A case involving one horse was registered in April at the Deodoro Military Complex directly adjacent to the Equestrian Centre, while results for another came back inconclusive and at least one other animal was infected in a neighbouring State.

In response, the site has been completely fenced off since February 6, with this week's test event marking the first and only occasion in which horses are expected to be allowed on the site before the start of the Games in a year's time,

All those attending are subject to measures such as sanitising shoe-dips when they enter the venue, including Rio de Janeiro Mayor Eduardo Paes and Rio 2016 President Carlos Nuzman when they visited.

"We are very confident that there is no issue, simply because the best way to avoid athlete disease contaminaton is not to have horses on site and for six months this site hasn’t had any horses," insisted the Rio 2016 director of venue management Gustavo Nascimento.

"According to the international entities, we have excellent sanitary conditions.

"We followed a good procedure of taking horses straight to the site and are very confident this won’t jeopardise the event or risk the welfare of the athletes."

Tim Hadaway, the International Equestrian Federation's Director of Games and Championships, added: "Measures have been put In place coming into the venue, which will protect its regionalised status.

"We’re not seeing anything at this stage that gives us cause for concern."

Glanders, a highly infectious disease usually associated with cramped and unsanitary stable conditions, is caused by the passing of bacteria which leads to nodules forming on the lungs and liver, almost always leading to death or euthenasia. 

Cases have been registered involving humans as well as other animals, with it thought to have been deployed as a biological warfare tactic by the Germans in the First World War and the Japanese in the Second World War. 

Although it has been largely eradicated in North America and Europe, it is still a major issue in other parts of the world, including Africa and the Middle East, as well as South America.

It is feared that the failure of the Brazilian Ministry of Agriculture, Livestock and Supply to confirm its final health protocol in time contributed to no international teams competing at the test event here, a three-day eventing competion.

Unlike during the Games itself, no financial support is given by Rio 2016, meaning the extra expense of transporting riders and horses here for a two-star calibre event with no Olympic qualification opportunities is also likely to have deterred teams from competing.

Just 13 riders are here in comparison with initial plans for 35, while the event is unticketed, meaning only a small proportion of the 20,000 spectators envisaged during Games-time are here.

Representatives from 16 National Federations are present for an ongoing Observer Programme, however, including all the leading equestrian nations.

Brazilian officials claim they remain confident the event is still fulfilling its primary function of testing key logistical and organisational factors.

More progress is still required, including the rennovation of 180 stables and the installation of cabling and other infrastructural groundwork, officials admitted, but they were keen to point out the progress that has already taken place.

"I was here only six weeks ago and it’s fair to say they still had a lot to do," added Hadaway, the Equestrian Competition Manager at London 2012.

"To achieve what they’ve achieved in these six weeks is amazing.

"There have been well documented concerns about preparedness with all the venues and we were struggling with that ourselves.

"But what we’ve now seen is how an ability, vision and drive to make things happen is absolutely there."

With Toronto 2015 Pan American Games silver and bronze medallist Ruy Fonseca a late withdrawal following his horse being declared unfit to compete, the leader after the dressage test is Marcelo Tosi, who rode Briefing DB Z to just 37.60 penalty points.

Cross-country action is due take place tomorrow ahead of a showjumping finale on Sunday (August 9).

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