The case was confirmed on November 25 and reported to the World Organisation for Animal Health (OIE) on December 1.
The report described the case as a sub-clinical infection and listed 49 equidae as potentially susceptible.
The source was listed as unknown or inconclusive. It said quarantine measures and movement controls were in place, and screening for the infection was under way.
In its first weekly update, dated December 6, Dr Marabelli said no new cases had been detected.
Two cases of dourine in Campania, in central Italy, were notified to the world body in June. Subsequently, nine further cases were identified, with two animals destroyed as a consequence.
Dourine is a parasitic disease, unusual in that it is transmitted almost exclusively during covering (hence it is sometimes referred to as "covering sickness"), or from mares to their foals in some cases, rather than requiring a vector such as a fly or tick.
It is caused by the protozoan, Trypanosoma equiperdum, and can result in an acute or chronic form.
Signs include genital swelling and discharge, weight loss (which may be severe), and loss of co-ordination and weakness.
Once a widespread disease, dourine is currently considered endemic only in Africa and parts of Asia.
Outbreaks also occur in the Middle East and Russia.
Treatment is possible, but in certain cases can lead to horses becoming carriers. There is currently no vaccine available, and many affected animals die.