Hantavirus response appropriate, but preparedness gaps remain: Top virologist Dr Shahid Jameel
Dr Shahid Jameel said the hantavirus response linked to the MV Hondius outbreak appears appropriate. He said the episode highlights global gaps in surveillance and the need for sustained preparedness.
Dr Jameel, to begin with, please help us understand this outbreak. Hantavirus has existed for decades, so why is there suddenly so much concern around it, with some even fearing another pandemic?
This is not a new virus. Hantavirus has been causing periodic outbreaks for decades in regions where it is endemic. In fact, the last major outbreak before COVID-19 was in 2018, when a little over a hundred people were infected and more than 30 died.
What has changed is the context. We are now living in a post-COVID world, where people are understandably much more sensitive to outbreaks and emerging infections. That heightened awareness is one reason this outbreak has drawn attention.
The other reason is the nature of transmission in this particular incident. Whenever you place one or two infected individuals in a closed environment with a high density of people, any virus capable of human-to-human transmission will spread more easily. A cruise ship is essentially an isolated ecosystem – almost like putting people in a room and shutting the windows. That is likely what happened here.
Is there concern that the virus could now spread to newer populations or countries where people have not been exposed before?
It is a concern, but not a major one at this point. People from around 23 different countries were reportedly on the cruise ship, and some may have been exposed. However, the latest reports suggest that exposed individuals are being isolated and monitored wherever they have traveled.
Importantly, this virus does not transmit very easily from one person to another. It can spread, but not nearly as efficiently as SARS-CoV-2 did during COVID-19. As long as authorities continue monitoring exposed individuals and their contacts, I expect that within a couple of weeks this outbreak will no longer pose a major threat.
There was also a reported case of transmission during a flight. Does that indicate the virus may spread more easily than previously believed?
I do not know the exact details of that specific case, so it is difficult to comment conclusively.
What we do know is that aeroplanes are also closed ecosystems. Around 80 percent of the air in aircraft cabins is recirculated. So, in that sense, an aeroplane resembles the same kind of enclosed setting as a cruise ship.
If we started seeing infections occurring in open environments, among people without known contact histories, then I would be much more concerned that the virus was circulating more freely and transmitting more efficiently. But if the only positive cases are among known contacts of earlier patients, then I do not think there is reason for alarm.
Genomic sequencing of the virus has now been made public. Have you had a chance to review it? Is there any indication that the virus has changed?
I have not personally reviewed the sequencing data yet, so I cannot comment in detail. What has been reported publicly is that the virus involved is the Andes strain, which makes sense because the initial patients had reportedly traveled through regions such as southern Argentina, Chile, and Uruguay, where the Andes strain is endemic.
So far, there is nothing unusual in those reports. However, I have not directly compared the new sequences with previously known Andes strain sequences, so I cannot say whether any significant mutations have occurred.
Hantavirus is not entirely new to India either. A few cases have previously been reported in states such as Kerala and Tamil Nadu. Could you explain how strains differ across regions?
Yes, the disease manifestations differ quite significantly across regions. The strains found in the Americas are typically associated with cardiopulmonary disease, meaning they primarily affect the lungs and heart. In contrast, strains seen in Asia and Africa are more often hemorrhagic, meaning they can cause bleeding complications.
These differences may arise from two factors. One is how the human host responds immunologically to the virus, and the other could be linked to genetic differences in the virus itself.
We also have to remember that human populations are genetically distinct across regions. Populations in the Americas differ genetically from populations in South Asia or Africa, and that may influence disease outcomes as well.
Many scientists have warned that climate change and deforestation are increasing the risk of zoonotic spillovers. Can this outbreak also be viewed through that lens?
Absolutely. It is increasingly clear that zoonotic spillovers are becoming more frequent because of climate change and environmental destruction.
If you look at mammals that commonly harbour viruses, rodents and bats are among the largest groups. Humans are another. Normally, these species remain separated because their habitats differ. But when forests are destroyed or biodiversity declines due to climate change, animals are forced to move closer to human settlements in search of food and shelter.
Bats may move toward orchards or farms. Rodents may enter human habitation. That inevitably increases opportunities for viruses to jump into humans.
As the planet warms and habitats continue to overlap, these events will keep occurring more frequently.
What lessons does this outbreak offer for future preparedness?
