Contents

• USGS Activities Related to Human Health  
• Upcoming Meetings
• New Publications

Newsletter Home

The USGS Studies Sand Fly-Borne Leishmaniasis Disease in Tunisia

The salt tolerant plants (halophytic chenopods) in this open saline area in central Tunisia serve as the main food source for sand rats, Psammomys obesus. The sand rats are host to the pathogen Leishmania major and the sand flies that transmit the pathogen to people. A small farming community where the families raise sheep and grow olives is in the background. (Larger version)

USGS scientist Dr. Howard S. Ginsberg is participating in a study of the transmission and prevention of the disease Zoonotic Cutaneous Leishmaniasis (ZCL) in Tunisia. Diseases that are transmitted from animals to humans are called zoonotic diseases. Leishmaniasis is caused by several pathogenic species of single celled parasites in the genus Leishmania. In this case, Leishmania major is transmitted to humans by a sand fly (Phlebotomus papatasi), which is common in many parts of Africa. The pathogen is carried by rodents, notably sand rats (Psammomys obesus), and jirds (Meriones shawi). ZCL causes severe skin lesions, which generally take months to heal, and sometimes leave disfiguring scars. Leishmaniasis is primarily a disease of children, with thousands of cases per year in Tunisia.

Dr. Ginsberg was invited to work on this problem by scientists at the Pasteur Institute in Tunis (Institut Pasteur de Tunis). The research group at the Pasteur Institute (led by Dr. Elyes Zhioua) has developed a potential approach to managing the disease. The approach involves establishing rabbit holes near the homes of farming families in central Tunisia where the infection is most prevalent. Their work suggests that rabbit holes could deflect the sand flies from entering houses, lowering the number of flies that might potentially bite people. Dr. Ginsberg is working with the research group at the Pasteur Institute on a comprehensive study of sand fly movement patterns and Leishmania major transmission dynamics to determine whether their approach will work on a large scale.

More Information

• For more information contact Dr. Howard S. Ginsberg
• Leishmaniasis, World Health Organization
• Leishmania major, National Center for Biotechnology Information (NCBI) Taxonomy Database
• Vector-borne Diseases and Zoonotic Diseases

Is Methylmercury in Pacific Ocean Fish of Human Origin?

Scientists prepare to lower a "rosette" of 12 Niskin bottles on the vessel R/V Thomas G. Thompson. The device enables the collection of samples in the ocean via remote triggering of each bottle at different depths. Extreme care was taken to ensure that the rosette did not contaminate the samples. Photo courtesy of William Landing, Florida State University. (Larger version)

Given the obvious importance of marine food webs to human methylmercury exposure, it is remarkable that scientists are still wondering: where do fish, such as Pacific Ocean tuna, acquire their methylmercury? A U.S. Geological Survey (USGS) scientist and his university colleagues have discovered that bacteria in ocean water convert elemental mercury from atmospheric deposition to methylmercury when the bacteria degrade the remains of dead phytoplankton that “rain” down to ocean mid-depths. Before this work, some scientists hypothesized that methylmercury in the open ocean was geologic in origin and associated with deep-sea spreading centers. The results from these scientists' work do not support the geologic origin hypothesis.

Consumption of ocean fish and shellfish account for over 90 percent of human methylmercury exposure in the United States, and tuna harvested in the Pacific Ocean account for 40 percent of this total exposure. Currently, national and international groups are seeking the most effective ways to minimize human methylmercury exposure, and the scientists' article in Global Biogeochemical Cycles presents the first evidence linking current atmospheric mercury deposition to methylmercury in Pacific Ocean fish. Environmental professionals, regulators, resource managers, and other decision makers can use these results to help make informed decisions about atmospheric mercury emissions and potential human exposure to methylmercury from fish consumption.

More Information

• A New Source of Methylmercury in the Pacific Ocean
• Mercury sources, distribution, and bioavailability in the North Pacific Ocean--Insights from data and models: Sunderland, E.M., Krabbenhoft, D.P., Moreau, J.W., Strode, S.A., and Landing, W.M., 2009, Global Biogeochemical Cycles, v. 23, no. 2, p. 1-14, GB2010, doi:10.1029/2008GB003425.
• Ocean mercury on the increase--Rise may affect neurotoxin levels in fish: Lubick, N., 2009, Nature, doi:10.1038/news.2009.218
• Mystery at Sea--How mercury gets into tuna and other fish in the ocean has scientists searching from the coast to the floor: Jaffe, E., September 27, 2007, Smithsonian
• Mercury in Aquatic Ecosystems
• USGS National Mercury Research Laboratory

Studying Avian Influenza: Tracking Wild Birds in India and Hong Kong

A bar-headed goose with GPS satellite transmitter, awaiting release. This goose was from the Koonthankulum Sanctuary in India. (Larger version)

