Hantavirus outbreak linked to 4 deaths in Arizona
Key Takeaways
Hantavirus is rare, with about 30 cases nationwide each year.
In the first half of the year, 4 people have died in Arizona, and 6 people in the U.S. have died in total.
Recent contact with rodents is the most important differential factor when diagnosing Hantavirus pulmonary syndrome.
Arizona health officials issued a state-wide health alert earlier this month after an increase in hantavirus pulmonary syndrome (HPS) fatalities.[] There have been seven documented cases of HPS in the state in the first six months of 2024.[] Four cases have been fatal. Hantavirus pulmonary syndrome is caused by the hantavirus, a group of viruses most often transmitted to humans through contact with rodents.[]
In the US, HPS is primarily seen throughout the West and Southwest, but cases have been reported nationwide.[] The current Arizona outbreak is the largest and most deadly outbreak so far in 2024. Between February and April 2024, there were two reported cases of HPS: a fatal case in Sierra County, CA, and a nonfatal case in San Juan County, NM.[][] In June 2024, a man in Grant County, WA, died of HPS.[]
Reporting hantavirus cases
The numbers in Arizona are similar to those of other small outbreaks observed in recent years.[] Hantavirus pulmonary syndrome is rare. The Centers for Disease Control and Prevention (CDC) reported 850 known cases nationwide between 1993 and 2021. According to the CDC’s data, cases have been seen in small outbreaks ranging from 1 to 11 reported cases and have primarily been clustered in the Southwest.
It’s possible that hantavirus transmission is under-reported as HPS causes respiratory symptoms that can, in mild cases, resemble the flu or other common conditions.
“The exact numbers of those who acquire a hantavirus infection, but who remain asymptomatic or have a mild febrile illness, are unknown,” Norman L. Beatty, MD, FACP, Assistant Professor of Medicine at the University of Florida College of Medicine, says.
People who only develop mild symptoms might not seek medical care at all. If they do, symptoms are likely to be easily treatable, and testing for hantavirus is unlikely to be done. Dr. Beatty says it’s rare for a hantavirus test to be ordered.
“You have to do specific epidemiological studies to make a diagnosis of hantavirus cardiopulmonary syndrome. We need to look for the virus itself or antibodies that are created to it, and those tests aren’t readily available,” Dr. Beatty explains. “We usually have to reach out to the state health departments and CDC to help navigate the testing.”
Differential diagnosis
Hantavirus symptoms can take 1 to 8 weeks to appear after contact with an infected rodent.[] Early symptoms such as fever, muscle aches, and fatigue can progress to respiratory symptoms such as shortness of breath. The CDC estimates that hantavirus may be fatal in 38% of people who develop respiratory symptoms from the disease.
Since HPS can cause symptoms that overlap with those of other respiratory infections, Dr. Beatty says that recent exposure to rodents can be the most important diagnostic factor.
“When a person is presenting with a flu-like illness, getting a good history of their travel or their exposure to a potential region would be important and could help a clinician think about a disease like hantavirus infection.”
Dr. Beatty says that factors such as recent vacation stays, camping trips, and other travel can all be important.
“In certain mountain ranges, where there are a lot of cabins and human dwellings that people live in sporadically, the rodents will kind of live amongst them,” Dr. Beatty explains. “Some cases I saw in Arizona were related to individuals going to a cabin to stay the weekend or for the summer who inhaled infectious particles while sweeping out the cabin.”
Treating hantavirus
Currently, there’s no specific treatment for HPS.[] Patients who are hospitalized often receive supportive treatments, which may include intubation and other types of breathing support to help reoxygenate the blood.
“Most folks who do become very ill end up in a medical ICU on a mechanical ventilator, and some may need extracorporeal membrane oxygenation,” Dr. Beatty says.
The Food and Drug Administration has not approved antiviral medications to treat HPS. However, such medications have sometimes been used in severe cases.
“I have seen ribavirin being used, and for compassionate use purposes, but at this time, to my knowledge, there’s no known antiviral that is used to target the virus itself,” Dr. Beatty tells MDLinx.
Prevention
Hantavirus is spread through contact with rodents.[] This includes contact with rodent droppings, urine, saliva, nesting materials, and dander.
Rodent control is the best way to prevent the spread of HPS. The CDC advises taking steps such as sealing holes and gaps that can allow rodents to access the home; cleaning up food and other scraps from tables, campsites, and other areas; and using traps.[]
“Prevention is centered on keeping rodents outside of the home and utilizing pest management to help with that,” Dr. Beatty confirms. “I think one important thing for homeowners is assessing the home itself and keeping out the things that can attract rodents, such as wood piles and clutter around the home.”
What this means for you
Hantavirus is rare, but cases are reported nationwide each year. Hantavirus can be severe and even fatal, and early detection and treatment can improve outcomes. Inquiring about a patient’s recent travel and leisure activity during assessment can be an important step in determining if HPS is a potential diagnosis, especially if you practice in the Southwestern US.