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NAHLN Surveillance Efforts

   
 

NAHLN has collaborated with other groups within APHIS, the National Veterinary Services Laboratories, National Surveillance Unit, National Center for Animal Health Programs, National Center for Animal Health Emergency Management, and Wildlife Services to implement surveillance programs. NAHLN laboratories routinely participate in surveillance programs for bovine spongiform encephalopathy (BSE), classical swine fever (CSF), chronic wasting disease (CWD), scrapie, swine influenza virus (SIV), and swine pseudorabies virus (PRV). Additionally, NAHLN laboratories are proficiency tested and approved to conduct testing for avian influenza, exotic Newcastle disease, foot and mouth disease, and vesicular stomatitis virus when needed.

NAHLN laboratories play a critical role in USDA-Veterinary Services (VS) surveillance programs by providing rapid standardized testing and results reporting for the above-mentioned diseases that are targeted in national animal disease surveillance and emergency preparedness initiatives.

Avian Influenza
Currently, under the NAHLN program, there is not an active surveillance stream for Avian Influenza (AI). However, as part of their routine business outside of the NAHLN program, many of the NAHLN laboratories do conduct much AI testing for various VS and State surveillance programs. Historically, NAHLN laboratories have partnered with APHIS Wildlife Services in the wildbird avian influenza surveillance program that was active from 2006-2011.

Personnel in AI-approved NAHLN laboratories maintain current training and proficiency testing status for preparedness purposes and application to other AI programs. The preparedness measure provides confidence and the option during a foreign animal disease investigation for duplicate sample collection, as outlined in Veterinary Services (VS) Guidance 12001 (446KB; formerly VS Memorandum 580.4). If the State Animal Health Official (SAHO) and VS Associate District Director agree, one set of samples collected during a foreign animal disease investigation may be sent to NVSL for confirmatory testing and a duplicate set of samples sent to the local NAHLN laboratory for a preliminary screening test to provide faster preliminary information for decision-making.

More information on AI in the United States can be found here.

Bovine Spongiform Encephalopathy (BSE) Surveillance
The USDA has conducted surveillance for bovine spongiform encephalopathy (BSE) since 1990. In 2004, following the December 2003 detection of BSE in an imported cow, USDA implemented an enhanced BSE surveillance program to determine more accurately the prevalence of the disease in the U.S. cattle population.

USDA concluded that the prevalence of BSE in the United States is extremely low (less than 1 case per million adult cattle), and in 2006, transitioned to an ongoing BSE surveillance program that tests at a level more commensurate with this extremely low level of risk. Ongoing BSE surveillance exceeds guidelines set forth by the World Organization for Animal Health (OIE), providing for testing at a level 10 times that which is recommended by OIE.

Personnel in BSE-approved NAHLN laboratories have provided BSE surveillance testing since 2004.  These laboratories continue to conduct testing to detect BSE at the very low level of less than 1 case per million adult cattle, assess any change in the BSE status of U.S. cattle, and identify any rise in BSE prevalence in this country. The NVSL Pathobiology Laboratory in Ames, Iowa performs surveillance and confirmatory testing on all samples identified as suspect (potential positive) for BSE by the NAHLN laboratories.

Click here for more information on VS' involvement in BSE.

Chronic Wasting Disease (CWD) Surveillance
Since 2001, USDA has worked to develop and implement a CWD program to prevent and control this disease in farmed/captive cervids, establish a national CWD Herd Certification Program, and assist States and tribes in CWD surveillance in wild deer, elk, and moose. The CWD Interim Final Rule became effective on August 13, 2012 and established minimum federal standards for a voluntary Approved State CWD Herd Certification Program (HPC). The CWD HCP is a cooperative effort between APHIS, State animal health or wildlife agencies, and farmed/captive deer, elk, or moose owners. The CWD program supports these efforts through ongoing surveillance in farmed cervid herds to detect CWD-positive animals and conducting follow-up investigations to trace CWD-infected animals to epidemiologically linked herds.

The NVSL Pathobiology Laboratory in Ames, Iowa performs confirmatory testing on all samples identified as suspect (potential positive) for CWD by the CWD-approved NAHLN laboratories.