USGS experts in satellite telemetry are helping track the movements of wild waterfowl in support of surveillance programs in countries with avian influenza outbreaks. Waterfowl were captured during December 2008 in Hong Kong at the Mai Po Nature Reserve and in Orissa, India, at Koonthankulum Sanctuary, Tamil Nadu, and Chilika Lagoon. The waterfowl were outfitted with miniaturized global positioning system (GPS) transmitters. The transmitters allow USGS scientists to track birds to help the scientists understand whether relationships exist between the locations of these marked birds and avian influenza outbreaks along the birds’ migratory pathways. The USGS is working with the United Nations Food and Agriculture Organization, government agencies, and non-governmental organizations in this effort. This collaborative effort will provide insights into the movement of avian influenza viruses and other diseases in East Asian flyways, improve the knowledge base on the ecological habits of waterfowl internationally, and enhance health professionals' understanding of the interactions among wild and domestic birds.

An example of a map showing the location of India waterfowl that were outfitted with GPS satellite transmitters. More information on how to read and use the maps is available. This map was generated on July 8, 2009. (Larger version)

More Information

• Movements of Wild Birds and Emerging Disease Risk From India
• Movements of Wild Birds and Emerging Disease Risk from Hong Kong
• USGS News Release: Technical Announcement: Satellite-Tracked Birds from India Will Provide Clues on How Avian Influenza Spreads: International Team Conducts Research
• New Study in India on Wild Birds and Avian Influenza, Supporting Images

Contaminants in 20 Percent of U.S. Domestic Wells

Domestic wells sampled in this study are located in 48 States and parts of 30 of the 62 principal aquifers of the United States. Domestic wells (colored circles) are categorized by principal aquifer rock type. (Larger version)

More than 20 percent of private domestic wells sampled across the United States contain at least one contaminant at levels of potential health concern. Fifteen percent of the Nation's population - about 43 million people - use drinking water from private wells, which are not regulated by the Federal Safe Drinking Water Act. USGS scientists sampled about 2,100 private wells in 48 States and found that the contaminants most frequently measured at concentrations of potential health concern were inorganic contaminants, including radon and arsenic. These contaminants are mostly derived from the natural geologic materials that make up the aquifers from which well water is drawn. Manmade organic chemicals were detected in more than half of the sampled wells but seldom at concentrations of potential human-health concern. Concentrations were considered of potential human-health concern when they exceeded U.S. Environmental Protection Agency Maximum Contaminant Levels (MCLs) or calculated Health-Based Screening Levels. The wells were sampled prior to any in-home water treatment.

More Information

• Quality of Water from Domestic Wells in the United States
• USGS New Release: Water Quality of Potential Concern in U.S. Private Wells
• USGS Podcast: Contaminants in 20 Percent of U.S. Private Wells

Estrogen Exposure Linked to Lowered Immunity in Fish

USGS and U.S. Fish and Wildlife Service biologists processing fish samples. (Larger version)

USGS scientists have found that exposure to estrogen reduces the production of immune-related proteins in fish. This suggests that certain compounds, known as endocrine disruptors, may make fish more susceptible to disease. The study may provide new indications of why intersex fish (the presence of both male and female characteristics within the same fish), fish kills, and fish lesions often occur together in the Shenandoah and Potomac Rivers. The results of the study showed that large-mouth bass injected with estrogen produced lowered levels of hepcidin, an important iron-regulating hormone in mammals that is also found in fish and amphibians. This was the first published study demonstrating control of hepcidin by estrogen in any animal. Besides being an important iron-regulating hormone, the scientists also conjecture that hepcidin may act as an antimicrobial peptide in mammals, amphibians, and fish. Antimicrobial peptides are the first line of defense against disease-causing bacteria, fungi, and viruses in animals.

More Information

• USGS News Release: One Step Closer to Understanding Fish Health in Potomac and Shenandoah Rivers
• Robertson, L.S., Iwanowicz, L.R., and Marranca, J.M., 2009, Identification of centrarchid hepcidins and evidence that 17[beta]-estradiol disrupts constitutive expression of hepcidin-1 and inducible expression of hepcidin-2 in largemouth bass (Micropterus salmoides): Fish and Shellfish Immunology, v. 26, no. 6, p. 898-907, doi:10.1016/j.fsi.2009.03.023.
• Detailed Project Information

Mixed News on Mercury in Indiana’s Water

USGS scientist processing a weekly precipitation sample. The sample will be analyzed for mercury. (Larger version)

