American Fancy Rat & Mouse Association

The AFRMA Rat and Mouse Information Pages - Health Care
  •  Seoul Hantavirus 

Hantavirus outbreak in U.S. Midwest, Jan. 20, 2017.

This is found in wild rats around the world so DO NOT bring in wild rats, and keep wild rodents away from your animals as well as their food and bedding. Rats do not display symptoms or get sick with this virus. Quarantining new animals won’t determine if they carry this, only laboratory testing (IDEXX or Charles River; antibody test). There have been very few reports of human infections and majority of the people that get this do not show symptoms.

U.K. Seoul Virus  CDC/State Health Articles  Research Articles
Diagnostic Testing Info.  News Stories  General Articles

  • U.K. Seoul Virus
  • Hantavirus Found In Pet Rats In The U.K. (2013)
    • Pet rats as a source of hantavirus in England and Wales, 2013 - 1. Jameson L, Taori S, Atkinson B, Levick P, Featherstone C, van der Burgt G, et al. Eurosurveillance, Volume 18, Issue 9, 28 February 2013. An owner and his two pet rats in Wales tested positive for a strain of SEOV (named Cherwell); 7 of 21 of the breeder’s rats (supplied the 2 pet rats) were positive for same strain and her husband tested positive for past infection (late 2011); of 4 people tested, 2 hospitalized, 1 positive with no symptoms, 1 negative; all rats euthanized on order to further scientific understanding of hantavirus infection in pet rats; U.K. has two strains – Humbar (Jan. 2013) and Cherwell (Feb. 2013). (PDF)
    • High prevalence of Seoul hantavirus in a breeding colony of pet rats - L. M. McElhinney, et al. Epidemiol Infect. 2017 Nov;145(15):3115–3124. Further investigation of case of SEOV positive rats in Wales and England (Cherwell and Cheltenham); some of the rats had very high antibody titres of 10240; each hantavirus restricted to single host species.
    • Hantavirus infection in people: sero-surveillance study in England - from Public Health England (Sept. 2014). Of the rat fancy rat breeders tested, 32.9% were positive; urine samples were collected from rats but results not given. PDF
    • HAIRS risk assessment: hantavirus - from Public Health England (Feb. 2016). Is endemic in the U.K.; people with pet rats most as risk; at least 100,000 pet rats in country (2014 survey) but number of diagnosed infections remains small; not highly infectious in humans; humans and other species of animals dead-end hosts; persistently infected rodents do not excrete large amounts of virus; vaccine used in China and Korea but no licensed vaccines available in other regions, one DNA-based vaccine for the PUUV and HTNV viruses has reached phase 1 clinical trial PDF
    • Pets, Purity and Pollution: Why Conventional Models of Disease Transmission Do Not Work for Pet Rat Owners - Charlotte Robin, Elizabeth Perkins, Francine Watkins, and Robert Christley. Int. J. Environ. Res. Public Health 2017, 14(12), 1526. In-depth, semi-structured interviews of 7 pet rat owners on how they view their pets rats in light of the Seoul Hantavirus 2012 outbreak in the U.K.
    • Reducing the risk of human infection from pet rodents (PDF) - from the U.K. Health Protection Agency (now known as Public Health England) (Feb. 2013)
    • Reducing the risk of human infection from pet rodents (PDF) - brochure from the U.K. Health Protection Agency (now known as Public Health England) (2013)

