Mouse Fever- "Trench Nephritis"

During December of 2023, reports of Russian soldiers falling ill with fever, back and abdominal pain, red eyes, and kidney problems began to emerge from the trenches of Eastern Ukraine. Ukraine's Military Intelligence Directorate (GUR), has blamed the reports on "mouse fever", or Hemorrhagic Fever with Renal Syndrome (HFRS).

Although HFRS is poorly researched, it is likely this hemorrhagic viral disease accompanied many wars of the past. HFRS (aka Korean Hemorrhagic Fever, Epidemic Hemorrhagic Fever, or Nephropathia Epidemica), is a rodent-borne group of hantaviruses, of the family Bunyaviridae. Strains, which differ in their symptoms and epidemiology, include Hantaan, Dobrava (found in the Balkans), Saaremaa, Seoul (found worldwide), and Puumala (in Scandinavia, Russia, and W Europe). Poor wartime living conditions for soldiers and displaced populations contribute to both increases in rodent populations, and increased exposure to virus shed in the rodents' urine and feces. In Ukraine this year, warm fall weather and unharvested crops in fallow fields have led to a large winter rodent population. Life in the trenches increases soldiers' exposure to rodents. HFRS is spread by striped and yellow-necked field mice, norway rats, and bank voles, amongst others. 

Unlike New World hantaviruses, which cause pulmonary disease with mortality rates of 40-50%, Old World hantaviruses tend to create generalized hemorrhagic symptoms and kidney problems. They are more likely to spread as epidemics and have lower case fatality rates (CFR 2-20%). Reports of wartime HFRS-like diseases have cropped up in many wars throughout history, often referred to as "trench nephritis", or mis-diagnosed as other conditions. 

The first known written mention of HFRS was likely made in a Chinese medical book in AD 960. Mentions of "trench nephritis" during the US Civil War may be attributable to a kidney-targeting hantavirus, such as the Seoul strain. "Mouse Fever" appeared in a 1913 Vladivostok hospital record. "Field nephritis" affected both Allied and German troops in Flanders in WWI. During WWII, 10,000 Japanese soldiers fell victim to a HFRS-like illness in Manchuria, as did several hundred Russian soldiers in the Far East. More than 1,000 Finnish and German soldiers contracted what was probably the Puumala strain in Finland. 3,200 cases of HFRS were diagnosed amongst UN soldiers during the Korean War; these experienced a mortality rate of 15-20%. Numerous soldiers fell ill with HFRS symptoms during the Balkans war. Currently, an estimated 100,000 cases of HFRS occur each year worldwide. In Ukraine, one study found that 1.6% of healthy individuals have antibodies to hantaviruses.

HFRS is contracted by inhaling dried rodent urine, droppings, or saliva, or by touching mucous membranes after touching surfaces contaminated with rodent excrement. After a 1-2 week incubation, patients experience a sudden onset of flu-like symptoms. These can include severe headache, abdominal pain, nausea, vomiting, back pain, fever, chills, back pain, flushed face, red eyes, and blurred vision. In severe cases, the disease may progress to kidney failure, fluid overload, vascular leakage, hypotension, and possibly death. Hantaan and Dobrova strains are more like to cause severe illness; other strains tend to be more moderate. Ribavirin, if given very early, may help. Otherwise, supportive care focuses on maintaining fluid and electrolyte balance. Dialysis may be required. CFR ranges from 5-20% for Hantaan to <1% for Puumala virus. Complete recovery can take weeks or months. A vaccine for the Hantaan strain exists in Korea, but is little-used. 

CDC HFRS page https://www.cdc.gov/hantavirus/hfrs/index.html

Article: Hemorrhagic Fever with Renal Syndrome

Hantaviruses: History and Overview