The biggest lesson is that we need continuous surveillance.
We must routinely monitor both human populations and animal ecosystems, especially rodents and bats. COVID-19 demonstrated how valuable genomic sequencing can be, and the cost of sequencing has fallen dramatically.
We also saw during COVID that wastewater surveillance could predict outbreaks weeks in advance in localised populations. These are tools we should be using continuously.
If we fail to maintain that kind of surveillance infrastructure, outbreaks like this will continue to surprise us.
If you had to identify virus families that deserve especially close monitoring, which ones would they be?
Influenza would certainly be high on that list.
Bird flu viruses already infect both birds and mammals. At present, they do not infect humans efficiently, but when they do infect humans, mortality can be high – somewhat similar to what we are seeing with hantavirus.
The concern is that influenza viruses mutate constantly. Most mutations go nowhere, but occasionally a mutation improves transmission. Those are the strains that survive and spread.
What is especially worrying is that bird flu has now crossed into cattle in the United States. That is a significant evolutionary jump because it means the virus is no longer confined to birds.
We should be asking whether similar spillovers are happening elsewhere, including in countries like India. If there are no reports, does that mean we looked and found nothing, or are we simply not looking carefully enough?
How do you assess the current response to this hantavirus outbreak?
The response so far appears appropriate. The key is to isolate exposed individuals and monitor them carefully. Importantly, isolation is different from quarantine. You do not need to forcibly confine people in institutions. Home isolation, with proper monitoring and privacy protections, is sufficient in most cases.
We should avoid the kind of stigma and panic we saw during early COVID, when homes were marked and communities reacted fearfully. That kind of response is unnecessary and counterproductive.
This outbreak will likely die down, but it should serve as a warning that such events will keep occurring unless we invest in long-term surveillance and preparedness.
You mentioned surveillance gaps. Are you referring specifically to India or globally?
Globally. Of course, I speak more about India because I know the system better and care deeply about it. But the problem is worldwide.
For example, the United States has weakened parts of its public health surveillance infrastructure. The CDC divisions responsible for monitoring certain risks, including those associated with cruise ships, have reportedly been reduced.
When institutional systems weaken, vulnerabilities increase. Preparedness is built during peacetime, not during crises.
Finally, what about vaccines? We were told after COVID that mRNA platforms would allow rapid vaccine development for future outbreaks. Does that still hold true here?
The technology certainly exists. mRNA platforms can accelerate vaccine development significantly.
However, developing a vaccine is only part of the challenge. Testing it becomes difficult when dealing with viruses that cause only sporadic outbreaks. Conducting large human trials requires enough cases, and that may not always happen.
So, while vaccine technology is promising, I would not rely entirely on vaccines at this stage. Right now, the priority should be containing this outbreak through isolation, contact monitoring, and stronger surveillance systems. Otherwise, these kinds of outbreaks will continue to emerge unexpectedly.
Dr Jameel, to begin with, please help us understand this outbreak. Hantavirus has existed for decades, so why is there suddenly so much concern around it, with some even fearing another pandemic?
This is not a new virus. Hantavirus has been causing periodic outbreaks for decades in regions where it is endemic. In fact, the last major outbreak before COVID-19 was in 2018, when a little over a hundred people were infected and more than 30 died.
What has changed is the context. We are now living in a post-COVID world, where people are understandably much more sensitive to outbreaks and emerging infections. That heightened awareness is one reason this outbreak has drawn attention.
The other reason is the nature of transmission in this particular incident. Whenever you place one or two infected individuals in a closed environment with a high density of people, any virus capable of human-to-human transmission will spread more easily. A cruise ship is essentially an isolated ecosystem – almost like putting people in a room and shutting the windows. That is likely what happened here.
Is there concern that the virus could now spread to newer populations or countries where people have not been exposed before?
It is a concern, but not a major one at this point. People from around 23 different countries were reportedly on the cruise ship, and some may have been exposed. However, the latest reports suggest that exposed individuals are being isolated and monitored wherever they have traveled.
Importantly, this virus does not transmit very easily from one person to another. It can spread, but not nearly as efficiently as SARS-CoV-2 did during COVID-19. As long as authorities continue monitoring exposed individuals and their contacts, I expect that within a couple of weeks this outbreak will no longer pose a major threat.