  • CDC/State Health Articles

  • Research Articles
  • Hantavirus - The Center for Food Security & Public Health, Iowa State University (2009). Has disinfection information–susceptible to disinfectants, detergents, heating, drying; recently infected animals tend to shed larger amounts of virus, virus shedding decreases by 8 weeks after infection. (PDF)
  • Wounding: The Primary Mode Of Seoul Virus Transmission Among Male Norway Rats - Ella R. Hinson, Scott M. Shone, M. Christine Zink, Gregory E. Glass, and Sabra L. Klein. Am J Trop Med Hyg March 2004 vol. 70 no. 3 310–317. Study done with wild rats in Maryland; only during limited time are animals shedding virus and capable of infecting uninfected individuals; virus shedding typically occurs immediately after infection followed by a chronic period of infection characterized by active immune responses in the absence of virus shedding; during this time of chronic infection animals often fail to transmit virus to uninfected cage mates; adult males/aggressive males more likely to have virus due to wounding and to shed virus than young rats.
  • Association of intraspecific wounding with hantaviral infection in wild rats (Rattus norvegicus) - G. E. Glass, J. E. Childs, G. W. Korch, and J. W. LeDuc. Epidemiol Infect. 1988 Oct; 101(2): 459–472. 1988 article on 6-year study done with wild rats in Baltimore, MD; infection associated with wounding, severe body wounds had high titres (high ≥128; ≥32 considered positive, 32 to <128 considered low seropositive), wounding is the primary route of transmission, sexually mature males most affected, rats sexually mature after 200 g (seroconversion median age was 6 months), most seroconversions occurred during spring and autumn when wounding peaked with reproductive activity, young rarely wounded/seropositive. (PDF)
  • Seoul virus infection increases aggressive behaviour in male Norway rats - Sabra L.Klein, M.Christine Zink, Gregory E. Glass. Animal Behaviour. Volume 67, Issue 3, March 2004, Pages 421–429. Male lab rats tested 30 days after inoculation (i.e. during the persistent phase of infection) spent more time engaged in aggression than either uninfected males or males tested during the acute phase of infection (i.e. 15 days after infection); virus shedding, however, was not correlated with aggression.
  • Epizootiology of Hantavirus infections in Baltimore: isolation of a virus from Norway rats, and characteristics of infected rat populations - James E. Childs, George W. Korch, Gregory E. Glass, James W. LeDuc, and Keerti V. Shah. Am J Epidemiol. 1987 Jul;126(1):55–68. A 6-year-study of wild Norway rats in Baltimore, MD found Hantaan-related virus enzootic in the city; older rats more likely to be seropositive and have higher titers than younger rats (a titer of 1:32 considered positive; 48.2% were positive); varied by season with spring (March to May) being low and increased linearly through winter (Dec. to Jan.); Wistar rats inoculated with the virus showed seroconversion at day 26–30 with majority by day 40–44. (PDF)
  • Sex Differences in Seoul Virus Infection Are Not Related to Adult Sex Steroid Concentrations in Norway Rats - Sabra L. Klein, Brian H. Bird, and Gregory E. Glass. J Virol. 2000 Sep; 74(17): 8213–8217. Male Long Evans rats inoculated with Seoul virus had higher IgG on days 20, 30, and 40 postinoculation than females; males shed virus in saliva and feces longer; more males shed virus in saliva on day 10 and 30 and in feces on day 30 than females; antibody detectable 15 to 30 days postinoculation with no difference between males and females; testing done on intact and gonadectomized males and females; male rats higher IgG2a than females on days 30 and 40 postinoculation despite hormone manipulation; positive was optical density ≥0.100
  • Sex Differences In Immune Responses And Viral Shedding Following Seoul Virus Infection In Norway Rats - S L Klein, B H Bird, G E Glass. Am J Trop Med Hyg. 2001 Jul;65(1):57–63. Long Evans lab rats tested; antibodies develop typically by day 30 after inoculation; males higher levels than females of IgG titers for Seoul virus 40 days post-inoculation; not all shed virus; more males shed virus in saliva, or multiple routes than females; high levels of testosterone increase fighting; castrated vs. intact males similar anti-Seoul virus IgG21 responses; sexes are equally susceptible to infection but have different immune responses so males more likely to shed virus
  • Environmental and Physiological Factors Associated with Seoul Virus Infection Among Urban Populations of Norway Rats - Sabra L. Klein, Brian H. Bird, Randy J. Nelson, Gregory E. Glass. Journal of Mammalogy, Volume 83, Issue 2, 1 May 2002, pages 478–488. Study of wild-caught rats in Baltimore, MD from 1996–2000; approximately 50% infected with Seoul virus; adults and older rats more likely to be infected and have higher antibody responses than younger adults; this study found females higher IgG than males [compared to other studies where males had more]; seasonal changes not observed [one study found changes with more in spring and autumn, another study was less in spring to more in winter]; antibody changes also not observed in changes in photoperiod but higher IgG responses found during low temps.; antibody positive if optical density was ≥0.100; physiological and behavioral changes with sexual maturity (body mass not age) best predictors of Seoul virus
  • A survey of zoonotic pathogens carried by Norway rats in Baltimore, Maryland, USA - Epidemiol Infect. 2007 Oct; 135(7): 1192–1199. 201 wild rats were tested during 2005–2006 for panel of viruses, bacteria, and parasites; found 57.7% had SEOV, 87.9% had roundworms, and more than a third had tapeworms, among other things; LCMV was not found (natural LCMV infection not reported in Norway rats and does not appear to be transmitted from rats to humans); the presence of antibodies against Seoul virus was not correlated with the likelihood of being infected with any of the other pathogens tested; the presence of antibody does not necessarily indicate an ongoing infection.
  • Aerosol Transmission of Hantaan and Related Viruses to Laboratory Rats - Edwin O. Nuzum, Cynthia A. Rossi, Edward H. Stephenson, James W. LeDuc. The American Journal of Tropical Medicine and Hygiene, Volume 38, Issue 3, May 1988, p. 636–640. Study done on 12–16-week-old female Wistar Norway rats using intramuscular and aerosol routes of infection; positive titers were ≥32; intracage transmission did not occur; wounding from infectious saliva a factor in transmission; intramuscular exposure had higher antibody titers and seroconversion rates.
  • Experimental Transmission Of Hantavirus Infection In Laboratory Rats - Kayoko Dohmae, Masaru Okabe, Yoshitake Nishimune. The Journal of Infectious Diseases, Volume 170, Issue 6, 1 December 1994, pages 1589–1592. Normal rats did not transmit Hantavirus to normal cagemates but did to Rowett nude rats (T-cell deficient); nude rats highly susceptible to the Hantavirus infection and gave it to normal cagemates.
  • Old World Hantaviruses in Rodents in New Orleans, Louisiana - Cross RW, Waffa B, Freeman A, et al. Am J Trop Med Hyg. 2014 May 7; 90(5): 897–901. 3.4% of wild brown [Norway] rats tested positive compared to 1980s when over 30% trapped in New Orleans tested positive; over 25 years since first discovery suggests stable endemicity; found in almost all cities in the world; each virus specific to host species.
  • Immunological Mechanisms Mediating Hantavirus Persistence in Rodent Reservoirs - Judith D. Easterbrook and Sabra L. Klein, PLoS Pathog. 2008 Nov; 4(11): e1000172. Rats are not immunosuppressed with SEOV; antibodies detectable after the first 2 weeks of infection, increases for next 4–6 weeks, then declines; acute phase first 2–3 weeks of infection; maternal antibodies protect young first 2 months of life; T-cells contribute to control of virus replication.
  • Old-World Hantaviruses: Global Status: 2017 edition - Dr. Stephen Berger, GIDEON Informatics, Inc., e-book series
  • About Hantavirus Hantavirus infections, diagnosis and treatment from Reagena (archived page)

