Leptospirosis is an important disease worldwide. Not only does it affect seven to ten million people annually, it also infects animals causing economic and personal loses. The disease itself is caused by a genus of bacteria called Leptospira with up to 13 different genetic types of Leptospira able to cause disease. In the UK, an important reservoir for leptospirosis is cattle. Not only does this cause problems in terms of cattle health, but can also pose a public health risk to the farmers who look after them.

In terms of cattle health, leptospirosis can be tricky to diagnose and treat. The symptoms, such as reduced milk production, abortion, weak calves and other fertility problems, are not unique to leptospirosis so can be challenging to diagnose. What’s more, not all cattle with show obvious clinical signs with some affected by subclinical disease which is difficult to detect. Further complicating the picture is the fact that Leptospira can live in the kidneys of recovered cows for years without causing disease, but still infecting other individuals in the herd. A recent survey found that up to 60% of UK farms tested positive for leptospirosis.

Many cattle in the UK are vaccinated against leptospirosis. The current leptospirosis vaccine is an “inactivated” vaccine in which Leptospira unable to cause disease are injected into the cow to stimulate an immune response and immunity. While this produces good immunity to the type of Leptospira in the vaccine it doesn’t necessarily provide protection, or cross-protection, against other strains or species of Leptospira. This lack of cross-protection is one of the weaknesses of the current vaccine. There is a real need for more modern vaccines against Leptospira to be developed. One of the scientists working in this field is Intan Kamaruzaman, a PhD student at IGH. She is currently looking at alternatives to the current vaccine using a reverse vaccinology approach.