Sylvatic typhus associated with flying squirrels (Glaucomys volans) in New York State, United States.

Sylvatic typhus is an infrequent, potentially life-threatening emerging zoonotic disease. In January of 2009, the New York State Department of Health was notified of a familial cluster of two suspected cases. Due to the paucity of typhus cases in New York, epidemiologic and environmental investigations were conducted to establish rickettsial etiology and determine potential sources of infection. Patients presented with symptoms consistent with typhus, and serologic testing of each patient confirmed infection with typhus group rickettsiae. Serologic analysis of blood obtained from southern flying squirrels (Glaucomys volans) captured from the attic crawlspace above an enclosed front porch of the cases' residence indicated evidence of infection with Rickettsia prowazekii, with 100% seroprevalence (n=11). Both patients reported spending significant time on the porch and hearing animal activity above the ceiling prior to onset of illness, implicating these flying squirrels as the likely source of infection.

A national case-control study identifies human socio-economic status and activities as risk factors for tick-borne encephalitis in Poland.

BACKGROUND: Tick-borne encephalitis (TBE) is endemic to Europe and medically highly significant. This study, focused on Poland, investigated individual risk factors for TBE symptomatic infection. METHODS AND FINDINGS: In a nation-wide population-based case-control study, of the 351 TBE cases reported to local health departments in Poland in 2009, 178 were included in the analysis. For controls, of 2704 subjects (matched to cases by age, sex, district of residence) selected at random from the national population register, two were interviewed for each case and a total of 327 were suitable for the analysis. Questionnaires yielded information on potential exposure to ticks during the six weeks (maximum incubation period) preceding disease onset in each case. Independent associations between disease and socio-economic factors and occupational or recreational exposure were assessed by conditional logistic regression, stratified according to residence in known endemic and non-endemic areas. Adjusted population attributable fractions (PAF) were computed for significant variables. In endemic areas, highest TBE risk was associated with spending ≥10 hours/week in mixed forests and harvesting forest foods (adjusted odds ratio 19.19 [95% CI: 1.72-214.32]; PAF 0.127 [0.064-0.193]), being unemployed (11.51 [2.84-46.59]; 0.109 [0.046-0.174]), or employed as a forester (8.96 [1.58-50.77]; 0.053 [0.011-0.100]) or non-specialized worker (5.39 [2.21-13.16]; 0.202 [0.090-0.282]). Other activities (swimming, camping and travel to non-endemic regions) reduced risk. Outside TBE endemic areas, risk was greater for those who spent ≥10 hours/week on recreation in mixed forests (7.18 [1.90-27.08]; 0.191 [0.065-0.304]) and visited known TBE endemic areas (4.65 [0.59-36.50]; 0.058 [-0.007-0.144]), while travel to other non-endemic areas reduced risk. CONCLUSIONS: These socio-economic factors and associated human activities identified as risk factors for symptomatic TBE in Poland are consistent with results from previous correlational studies across eastern Europe, and allow public health interventions to be targeted at particularly vulnerable sections of the population.

West Nile virus surveillance in mosquitoes in New York State, 2000-2004.

A West Nile virus (WNV) surveillance system was created and implemented in New York State (NYS) in 2000 and described previously (White et al. 2001). We examine and evaluate the results of mosquito and virus surveillance for 2000 through 2004 exclusive of New York City. Forty-nine counties submitted 1,095,426 mosquitoes in 35,280 pools for WNV assay. Specimens of 47 species were tested, with Culex species accounting for 47.6% of all pools tested. WNV was detected in 814 pools from 10 species, with combined Culex pipiens/Culex restuans pools accounting for 90.8% of all detections. Pools submitted from gravid traps were 5.7 times more likely to be positive than submissions from carbon dioxide-baited light traps. Most human WNV cases resided in counties that conducted mosquito surveillance. Local health departments' use of mosquito surveillance information often led to an enhanced disease prevention response. In NYS, Cx. pipiens/Cx. restuans groups are most likely vectors of WNV. Future efforts to improve system efficacy are discussed.

Prevalence of Borrelia burgdorferi in small mammals in New York state.

