Skip Navigation LinksSkip Navigation Links
Centers for Disease Control and Prevention
Safer Healthier People
Blue White
Blue White
bottom curve
CDC Home Search Health Topics A-Z spacer spacer
Blue curve MMWR spacer

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:

  1. 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.


  1. CDC. Outbreak of acute illness -- Southwestern United States, 1993. MMWR 1993;42:421-4.

  2. CDC. Update: outbreak of hantavirus infection -- Southwestern United States, 1993. MMWR 1993;42:441-3.

  3. CDC. Update: outbreak of hantavirus infection -- Southwestern United States, 1993. MMWR 1993;42:477-9.

Disclaimer   All MMWR HTML versions of articles are electronic conversions from ASCII text into HTML. This conversion may have resulted in character translation or format errors in the HTML version. Users should not rely on this HTML document, but are referred to the electronic PDF version and/or the original MMWR paper copy for the official text, figures, and tables. An original paper copy of this issue can be obtained from the Superintendent of Documents, U.S. Government Printing Office (GPO), Washington, DC 20402-9371; telephone: (202) 512-1800. Contact GPO for current prices.

**Questions or messages regarding errors in formatting should be addressed to

Page converted: 09/19/98


Safer, Healthier People

Morbidity and Mortality Weekly Report
Centers for Disease Control and Prevention
1600 Clifton Rd, MailStop E-90, Atlanta, GA 30333, U.S.A


Department of Health
and Human Services

This page last reviewed 5/2/01