Leptospirosis is a type of bacterial infection that is spread by animals. It is caused by a strain of bacteria called leptospira.
Types of leptospirosis
There are two main types of leptospirosis infection:
- Mild leptospirosis is where a person develops flu-like symptoms, such as headache, chills and muscle pain.
- Severe leptospirosis is where a person goes on to develop severe, sometimes life-threatening symptoms, including organ failure and internal bleeding. This is caused by the bacteria infecting major organs, such as the liver and kidneys.
Mild leptospirosis is the most common type of leptospirosis, accounting for 90% of cases. It is unclear why a few people go on to develop serious symptoms.
Risk factors for developing severe leptospirosis include:
- being under five years old
- being over 65 years old
- already having a serious health condition, such as pneumonia
How common is leptospirosis?
Leptospirosis is most common in tropical areas of the world. However, it is becoming increasingly widespread in urban areas that have low levels of sanitation, such as in poor areas of large cities in the developing world.
Most cases of leptospirosis are sporadic (infrequent), although large outbreaks have been reported after flooding.
Globally, it is estimated that 10 million people will get leptospirosis every year. It is difficult to estimate exactly how many people die from leptospirosis because many cases occur in parts of the developing world where causes of death are not routinely reported.
In the coming years, it is anticipated that the number of cases of leptospirosis will continue to increase as a result of global warming and the expected increase in flooding. Some experts have estimated that the fatality rate from leptospirosis could be anywhere between 5 and 25%. Deaths from leptospirosis tend to be higher in countries where access to good quality healthcare is limited.
Cases in England
Rarely, leptospirosis occurs in temperate climates, such as England. For example, in 2009, there were 33 reported cases of leptospirosis in England and Wales, 14 of which were acquired abroad.
Most cases either involved:
- people who regularly worked with animals and/or water, such as farmers and sewer workers
- people who took part in water-based activities, such as canoeing or sailing
See Leptospirosis - causes for more information.
In England, death rates for people with severe leptospirosis are much lower than in other parts of the world due to the quality of healthcare that is available. In 2009, there were only three deaths as a result of leptospirosis.
Outlook
Mild leptospirosis responds very well to treatment with antibiotics and most people will make a full recovery within a week.
Most people with severe leptospirosis will require admission to hospital so the functions of their body can be supported while the underlying infection is treated with injections of antibiotics.