Intensive small mammal trapping was conducted in 12 counties in New York state during 1998-2000 to investigate the prevalence and site specificity of the Lyme disease spirochete, Borrelia burgdorferi in, and presence of the blacklegged tick, Ixodes scapularis Say on, the wild mice Peromyscus leucopus Rafinesque and Peromyscus maniculatus Wagner and other small mammal species. Previously captured mice (1992-1997) from throughout New York state also were recruited into the study, providing a total of 3,664 Peromyscus from 107 sites in 31 counties. Infection with B. burgdorferi was determined by polymerase chain reaction testing of ear tissue, and rates were determined by species, counties, and regions of the state. B. burgdorferi was detected in 10 small mammal species captured during 1998-2000. Peromyscus captured from Dutchess County in the lower Hudson Valley had the highest infection rate of 21%. The next highest infection rates were in counties within the Capital District: Albany (18%), Rensselaer (17%), and Columbia (13%). From 4,792 small animals examined, we recovered 2,073 ticks representing six species from 414 individuals of 12 mammal species, including 1,839 I. scapularis collected from 315 Peromyscus trapped in five counties. I. scapularis were most often collected from animals trapped in Albany, Rensselear, and Dutchess counties. We used protein electrophoresis of salivary amylase to distinguish between P. leucopus and P. maniculatus species. I. scapularis burdens were 5.7 ticks per P. leucopus and 14.3 ticks per P. maniculatus.

Spatiotemporal Bayesian analysis of Lyme disease in New York state, 1990-2000.

Mapping ordinarily increases our understanding of nontrivial spatial and temporal heterogeneities in disease rates. However, the large number of parameters required by the corresponding statistical models often complicates detailed analysis. This study investigates the feasibility of a fully Bayesian hierarchical regression approach to the problem and identifies how it outperforms two more popular methods: crude rate estimates (CRE) and empirical Bayes standardization (EBS). In particular, we apply a fully Bayesian approach to the spatiotemporal analysis of Lyme disease incidence in New York state for the period 1990-2000. These results are compared with those obtained by CRE and EBS in Chen et al. (2005). We show that the fully Bayesian regression model not only gives more reliable estimates of disease rates than the other two approaches but also allows for tractable models that can accommodate more numerous sources of variation and unknown parameters.

Epidemic and spatial dynamics of Lyme disease in New york State, 1990-2000.

Lyme disease (LD) occurrence in New York State (NYS) has not only increased over time but also spread throughout the state from the original disease focus in southeastern NYS. Few studies have investigated this epidemic and spatial dynamic in great detail. Using data from the NYS Department of Health Lyme Registry Surveillance System, we summarized epidemic and spatial characteristics of LD in NYS for the 11-yr time period from 1990 through 2000. New epidemiological trends associated with age, sex, and residential influences on LD over time were found. An empirical Bayes approach was used to produce maps of smoothed incidence at different time points to give a foundation for future state and local health funding plans and education programs.

Survey of repellent use by service members arriving in Kuwait for Operation Iraqi Freedom 2.

The 8th Medical Brigade, deployed to Kuwait in January 2004 in support of Operation Iraqi Freedom provided theater-wide health service support and medical command and control. An historic "surge" of troops and equipment occurred during our deployment as 140,000 service members (SMs) redeployed out of theater and 110,000 arrived to take their place. The brigade's preventive medicine personnel conducted a questionnaire-based survey at military camps in northwestern Kuwait in mid-March to determine whether SMs had been provided with supplies and information to protect them against endemic vector-borne diseases. Of 1,200 questionnaires distributed, 870 (73%) were returned. In addition to military affiliation information, the survey contained specific questions related to the provision of n-diethyl-m-toluamide repellents, permethrin and treated uniforms, and medical threat briefings. On average, less than one-half of the SMs received these resources before their arrival in Kuwait. Significant differences of resource provision existed among service branches, components, and mobilization or deployment stations.

Babesia microti, upstate New York.

Five cases of human babesiosis were reported in the Lower Hudson Valley Region of New York State in 2001. An investigation to determine if Babesia microti was present in local Ixodes scapularis ticks yielded 5 positive pools in 123 pools tested, the first detection of B. microti from field-collected I. scapularis in upstate New York.