West Nile virus (WNV) is a member of the Flaviviridae family. It is now endemic in the United States. Since 1999 >30,000 people in the United States have been infected by WNW (United States Center for Disease Control (CDC) report). Infection results in well documented short-term effects, such as meningitis, encephalitis, acute kidney injury and even death. However, longer term effects of WNW are poorly understood.
A recent study by Melissa Nolan and colleagues from Baylor published in PLoS provides evidence for WNV causing chronic kidney disease with hematuria and proteinuria.
Nolan and colleagues followed propspectively a cohort of 139 subjects previously infected with WNV. They report:
1. Study participants were primarily male (60%) and non-Hispanic white (86%) with a mean age of 57 years.
2. Most (83%) were four to nine years post-infection at the time of this study.
3. 40% of participants had evidence of CKD (by KDOQI staging), with 10% having Stage III or greater and 30% had Stage I–II.
4. By urinary dipstick testing, 26% of patients had proteinuria and 23% had hematuria.
5. After multivariate analysis, only "Neuroinvasive WNV disease" (p = 0.058, OR = 1.95) was found to be significantly associated with any stage of CKD. In other words, CKD tends to occur mostly in patients who also develop neuroinvasive disease.
A recent study by Melissa Nolan and colleagues from Baylor published in PLoS provides evidence for WNV causing chronic kidney disease with hematuria and proteinuria.
Paraphrasing the Nolan paper's introduction...Acute experimental infection with WNV in animals is associated with kidney disease. After clinical recovery from WNV infection, animals develop chronic kidney infection with histopathological changes in renal tissue and viuria detectable for up to 8 months after acute infection. 3 studies in humans show evidence of virus in the urine of human WNV patients; however, these studies did not assess the renal impact of WNV infection.
In Houston, Nolan et al previously reported that 9% of hospitalized WNV patients developed acute renal failure at the time of initial infection. In Colorado a recent study assessing delayed mortality several years post infection, found that 21% of deceased WNV patients had documented renal failure as a contributory cause or underlying condition.
Is this association with CKD important - yes because the number of infected humans in the US is growing. The CDC reports:
"Thus far in 2012, 47 states have reported West Nile virus infections in people, birds, or mosquitoes. A total of 1118 cases of West Nile virus disease in people, including 41 deaths, have been reported to CDC. Of these, 629 (56%) were classified as neuroinvasive disease (such as meningitis or encephalitis) and 489 (44%) were classified as non-neuroinvasive disease. The 1118 cases reported thus far in 2012 is the highest number of West Nile virus disease cases reported to CDC through the third week in August since West Nile virus was first detected in the United States in 1999. Approximately 75 percent of the cases have been reported from 5 states (Texas, Mississippi, Louisiana, South Dakota, and Oklahoma) and almost half of all cases have been reported from Texas."
Nolan and colleagues followed propspectively a cohort of 139 subjects previously infected with WNV. They report:
1. Study participants were primarily male (60%) and non-Hispanic white (86%) with a mean age of 57 years.
2. Most (83%) were four to nine years post-infection at the time of this study.
3. 40% of participants had evidence of CKD (by KDOQI staging), with 10% having Stage III or greater and 30% had Stage I–II.
4. By urinary dipstick testing, 26% of patients had proteinuria and 23% had hematuria.
5. After multivariate analysis, only "Neuroinvasive WNV disease" (p = 0.058, OR = 1.95) was found to be significantly associated with any stage of CKD. In other words, CKD tends to occur mostly in patients who also develop neuroinvasive disease.
