Pathogens

NEON assesses the pathogen status of a subset of collected ticks, mosquitoes and small mammals from its terrestrial field sites during observational sampling bouts. Laboratory testing is conducted to determine whether the collected organisms are carrying certain pathogens (such as Lyme disease, West Nile virus or hantaviruses) that can be transmitted to humans or livestock. One of the major predictions from current global change models is that species (including those that act as disease vectors) will shift continentally in response to changes in climate, thus potentially spreading the pathogens they host to new areas over time.

Pathogens have large impacts on natural ecosystems as well as human populations and agricultural productivity. In recent decades, some pathogens carried by mosquitoes, ticks and rodents have emerged or re-emerged as significant public health concerns for both humans and livestock. NEON data provide important insights into pathogen spread and how host insects and mammals and the pathogens they carry respond to changes in climate, land use and ecosystem composition. The data could be used to identify areas of the country where humans or livestock may be at heightened risk for insect- or rodent-borne pathogens and predict how diseases may spread in the future.

Pathogen testing is specific to each organism type and targets common diseases associated with each, including (but not limited to):

  • Ticks: Lyme disease, Anaplasmosis, Monocytic Ehrlichosis, Tularemia, Rocky Mountain Spotted Fever, Babesiosis
  • Mosquitos: Including (but not limited to) West Nile virus, Dengue, Eastern Equine Encephalitis
  • Rodents: Hantaviruses

Tick-borne Pathogen Status

Tick sampling is conducted at terrestrial field sites during the growing season. Once ticks have been positively identified by species, sex and life stage, a subset of positively identified nymphal ticks are tested for the presence of viral and protozoan pathogens. Nymphs are selected for testing because humans are most commonly infected by ticks in the nymph stage rather than the adult stage.

Six species of ticks are targeted for tick-borne pathogen testing: Ixodes scapularis (black-legged tick), I. pacificus (western black-legged tick), Amblyomma americanum (lone star tick), A. maculatum (Gulf coast tick), Dermacentor andersoni (Rocky mountain wood tick), and D. variabilis (American dog tick). A minimum of ten and a maximum of 100 nymphal ticks of each species are analyzed from each sampling event at each site. Ticks are tested individually for a wide range of pathogens including diseases caused by the genera Anaplasma (anaplasmisis), Borrelia (Lyme disease), Ehrlichia (monocytic ehrlichosis), Francisella (tularemia), and Rickettsia (Rocky Mountain Spotted Fever).

The related pathogen data and protocols are openly available through the NEON data portal.

Related Archival Samples Collection

Species-identified but untested nymphal and adult-stage ticks, unidentified ticks of all life stages, and products generated during pathogen testing (e.g. genomic extractions, PCR products) are sent to the U.S. National Tick Collection at Georgia Southern University. Learn more about our complete catalog of archival samples.

Mosquito-borne Pathogen Status

Mosquitos are collected at terrestrial field sites every two weeks (for core sites) or four weeks (for relocatable sites) while temperatures are at or above 4°C (39.2°F) using CO2 light traps. A subset of female mosquitos of the family Culicidae are screened for pathogens that can be transmitted to humans. Females are tested because only females bite and transmit diseases to humans.

Females are pooled by species for pathogen screening using PCR-based and/or Vero cell culture methods. This screening broadly tests for the presence of alphaviruses, bunyaviruses and flaviviruses. Virus-positive pools are subjected to additional pathogen-specific tests to identify the pathogens that are present. Alphaviruses present in North America include several Equine Encephalitis species, which can cause disease in both humans and horses. The bunyaviridae family includes numerous viruses causing febrile diseases in humans, including La Cross encephalitis and California encephalitis. Flaviviruses include West Nile, dengue, St. Louis encephalitis and Zika.

Mosquitos in the genera Aedes and Culex are the primary vectors of diseases that impact humans, so species within these genera are given priority for screening. Other species are tested as resources and samples sizes allow. Mosquitos are tested in pools of 10 to 50 individuals grouped by species at the site level, with a target of 1,000 individual mosquitos tested per species for each site each year (if available). 

The related pathogen data and protocols are openly available through the NEON data portal.

Related Archival Samples Collection

Species-identified but untested mosquitos and products generated during pathogen testing (e.g. genomic extractions, PCR products) are archived in the NEON Biorepository. Learn more about our complete catalog of archival samples.

Rodent-borne Pathogen Status

Small mammal box trapping is conducted at regular intervals year-round at NEON terrestrial field sites. Blood samples are collected from individuals of target rodent species, including members of the rodent families Cricetidae, Muridae and Dipodidae. A subset of blood samples are tested for seroposivity to hantaviruses, a family of rodent-borne viruses that cause varied diseases including Hantavirus Pulmonary Syndrome (HPS).

Rodent species within the Peromyscus genera of the Cricetidae family are of special interest, particularly P. maniculatus (deer mouse) and P. leucopus (white-footed mouse). These species are broadly distributed, often present at high abundance, and are known reservoirs for hantaviruses. Blood samples are collected from other rodent taxa when sampling does not significantly increase mortality or morbidity. Samples are only collected from individuals that weigh at least 10 grams and are in good physical condition.

Samples are tested at the individual level using enzyme-linked immunosorbent assay (ELISA) tests to detect antibodies reactive against hantaviruses. Samples are also screened against arenaviruses if resources permit. Approximately 140 samples are tested per site per year.

The related pathogen data and protocols are openly available through the NEON data portal

Related Archival Samples Collection

Untested blood samples are archived in the NEON Biorepository. Learn more about our complete catalog of archival samples.

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