C. Ben Beard

Ecologic Niche Modeling and Potential Reservoirs for Chagas Disease, Mexico

Ecologic niche modeling may improve our understanding of epidemiologically relevant vector and parasite-reservoir distributions. We used this tool to identify host relationships of Triatoma species implicated in transmission of Chagas disease. Associations have been documented between the protracta complex (Triatoma: Triatominae: Reduviidae) with packrat species (Neotoma spp.), providing an excellent case study for the broader challenge of developing hypotheses of association. Species pairs that were identified coincided exactly with those in previous studies, suggesting that local interactions between Triatoma and Neotoma species and subspecies have implications at a geographic level. Nothing is known about sylvatic associates of T. barberi, which are considered the primary Chagas vector in Mexico; its geographic distribution coincided closely with that of N. mexicana, suggesting interaction. The presence of the species was confirmed in two regions where it had been predicted but not previously collected. This approach may help in identifying Chagas disease risk areas, planning vector-control strategies, and exploring parasite-reservoir associations for other emerging diseases.

Update on the epidemiology and transmission of Pneumocystis carinii.

Although Pneumocystis carinii pneumonia is one of the leading causes of morbidity and mortality among patients with the acquired immunodeficiency syndrome, many questions about its epidemiology and transmission remain unanswered. Whereas traditional theory postulates that the disease results from reactivation of latent infection, recent data suggest that active acquisition of infection, either through environmental exposure or person-to-person transmission, may occur. This review summarizes the current state of knowledge about the epidemiology and transmission of P. carinii and reports on evolving techniques that may improve our understanding of this organism in the future.

Persistence of Yersinia pestis in Soil Under Natural Conditions

As part of a fatal human plague case investigation, we showed that the plague bacterium, Yersinia pestis, can survive for at least 24 days in contaminated soil under natural conditions. These results have implications for defining plague foci, persistence, transmission, and bioremediation after a natural or intentional exposure to Y. pestis.

Molecular tools and triatomine systematics: a public health perspective

Triatomines, or kissing bugs, are vectors of Chagas disease to humans. This disease is a substantial public health problem affecting up to 12 million people throughout the Americas, and its control relies mainly on the insecticide treatment of triatomine-infested houses within villages. In this article, Fernando Monteiro, Ananias Escalante and Ben Beard review how molecular markers have been used to clarify triatomine systematics, and give examples of how our understanding of triatomine population structure and accurate vector identification can be used to optimize vector control.

Identification and characterization of microsatellite markers in the Chagas disease vector Triatoma dimidiata

Triatoma dimidiata, one of the major vectors of Chagas disease in Central America, is found in both domestic and peri-domestic habitats. Questions concerning population boundaries, infestation rates, insecticide resistance, and geographic dispersal of triatomine bugs persist and may be resolved using genetic markers such as microsatellites. Microsatellites are short tandem repeats found dispersed throughout a genome and can be useful for genotypic identification. We developed a plasmid library from the genomic DNA isolated from a single T. dimidiata adult collected in Guatemala. Ten thousand clones were screened using a probe consisting of nine microsatellite oligonucleotides. Eight loci appear polymorphic among populations found in Guatemala, Honduras, and Mexico, and thus are potentially useful for population genetic applications.

Multiple Francisella tularensis Subspecies and Clades, Tularemia Outbreak, Utah

In July 2007, a deer fly–associated outbreak of tularemia occurred in Utah. Human infections were caused by 2 clades (A1 and A2) of Francisella tularensis subsp. tularensis. Lagomorph carcasses from the area yielded evidence of infection with A1 and A2, as well as F. tularensis subsp. holarctica. These findings indicate that multiple subspecies and clades can cause disease in a localized outbreak of tularemia.

TickNET—A Collaborative Public Health Approach to Tickborne Disease Surveillance and Research

TickNET, a public health network, was created in 2007 to foster greater collaboration between state health departments, academic centers, and the Centers for Disease Control and Prevention on surveillance and prevention of tickborne diseases. Research activities are conducted through the Emerging Infections Program and include laboratory surveys, high-quality prevention trials, and pathogen discovery.

Vector-borne infections.

Infections with vector-borne pathogens are a major source of emerging diseases. The ability of vectors to bridge spatial and ecologic gaps between animals and humans increases opportunities for emergence. Small adaptations of a pathogen to a vector can have profound effects on the rate of transmission to humans.

Pneumocystis jirovecii Dihydropteroate Synthase Gene Mutations and Human Immunodeficiency Virus‐Associated Pneumocystis Pneumonia

LAURENCE HUANG, DAVID A. WELSH, ROBERT F. MILLER, C. BEN BEARD, GENA G. LAWRENCE, MELISSA FOX, ALEXANDRA SWARTZMAN, MATTHEW R. BENSLEY, DENISE CARBONNET, J. LUCIAN DAVIS, AMY CHI, BECKY J. YOO and JEFFREY L. JONES HIV/AIDS Division, Division of Pulmonary and Critical Care Medicine, San Francisco General Hospital, University of California San Francisco, San Francisco, California 94110, and Division of Pulmonary and Critical Care Medicine, San Francisco General Hospital, University of California San Francisco, San Francisco, California 94110, and Pulmonary and Critical Care Medicine, Medical Center of Louisiana at New Orleans, Louisiana State University Health Sciences Center, New Orleans, Los Angeles, and Department of Population Sciences and Primary Care, Centre for Sexual Health and HIV Research, Royal Free and University College Medical School, University College London, London, United Kingdom, and Division of Vector-Borne Infectious Diseases, Bacterial Diseases Branch, U.S. Centers for Disease Control and Prevention, Fort Collins, Colorado, and Division of Parasitic Diseases, National Center for Infectious Diseases, U.S. Centers for Disease Control and Prevention, Atlanta, Georgia

Exposure science in an age of rapidly changing climate: challenges and opportunities

Climate change is anticipated to alter the production, use, release, and fate of environmental chemicals, likely leading to increased uncertainty in exposure and human health risk predictions. Exposure science provides a key connection between changes in climate and associated health outcomes. The theme of the 2015 Annual Meeting of the International Society of Exposure Science—Exposures in an Evolving Environment—brought this issue to the fore. By directing attention to questions that may affect society in profound ways, exposure scientists have an opportunity to conduct “consequential science”—doing science that matters, using our tools for the greater good and to answer key policy questions, and identifying causes leading to implementation of solutions. Understanding the implications of changing exposures on public health may be one of the most consequential areas of study in which exposure scientists could currently be engaged. In this paper, we use a series of case studies to identify exposure data gaps and research paths that will enable us to capture the information necessary for understanding climate change-related human exposures and consequent health impacts. We hope that paper will focus attention on under-developed areas of exposure science that will likely have broad implications for public health.