The severity of a diarrhoeal disease could be down to the bacteria in your gut, according to new research from the University of East Anglia.


Source: CDC/ J Infect Dis. 1983 May;147(5):824-8

Photomicrograph of a direct fecal smear, stained to detect Cryptosporidium sp. intracellular protozoan parasites.

Cryptosporidiosis is responsible for more than 100,000 deaths annually – predominantly in children under five.

It also affects animals, and a new study shows that large animals – including primates - with less different kinds of bacteria in their gut are the more severely affected.

It reveals that introducing more diverse gut bacteria can improve outcomes – including reducing diarrhoea and potential for the disease to spread.

Targeting the disease

The team, led by Prof Kevin Tyler at UEA’s Norwich Medical School, say that diet, probiotics and faecal transplant therapy could help target the disease by improving gut bacteria in people and animals.

Prof Tyler said: “The vast majority of infections and deaths happen in low-income countries, but outbreaks also occur in the UK and elsewhere in Europe.

“In the UK, the disease is currently re-emerging and cases this year are increasing dramatically, suggesting the disease is currently epidemic. There are no human vaccines and only one drug licensed for human use, which is not effective for many who are affected.

“So, understanding what that can improve outcomes is critical to tackling outbreaks.

Gut bacteria

“We wanted to know whether some of the variation in symptoms might relate to the make-up of an infected person or animal’s gut bacteria and whether that composition was in turn affected by having cryptosporidiosis.”

The team collected all studies that had looked at the composition of gut bacteria in mammals which were infected by cryptosporidium and for which the data had been made publicly available.

They compared these to answer questions about the significance of gut bacterial diversity and the effect of cryptosporidium infection.

Deadly parasite

Lead researcher Georgina Hurle, also from UEA’s Norwich Medical School, said: “The Cryptosporidium parasite is one of several microorganisms that cause diarrhoeal disease. It affects both babies and new-born livestock and it can be contracted either from animals or from people.

“Most people contracting cryptosporidiosis will recover naturally, but some people and animals will require treatment, suffer long term consequences from the infection, and may even die.

“The severity of the disease is known to be affected by prior exposure, so adults are generally less severely infected and recover better.

“We found that more severely affected large animals such as cows, sheep and primates, have less different kinds of bacteria in their gut.

“We also found that having and even introducing more diverse gut bacteria can improve outcomes, reducing diarrhoea and potential for disease transmission.

Understanding changes

“Gut bacteria composition can be affected by diet, by consumption of probiotics and pre-biotics and by therapies like faecal transplant therapy.

“Understanding the changes that accompany infections and outcomes provides an opportunity for such relatively affordable but novel therapies in targeting a disease for which very few interventions are currently available.

“This study is important in showing that these approaches may be effective at reducing disease severity in those affected and at-risk groups and populations.”

‘Microbiome diversity is a modifiable virulence factor for Cryptosporidiosis’ is published in the journal Virulence.