Worldwide, over 5 million people contract syphilis every year. it’s not the number 1 STD Tested disease, but it’s a very serious one. And very difficult to develop a vaccine. The secret to developing it lies in the genes of the microorganism.

Syphilis and vaccine: where are we at? When you pronounce the single word, syphilis, the response you receive is: but why does it still exist? Yes, it may be socially obsolete as a disease, but it exists and “lives and fights against us”, paraphrasing a 1968 saying to say that it is on the increase. Globally, it is the second cause of stillbirths and abortions. If left untreated, it can cause stroke, dementia and other neurological problems. Until now, the medical procedure has been to treat infected people and their sexual partners plus any partners of the latter, but now a radical discovery is on the horizon: arriving at a vaccine. This is the weapon that could eradicate this terrible and highly contagious disease.


The World Health Organization informs that 10.7 million people aged 15-49 are infected worldwide. 5.6 million people contract this STD disease every year. In the United States, in particular, HIV tests show that the prevalence is increasing, especially in men who have sexual relations with other men. In many developing countries, prostitutes and their clients lead the list. «As a disease, syphilis is a great imitator – Dr. Juan C. Salazar, head of Pediatrics at the University of Connecticut (USA), writes in mBio, the American Society of Microbiology magazine. – It may appear as hyperpigmentation or other structures.”


Syphilis is difficult to study because it cannot be grown in the laboratory or mice. Apart from humans, the only animal suitable for these studies in a laboratory is the rabbit. But the rabbit quickly frees itself from this disease, so it is necessary to infect new rabbits regularly to maintain a line of Treponema pallidum, which is the bacterium that causes syphilis. The syphilis bacterium test is common, but the second reason why it is difficult to study this sexually transmitted disease is that its bacterium is very delicate and fragile.

Most bacteria that cause diseases are tough:

With a microscope, you can wash, dry, and observe all their external features. Treponema pallidum, on the other hand, opens up, lets its contents slide out, creates a mess, and makes it impossible to understand what proteins might be located on its outside. These proteins represent a key through which our self-defence immune system recognises invading bacteria. And this is how – coincidentally – how vaccines work.

But these, usually stable, change when it comes to life or death so as not to be recognised by the immune system. Here is the further difficulty in arriving at a vaccine and defeating syphilis. With further research, scholars at the University of Connecticut, in connection with various universities worldwide, have arrived at the possibility of using external proteins that mutate less to immunise a rabbit: the first possible STD test for a vaccine.

«The real name of the syphilis bacterium is Spirochete. The specialist Antonio Cristaudo, director of the Dermatological Institute for Sexually Transmitted Diseases at the San Gallicano Irccs in Rome, says it is called “pallidum” because staining the bacteria was impossible in laboratory cultures. And the great difficulty is that you can’t even cultivate it. In the Connecticut research, they started with the genetic mapping of material coming from very distant locations. They saw that STD bacteria are always the same in every part of the world. Therefore, if the vaccine were found, it would be usable everywhere.” But the goal is not close, warns Dr Cristaudo. Certain bacterium proteins have indeed produced antibodies, but we are still far from STD tests on animals.


«For gonorrhoea, however, we are already experimenting on people, which is phase 3 of research. At the end of the year, we will also participate in a study – says Cristaudo. However, the University of Connecticut’s investigation is important: it shows a door to continue studying». But in common opinion, this disease should be extinct. However, Syphilis Tests have detected the bacterium more and more recently. Yes, it seemed to have died out in the twentieth century, but 2004-05, there was a peak in Italy.

It is an important disease in all countries, developed and poor. In itself, the bacterium is not aggressive; however, for example, it facilitates HIV tests for infection, which is the AIDS virus. Theoretically, it is also easy to fight. It costs very little to use penicillin. But an early diagnosis helps to avoid weight issues.” Today, there are two categories at risk: men who have sex with men, as already mentioned above, but why? «Because they are closed societies, circular environments, also because of certain practices they adopt», explains Antonio Cristaudo. The other type of people at risk are sex workers.