Taken from the 2012 ICAAC meeting...
Outbreaks of enteric disease are most common in highly populated areas. Caused by both bacteria and viruses that often reside in the food we eat, the water we drink, or on surfaces we touch, enteric diseases produce a variety of symptoms including nausea, severe stomach pain, high volumes of watery diarrhea, vomiting, and often fever. The duration of these symptoms depends on the nature of the pathogen and the individual’s health status. Often found in hospital settings, daycare centers, and aboard cruise ships, norovirus is one of the heartiest viruses capable of causing acute viral gastroenteritis (GE). Norovirus, also known as Norwalk virus after the town in Ohio where it was first identified, is spread through contaminated food, person-to-person contact, or inhalation of aerosolized vomitus or stool from an infected person. The majority of norovirus outbreaks normally originate from a single infected food handler. Though rarely fatal, and provides no long-term immunity for infected persons, norovirus produces symptoms for 12-48 hours; after which time, the individual remains infectious for up to three days as the virus continues to shed.
It is estimated that norovirus infections cause more outbreaks of GE aboard deployed U.S. Naval vessels than any other virus. Outbreaks bacterial in origin also pale in comparison to the impact norovirus infections have on financial cost, mission readiness, and troop morale. According to statistics compiled by the Navy and Marine Corps Public Health Center (NMCPHC) headquartered in Portsmouth, Virginia, between 2009 and 2010, 3,060 working days and an estimated $9 million dollars were lost by the Navy to acute GE-related illnesses. Based only on disease symptomology, greater than half of such outbreaks were likely caused by norovirus (surveillance was not conducted to determine the absolute cause).
Using the Whatman™ FTA™ MicroCard, microbiologists from the Navy’s Environmental and Preventive Medicine Unit TWO (NEPMU-2), based out of Norfolk, Virginia, in conjunction with colleagues at the U.S. Centers for Disease Control and Prevention’s Calicivirus Laboratory, developed a novel approach to conducting surveillance aboard deployed U.S. Naval vessels for the purpose of compiling comprehensive epidemiological data about the burden of norovirus-caused GE illness among U.S. military forces. Such information will provide health officials and medical officers early warning to protect troops from norovirus infections, including earlier detection and isolation of suspected cases, along with promoting higher standards of personal hygiene. To date, norovirus surveillance aboard deployed vessels involved a complicated protocol of storing and shipping stool samples in universal transport media (UTM) to preserve the integrity of the pathogen. This protocol required storing samples at -70°C and shipping on dry ice; making surveillance by this method virtually impossible for most deployed vessels that do not have this capability. The filter card method validated by NEPMU-2 allows easy stool sampling by either the patient or provider on a sterile swab. The stool is then mixed with a small volume of UTM and applied to the filter card. After only one hour of drying at room temperature, the sample is ready for shipping to NEPMU-2 for analysis by the quantitative real-time polymerase chain reaction (qRT-PCR) assay using the Applied Biosystems™ ABI 7500 instrument. Our qRT-PCR method detects and amplifies genetic material (i.e. DNA, RNA) based on a specific target sequence within the norovirus genome. Analysis of samples by NEPMU-2 indicated that two distinct norovirus genotypes (G1 and G2) could be detected up to 42 weeks post-sampling when stored at room temperature. Therefore, all vessels, including those without access to cold storage and shipping capability while underway, can use this technique to conduct norovirus surveillance.
NEPMU-2 and NMCPHC comprise a small part of the 63,000 Navy health professionals dedicated to providing quality healthcare to over one million beneficiaries worldwide. Navy Medicine personnel deploy with Sailors and Marines around the world providing critical support aboard ships, under water, in the air, and on the battlefield. Funding was supplied by the Armed Forces Health Surveillance Center, Global Emerging Infections Surveillance and Response System (AFHSC-GEIS). The validation work was completed by Dr. Chris Coetzer and Steven Maier, with technical support from Dr. Robert Hontz, Nicole Gregoricus, and Dr. Jan Vinjé, Dr. Ben Espinosa, and Dr. Jamal Dejli.