From the 1811 Dictionary of the Vulgar Tongue.
FRENCHIFIED. Infected with the venereal disease.
The mort is Frenchified: the wench is infected.
And just a few lines above...
FRENCH DISEASE. The venereal disease, said to have been
imported from France. French gout; the same. He suffered
by a blow over the snout with a French faggot−stick;
i.e. he lost his nose by the pox.
I'd like to seize the opportunity to clarify the circumstances of the phrase French Disease.
The story of the French disease as far as I know it, is as follows (also confirmed in the Wikipedia article about syphilis).
From a previous life in Naples I remember being struck by the fact that syphilis which I knew was known in Medieval France as mal de Naples was symmetrically known in Naples as mal francese.
Around the same time I was reading the book "Love stories of French History" of which I can't resist citing (translating) the tastier (albeit heavily romanticised) relevant excerpts...
We are in April 1495 in Naples; America has been discovered 3 years ago and the French king Charles VIII has just sent the incumbent Spanish king of Naples Alfonso II away for a while. Charles gives splendid banquets to celebrate his new possession... (op. cit. p. 268).
One fine day, a knight started to feel a funny tingle. On the following day the itching turned into aches and his body was soon covered with poxes.
Understandably anxious he called for the doctor who actually could not come to help, for at the same time nearly all the king's guests were subject to the same mysterious illness.
The poor souls were paying a heavy price for a short lapse of entertainment; they were covered with blisters; some were loosing their lips or their eyes and those were the luckiest, for they were spared the painful sight of witnessing their "virility" dropping on the floor like a ripe fruit...
In actuality they had been contaminated by syphilis contracted by Christopher Columbus sailors and imported in Italy by the Spanish mercenaries serving the ousted Spanish King.
The disease spread like wildfire and even high ranking personalities were affected. Bishops and Cardinals lost their nose and even the Pope was not spared. Charitable doctors then eruditely revealed that the ailment could propagate in the air through breath and even in holy water, so that the honour of the holy men was safe.
As the king's army pathetically limped back northwards to France, wary Italians on the way kept aloof lest they would be contaminated by what thence came to be known as the mal francese - the French disease.