Ashutosh Mangalam, University of Iowa

Multiple sclerosis is a disease that results when the immune system mistakenly attacks the brain and spinal cord. It affects nearly one million people in the U.S. and over 2.8 million worldwide. While genetics play a role in the risk of developing multiple sclerosis, environmental factors such as diet, infectious disease and gut health are major contributors.

The environment plays a key role in determining who develops multiple sclerosis, and this is evident from twin studies. Among identical twins who share 100% of their genes, one twin has a roughly 25% chance of developing MS if the other twin has the disease. For fraternal twins who share 50% of their genes, this rate drops to around 2%.

Scientists have long suspected that gut bacteria may influence a person’s risk of developing multiple sclerosis. But studies so far have had inconsistent findings.

To address these inconsistencies, my colleagues and I used what researchers call a bedside-to-bench-to-bedside approach: starting with samples from patients with multiple sclerosis, conducting lab experiments on these samples, then confirming our findings in patients.

In our newly published research, we found that the ratio of two bacteria in the gut can predict multiple sclerosis severity in patients, highlighting the importance of the microbiome and gut health in this disease.

Bedside to bench

First, we analyzed the chemical and bacterial gut composition of patients with multiple sclerosis, confirming that they had gut inflammation and different types of gut bacteria compared with people without multiple sclerosis.

Specifically, we showed that a group of bacteria called Blautia was more common in multiple sclerosis patients, while Prevotella, a bacterial species consistently linked to a healthy gut, was found in lower amounts.

In a separate experiment in mice, we observed that the balance between two gut bacteria, Bifidobacterium and Akkermansia, was critical in distinguishing mice with or without multiple sclerosis-like disease. Mice with multiple sclerosis-like symptoms had increased levels of Akkermansia and decreased levels of Bifidobacterium in their stool or gut lining.

Bench to bedside

To explore this further, we treated mice with antibiotics to remove all their gut bacteria. Then, we gave either Blautia, which was higher in multiple sclerosis patients; Prevotella, which was more common in healthy patients; or a control bacteria, Phocaeicola, which is found in patients with and without multiple sclerosis. We found that mice with Blautia developed more gut inflammation and worse multiple sclerosis-like symptoms.

Even before symptoms appeared, these mice had low levels of Bifidobacterium and high levels of Akkermansia. This suggested that an imbalance between these two bacteria might not just be a sign of disease, but could actually predict how severe it will be.

We then examined whether this same imbalance appeared in people. We measured the ratio of Bifidobacterium adolescentis and Akkermansia muciniphila in samples from multiple sclerosis patients in Iowa and participants in a study spanning the U.S., Latin America and Europe.

Our findings were consistent: Patients with multiple sclerosis had a lower ratio of Bifidobacterium to Akkermansia. This imbalance was not only linked to having multiple sclerosis but also with worse disability, making it a stronger predictor of disease severity than any single type of bacteria alone.

How ‘good’ bacteria can become harmful

One of the most interesting findings from our study was that normally beneficial bacteria can turn harmful in multiple sclerosis. Akkermansia is usually considered a helpful bacterium, but it became problematic in patients with multiple sclerosis.

A previous study in mice showed a similar pattern: Mice with severe disease had a lower Bifidobacterium-to-Akkermansia ratio. In that study, mice fed a diet rich in phytoestrogens – chemicals structurally similar to human estrogen that need to be broken down by bacteria for beneficial health effects – developed milder disease than those on a diet without phytoestrogens. Previously we have shown that people with multiple sclerosis lack gut bacteria that can metabolize phytoestrogen.

Although the precise mechanisms behind the link between the Bifidobacterium-to- Akkermansia ratio and multiple sclerosis is unknown, researchers have a theory. Both types of bacteria consume mucin, a substance that protects the gut lining. However, Bifidobacterium both eats and produces mucin, while Akkermansia only consumes it. When Bifidobacterium levels drop, such as during inflammation, Akkermansia overconsumes mucin and weakens the gut lining. This process can trigger more inflammation and potentially contribute to the progression of multiple sclerosis.

Our finding that the Bifidobacterium-to-Akkermansia ratio may be a key marker for multiple sclerosis severity could help improve diagnosis and treatment. It also highlights how losing beneficial gut bacteria can allow other gut bacteria to become harmful, though it is unclear whether changing levels of certain microbes can affect multiple sclerosis.

While more research can help clarify the link between the gut microbiome and multiple sclerosis, these findings offer a promising new direction for understanding and treating this disease.

Ashutosh Mangalam, Associate Professor of Pathology, University of Iowa

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Daniel Speed Thompson, University of Dayton

For more than two weeks, eyes have been on the Vatican, awaiting news about Pope Francis’ health. The pope has been at Rome’s Gemelli Hospital since Feb. 14, 2025, being treated for double pneumonia and other complications.

