Patients with meningococcal infection generally develop symptoms including a high temperature, vomiting and a stiff neck. But they might also just have a bad stomach ache. This can be so severe that they are sometimes wrongly operated for appendicitis. Researchers decided to investigate the question. And the results speak for themselves: 10% of patients infected by the meningococcal strain that is on the rise in Europe suffer from abdominal pain.

Patients with meningococcal infection generally develop symptoms including a high temperature, vomiting, and a stiff neck… but they might also just have a bad stomach ache. This can be so severe that they are sometimes wrongly operated for appendicitis. Teams from the Institut Pasteur and the Department of Pediatrics at Bicêtre Hospital (AP-HP) decided to investigate the question.

And the results speak for themselves: 10% of patients infected by the meningococcal strain that is on the rise in Europe suffer from abdominal pain. This atypical form of the disease is becoming increasingly common and needs to be brought to the attention of physicians. The findings are published in Clinical Infectious Diseases.

Within the first 24 hours of meningococcal infection — which can give rise to meningitis and septicemia as well as arthritis, peritonitis, etc. -, patients generally suffer from headaches, vomiting and a stiff neck. Over the past few years, however, abdominal pain has been observed as another early clinical sign — but physicians tend not to think of invasive meningococcal disease.

"When doctors see patients suffering from stomach pain, invasive meningococcal disease doesn't immediately spring to mind. They tend to think of gastroenteritis or possibly appendicitis," explains Muhamed-Kheir Taha, lead author of the study and Head of the National Reference Center for Meningococci (CNRM) at the Institut Pasteur.

"But delays in diagnosis and appropriate treatment for those affected can be deadly. Invasive meningococcal disease is fatal in virtually all cases if antibiotics are not administered rapidly." Researchers decided to take a closer look at these abdominal forms to assess their frequency and raise awareness among physicians of this new face of the disease.

Since the meningococcal disease is a notifiable condition, the CNRM has received all the bacterial strains responsible for meningococcal infections in France since the 1980s. So the scientists were able to analyze some 12,000 meningococcal strains kept at the CNRM between 1991 and 2016 and examine the clinical presentations of the patients infected.

The research team sequenced all the genomes of the bacteria in their collection to identify what sets them apart from other strains and what might explain the resulting abdominal pains. Here again, the scientists' findings were relatively clear. The group W bacterial strain that is currently spreading across Europe and the world has around a hundred specific genes, some of which are involved in the inflammatory response.

"We should remember that the bacteria infect the vessels which supply blood to the abdomen and the digestive system," emphasizes Muhamed-Kheir Taha. "If these bacteria are likely to induce a stronger inflammatory response in tissues, that could explain the abdominal pains."