The data, published in BMC’s Microbiome journal, suggests that manipulating the gut microbiome environment – perhaps through the use of probiotic or prebiotic supplements – could help protect communities in developing countries from intestinal parasites.
Current World Health Organisation (WHO) estimates suggest that around 1.5 billion people worldwide (and approximately a quarter of all people on earth) are affected by such intestinal parasites, the US-based team behind the work noted.
By studying communities in Liberia and Indonesia, the team were able to compare the gut microbiomes of people able to clear the infections without drugs were and those who could not clear the infections. The team from the Washington University School of Medicine in St. Louis found that people who were able to fight off the infection naturally all had similar microbiome profiles, and that these were distinctly different from those people who could not clear the infections without treatment.
"People who have sustained infections or who experience multiple infections have a different microbiome to start with compared with those who do not have as much trouble with infection," commented senior author Dr Makedonka Mitreva.
"Our work included samples from a placebo-controlled trial of drugs against these parasitic worms,” she said. “It suggests that the microbiomes of people who retained infection are somehow compromised to begin with. Something about their microbiomes makes them more prone to getting infected and to maintaining a chronic infection."
The researchers analysed about 400 faecal samples from 250 people living in different villages in Liberia and Indonesia.
In doing so, the authors identified 12 microbial strains associated with worm-infected individuals and one type of bacteria associated with uninfected individuals. They noted that the one linked with a reduced severity and recurrence was Lachnospiracae – which is associated with increased inflammation.
Meanwhile, 12 bacterial taxa were significantly associated with infection in both countries, including Olsenella (associated with reduced gut inflammation), which also significantly reduced in abundance following clearance of infection, said the team.
Given that the single type of bacteria linked to unaffected individuals is linked to increased inflammation and one of the 12 types linked to higher infection linked to lower inflammation the team suggested that it is perhaps a certain type of inflammatory environment that makes it harder for the worms to establish themselves in the gut.
One of the study's strengths, Mitreva said, is that it established common gut microbiome patterns associated with high and low risk of worm infections in two distant geographic regions -- West Africa and Southeast Asia, where such infections are prevalent.
"There are good drugs against most -- but not all -- of these infections,” said Mitreva. “We are beginning to see more responses to treatment that are less than optimal, indicating the worms are starting to develop resistance to some of these treatments.”
"The big problem is reinfection,” she said. “Even if the therapy works and the infection is cleared, the exposure to contaminated soil is so pervasive that new infections are extremely common.”
“Building on the information from this study, our ultimate long-term goal is to develop a way to alter the gut microbiome so that it protects people from reinfection."
Furthermore, since the study found characteristics of the microbiome that are discriminative of infection, the team suggested that this information could be used to predict who is most likely to develop severe and chronic infections and direct more preventive efforts to those individuals.
"Ideally, we would like to be in a position to suggest some local fermented foods that could alter the microbiome and result in a decreased rate of reinfection," said the lead author.
"Rather than give more antihelminthic drugs, we want to help people fight off the infection by themselves. Right now, we are looking at the bacteria that we found were associated with protection against infection and studying their effects in mice with intestinal worm infections."
Published online, Open Access, doi: 10.1186/s40168-018-0416-5
“Differential human gut microbiome assemblages during soil-transmitted helminth infections in Indonesia and Liberia”
Authors: Bruce A. Rosa, et al