Arizona Public Health Officials Warn of Rising Hantavirus Cases Amid Increased Rodent Activity

PHOENIX, AZ — Arizona public health officials have issued an urgent alert regarding a concerning rise in hantavirus cases, a disease transmitted from rodents to humans, linked to a potentially fatal lung syndrome. Over the past six months, the state has confirmed seven cases of hantavirus infection and reported three associated deaths. This uptick signifies a troubling escalation of what is typically a rare but serious illness.

Hantavirus Epidemiology

Hantavirus is most commonly reported in the Western and Southwestern regions of the United States. Historically, states such as California report only one to four cases annually. This year, California has documented two hantavirus infections, reflecting a broader trend of increased regional activity. According to the Centers for Disease Control and Prevention (CDC), Arizona has one of the highest rates of hantavirus infections in the U.S. Data from the Arizona Department of Health Services indicates that from 2016 to 2022, the state recorded a total of 11 cases: four in 2016, two in 2017, four in 2020, and one in 2022.

Understanding Hantavirus and Its Impact

Dr. Aaron Glatt, Chief of Infectious Diseases at Mount Sinai South Nassau Hospital in Long Island, New York, provides insight into the severity of the illness. “Hantavirus is a rare but significant cause of severe respiratory illness,” he explains. “It is primarily transmitted by rodents, particularly the deer mouse. While some cases may present with mild symptoms, a considerable percentage of those infected can develop a fatal illness.”

San Diego County has reported an increase in rodent activity associated with hantavirus, with 17 western harvest mice testing positive for the virus this year. Despite this, the California Department of Public Health notes that while hantavirus activity can vary annually, this year’s levels are not exceptionally unusual compared to historical data.

Potential Causes for the Increase

The CDC has documented 850 hantavirus cases from 1993 to 2021, averaging around 30 cases annually. Trish Lees, Public Information Officer at Coconino County Health and Human Services, suggests that the recent surge in Arizona cases may be linked to fluctuations in rodent populations, which vary seasonally and annually.

Hantavirus cases typically rise during the summer months due to increased rodent activity and greater human exposure as people spend more time outdoors and enter rodent-prone spaces like sheds or barns. While weather conditions, such as heavy spring rains, can enhance food resources for deer mice and potentially lead to population increases, there is no established connection between extreme heat and heightened hantavirus activity, according to the California Department of Public Health.

Climate change may exacerbate the situation. Dr. Camilo Mora, Professor in the Department of Geography and Environment at the University of Hawaii at Mānoa, notes that extreme weather conditions drive both humans and wildlife to seek shelter. “Many species that harbor diseases, including hantavirus, also seek refuge from harsh weather conditions. Climate change could potentially intensify outbreaks of vector-borne diseases due to these shifts in animal behavior,” he asserts.

Dr. Scott Roberts, Associate Medical Director of Infection Prevention at Yale School of Medicine, adds that fluctuating environmental conditions may lead to changes in animal populations. Consequently, increases in rodent populations in hantavirus-endemic areas will naturally heighten the risk of human exposure.

Symptoms and Diagnosis

Hantavirus pulmonary syndrome (HPS) is the primary illness associated with hantavirus infection. The virus becomes airborne when rodent urine, saliva, or droppings are disturbed, leading to inhalation of the pathogen. Hantavirus was first identified in 1993 following a mysterious outbreak among members of a Navajo tribe in the southwestern U.S., with an alarming mortality rate of approximately 80% at that time.

Symptoms of hantavirus infection typically manifest one to eight weeks after exposure to infected rodents and progress in two phases:

1. Early Phase:

- Fever

- Fatigue

- Muscle aches, particularly in the thighs, back, and shoulders

- Nausea, vomiting, and abdominal pain

2. Late Phase:

- The illness may escalate to severe respiratory symptoms, including fluid accumulation in the lungs, leading to shortness of breath, chest tightness, and persistent cough. Approximately 38% of individuals who develop these lung symptoms may succumb to the disease.

Preventive Measures

Preventing hantavirus infection involves avoiding contact with rodents and their waste products. Dr. Glatt emphasizes the importance of thorough cleaning and disinfection of areas where rodents have been present.

The Wyoming Department of Health advises extra caution during spring cleaning, especially in cabins, sheds, barns, or storage areas that have been closed for extended periods. When entering such spaces, it is recommended to air out the area for at least 30 minutes before cleaning. For heavily contaminated areas, protective gear such as gloves, shoe covers, coveralls, and N95 masks should be worn to minimize exposure.

In 2012, an outbreak of hantavirus in Yosemite National Park resulted in at least 10 illnesses and three deaths among visitors who stayed in tent cabins. This underscores the critical importance of vigilance and preventive measures when dealing with environments prone to rodent infestations.

Conclusion

The recent rise in hantavirus cases in Arizona serves as a stark reminder of the health risks associated with rodent-borne diseases. As public health officials and researchers continue to investigate the factors contributing to this increase, individuals are encouraged to take preventive steps to safeguard themselves from hantavirus and similar infections. The ongoing vigilance and proactive measures are essential in mitigating the risks posed by this potentially fatal virus.