Rain and snow falling in Indiana contains less mercury than it did in years past. Yet some of the State's major waterways have mercury levels that could be harmful to humans and wildlife. State health officials advise people to limit their consumption of some fish caught in Indiana because of mercury contamination. USGS scientists demonstrated that mercury levels in the State vary from place to place, season to season, and year to year. According to their report on mercury in streams, nearly 6 percent of water samples collected from 2004 to 2006 had mercury levels that exceeded the Indiana water-quality standard established to protect human health. Mercury concentrations in 73 percent of the samples exceeded the more restrictive State water-quality standard protecting wildlife. More than 80 percent of the water samples had detectable methylmercury, the most toxic form of mercury that accumulates in fish, birds, and mammals at the top of food chains. The USGS, in cooperation with the Indiana Department of Environmental Management, has a long-term program to monitor mercury statewide, whereby mercury in precipitation is measured every week at five stations in Indiana and every season at 25 stream sites in the State's major watersheds.

More Information

• USGS New Release: Mixed News on Mercury in Indiana’s Water
• Investigations and Monitoring of Mercury in Indiana

USGS Collaborating on a Study to Determine the Factors that Control the Geographic Distribution of Lyme Disease

Deer tick (Ixodes scapularis) can be found throughout the eastern part of the country

The USGS is working on a large-scale study to determine the causes for the observed distribution of Lyme disease in the eastern United States. The disease-carrying deer tick, Ixodes scapularis, can be found throughout the eastern part of the country; while Lyme disease in humans is common in the northeast and northern Midwest states, it is rare in southern states. The USGS is collaborating on a National Science Foundation funded project with scientists from several universities (Michigan State University, University of Rhode Island, Hofstra University, Georgia Southern University, University of Tennessee, and University of Montreal). The research team is looking at patterns of vertebrate community structure, cyclic and seasonal tick behavior, and tick genetics in four regions of the United States (northeast, north central, southeast, and south central), to assess the contributions these factors might have on the transmission the Lyme bacterium, Borrelia burgdorferi.

More Information

• For more information contact Dr. Howard S. Ginsberg
• Lyme Disease and Vector-Borne Pathogen Studies
• Tick-borne: Lyme Disease
• Vector-borne Diseases and Zoonotic Diseases

Invasive Fish Tilts the Mercury Scales

Threadfin shad (Dorosoma petenense) www.nativefish.org

When the threadfin shad fish invaded California's Clear Lake, it shook up the food web by eating all the tiny animals, known as zooplankton [http://www.absc.usgs.gov/research/seabird_foragefish/marinehabitat/home.html#zooplankton], that many other small fish depend on for food. As a result, the resident small fish became more dependent upon bottom-dwelling prey such as the larvae of small flies called midges, which live in methylmercury contaminated sediments. Methylmercury is a very toxic form of mercury found in some aquatic ecosystems, and at high exposure levels, methylmercury can affect the nervous and reproductive systems of fish, wildlife, and humans. Thus, high levels of methylmercury in small fish may not only impact their health, but also increase the risk of exposure to animals higher in the food chain that eat them. USGS scientists found that during times of high shad abundance, total mercury concentrations in the resident fish increased by approximately 50 percent compared to when shad were not present in the lake.

More Information

• Fish Invasions Alter Lake Food Web Structure and Mercury Bioaccumulation
• For more information contact Collin Eagles-Smith

HealthMap: Alerts on Global Wildlife and Human Diseases

HealthMap is a new tool providing alerts on human, domestic animal, and wildlife diseases throughout the world - and it's all on one map! Information comes from various news media and other sources, including the USGS wildlife disease news. This integrated approach of combining health information for wildlife, humans, and domestic animals supports the growing belief that examining their interrelationships may lead to new discoveries. HealthMap was created by Harvard-MIT and the Children's Hospital Informatics Program.

More Information

• HealthMap
• USGS Global Wildlife Disease News Map

Watershed Characteristics Determine How Much Atmospherically Deposited Mercury Ends Up in Fish

USGS scientists electrofishing on the St. Marys River, Florida. Captured fish were analyzed for mercury. (Larger version)

A recent published series of papers resulting from a USGS study on the fate of atmospherically deposited mercury in eight watersheds shows that some stream ecosystems are much more sensitive to atmospheric deposition of mercury than others. The results showed that total mercury and methylmercury concentrations in the streams were much more variable than the observed variation in the atmospheric deposition of mercury (9-fold for streams and 4-fold for atmospheric deposition). The characteristics of the watershed, particularly the abundance of wetlands and amount of natural organic carbon in stream water, are the primary determinants for how mercury is transported and bioaccumulated in stream food webs. The eight streams in the study were located in Oregon, Wisconsin, and Florida. Streams in urban areas (Portland, Oregon; Milwaukee, Wisconsin; and Orlando, Florida), and streams in relatively undeveloped areas in these States were included in the study. The findings from this study can help decision makers to better anticipate concentrations of mercury and methylmercury and how mercury makes its way into fish in unstudied streams in comparable environmental settings.

