Iranian epidemiologists say the symptoms associated with COVID-19 in Iran have changed from respiratory to gastrointestinal.

They also believe the shift to gastrointestinal symptoms which are often accompanied with no fever or only low fever cause a delay in diagnosis and result in the further spread of the virus by those who are infected but have no obvious respiratory symptoms to be tested.

"COVID-19 had symptoms such as coughs, shortness of breath and high fever before. These symptoms were observed in the first two months after the outbreak. But now the most important symptoms of COVID-19 are gastrointestinal, " Dr. Mohammad-Reza Mahboubfar, a viral epidemiologist and member of the Coronavirus Taskforce, said on Monday.

According to Dr. Mahboubfar symptoms such as acute diarrhea, abdominal spasms, stomachache, nausea, vomiting, loss of appetite, low fever and loss of taste and smell are more prevalent now in COVID-19 patients from various age groups including the elderly and children.

On May 16, Dr. Seyed Dr. Hassan Abedi, a gastroenterologist of Babol Medical Sciences University, warned about the change in the symptoms of COVID-19 and said fewer patients with respiratory symptoms were being hospitalized but there was an increase in those suffering from gastrointestinal complications.

Dr. Abedi maintains that a quarter of all COVID-19 patients only show gastrointestinal symptoms and for the same reason seek medical care later than those whose respiratory symptoms are more pronounced. He warns that delayed diagnosis of coronavirus in patients with milder gastrointestinal symptoms may cause the virus to spread at a higher rate.

According to Dr. Abedi who serves at one of the hospitals for coronavirus patients in the northern city of Babol, one of the earliest hotspots of the epidemic, gastrointestinal symptoms are not accompanied with high temperature in about one-third of patients but diarrhea in these patients is acute, may occur at least five times a day and last up to two weeks.

Some Iranian health specialists have pointed out that coronavirus can also cause liver and pancreas damage in COVID-19 patients. Dr. Seyed Reza Fatemi, a gastroenterologist from Shahid Beheshti University of Tehran, says that up to 50 percent of COVID-19 patients show gastrointestinal symptoms and that the virus causes liver damage and inflammation of the pancreas in 20 to 30 percent of all patients, especially those with other acute symptoms.

Cases of brain stroke due to coronavirus have also been reported in Iran. Dr. Mahmoud-Reza Ashrafi, a professor of medicine at Tehran University of Medical Sciences says in March there were even several cases of brain stroke in children which may have been due to coronavirus. "Oxygen deprivation and inflammation resulting from COVID-19 can result in thrombosis in arteries and brain strokes," he says.

Some experts, however, say mutation of the virus which may be the cause of new symptoms should not cause too much concern. "Coronavirus is not like the common flu virus that mutates constantly. It may change over time and cause atypical symptoms such as gastrointestinal symptoms, but we shouldn't worry that it will mutate quickly to the point of infecting those who have become immune again," Dr. Hossein Keivani, professor of virology at Tehran University told Radio Farda.

Dr. Mahboubfar who is also a crisis management expert says the change of the symptoms may be affecting the Health Ministry's official statistics on COVID-19. The Ministry's figures do not include patients with the newly emerged gastrointestinal symptoms who are not tested and are therefore lower than the real figures, he says.

Chinese researchers have also noted that the characteristics of gastrointestinal symptoms in COVID-19 are more insidious than the respiratory symptoms, making them easy to overlook.

Their findings show that patients might have only gastrointestinal symptoms during the whole course of this disease, and some continue to shed the virus in faeces, despite respiratory samples testing negative.

Dr. Mahboubfar predicts that the official number of cases and deaths is going to rise in the coming days because the disease is spreading again in places where it was on decline. "The second wave of coronavirus epidemic has happened as we had predicted," he notes.

Dr. Mahboubfar attributes the relaxation of the lockdown in the country to the government's concerns about the economic and social consequences of the lockdown rather than the spread of the virus having come under control.

According to official figures which many believe are too low due to being based solely on cases confirmed by testing, 125,000 cases of COVID-19 have been diagnosed and more than 7,000 have lost their lives since mid-February.