The ascendancy of \u3ci\u3eAmblyomma americanum\u3c/i\u3e as a vector of pathogens affecting humans in the United States

Until the 1990s, Amblyomma americanum was regarded primarily as a nuisance species, but a tick of minor importance as a vector of zoonotic pathogens affecting humans. With the recent discoveries of Ehrlichia chaffeensis, Ehrlichia ewingii, and “Borrelia lonestari,” the public health relevance of lone star ticks is no longer in question. During the next 25 years, the number of cases of human disease caused by A. americanum-associated pathogens will probably increase. Based on current trajectories and historic precedents, the increase will be primarily driven by biological and environmental factors that alter the geographic distribution and intensity of transmission of zoonotic pathogens. Sociologic and demographic changes that influence the likelihood of highly susceptible humans coming into contact with infected lone star ticks, in addition to advances in diagnostic capabilities and national surveillance efforts, will also contribute to the anticipated increase in the number of recognized cases of disease

Infections Associated with Bartonella Species in Persons Infected with Human Immunodeficiency Virus

Two members of the genus Bartonella, Bartonella quintana (formerly Rochalimaea quintana) and Bartonella henselae (formerly Rochalimaea henselae), have recently been recognized as agents of severe or fatal disease in patients infected with human immunodeficiencyv irus (HIV). The development of infection with B. henselae in HIV-infected individuals has been associated with traumatic contact with cats (scratches or bites), and domestic cats have been identified as a major reservoir for this organism. Specific information regarding the transmission of B. henselae to humans is not yet available, but common-sense precautions that minimize exposure to cat-associated organisms are appropriate. Preliminary accounts suggest that B. quintana infections are more common than B. henselae infections among HIV-infected individuals in San Francisco. The source of infection with B. quintana and the mechanism of its transmission remain unknown

Determining Matrilines by Antibody Response to Exotic Antigens

The antibody responses of female Microtuspennsylvanicus inoculated with a series of antigens not normally encountered under field conditions were examined, and the kinetics of maternally acquired antibody loss in their offspring were determined. The initial antibody response in adults was rapid, peaking in 4-9 weeks, and long-lasting, with a half life of 4-5 months. Antibody levels in females were unaffected by parity, and more than one antigen could be given without affecting circulating-antibody titers. Antibody titers could be enhanced with additional inoculations. Maternal antibody in offspring increased until weaning at 3 weeks then declined exponentially. Minimal detectable titers were reached at 7-11 weeks. In many instances, maternal antibody remained detectable even after offspring reached adult (35 g) size. Examination of uninoculated wild-caught voles showed only one of 130 tests produced a false positive response. The exotic-antigen technique may be generally applicable for determining maternity in small, secretive mammals

Long-term studies of hantavirus reservoir populations in the southwestern United States: a synthesis.

A series of intensive, longitudinal, mark-recapture studies of hantavirus infection dynamics in reservoir populations in the southwestern United States indicates consistent patterns as well as important differences among sites and host-virus associations. All studies found a higher prevalence of infection in older (particularly male) mice; one study associated wounds with seropositivity. These findings are consistent with horizontal transmission and transmission through fighting between adult male rodents. Despite very low rodent densities at some sites, low-level hantavirus infection continued, perhaps because of persistent infection in a few long-lived rodents or periodic reintroduction of virus from neighboring populations. Prevalence of hantavirus antibody showed seasonal and multiyear patterns that suggested a delayed density-dependent relationship between prevalence and population density. Clear differences in population dynamics and patterns of infection among sites, sampling periods, and host species underscore the importance of replication and continuity of long-term reservoir studies. Nevertheless, the measurable associations between environmental variables, reservoir population density, rates of virus transmission, and prevalence of infection in host populations may improve our capacity to model processes influencing infection and predict increased risk for hantavirus transmission to humans

