Worms, germs and you

Our bodies are covered in billions of so called ‘good’ bacteria, particularly the skin, mouth and gut. In fact, we have more bacterial cells in and on our bodies than our own cells! My PhD is looking at the bacteria that live in our gut, and their DNA, also known as the gut microbiome.

The bacteria in our gut have an extremely important role in keeping us healthy. They help keep our body’s defence system strong and also aid the breakdown and digestion of certain types of food. This is something our bodies cannot do themselves.

However, these bacteria are not always alone in the gut. In tropical countries where conditions are unhygienic, intestinal parasites such as whipworm are common. Around 800 million people in the world are thought to be infected, with young children being particularly at risk. But these worms are not the kind you find at the bottom of the garden. They are much smaller and whip-shaped, as their name suggests, and are dependent on mammals such as humans or mice to survive, reproduce and spread infection.

These worms cause infection when someone eats food or water containing whipworm eggs. These eggs hatch in the gut and the resulting worms burrow into the gut lining. Although not fatal, the results can be devastating for infected individuals, with symptoms including bloody diarrhoea, weight loss and in the long term, anaemia and reduced growth.
Researchers have found that whipworm eggs hatch in response to the bacteria that live in your gut, triggering infection. This has led to a closer look at the relationship between the bacteria in your gut, the body’s defence system and whipworm. This is the focus of my research.

Interestingly, infection with whipworm causes a considerable change to the gut microbiome i.e. what bacteria and the numbers of bacteria that are present in the gut. This is fascinating as the gut microbiome is usually stable over time, so any big changes could have negative effects on our health and cause disease.

Whipworms have been found to survive in the guts of infected individuals for up to five years. How they manage to survive and avoid destruction by our immune system is not fully understood. My research is looking at how the gut microbiome may help these worms survive in the gut and cause infection.

It could be that the worms encourage changes to the gut microbiome, creating an environment that would benefit their long term survival. This could result in changes to our health. For example, one symptom associated with infection is weight loss. This could be due to a decrease in the bacteria responsible for food digestion, preventing us from getting all of the nutrients from our food and therefore losing weight.

Parasitic infection is not the only thing that can change the gut microbiome. Obesity is associated with an increase in the bacteria that can efficiently harvest energy from our food, leading to weight gain. However, it’s not all bad. Pregnancy also causes changes to the gut microbiome. These changes allow the body to cope with and provide for two people rather than one.

Treatment for whipworm infection currently depends on a type of medicine that expels parasites from the body, called an anthelmintic. However, resistance to these drugs is growing, like bacterial resistance to antibiotics, reducing their effectiveness. By understanding the interactions between the gut microbiome, our body’s defence system and whipworm, it may be possible to generate new alternative, more effective treatments.


By Emily White, PhD student on placement with Nowgen working on schools and public engagement activities.