The newly emerged Fizzer worm has displaced Klez as the most common viral menace on the Internet over the last month.

Managed services firm Messagelabs blocked Fizzer 497,846 times in May, relegating Klez-H (293,028 interceptions) to fourth place in the firm's monthly viral charts.

MessageLabs reports that one in 145 emails it processed this month contained a virus.

The company also operates an anti-spam service. In May, for the first time, spam exceeded legitimate email in percentage terms. The global ratio of spam in email scanned by MessageLabs Anti-Spam service was 1 in 1.8 (55.1 per cent) emails.

Over at anti-virus firm Sophos the Palyh (Microsoft support) worm was the most common subject of support calls with Fizzer coming in as the second most commonly reported irritant. In MessageLabs chart Palyh went straight in at number three. ®

Top ten viruses blocked by MessageLabs in May

1. 
   
2. Fizzer
   
3. Yaha-E
   
4. Palyh (Sobig-B)
   
5. Klez-H
   
6. Sobig-A
   
7. Yaha-K!e2a2
   
8. SirCam-A
   
9. Yaha-P
   
10. BugBear
    
11. Lovgate-F