More information on VS' involvement in CWD can be found here.

Classical Swine Fever Surveillance
The classical swine fever (CSF) surveillance program was initiated in 2006 to detect CSF virus rapidly and monitor the risk of introducing the virus in the U.S. swine herd. The surveillance program targets five specific swine populations for testing:

  • Sick pig submissions to veterinary diagnostic laboratories (VDLs)
  • Slaughter swine with high risk of CSF exposure
  • Feral swine
  • Swine populations (including waste feeding operations)with high risk of CSF exposure in Florida, Texas, and Puerto Rico
  • Swine highly suspicious for CSF and entered into a Foreign Animal Disease Investigation
     

NAHLN laboratories conduct CSF surveillance testing for the first two surveillance streams listed above; samples from the remaining three surveillance streams are tested at NVSL's Foreign Animal Disease Diagnostic Laboratory (FADDL), the CSF confirmatory laboratory. Additionally, NAHLN laboratories are able to support foreign animal disease investigations on CSF-suspect or rule-out animals. As outlined in Veterinary Services (VS) Guidance 12001 (446KB; formerly VS Memorandum 580.4) , if the State Animal Health Official (SAHO) and VS Associate District Director agree, one set of samples collected during a foreign animal disease investigation can be sent to NVSL for confirmatory testing and a duplicate set of samples sent to the local NAHLN laboratory for a preliminary screening test to provide faster preliminary information for decision-making.

More information on VS' involvement in CSF and the procedure manual can be found at: here.

Exotic Newcastle Disease (END)
Currently, there is not an active national surveillance program for Exotic Newcastle Disease (END) in the NAHLN laboratories. However, personnel in END-approved NAHLN laboratories maintain current training and proficiency testing status for preparedness purposes. This preparedness measure provides the option and confidence during a foreign animal disease investigation for duplicate sample collection, as outlined in Veterinary Services (VS) Guidance 12001 (446KB; formerly VS Memorandum 580.4). If the State Animal Health Official (SAHO) and VS Associate District Director agree, one set of samples collected during a foreign animal disease investigation can be sent to NVSL for confirmatory testing and a duplicate set of samples sent to the local NAHLN laboratory for a preliminary screening test to provide faster preliminary information for decision-making.

Foot and Mouth Disease (FMD)
Currently, there is not an active national surveillance program for Foot and Mouth Disease (FMD) in the NAHLN laboratories. However, personnel in FMD-approved NAHLN laboratories maintain current training and proficiency testing status for preparedness purposes. This preparedness measure provides the option and confidence during a foreign animal disease investigation for duplicate sample collection, as outlined in Veterinary Services (VS) Guidance 12001 (446KB; formerly VS Memorandum 580.4). If the State Animal Health Official (SAHO) and VS Associate District Director agree, one set of samples collected during a foreign animal disease investigation can be sent to NVSL for confirmatory testing and a duplicate set of samples sent to the local NAHLN laboratory for a preliminary screening test to provide faster preliminary information for decision-making.

Scrapie Surveillance
USDA initiated the National Accelerated Scrapie Eradication Program in 2001 with the goal of eradicating scrapie from the U.S. sheep and goat populations. Since 2003, surveillance for the program has been conducted primarily through the Regulatory Scrapie Slaughter Surveillance (RSSS) program, which targets sheep and goat populations that have been recognized as having higher than average scrapie prevalence.

Other scrapie surveillance also targets scrapie-exposed and potentially exposed sheep and goats found through investigations of infected animals; clinical-suspect animals and other mature sheep and goats submitted to veterinary diagnostic laboratories; rabies-suspect animals that test negative for rabies; and voluntary on-farm testing of flocks with risk factors for scrapie or as part of the Scrapie Flock Certification Program.

The NVSL Pathobiology Laboratory in Ames, Iowa performs confirmatory testing on all samples identified as suspect (potential positive) by the scrapie-approved NAHLN laboratories.

More information on VS' involvement in Scrapie can be found here.

