.6% of P. leucopus were infected with B. burgdorferi. Sequence and phylogenetic analysis revealed that only B. burgdorferi sensu stricto circulated in southern Maryland. Feral house mice and voles also were infected and may serve as secondary hosts. Peromyscus gender, age and month of capture were significantly associated with infection status. Larval I. scapularis were the dominant ectoparasite collected from captured rodents even though host seeking A. americanum and D. variabilis were collected in greater numbers across the sampling region. Our findings illustrate that the enzootic cycle of LD is maintained in the western Coastal Plains region of southern Maryland between I. scapularis and P. leucopus as the dominant reservoir.

Norway rats are reservoirs for several zoonotic agents, including hantaviruses, and are implicated in the transmission of pathogens to humans in urban environments. The rat population of Baltimore, Maryland was estimated from surveys in 1949 and again in 1952, but has not been evaluated for more than 50 years. Previously identified sociodemographic risk factors for rat infestation, including median income, human density, and percentage of rental properties, were used to categorize census block groups in Baltimore. Rat infestation risk factors, including median income and human density, have improved over the last 50 years in Baltimore. Rat infestation was determined both by observation and trapping of rats in alleys that were representative of the different strata of risk factors. Despite improvements in risk factors, the outdoor, residential rat population of Baltimore in 2004 was estimated to be approximately 48,420 +/- 14,883 rats, which is comparable to the 1949 and 1952 estimates. Approximately half of the rats trapped in Baltimore City had detectable antibody against Seoul virus. The failure to substantially impact rat population levels in the past 50 years indicate that alternative control strategies for rat infestation are needed to reduce the risk of rat-borne pathogen spillover to the human population.

The relationship between the risk of hantaviral pulmonary syndrome (HPS), as estimated from satellite imagery, and local rodent populations was examined. HPS risk, predicted before rodent sampling, was highly associated with the abundance of Peromyscus maniculatus, the reservoir of Sin Nombre virus (SNV). P. maniculatus were common in high-risk sites, and populations in high-risk areas were skewed toward adult males, the subclass most frequently infected with SNV. In the year after an El Niño Southern Oscillation (ENSO), captures of P. maniculatus increased only in high-risk areas. During 1998, few sites had infected mice, but by 1999, 1820 of the high-risk sites contained infected mice and the crude prevalence was 30.8%. Only 118 of the low-risk sites contained infected rodents, and the prevalence of infection was lower (8.3%). Satellite imagery identified environmental features associated with SNV transmission within its reservoir population, but at least 2 years of high-risk conditions were needed for SNV to reach high prevalence. Areas with persistently high-risk environmental conditions may serve as refugia for the survival of SNV in local mouse populations.

Hepatitis E is an important medical pathogen in many developing countries but is rarely reported from the United States, although antibody to hepatitis E virus (anti-HEV) is found in > 1% of U.S. citizens. Zoonotic spread of the virus is suspected. Sera obtained from 239 wild rats trapped in widely separated regions of the United States were tested for anti-HEV. Seventy-seven percent of rats from Maryland, 90% from Hawaii, and 44% from Louisiana were seropositive for anti-HEV. Rats from urban as well as rural areas were seropositive and the prevalence of anti-HEV IgG increased in parallel with the estimated age of the rats, leading to speculation that they might be involved in the puzzling high prevalence of anti-HEV among some U.S. city dwellers. The discovery of a in rats in the United States and the recently reported discovery that HEV is endemic in U.S. swine raise many questions about transmission, reservoirs, and strains of HEV in developed countries.

The maintenance of Borrelia burgdorferi in a population of Peromyscus leucopus was investigated from 202 mark and recapture mice and 61 mice that were removed from a site in Baltimore County, Maryland. Borrelia burgdorferi infection was detected by culture and polymerase chain reaction (PCR) of ear tissue, and exposure to the spirochete was quantified by serology. Overall prevalence of B. burgdorferi, as determined by culture and PCR of ear tissue at first capture, was 25% in the longitudinal sample and 42% in the cross-sectional sample. Significantly more juvenile mice were captured in the longitudinal sample (18%) than in the cross-sectional sample (0%). Among 36 captured juvenile mice, only one was infected with B. burgdorferi; this contributed to a significant trend for infection with B. burgdorferi with age. Recovery from infection with B. burgdorferi was not detected among 77 mice followed for an average of 160 days. The incidence rate of infection with B. burgdorferi was 10 times greater in mice captured during two periods of high risk of exposure to nymphal Ixodes scapularis ticks compared with a period of low risk. Maintenance of B. burgdorferi in this population was dependent on indirect transmission of the organism from infected ticks to susceptible mice and development of chronic infection with the spirochete, which had no measurable effect on the survival of infected mice.

The potential for hantaviral transmission among wild Norway rats by wounding associated with aggressive interactions was evaluated using a prospective sero-epidemiological study coupled with a mark-release-recapture survey. There was a significant association between an animal's serological status and the presence of wounds. Longitudinal studies of marked and released animals showed seroconversion between captures was associated with wounding between captures more often (33%) than expected by chance, while unwounded animals seroconverted less often (8%) than expected. Typically, less than a 5% difference was found when comparing the incidence of seroconversion with the predicted rate based on wounding and seroprevalence. Infection was highly associated with the onset of sexual maturity and aggression but decoupled from rat age and the length of environmental exposure. Seroconversions occurred at times most associated with aggressive encounters and least associated with amicable behaviours that could lead to aerosol transmission.

Rats trapped from 14 locations in Baltimore, Maryland, were shown to have antibody to Hantavirus. Antibody prevalence rates were higher in residential locations than in parks. Infected rats were obtained continuously over a six-year period from 1980-1985 at five locations, indicating the enzootic nature of this infection in urban rats in the United States. Prevalence of antibody and geometric mean titers increased with rat mass and sexual maturity, suggesting that infections in rats are acquired through age-related mechanisms. Three isolates of Hantavirus were obtained from rats. One of these isolates was shown by serologic tests and monoclonal antibody reactivity patterns to be similar, if not identical, to rat virus previously obtained from Philadelphia. The presence of rats in many urban settings and the high prevalence of Hantavirus infection in this species suggest that human exposure to this virus is occurring in the United States, although human disease from this exposure has not been recognized.

Zoonotic disease surveillance is typically triggered after animal pathogens have already infected humans. Are there ways to identify high-risk viruses before they emerge in humans? If so, then how and where can identifications be made and by what methods? These were the fundamental questions driving a workshop to examine the future of predictive surveillance for viruses that might jump from animals to infect humans. Virologists, ecologists and computational biologists from academia, federal government and non-governmental organizations discussed opportunities as well as obstacles to the prediction of species jumps using genetic and ecological data from viruses and their hosts, vectors and reservoirs. This workshop marked an important first step towards envisioning both scientific and organizational frameworks for this future capability. Canine parvoviruses as well as seasonal H3N2 and pandemic H1N1 influenza viruses are discussed as exemplars that suggest what to look for in anticipating species jumps. To answer the question of where to look, prospects for discovering emerging viruses among wildlife, bats, rodents, arthropod vectors and occupationally exposed humans are discussed. Finally, opportunities and obstacles are identified and accompanied by suggestions for how to look for species jumps. Taken together, these findings constitute the beginnings of a conceptual framework for achieving a virus surveillance capability that could predict future species jumps.