When a pope is ill, resigns or passes away, who steps in? And who else helps lead the Holy See? The Conversation U.S. asked Daniel Speed Thompson, a theologian at the University of Dayton, for some insight into Vatican City.

Who are the most powerful people at the Vatican, besides the pope?

The Vatican houses the central government of the Catholic Church and is also an independent city-state. The pope is both the head of the Catholic Church and head of state.

In order to govern both, he has the Roman Curia, meaning “court.” In modern terms, the Curia is the papal bureaucracy. It is an extension of the pope’s authority.

In Catholic doctrine, the pope has the highest authority in the church. He can exercise it alone or with the College of Bishops, made up of all the bishops in the world. Bishops named by the pope to the office of “cardinal” can, if under 80 years old, vote to elect a new pope. Some cardinals, but by no means all, serve in the papal Curia in Rome.

Besides the pope, curial officials who oversee important aspects of the church’s political and religious life are often powerful figures. For example, the secretariat of state, headed by Cardinal Pietro Parolin, oversees relations with other countries and international organizations. It also oversees the Vatican’s diplomatic corps.

The Dicastery – “department” – for the Doctrine of the Faith, led by Cardinal Víctor Manuel Fernández, addresses questions about correct Catholic teaching on faith and morals. The Dicastery of Bishops, headed by Cardinal Robert Prevost, coordinates the nominations of new bishops around the world.

All these officials work under the authority of the pope, advocating for and implementing his agenda. For example, Prevost has suggested that all Catholics should be involved in the selection of bishops. This idea is linked with Francis’ call for a more “synodal” church: one that is less hierarchical and shaped by lay Catholics’ concerns and challenges.

If a pope can’t fulfill his duties, who steps in?

When a pope dies – or resigns, like Benedict XVI did in 2013 – the governance of the Catholic Church formally falls to the College of Cardinals. However, the authority of the college is very limited. On their own, cardinals cannot make any significant decisions concerning faith, morals and worship. Nor can they undo previous papal decisions or change church laws about electing a new pope.

All the heads of the dicasteries lose their office upon the death or resignation of a pope. The College of Cardinals serves as a caretaker government whose primary purpose is to prepare for the election of the new pope and oversee day-to-day workings of the Vatican.

One cardinal, known as the “camerlengo,” is responsible for confirming the pope’s death or resignation. He then assumes control over the pope’s residence and coordinates the funeral, if needed. The camerlengo also takes custody of the Vatican’s property in Rome and supervises details for the upcoming conclave.

The day-to-day business of the Catholic Church continues, but no big decisions can be made in the absence of a pope. The church cannot appoint new bishops, and the Vatican cannot start new diplomatic efforts.

Are officials at the Vatican often nominated to be pope?

Sometimes. Francis was a cardinal from Argentina before his election as pope and had not served in the Roman Curia. However, Benedict XVI, Francis’ predecessor, did serve as the prefect of the Congregation – now called Dicastery – for the Doctrine of the Faith. Some recent popes served in the Curia earlier in their career but not immediately before their election.

What do you wish more people understood about the Vatican?

Three things. First, the Vatican is unlike any organization in the world. Its religious mission and political status rest on nearly 2,000 years of history. This complicated story provides a unique tradition that anchors the institution of the Catholic Church, but can also block the church from critical self-examination and renewal.

Second, the Vatican is like every organization in the world. Vatican officials can be faithful to the highest standards of their religion, truly wishing to serve the church and the common good of humanity. But they can also be flagrantly immoral, even criminals, and careerist seekers of status or luxury. Francis has consistently called out priests and bishops who see themselves as somehow superior by virtue of their office or their ordination.

Finally, compared with the massive bureaucracies of modern governments and corporations, the Vatican is relatively small and not as wealthy as it is often portrayed.

Although the Curia manages a vast international organization, its resources are far closer to my own midsize Catholic university than to the U.S. government or Apple. Vatican City and the Holy See employ about 2,000 people, with an operating budget of about US$835 million.

Yes, the Catholic Church has wealth – and the ongoing problem of deficits and financial corruption. But the Vatican’s resources pale in comparison with what a modern state or large company can muster.

Daniel Speed Thompson, Associate Professor of Religious Studies, University of Dayton

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Annette Regan, University of California, Los Angeles

In February 2025, flu rates spiked to the highest levels seen in at least 15 years, with flu outpacing COVID-19 infections and hospitalizations for the first time since the beginning of the COVID-19 pandemic. The Centers for Disease Control and Prevention has classified this flu season as having “high” severity across the U.S.

The Conversation asked epidemiologist Annette Regan to explain why this flu season is different from last year’s and what people can do to help reduce the spread.

How do flu cases and hospitalizations this year compare with previous years?

Beginning in late January and extending through February 2025, flu hospitalizations have been higher than any other week since before 2009.

