Co-infection with malaria weakens immune response to helminth worms

06 July 2015

Helminth worm

Image: Helminth worm©  Mark Wilson

New research by Francis Crick Institute scientists shows that mice simultaneously infected with gastrointestinal worms and the parasite that causes malaria will focus their immune response on the more dangerous malaria parasite, allowing the worms to persist long-term. 

The research identifies complexities relating to simultaneous infection with the worms, called helminths, and the malaria parasite, called Plasmodium. The work was led by Drs Mark Wilson and Jean Langhorne, currently based at Mill Hill. 

Dr Wilson said: "Helminth worms infect almost a third of the world's population, with many of them causing long-term infections and significant illness. In areas where helminth infections are widespread, co-infections with other parasites, bacteria and viruses are more common than single helminth infections." 

The scientists used state-of-the-art molecular biology techniques to simultaneously track single immune cells responding to the helminth infection or the malaria parasite infection or, in some cases, both. This showed that when the mice were infected with the malaria parasite as well as the helminth, the immune cells that were responding to the helminth infection completely changed their focus and started responding to the malaria parasite instead.

This preferential response to more life-threatening infections may come at the cost of allowing less-pathogenic parasites to persist, contributing to chronic infection, suggest the researchers. 

Dr Wilson said: "This study highlights the complexity of co-infection and specifically identifies the demands placed upon the host immune system during co-infection. Reducing the frequency of life-threatening infections such as malaria may enhance the effectiveness of anti-helminth treatments."

The paper, IFNγ and IL-12 Restrict Th2 Responses During Helminth/<i>Plasmodium</i> Co-infection and Promote IFNγ from Th2 Cells, is published in PLOS Pathogens.

  • Francis Crick Institute researchers have shed light on weaker immune responses to helminth worms for patients infected with the malaria parasite at the same time. The weaker reponse to the worms may allow them to persist long term, causing chronic infection.
  • The work has implications for the treatment of helminth worms, and suggests that malaria prevention may make anti-helminth treatment more effective.
  • The work was supported by the Medical Research Council.