More Cases of Very Rare, Deadly Virus Detected in Idaho

Since the mid-2000s, Idahoans have come to expect at least a few headlines about dangerous mosquito borne illnesses every summer. However, it’s not just West Nile making news this year. 

A History of West Nile in the Boise Area

West Nile Virus was first detected in mosquitoes in Ada County in 2005. By the next summer, the number of cases didn’t just explode. Our little corner of the country actually led the entire country for the most reported cases. 

READ MORE: Add These 11 Plants to Your Idaho Garden to Keep Mosquitoes Away

While about 80% of people who contract West Nile will probably go unaware that they’ve contracted the disease, there are individuals that start presenting symptoms like fever, vomiting/diarrhea and fatigue. About 1 in 150 West Nile patients will develop symptoms that affect their nervous system. We’re talking about things like encephalitis or meningitis. They’re the patients most likely to die from complications. 

Since 1999, Idaho has reported 1439 human cases of West Nile. 277 of those were neuroinvasive. Two people, a man from Owyhee County and a woman from Gooding County, died from West Nile complications last year. 

So far in 2024? No human cases have been reported in the Gem State, but the CDC shows that it has been detected in mosquitoes in Ada, Canyon, Gem, Bannock, Bingham and Twin Falls Counties This Year. 

Another Rare Mosquito Borne Illness Surfaces in Idaho

Earlier this summer, we shared the CDC’s health advisory confirming an alarming number of dengue cases in the Americas. Like West Nile, it’s possible to have dengue and not know it. The CDC says that only about 1 in 4 people experience symptoms. Those typically manifest 3-10 days after exposure. Those with an active case of dengue will experience a fever which may be accompanied with pain behind the eyes, muscle pain, bone pain, joint pain, a rash, nausea or vomiting. 

The Mayo Clinic explains that there is no medication to treat the viral infection. Healthcare providers normally tell those with a confirmed case to treat the fever with acetaminophen and treat the other symptoms with increased fluids and rest. Most dengue patients start to feel better within a week. 

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That said, not everyone clears the virus easily. The CDC estimates that 1 in 20 patients ends up with severe dengue, which is considered a medical emergency. Severe dengue patients’ conditions can deteriorate in a matter of hours, leading to shock, internal bleeding or death. 

Warning signs of severe dengue include belly pain, vomiting three or more times in 24 hours, unexplained bleeding from the nose or gums, vomiting blood, blood in the stool and exhaustion. What’s unnerving is these symptoms manifest 1-2 days after the fever has passed. 

At this time, 3,861 cases of dengue have been reported in the United States in 2024. Those cases have affected 46 states, including Idaho. 

How Likely Am I to Get Dengue in Idaho?

While all of that sounds terrifying, there’s really no need to panic as the cases in Idaho are hardly an outbreak. 

Yes, the number of dengue cases in Idaho has increased. When we originally shared the CDC advisory there was only a single case reported in Ada County. That number has now jumped to a total of three, including additional cases in Owyhee and Shoshone counties.

All three of the Idaho cases are associated with travel. That means the individuals with dengue acquired the disease somewhere outside of Idaho. They likely traveled to an at risk area like the Caribbean, Central America, South America, Southeast Asia or the Pacific Islands. 

That doesn’t surprise health officials, as the Aedes aegypti and Aedes albopictus species known to be vectors do not occur naturally in our area, nor have they been detected by the Ada County Mosquito Abatement District while they’ve been monitoring mosquitoes for West Nile. 

So your chances of getting dengue in Idaho are very, very low but it’s good to be aware of the signs and symptoms if you travel. And it’s also good to follow basic mosquito bite prevention techniques since Idaho does regularly have a problem with West Nile Virus. The same prevention steps you’d use for dengue also apply to West Nile.