You are probably reading this because you are a responsible user of the Diseases Database whose access has been denied.
Site defences may block innocent users sharing a proxy server or netblock with bot infected machines, hackers or abusers. This is unfortunate but service levels of our site depend on this capability. Certain automated web page downloading software applications (robots or 'bots') cause a site like ours difficulties if counter-measures are not taken. Protection mechanisms can deny access to entire internet service providers or institutions including prominent educational and healthcare institutions when these are the origin of denial of service attacks.
Please find further explanation of our rationale below.
The Diseases Database has over 100,000 potential pages. There is limited bandwidth on our side. Attempts to rapidly download all (or a large proportion) of our pages impairs other user's access.
Our site would suffer dozens of partial outages per day if unprotected. This issue is not unique to smaller sites - the 'brown-outs' and intermittent losses of service often experienced on prominent sites are frequently the consequence of malware robots.
Denial of service is seldom the intent of badly designed robot software but often the outcome. Those responsible don't consider the consequences of bandwidth hogging. In the unlikely event a miscreant reads this we ask them to please desist. The average broadband user typically has more bandwidth than a small business web server. Web sites may be either pay their ISP per kilobyte uploaded or be 'capped' (although thankfully not ours). It's not clever to bring down web sites and doing so might even hinder the malware author's illicit purpose.
Please do not attempt to download the Diseases Database web site for off line use.
See also http://en.wikipedia.org/wiki/Offline_reader
We block the following...
Comment spam, referrer spam and spam sent to our published e-mail addresses is antisocial and annoying but not the main issue. Rather the associated bot ripping through the entire site while harvesting or delivering payloads may lead to bandwidth saturation.
This class of software pre-emptively downloads all links from a page 'in case' you want to look at them http://en.wikipedia.org/wiki/Web_accelerator
The principle of accelerators is arguably bogus: if you have good bandwidth you don't need one; if you have poor bandwidth they waste it and often anticipate the user's next action wrongly. Please turn them off and do yourself, us and the web in general a favour.
The Diseases Database is engineered to be highly responsive to individual requests - also our pages are small enough to race along a piece of wet string. On the other hand some of our pages have several hundred internal links and downloading all of them near simultaneously causes problems.
We routinely block several anonymous proxy services.
We acknowledge legitimate uses for anonymous proxies. However an audit of Diseases Database hits revealed most (of many) accesses via Tor over a three month period were by illegitimate bots (largely comment or referrer spammers).
Please access the Diseases Database site directly or flee now: if your government or employer is so oppressive they object to our content you have bigger problems to deal with =:-0
Few of the major search engine robots consume excessive bandwidth.
Spiders which misbehave are banned politely via our robots.txt file only if their operator maintains a web site explaining their intention and which explicitly states the 'name' their robot will recognise in robots.txt. Otherwise (or if robots.txt is ignored) blocking mechanisms kick in.
PCs can be infected by malware. We thank you for ensuring your PC is not host to these.
Otherwise if you find yourself blocked the probability is you unknowingly follow in the wake of incidents of abuse by other users or machines. It is almost impossible to trigger the defences with anything remotely resembling normal web browsing behaviour. It is difficult to invoke them deliberately even with insider knowledge using a conventional browser.
Some language translation services appear to "read ahead" like web accelerators and thus trigger defences. Similarly proxy servers can pre-fetch. (This is an unusual configuration but those setting up proxies for mobile phones sometimes appear to have done this.) However such facilities are so frequently hijacked as portals for hacking and malware attacks it is hard for us to determine what is happening or whitelist them.
We invite and very much welcome reports of "false positive" blocks. We have both the means and strong motivation to fix or work around these.