As the weather warms, many Greeks are preparing for summer getaways to the countryside, villages, and islands. Encounters with venomous snakes are certainly not part of the ideal holiday plan -neither is a hunt for an antivenom after getting bit- yet in a country like Greece, which boasts the greatest diversity of vipers in all of Europe, such encounters are not the stuff of science fiction.

Currently, all antivenoms administered in Greece — known as antivenom serums — are imported. Since these have not been developed based on the specific characteristics of Greece’s native snake species, their effectiveness may be somewhat limited. Now, a new study analyzing the venom of five different Greek viper species is laying the groundwork for the country’s first domestically produced antivenom — one that could potentially be exported to save lives in other countries as well.

A Rich Herpetofauna

According to Professor Panagiotis Pafilis, biologist at the National and Kapodistrian University of Athens (NKUA) and president of the Hellenic Herpetological Society, Greece is fortunately not among the countries with a high number of snakebite fatalities. “About 200 snakebites are recorded annually in Greece, but over a 23-year period (2000–2022), only eight deaths were reported — all involving people with underlying health conditions or allergies.”

Greece is home to 23 species of snakes, only seven of which are venomous. Of those, five viper species pose potential danger to humans. “Out of the 13 viper species found in Europe, five are present in Greece — giving us the greatest viper diversity on the continent,” explains Pafilis. However, only three of these are commonly encountered; the remaining two live at altitudes above 1,500 meters and have very mild venom.The three most common viper species in Greece are:

  • The horned viper (Vipera ammodytes), found in most parts of the country;
  • The Ottoman viper (Montivipera xanthina), present on islands in the Northeastern and Eastern Aegean (Samothraki, Lesvos, Chios, Samos, Kos, Fournoi) and Eastern Thrace;
  • The Milos viper (Macrovipera schweizeri), the only endemic viper species in Greece, also found on Kimolos, Polyaigos, and Sifnos — with an estimated population of 2,000–3,000 across these four islands.

The other two rare species are the Bosnian viper (Vipera berus bosniensis) and the Pindus viper (Vipera graeca).

Viper, as seen at Parnassos. Credit: C. Novak

Toxic Mixtures

The good news: Greek viper venom contains hemotoxins, which must enter the bloodstream to cause significant harm. “This means there’s generally enough time for the victim to reach a hospital and receive an antivenom — which should always be administered by medical professionals,” Pafilis emphasizes. Yet, until now, the precise composition of Greek viper venom has remained largely unknown. Dr. Kostas Sagonas, assistant professor of biology at Aristotle University of Thessaloniki (AUTh), notes that “snake venoms are complex biological mixtures with a wide range of bioactive compounds and considerable variability in composition. This makes the use of existing antivenoms — developed from different species or populations abroad — potentially inadequate for Greek vipers.” Currently, only the BulBio antivenom from Bulgaria — an older intramuscular serum that may take 3 to 24 hours to become effective — is imported and used in Greece.

Proteomic Breakthrough

To address this knowledge gap, Sagonas and PhD candidate Thomas Daftsios, in collaboration with the Institute of Biomedicine in Valencia (Prof. Juan José Calvete), NKUA (under Prof. Pafilis), and the Hellenic Pasteur Institute (Dr. Dionysios Sgouras) have launched Greece’s first study into the proteomic profile and toxicological characteristics of native viper venoms. The team, which also includes postdoctoral researcher Dr. Fotini Paraskevopoulou from AUTh, aims to develop the first “Made in Greece” antivenom, specifically tailored to Greek vipers — and potentially useful for related species abroad.

Debunking Myths

While the research is still ongoing, Daftsios shares some early, intriguing findings. Contrary to popular belief, the most toxic venom belongs to the common horned viper, not the Milos viper. “The Milos viper’s venom ranks third in potency after the common and Ottoman vipers. Despite its fearsome reputation, there is not a single recorded death from a Milos viper bite,” he says. Another myth busted: the so-called “red Milos viper” is not more toxic than its grey counterpart — it’s simply a color variation. The team analyzed venom from both color morphs and found identical toxicity levels. They also found that while venom composition does vary slightly between juvenile and adult snakes, the difference is not clinically significant. Moreover, venom is not more toxic after hibernation — in fact, the quantity released immediately post-hibernation is much lower than expected.

Toward a Greek Antivenom for Vipers

The path to developing an effective antivenom — planned for intravenous use to ensure rapid action — will likely take another 3 to 5 years, depending on funding. An important joint research proposal has been submitted by AUTh’s Department of Biology, NKUA’s Biology and Medical Schools, and the Pasteur Institute. Researchers expect two antivenoms will be needed to cover all five species- one for the more “Asian” types (Milos and Ottoman vipers) and one for the “European” types (horned viper and Bosnian viper).

Once developed, the Greek antivenom could also be exported. “For instance, the Milos viper’s venom is similar to that of the Cypriot viper, so the same product could work for both. We could also export to Turkey and Balkan or European countries where similar species exist,” says Daftsios. In this way, science might turn venom into gold — not just for public health, but also for the Greek economy.