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July 2006 Hantavirus cases might increase this yearIf you live in the Southwest, you might want to keep Hantavirus pulmonary syndrome (HPS) in your differential diagnosis of someone with febrile illness; the CDC is reporting that cases may increase this year.
From January until March, nine cases of HPS were confirmed in Arizona, New Mexico, North Dakota, Texas and Washington, according to the CDC. Researchers noted a similar rise during the early months of 1994, 1999 and 2000, and they subsequently had more HPS for the year. “During 1994, 1999 and 2000, more than six cases were confirmed in the first three months of each year, and all had a high yearly total of HPS cases. Nine cases of HPS were identified in the first three months of 2006, suggesting that a greater risk for human hantavirus infection might exist this year,” the CDC reported in a recent Morbidity and Mortality Weekly Report. The rodent-borne viral disease, usually caused by the Sin Nombre virus, has a case-fatality ratio of 30% to 40%, according to the CDC. When environmental conditions are right, such as with increased rainfall, there is an increase in deer mice, the main reservoir of virus, increasing the risk of viral transmission to humans. Exposure to the virus in rodent saliva or excreta is the typical route to transmission, the CDC reported, and people are often infected while cleaning up or working around their homes. Early disease is vague with signs of headache, fever and myalgia, but within 72 hours patients can develop bilateral diffuse interstitial edema, which often leads to severe respiratory compromise. Thrombocytopenia may also be present. Unfortunately, the only treatment is supportive. “The probability of surviving HPS increases with early recognition, hospitalization and aggressive pulmonary and hemodynamic support. All health care providers are strongly encouraged to become familiar with the signs and symptoms of HPS and to report suspected cases immediately to their state health departments,” the CDC said. Since 1993, when the disease was recognized in the United States, the CDC has confirmed 438 cases of HPS in 30 states; 35% (154) of the cases were fatal.
“Larger rodent populations and subsequent higher prevalence of hantavirus infection in rodent populations have been associated with higher risk for hantavirus exposure in human populations,” the CDC reported. “Environmental conditions, including increased rainfall during 2005, likely contributed to increased rodent populations in certain areas of the Southwest. Some rodent monitoring sites have continued to have high rodent population densities or high levels of hantavirus infection during spring 2006, suggesting an increased risk for hantavirus infection among human populations in certain rural areas. “The findings emphasize the need for renewed attention to reducing the risk for hantavirus exposure,” the CDC said. CDC’s Seal Up! Trap Up! Clean Up! is a public information campaign that offers information on preventing transmission of rodent-borne diseases. The CDC recommends that people seal up holes inside and outside the home, trap rodents around the home, clean up rodent food sources and nesting sites, and take precautions when cleaning. – Marie Rosenthal |