Dietary Habits of the Common Rodents in an Agrecosystem in Argentina

Dietary habits of five common rodents in agroecosystems on the central Argentine Pampa were studied for 15 months using microhistological analysis of stomach contents. All five rodent species were omnivorous, but proportions of major dietary items (arthropods, dicot leaves and seeds, monocot leaves and seeds) varied among species and seasons. Akodon azarae largely was entomophagous; arthropods formed 41-62% of the diet in all seasons. The other four species (Calomys musculinus, Calomys laucha, Bolomys obscurus, and Oligoryzomys flavescens) consumed most diet items throughout the year, but relative proportions varied among seasons. Leaves formed a relatively minor proportion of the diet (12- 16% overall for all species) throughout the year. All species except A. azarae consumed higher quantities of seeds (50-73% of stomach volume) than arthropods (15-35%) during autumn and winter but switched to higher quantities of arthropods (30-53%) in spring and summer. Diet breadth was narrower and overlap generally highest during winter when all species were forced to subsist on a reduced set of available resources. Of 28 plant species with \u3e2% cover in the environment, 25 were identified in stomachs of one or more of the five rodent species. The most important plant species in the diet were corn and soybeans (mostly grain), seed of Johnson grass (Sorghum halepense), chickweed (Stellaria media), and Amaranthus. High consumption of arthropods, especially by A. azarae, contraindicates the broad-scale use of rodenticides until the role of that rodent species in the control of pest insects can be ascertained

Effects of the Orion Launch Abort Vehicle Plumes on Aerodynamics and Controllability

Characterization of the launch abort system of the Multi-purpose Crew Vehicle (MPCV) for control design and accurate simulation has provided a significant challenge to aerodynamicists and design engineers. The design space of the launch abort vehicle (LAV) includes operational altitudes from ground level to approximately 300,000 feet, Mach numbers from 0-9, and peak dynamic pressure near 1300psf during transonic flight. Further complicating the characterization of the aerodynamics and the resultant vehicle controllability is the interaction of the vehicle flowfield with the plumes of the two solid propellant motors that provide attitude control and the main propulsive impulse for the LAV. These interactions are a function of flight parameters such as Mach number, altitude, dynamic pressure, vehicle attitude, as well as parameters relating to the operation of the motors themselves - either as a function of time for the AM, or as a result of the flight control system requests for control torque from the ACM. This paper discusses the computational aerodynamic modeling of the aerodynamic interaction caused by main abort motor and the attitude control motor of the MPCV LAV, showing the effects of these interactions on vehicle controllability

Dietary Habits of the Common Rodents in an Agrecosystem in Argentina

Dietary habits of five common rodents in agroecosystems on the central Argentine Pampa were studied for 15 months using microhistological analysis of stomach contents. All five rodent species were omnivorous, but proportions of major dietary items (arthropods, dicot leaves and seeds, monocot leaves and seeds) varied among species and seasons. Akodon azarae largely was entomophagous; arthropods formed 41-62% of the diet in all seasons. The other four species (Calomys musculinus, Calomys laucha, Bolomys obscurus, and Oligoryzomys flavescens) consumed most diet items throughout the year, but relative proportions varied among seasons. Leaves formed a relatively minor proportion of the diet (12- 16% overall for all species) throughout the year. All species except A. azarae consumed higher quantities of seeds (50-73% of stomach volume) than arthropods (15-35%) during autumn and winter but switched to higher quantities of arthropods (30-53%) in spring and summer. Diet breadth was narrower and overlap generally highest during winter when all species were forced to subsist on a reduced set of available resources. Of 28 plant species with \u3e2% cover in the environment, 25 were identified in stomachs of one or more of the five rodent species. The most important plant species in the diet were corn and soybeans (mostly grain), seed of Johnson grass (Sorghum halepense), chickweed (Stellaria media), and Amaranthus. High consumption of arthropods, especially by A. azarae, contraindicates the broad-scale use of rodenticides until the role of that rodent species in the control of pest insects can be ascertained

Risk Factors for Human Infection with Puumala Virus, Southwestern Germany

Risk factors are available bank vole habitat, abundant vole food supply, high human population density, and warmer climate

Mortality in Serologically Unconfirmed Mediterranean Spotted Fever [with Reply]

I read with interest the article by Paddock et al. [1], who described the detection of occult mortality due to Rocky Mountain spotted fever (RMSF) by demonstrating Rickettsia rickettsii antigens or DNA in blood and tissues. In Mediterranean countries, including Israel, spotted fever is caused by members of the R. conorii complex, which are antigenically related to R. rickettsii. ... To the Editor -- We appreciate the comments by Yagupsky, which underscore several of the salient features of spotted fever- group rickettsial infections that we emphasized in our report [2]. For patients, diagnosticians, and clinicians faced with the potentially tragic consequences of Rocky Mountain spotted fever or severe Mediterranean spotted fever (MSF), these points merit repeating. First, the nonspecific signs and symptoms early in the course of rickettsial infections mimic many other infectious and noninfectious syndromes. Second, the diagnostic challenges posed by these diseases are compounded by the lack of rapid and widely available confirmatory tests early in the course of the illnesses. Finally, spotted fevers have the potential to kill otherwise healthy persons in ^ week after onset of symptoms, emphasizing the need for early administration of appropriate therapy