Updates

By Carol A. Kemper, MD, FACP

Polio-Like Paralysis: What Next from West Nile Virus?

Source: MMWR Morb Mortal Wkly Rep. 2002;51(37):825-828.

This report from the CDC describes the occurrence of a newly recognized illness associated with West Nile Virus (WNV) infection: an acute flacid paralysis (AFP), similar to polio, which occurred in 6 adults in Mississippi and Louisiana in August of this year. All 6 patients had acute onset of painless, asymmetrical weakness without evidence of sensory abnormalities. The initial diagnosis in 2 patients was acute stroke, and the other patients were variously diagnosed with meningoencephalitis, postviral demyelinating syndrome, and Guillain-Barré Syndrome (GBS). Several received IVIG and/or corticosteroids. However, electrophysiologic studies confirmed a severe, asymmetric process involving anterior horn cells and/or their axons, similar to poliomyelitis. In addition, CSF pleocytosis was evident in all but 1 case. WNV infection was subsequently confirmed in all 6 cases based on IgM and neutralizing antibodies.

Of the 1641 laboratory-confirmed cases of WNV as of September, 2002, only these 6 cases have resulted in AFP (0.37%). Nevertheless, the CDC cautions that clinicians should be aware of the potential for WNV to cause AFP, and be quick to distinguish it from GBS. Unlike AFP, GBS generally causes an ascending, symmetric, paralysis with both motor and sensory changes; the CSF protein is increased in the absence of pleocytosis. Because these 6 cases only recently occurred, it remains unknown whether the paralysis will be permanent. Residual paralysis lasting greater than 60 days is one of the diagnostic criteria for possible polio—which could create confusion in countries where polio remains endemic.


Cat Scratch Disease: Not Just for Kids

Source: Ridder GJ, et al. Clin Infect Dis. 2002;35:643-649.

Ridder and colleagues from Germany, who were especially interested in cat scratch disease (CSD), surveyed all causes of cervical lymphadenopathy in 454 patients referred to the Head and Neck Service at the University of Freiberg from 1997 to 2001. Patients were screened with a battery of serologic studies (eg, bartonella, toxoplasma, EBV, CMV, mumps, lyme, brucellosis, and tularemia), and TST. CSD was defined based on 2 of 3 criteria (clinical symptoms, serologic conversion, or molecular evidence of Bartonella DNA in lymph node tissue). FNA or biopsy was performed in patients with a suspected malignancy or a lack of evidence of infection.

Overall, about one third of the patients had evidence of infection, one third had benign or malignant neoplasms, and one third remained undiagnosed. CSD was the leading cause of infection, occurring in 61 persons (13.4%), although 4 of these were also diagnosed with concomitant malignant tumors. All 61 cases were confirmed by serology, and 10 of 21 patients with lymph node specimens had Bartonella DNA detected.

Interestingly, Bartonella DNA was found in lymphatic tissues only during the first 6 weeks of illness, suggesting that methods to identify a cat scratch organism, whether by molecular, pathologic or microbiologic techniques, beyond 6 weeks are not likely to be successful.

Of those patients with CSD, there were a similar number of children and adults compared with those with lymphadenopathy due to other causes, and the median age for both groups was about 35 years. Slightly more than half (59%) of the CSD cases had bilateral cervical disease and the remainder had unilateral disease. Eleven (18%) had lymphadenopathy present for 3 or more months. Similar to other studies of CSD, only half of the patients could recall contact with cats. The diagnosis of CSD may therefore solely depend on serologic evidence of recent infection.

An obvious limitation to this study was that fully one third of cases remained undiagnosed, and there was no mention of mycobacterial infection (or studies to look for such, other than a screening TST). However, this study does suggest that CSD serologies should be performed more commonly in the evaluation of cervical lymphadenopathy in both children as well as adults.

Dr. Kemper, Clinical Associate Professor of Medicine, Stanford University, Division of Infectious Diseases; Santa Clara Valley Medical Center, is Associate Editor of Infectious Disease Alert.