Swine Influenza Virus Surveillance
The goals of the swine influenza virus (SIV) surveillance program are (1) to monitor the genetic evolution of endemic SIVs to better understand endemic and emerging influenza virus ecology, (2) make SIV isolates and associated epidemiologic data available for research and analysis, and (3) select proper isolates for the development of relevant diagnostic reagents, updating diagnostic assays, and vaccine seed stock products. The program was initiated in May 2009 with a focus on monitoring the pandemic H1N1 2009 [pH1N1 (2009)] virus in swine. As the human health threat of pH1N1 (2009) declined in 2010, SIV surveillance efforts were re-focused on monitoring all current circulating SIVs. Also in 2010, an anonymous submission protocol was adopted to encourage more industry participation and increase the number of samples available for monitoring SIV in the U.S. swine herd. SIV surveillance efforts are targeted towards these three swine populations:

  • Case-compatible sick pig submissions to VDLs
  • Swine exhibiting influenza-like illness at first points of concentration or commingling events i.e., markets, fairs
  • Swine populations that are epidemiologically linked to confirmed human cases involving SIV
     

NAHLN laboratories conduct SIV surveillance for the above-mentioned streams. The NVSL Diagnostic Virology Laboratory in Ames, Iowa is the SIV confirmatory laboratory.

More information on VS' involvement in SIV, and the procedure manual, are found here. 

Swine Pseudorabies Surveillance
The pseudorabies (PRV) surveillance program was initiated in 2009 as an extension of USDA's successful PRV eradication efforts. The program gathers surveillance data to support three specific objectives: (1) rapidly detect PRV entry and infection in U.S. commercial swine, (2) demonstrate freedom from PRV in commercial herds, and (3) monitor domestic sources of PRV.
Targeted Populations (surveillance streams)

  • Investigation and diagnosis of suspicious PRV cases
  • Sick pig submissions to veterinary diagnostic laboratories (VDLs)
  • Herds participating in routine serology and herd profiling
  • Herds classified as high risk
  • Herds with reported exposure to feral swine
  • Cull sow-boars at slaughter
  • Market swine at slaughter
  • Feral swine
     

PRV-approved NAHLN laboratories provide the diagnostic testing for sick pig submissions, routine serology and herd profiling, high risk swine populations, swine with known feral swine exposure, and feral swine. The NVSL Diagnostic Virology Laboratory performs confirmatory testing for suspect and positive submissions for PRV.

More information on VS' involvement in PRV can be found here. 

Vesicular Stomatitis Virus (VSV)
In April 2006, Veterinary Services' Deputy Administrator signed a decision memorandum that allowed for NAHLN laboratories located in States that had Vesicular Stomatitis Virus (VSV) in 2004 and/or 2005 to participate in a national testing program based on recommendations from the Vesicular Stomatitis Working Group. Personnel from the approved VSV NAHLN laboratories maintain current training and proficiency) on the Complement Fixation (CF) test for detection of VSV antibodies.

Activation of any of the VSV approved NAHLN laboratories may occur when: 1) VSV is confirmed in the State of the NAHLN laboratory and 2) the decision is made and communicated to activate the VSV-approved laboratory based on the need for additional capacity. This decision will be made by a group composed of the Situation Unit Leader, VS regions , NVSL representatives, State Animal Health Official and VS Associate District Director of the specific state.

Once a VSV-approved NAHLN laboratory is activated, the laboratory is approved to test samples from clinically ill equine species with VSV compatible clinical signs and located within the State of the NAHLN laboratory. Equine that are temporarily in the State of the NAHLN laboratory for purposes of a show, rodeo, sale, etc. can be tested at the activated NAHLN laboratory. Samples from equine located outside the State of the NAHLN laboratory should be forwarded to NVSL-Ames for testing. Samples from clinically ill non-equine species (such as bovine) regardless of the State of origin should be forwarded to NVSL-FADDL. Clinically ill equine can be tested ONLY by NAHLN laboratory personnel that have been trained by NVSL DVL and passed the current proficiency panel.

More information on VSV in the United States can be found here.

 

 



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