Is router can detect Viruses, worms or spywares on the network?

Can it detect them? Depends on the router.

That's what an antivirus and a firewall are for. Now, routers with built in firewalls and antiviruses can detect and block them to a point. To be honest, the firewall usage from normal purchase routers are not all that strong. I recommend security for each computer that uses it.

Is router can detect Viruses, worms or spywares on the network?computer protection

Generally, NO.

BUT. If I may ask you what type of router do you have? Where are you planning to implement(home, enterprise level, network operation center) the router?

If you have a SOHO(small office and home) router, I think most of them do not have such capabilities you mentioned. However, if you plan to implement it on enterprise level and your company could afford, you may install some CISCO advance router series with firewall and PIX equipped with intrusion detection systems(IDS). Configure the router and your shielded(but not 100%).

You may route all the traffic to pass through an enterprise server that will scann everything on transit, say you should install a Norton Enterprise Server(Yahoo Mail) or Trend Micro Enterprise Server(MSN aka Hotmail), before they reach any of your workstation.

Before implementing such, you should check all workstations inside your network for any presence of viruses, worms, malwares, or spywares.