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Outbreak of Hantavirus Infection --
Southwestern United States, 1993
An outbreak of illness associated with hantavirus infection
continues to be investigated by state health departments in New
Mexico, Arizona, Colorado, and Utah; the Indian Health Service; and
CDC, with the assistance of the Navajo Nation Division of Health
(1-3). This report updates information regarding the outbreak and
presents information on two cases that occurred in the 10 months
preceding this outbreak.
Laboratory evidence of acute hantavirus infection has been
confirmed in 15 patients who had onsets of illness from January 1
through June 30. Each of these patients has had one or more of the
following: positive enzyme-linked immunosorbent assay (ELISA)
serology with elevated immunoglobulin M titers indicating recent
infection, seroconversion by ELISA, positive immunohistochemistry
on formalin-fixed lung tissue, or amplification of hantavirus
nucleotide sequences from frozen tissue. Of the 15 cases, 10
occurred in New Mexico, three in Arizona, and one in Colorado; 12
(80%) occurred among persons aged 20-40 years. Eleven patients
died. Similar illnesses in an additional 23 persons, 10 of whom
died, are being investigated for possible hantavirus infection.
Since June 6, a total of 668 rodents have been trapped in and
around houses in 14 different rural sites. Peromyscus maniculatus
(deer mouse) comprised 63% (range: 36%-88%) of all rodents trapped
and 85% of those trapped in homes. Of the first 283 rodents tested,
hantavirus antibodies were detected in 23%.
In June 1993, two persons were identified who had evidence of
hantavirus infections in 1992. In November 1992, fever and acute
respiratory distress occurred in a resident of the outbreak area.
Recent serologic evaluation of an acute serum specimen obtained at
the time of illness showed evidence of hantavirus infection. In
August 1992, fever and myalgias followed by adult respiratory
distress syndrome occurred in a person who resided outside the
outbreak area; onset of illness was approximately 2 weeks after
this person had returned home from a trip to the four-state area.
The traveler had engaged in outdoor activities and was exposed to
rodents and rodent excreta during both indoor and outdoor
activities during the trip. A serum sample tested in June 1993
showed elevated immunoglobulin G titers to hantavirus. Although a
high immunoglobulin G titer in a single, recently obtained serum
sample does not definitively establish the occurrence of a
hantavirus infection at the time of illness, the serologic data and
the clinical illness are strongly suggestive of hantavirus
infection.
Reported by: F Koster, MD, H Levy, MD, G Mertz, MD, A Cushing, MD,
S Young, PhD, K Foucar, MD, J McLaughlin, PhD, B Bryt, MD, Univ of
New Mexico School of Medicine, T Merlin, MD, Lovelace Medical
Center, Albuquerque; R Zumwalt, MD, P McFeeley, MD, K Nolte, MD,
New Mexico Office of the Medical Investigator; MJ Burkhardt, MPH,
Secretary of Health, N Kalishman, MD, M Gallaher, MD, R Voorhees,
MD, M Samuel, DrPH, M Tanuz, G Simpson, MD, L Hughes, PhD, E
Umland, MD, G Oty, MS, L Nims, MS, CM Sewell, DrPH, State
Epidemiologist, New Mexico Dept of Health. R Levinson, MD, F
Yerger, MD, B Allan, MD, Scottsdale; P Rubin, Phoenix; K Komatsu,
MPH, C Kioski, MPH, K Fleming, MA, J Doll, PhD, C Levy, MS, TM
Fink, P Murphy, B England, MD, M Smolinski, MD, B Erickson, PhD, W
Slanta, L Sands, DO, Acting State Epidemiologist, Arizona Dept of
Health Svcs. P Shillam, MSPH, RE Hoffman, MD, State Epidemiologist,
Colorado Dept of Health. S Lanser, MPH, CR Nichols, MPA, State
Epidemiologist, Utah Dept of Health. L Hubbard-Pourier, MPH, Div of
Health, Navajo Nation, Window Rock, Arizona. J Cheek, MD, A Craig,
MD, R Haskins, MPH, B Muneta, MD, B Tempest, MD, M Carroll, MD, LA
Shands, MPH, JP Sarisky, MPH, RE Turner, L White, P Bohan, MS,
Indian Health Svc. Div of Field Epidemiology, Epidemiology Program
Office; National Center for Environmental Health; Div of Bacterial
and Mycotic Diseases, Div of Vector-Borne Infectious Diseases,
Scientific Resources Program, and Div of Viral and Rickettsial
Diseases, National Center for Infectious Diseases, CDC. Editorial Note
Editorial Note: The identification of two persons with evidence of
hantavirus infection that occurred in 1992 suggests that hantavirus
infection has been present previously but was not recognized.
Investigations are now in progress to identify whether changes in
the local environment or other factors have been associated with
the increased occurrence and/or transmission of this infection.
Preliminary data from field investigations indicate that P.
maniculatus is the likely reservoir of this virus. Although the
exact mechanism of hantavirus transmission to humans is unknown,
potentially hazardous exposures include direct aerosolization of
urine and other potentially infective rodent body fluids, secondary
aerosolization of dried rodent excreta, contamination of food, and
direct contact with virus-bearing rodents or their excreta or
saliva.
Additional studies are under way to identify practical and
effective means of preventing infection caused by hantaviruses.
Residents and travelers in New Mexico, Arizona, Colorado, and Utah
are advised to avoid any activities that may result in contact with
wild rodents or rodent excreta or disruption of rodent burrows. The
following specific recommendations for residents and travelers are
based on current knowledge of transmission of other hantaviruses:
avoid activities that can result in contact with wild rodents,
disruption of rodent burrows, or aerosolization of dried rodent
excreta; 2) store food appropriately to avoid contamination with
rodents and rodent excreta; and 3) dispose of food and trash
properly to avoid attracting rodents.
References
CDC. Outbreak of acute illness -- Southwestern United States,
1993. MMWR 1993;42:421-4.
CDC. Update: outbreak of hantavirus infection -- Southwestern
United States, 1993. MMWR 1993;42:441-3.
CDC. Update: outbreak of hantavirus infection -- Southwestern
United States, 1993. MMWR 1993;42:477-9.
Disclaimer
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