  • Maternal Transfer of Hantavirus Antibodies in Rats - Kayoko Dohmae and Yoshitake Nishimune. Laboratory Animal Science, Vol 48, No 4, August 1998. Japanese study with lab rats, cross fostered babies, some moms given non-lethal dose to induce immunity, antibodies from milk last longer than from in utero, rats from seropositive dams are protected from hantavirus infection for extended periods after birth due to immune transfer from dams. (PDF)
  • Protection against hantavirus infection by dam’s immunity transferred vertically to neonates - K. Dohmae, Y. Nishimune. Archives of Virology, January 1995, Volume 140, Issue 1, pp 165–172. Antibodies to hantavirus, Seoul type B-1 strain, were transferred to newborn rats from the moms and prevented lethal as well as persistent infection.
  • In utero and mammary transfer of hantavirus antibody from dams to infant rats - Dohmae K, Koshimizu U, Nishimune Y. Lab Anim Sci. 1993 Dec;43(6):557–61. Cross-fostered experiments showed maternal antibody was transferred either in utero or by breatfeeding and is protective against hantavirus infection for up to 15 weeks
  • Role of maternal antibody in protection from hemorrhagic fever with renal syndrome virus infection in rats - Zhang et. al., Archives of Virology, September 1988, Volume 103, Issue 3, pp 253–265. Protective effect of maternal antibodies remained up to 10 weeks in rats. (PDF)
  • Effects Of Hantaviral Infection On Survival, Growth and Fertility In Wild Rat (Rattus Norvegicus) Populations Of Baltimore, Maryland - James E. Childs, Gregory E. Glass, George W. Korch, and James W. LeDuc. Journal of Wildlife Diseases, 25(4), 1989, pp. 469–476, Wildlife Disease Association (PDF) - Antibodies from mom protect young rats for up to 10 weeks after birth; some rats seroconverted from positive to negative, low antibody titers were presumed to be due to maternal antibody rather than to viral infection; hantaviruses do not appear to influence the survival, size structure, or fertility of Norway rats. (PDF)

