An unusually wet spring in Andalucia has been linked to an outbreak of a bacterial disease that infected 10 people and claimed one life.

The outbreak occurred in Jerez after March 2025 became the third wettest month ever recorded at the city’s airport weather station, according to a study presented at the latest congress of the Spanish Society of Infectious Diseases and Clinical Microbiology (SEIMC).

Doctors at Jerez Hospital identified 10 cases of leptospirosis, a disease typically associated with contaminated water and flooding, with one patient dying after developing severe complications.

Jose Miguel Cisneros, president of SEIMC’s infectious diseases committee, described the outbreak as highly significant.

‘Spain usually records around 50 cases of leptospirosis each year,’ he explained. ‘But floods and extreme weather events can increase infections, particularly in warm climates. The Jerez outbreak is therefore very important.’

Leptospirosis is a bacterial disease caused by microorganisms from the Leptospira family and is most commonly spread through water contaminated by the urine of infected animals, particularly rodents.

People can become infected when contaminated water enters the body through cuts in the skin, through the eyes or by ingestion.

Heavy rainfall and flooding increase the risk because they can lead to greater contamination of water sources and attract larger numbers of rats and other animals that carry the bacteria.

Symptoms can range from mild flu-like illness to severe disease affecting the liver, kidneys, lungs or brain.

In its most dangerous form, known as Weil’s disease, leptospirosis can be fatal.

‘Most infected people either have no symptoms or only mild illness,’ said Cisneros. ‘But some patients develop severe complications, and unfortunately that happened in one of the cases in Jerez.’

The specialist praised doctors at Jerez Hospital for recognising and diagnosing the infection quickly despite its rarity.

‘Many hospitals see either one case a year or none at all, so their ability to identify the outbreak was extremely valuable,’ he said.

Because leptospirosis is relatively uncommon in Spain, health authorities classify the appearance of multiple linked cases as an outbreak.

The disease is also a notifiable infection, meaning doctors are required by law to report suspected or confirmed cases so public health officials can investigate and prevent further spread.

The outbreak has reignited discussion about the impact of climate change on infectious diseases.

Cisneros warned that warming temperatures, global travel and changing weather patterns are increasing the risk of outbreaks and future pandemics.

He pointed to diseases such as West Nile virus and Crimean-Congo haemorrhagic fever, both of which have already been detected in Spain, as examples of infections that are becoming more relevant due to environmental changes.

The expert also renewed calls for Spain to create a dedicated medical speciality in infectious diseases.

According to SEIMC, Spain remains the only country in the European Union without a formal infectious diseases speciality for doctors.

‘We’ve been warning for years that this anomaly harms patients with serious and complex infections,’ said Cisneros.

‘The doctors in Jerez did an excellent job, but they achieved it despite not having access to a dedicated specialist training pathway.’