More Information

• Mercury Cycling in Stream Ecosystems Summary (pdf)
• How Mercury Flows Downstream, Environmental Science and Technology
• Mercury in Stream Ecosystems, USGS National Water-Quality Assessment (NAWQA) Program
• Frequently Asked Questions on the "Mercury Cycling in Stream Ecosystems" Studies
• Mercury in Aquatic Ecosystems, USGS Toxic Substances Hydrology Program

References

Brigham, M.E., Wentz, D.A., Aiken, G.R., and Krabbenhoft, D.P., 2009, Mercury cycling in stream ecosystems--1. Water column chemistry and transport: Environmental Science and Technology, v. 43, no. 8, p. 2,720-2,725, doi:10.1021/es802694n. (Free Download)

Chasar, L.C., Scudder, B.C., Stewart, A.R., Bell, A.H., and Aiken, G.R., 2009, Mercury cycling in stream ecosystems--3. Trophic dynamics and methylmercury bioaccumulation: Environmental Science and Technology, v. 43, no. 8, p. 2,733-2,739, doi:10.1021/es8027567. (Free Download)

Marvin-DiPasquale, M., Lutz, M.A., Brigham, M.E., Krabbenhoft, D.P., Aiken, G.R., Orem, W.H., and Hall, B.D., 2009, Mercury cycling in stream ecosystems--2. Benthic methylmercury production and bed sediment-pore water partitioning: Environmental Science and Technology, v. 43, no. 8, p. 2,726-2,732, doi:10.1021/es802698v. (Free Download)

15th International Interdisciplinary Conference on the Environment, Daytona Beach, Florida, July 8-11, 2009

The Interdisciplinary Environmental Association (IEA) is conducting its 15th International Interdisciplinary Conference on the Environment. The conference is motivated by the increasing need to combine ideas and research findings from different disciplines to enhance our understanding of the interactions between the natural environment and human institutions.

Meeting Web Site

Environmental Health Risk 2009: Fifth International Conference on the Impact of Environmental Factors on Health, New Forest, United Kingdom, September 21-23, 2009

The conference aims to provide a forum for the dissemination and exchange of information on the diverse aspects of the impact of environmental factors on health across different disciplines.

Meeting Web Site

137th American Public Health Association (APHA) Annual Meeting and Exposition, Philadelphia, Pennsylvania, November 7-11, 2009

The theme of this year's meeting is Water and Public Health: The 21st Century Challenge. Water is a limited resource, the demands for which are fast increasing. In the United States, utility workers, scientists, sanitarians, engineers, government officials and many others work around the clock to provide safe and clean drinking water to AmericaÕs homes and businesses and are struggling to keep up with demand without compromising water supplies for future generations. The meeting is the largest gathering of public health professionals in the world.

Meeting Web Site

SETAC North America 30th Annual Meeting: Human-Environment Interactions: Understanding Change in Dynamic Systems, New Orleans, Louisiana, November 19-23, 2009

The Society of Environmental Toxicology and Chemistry (SETAC) North America is conducting its 30th annual meeting in New Orleans, Louisiana, on November 19-23, 2009. The theme of the meeting is Human-Environment Interactions: Understanding Change in Dynamic Systems. The following human heath related topical sessions will be held:

• Bridging the Gap: Integrating Human Health and Ecological Risk Assessments
• Ecotoxicity, and Risk Assessment of "Materials of Importance to the Military," and Innovative Methods to Carry Out Such Investigations
• Fate and Behavior of Pharmaceuticals in Treated Wastewaters, Sludge, and River Waters
• Ecological Restoration, Ecosystem Services and Human Well Being
• Toxic Substances in Urban and Rural Environments; Ecosystem Approaches to Human and Wildlife Consequences
• Water Quality Protection Regulatory Programs Internationally: Current Status, Latest Results, and Research Needs
• Hormones in the Environment

Meeting Web Site

International Conference on Engineering, Environment, Economics, Safety and Health (CONVEEESH 09), Manado Island, North Sulawesi Province, Indonesia, October 26-27, 2009

This conference focuses on sustainable development as one of the key issues for modern society. A wide range of environmental and health related topics will be presented.

Meeting Web Site

National Environmental Health Association 74th Annual Educational Conference and Exhibition, Albuquerque, New Mexico, June 5-9, 2010

National Environmental Health Association (NEHA) is hosting the National Environmental Health Association 74th Annual Educational Conference and Exhibition in Albuquerque, New Mexico, June 5-9, 2010. The conference will hold educational sessions covering a broad range of environmental health topics and issues. NEHAÕs 74th AEC and Exhibition looks to advance the field of environmental health and protection and the professionals that seek to provide a healthful environment for all.

Meeting Web Site