Prof Salim Safrudeen Abdool Karim
Image: Supplied
FOLLOWING a recent hantavirus outbreak linked to an international cruise ship, South African epidemiologist Salim Abdool Karim reassures the public that the risk of widespread transmission remains low, despite the virus's severe symptoms.
As fears of another global pandemic surface following Covid-19, Abdool Karim said the virus was unlikely to spread widely, despite its severe symptoms and high fatality rates in some cases.
Abdool Karim, one of South Africa’s foremost public health experts who played a key role in the country’s response to both HIV/Aids and Covid-19, told the POST that the hantavirus was naturally carried by rodents and only occasionally infected humans.
“The hantavirus normally infects rodents, mice, rats, hamsters and squirrels. The virus does not make the animals sick. They just live with the virus naturally,” he said.
According to Abdool Karim, transmission to humans occurs primarily through exposure to infected rodent urine or faeces.
“The rat’s faeces and urine came into contact with one of the passengers. The rat could have gotten on to the ship at one of the ports, or one of the patients could have picked it up in Argentina before they set sail. Either is feasible,” he said.
Hantavirus has only recently entered public discussion, but Abdool Karim noted that the disease had existed for centuries.
“Hantavirus have been infecting humans since before Christ. There are descriptions of hantavirus epidemics in ancient China.”
The virus was formally identified much later, during the aftermath of the Korean War. Thousands of United Nations soldiers stationed near Korea’s Hantan River became ill with what was then a mysterious disease.
“In 1978, a Korean scientist isolated the virus. It was named after the Hantan River in Korea.”
Scientists now understand that hantavirus is not a single virus, but rather a large family of related viruses.
“The hantavirus is not a single virus. There are many different viruses. They are cousins of each other.”
The strain currently under scrutiny is believed to be the Andean strain, commonly found in parts of South America including Argentina and Brazil.
“The one on the ship is called the Andean strain from the Andes mountains. That particular strain is quite common in Argentina and Brazil, so that is probably where they picked it up.”
While many infections remain mild or even unnoticed, hantavirus can become devastating in severe cases.
“When this hantavirus infects humans, it can lead to just a very mild infection, a bit like flu but it can also lead to a very severe form of disease.”
In its most dangerous form, hantavirus could trigger haemorrhagic fever, a condition marked by uncontrolled bleeding and organ failure, said Abdool Karim.
Drawing from his own experience running a haemorrhagic fever ward at Durban’s King Edward VIII Hospital during the 1990s, Abdool Karim described the terrifying progression of severe diseases.
“A patient with haemorrhagic fever has blood running from their eyes, ears … everywhere because they cannot stop the bleeding,” he said.
The Andean strain linked to the current outbreak predominantly attacks the lungs rather than the kidneys, leading to respiratory complications.
“The Andean strain of the hantavirus predominantly causes a respiratory infection; an infection in the lungs. That is probably how it is spreading from human to human.”
Most hantaviruses are classified as zoonotic diseases, meaning they spread from animals to humans but not between people. However, Abdool Karim warned that the Andean strain was one of the rare exceptions.
“Most hantaviruses do not spread from human to human. But this Andean strain has been shown to spread from person to person.”
Even so, transmission requires extremely close contact, "like sitting in the same bed with someone. It is not an easy virus to spread. It is not like Covid-19".
Evidence of such transmission has already emerged aboard the affected ship.
“The doctor on the ship got infected from the patient,” Abdool Karim revealed.
Despite decades of scientific knowledge about hantavirus, no vaccine or antiviral treatment currently exists.
“There is no vaccine for this virus. We can diagnose it, but we cannot really treat it.”
The primary method of controlling outbreaks remains quarantine and isolation.
“There is a test you can do in the lab on the blood that tells you this is a hantavirus,” Abdool Karim added.
Abdool Karim highlighted that research showed exposure to hantavirus could be more common than many realised.
“There was a study done of pet shop owners who sell rodents. About 80% of these pet shop owners had antibodies against hantavirus. They got infected and did not even know it.”
This suggests many people may contract mild or asymptomatic infections without ever developing severe disease.
However, for those who do become critically ill, outcomes can be grim.
“The survival rate can vary from around 66% to 98%, but once you get the haemorrhagic form of the disease, the survival rate is not good.”
Health authorities are now tracing passengers who disembarked from the cruise ship and travelled internationally before the outbreak was identified.
“Some patients got off and flew to their homes. That is how we got the patient who collapsed at the airport after flying from St Helena to Johannesburg.”
He expects additional infections may still emerge among close contacts and fellow travellers.
Abdool Karim remains confident the outbreak could be contained.
“I would bet that we will just see a handful of new infections and that would be the end of this outbreak,” he said.
In a world still shaped by the trauma of Covid-19, public anxiety around emerging viruses remains high. But Abdool Karim emphasised that hantavirus lacked the characteristics needed to spark a global pandemic.
“It is very unlikely that the virus would cause a pandemic. People do not need to panic.”
He noted that unlike Covid-19, hantavirus did not spread efficiently between humans and was already well understood by scientists.
“Now we know hantavirus, we understand how it spreads, and we know how to contain it.”