Most flu cases appear to be from influenza A strains, with a split between influenza A/H3N2 and influenza A/H1N1. These are two different subtypes of the influenza A virus.

Researchers believe that historically seasons that are predominated by influenza A/H3N2 infections tend to be more severe, but infections from influenza A/H1N1 can still be very severe.

This year’s season is also peaking “late” compared with the past three flu seasons, which peaked in early or late December.

Unfortunately, there have been a number of deaths from flu too this season. Since Jan. 1, 2025, alone, over 4,000 people, including 68 children, have died from flu. While the number of deaths do not mark a record number, it shows that flu can be a serious illness, even in children.

Why are flu cases so high this year?

There are a number of factors behind any severe season, including poor community protection from low immunization rates and low natural immunity, virus characteristics, vaccine effectiveness and increased human contact via travel, office work or schools.

Unfortunately, flu vaccination rates have declined since the COVID-19 pandemic. At the end of the 2023-24 flu season, 9.2 million fewer doses were administered in pharmacies and doctors’ offices compared with an average year before the pandemic.

In addition, since 2022, fewer and fewer doses of flu vaccine have been distributed by private manufacturers. Flu vaccination rates for adults have historically been in the 30% to 60% range, much lower than the recommended 70%. Before the COVID-19 pandemic, flu vaccination rates were increasing by around 1% to 2% every year.

Flu vaccination rates began dropping after the COVID-19 pandemic, especially in higher-risk groups. Flu vaccination in children has dropped from 59% in 2019-20 to 46% in 2024-25. In adults 65 years and older, the group with the greatest risk of hospitalization and death, flu vaccination rates dropped from 52% in 2019-20 to 43% in 2024-25.

Lower vaccination rates mean a greater portion of the population is not protected by vaccines. Data shows that vaccination reduces the risk of flu hospitalization. Even if a vaccinated person gets infected, they may be less likely to experience severe illness. As a result, low vaccination rates could contribute to higher flu severity this season.

However, low vaccination rates are probably not the only reason for the high rates of flu this season. In previous severe seasons, genetic changes to the viruses have made them better at infecting people and more likely to cause severe illness.

The effectiveness of annual flu vaccines varies depending on how well the vaccine matches the circulating virus. The effectiveness of vaccines ranges from 19% to 60% in any given season. In the 2023-24 flu season, the vaccine was 42% effective.

Similarly, early 2024-25 data from the U.S. shows that the vaccine was 41% to 55% effective against flu hospitalizations in adults and 63% to 78% effective against flu hospitalizations in children.

How do seasonal flu symptoms differ from COVID-19 and other illnesses?

It’s important to remember that people often incorrectly refer to “the flu” when they have a common cold. Flu is caused only by the influenza virus, which tends to be more severe than common colds and more commonly causes a fever.

Many of the signs and symptoms for flu, COVID-19 and other respiratory viruses are the same and can range from mild coldlike symptoms to pneumonia and respiratory distress. Common flu symptoms are fever, cough and fatigue, and may also include shortness of breath, a sore throat, nasal congestion, muscle aches and headache.

Some symptoms, such as changes in or loss of taste and smell, are more common for COVID-19. For both COVID-19 and flu, the symptoms do not start until about one to four days after infection, and symptoms seem to last longer for COVID-19.

The only way to know what virus is causing an infection is to test. This can be done using a rapid test, some of which now test for flu and COVID-19 together, or by seeing a doctor and getting tested using a nasal swab. There are prescription antiviral medications available to treat flu and COVID-19, but they need to be taken near the time that symptoms start.

Some people are at high risk of severe flu and COVID-19, such as those who are immunosuppressed, have diabetes or have chronic heart or lung conditions. In these cases, it is important to seek early care and treatment from a health care professional. Some doctors will also prescribe via telehealth calls, which can help reduce the strain on doctors’ offices, urgent care centers and emergency rooms when infection rates are high.

What can people do now to help steer clear of the flu?

There are a number of ways people can reduce their risk of getting or spreading flu. Since the flu season is still underway, it’s not too late to get a flu vaccine. Even in seasons when the vaccine’s effectiveness is low, it is likely to offer better protection compared with remaining unvaccinated.

Handwashing and disinfecting high-traffic surfaces can help reduce contact with the flu virus. Taking efforts to avoid contact with sick people can also help, including wearing a mask when in health care facilities.

Finally, remember to take care of yourself. Exercising, eating healthy and getting sufficient sleep all help support a healthy immune system, which can help reduce chances of infection.

Those who have been diagnosed with flu or are experiencing flu-like symptoms should avoid contact with other people, especially in crowded spaces. Covering coughs and sneezes can help reduce the amount of virus that is spread.

Annette Regan, Adjunct Associate Professor of Epidemiology, University of California, Los Angeles

This article is republished from The Conversation under a Creative Commons license. Read the original article.