    Worldwide There are several research articles about Hantavirus being in various countries in Europe for many years and rats worldwide are known to carry this virus. There are very few reports of human infections.
  • Migration of Norway Rats Resulted in the Worldwide Distribution of Seoul Hantavirus Today - Xian-Dan Lin, Wen-Ping Guo, Wen Wang, et al. J. Virol. January 2012 vol. 86 no. 2 972–981. Researchers hypothesize Seoul hantavirus came from China, exported to Europe, then spread through the New World through the migration of Norway rats; virus may have arisen in the last few centuries.
  • Hantaviruses: a global disease problem - C. Schmaljohn and B. Hjelle. Emerg Infect Dis. 1997 Apr-Jun; 3(2): 95–104. Infection not harmful to host; each hantavirus has a single natural reservoir and do not adapt readily to new hosts; highest antibody in mature animals; not transferred from dam to pup.
  • Laboratory rat associated outbreak of haemorrhagic fever with renal syndrome due to Hantaan-like virus in Belgium - Desmyter J, LeDuc JW, Johnson KM, Brasseur F, Deckers C, van Ypersele de Strihou C. Lancet. 1983 Dec 24-31;2(8365-66):1445–8. First confirmed cases outside of East Asia of Hantaan-like virus from lab rats found in Belgian university staff in 1983.
  • Seoul hantavirus in Europe: first demonstration of the virus genome in wild Rattus norvegicus captured in France - Heyman, P., Plyusnina, A., Berny, P. et al. European Journal of Clinical Microbiology & Infectious Diseases. Sep 2004, Vol. 23 Issue 9, p711–717. Rats occasionally have been found to be antibody positive though the viral genome has not been demonstrated in these animals.
  • Pet rat harbouring Seoul hantavirus in Sweden, June 2013 - Å Lundkvist, J Verner-Carlsson, A Plyusnina, L Forslund, R Feinstein, A Plyusnin. Eurosurveillance, Volume 18, Issue 27, 04 July 2013. One rat imported to Sweden from England in 2011 (20 total imported and all being tested) was found SEOV infected but found to not have a U.K. strain but rather a new strain that was most closely related to SEOV strains from Indonesia and Belgium; unclear if the rat had been infected in the U.K., or later in Sweden; hantavirus species have single reservoir host species.
  • First evidence of Seoul hantavirus in the wild rat population in the Netherlands - Jenny Verner-Carlsson, MSci, et al. Infect Ecol Epidemiol. 2015; 5: 10.3402/iee.v5.27215. Three out of 16 wild rats caught and tested in 2013 were positive for Seoul hantavirus; rats tested during 2008–2011 were not confirmed as having this; eradication unrealistic; SEOV only known hantavirus with a world-wide distribution due to the ubiquitous occurrence of its reservoir hosts, the brown and the black rat.

  • Diagnostic Testing Info.
  • Zoologix Zoologix - molecular diagnostic testing for animals, located in Chatsworth, CA (does Seoul Hantavirus testing - $85 per sample for PCR test—fecal, blood, swabs, etc.—discounts for 5 or more); will do custom panels for other assays

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Updated October 7, 2021