There was also a reported case of transmission during a flight. Does that indicate the virus may spread more easily than previously believed?
I do not know the exact details of that specific case, so it is difficult to comment conclusively.
What we do know is that aeroplanes are also closed ecosystems. Around 80 percent of the air in aircraft cabins is recirculated. So, in that sense, an aeroplane resembles the same kind of enclosed setting as a cruise ship.
If we started seeing infections occurring in open environments, among people without known contact histories, then I would be much more concerned that the virus was circulating more freely and transmitting more efficiently. But if the only positive cases are among known contacts of earlier patients, then I do not think there is reason for alarm.
Genomic sequencing of the virus has now been made public. Have you had a chance to review it? Is there any indication that the virus has changed?
I have not personally reviewed the sequencing data yet, so I cannot comment in detail. What has been reported publicly is that the virus involved is the Andes strain, which makes sense because the initial patients had reportedly traveled through regions such as southern Argentina, Chile, and Uruguay, where the Andes strain is endemic.
So far, there is nothing unusual in those reports. However, I have not directly compared the new sequences with previously known Andes strain sequences, so I cannot say whether any significant mutations have occurred.
Hantavirus is not entirely new to India either. A few cases have previously been reported in states such as Kerala and Tamil Nadu. Could you explain how strains differ across regions?
Yes, the disease manifestations differ quite significantly across regions. The strains found in the Americas are typically associated with cardiopulmonary disease, meaning they primarily affect the lungs and heart. In contrast, strains seen in Asia and Africa are more often hemorrhagic, meaning they can cause bleeding complications.
These differences may arise from two factors. One is how the human host responds immunologically to the virus, and the other could be linked to genetic differences in the virus itself.
We also have to remember that human populations are genetically distinct across regions. Populations in the Americas differ genetically from populations in South Asia or Africa, and that may influence disease outcomes as well.
Many scientists have warned that climate change and deforestation are increasing the risk of zoonotic spillovers. Can this outbreak also be viewed through that lens?
Absolutely. It is increasingly clear that zoonotic spillovers are becoming more frequent because of climate change and environmental destruction.
If you look at mammals that commonly harbour viruses, rodents and bats are among the largest groups. Humans are another. Normally, these species remain separated because their habitats differ. But when forests are destroyed or biodiversity declines due to climate change, animals are forced to move closer to human settlements in search of food and shelter.
Bats may move toward orchards or farms. Rodents may enter human habitation. That inevitably increases opportunities for viruses to jump into humans.
As the planet warms and habitats continue to overlap, these events will keep occurring more frequently.
What lessons does this outbreak offer for future preparedness?
The biggest lesson is that we need continuous surveillance.
We must routinely monitor both human populations and animal ecosystems, especially rodents and bats. COVID-19 demonstrated how valuable genomic sequencing can be, and the cost of sequencing has fallen dramatically.
We also saw during COVID that wastewater surveillance could predict outbreaks weeks in advance in localised populations. These are tools we should be using continuously.
If we fail to maintain that kind of surveillance infrastructure, outbreaks like this will continue to surprise us.
If you had to identify virus families that deserve especially close monitoring, which ones would they be?
Influenza would certainly be high on that list.
Bird flu viruses already infect both birds and mammals. At present, they do not infect humans efficiently, but when they do infect humans, mortality can be high – somewhat similar to what we are seeing with hantavirus.
The concern is that influenza viruses mutate constantly. Most mutations go nowhere, but occasionally a mutation improves transmission. Those are the strains that survive and spread.
What is especially worrying is that bird flu has now crossed into cattle in the United States. That is a significant evolutionary jump because it means the virus is no longer confined to birds.
We should be asking whether similar spillovers are happening elsewhere, including in countries like India. If there are no reports, does that mean we looked and found nothing, or are we simply not looking carefully enough?
How do you assess the current response to this hantavirus outbreak?
The response so far appears appropriate. The key is to isolate exposed individuals and monitor them carefully. Importantly, isolation is different from quarantine. You do not need to forcibly confine people in institutions. Home isolation, with proper monitoring and privacy protections, is sufficient in most cases.
We should avoid the kind of stigma and panic we saw during early COVID, when homes were marked and communities reacted fearfully. That kind of response is unnecessary and counterproductive.
This outbreak will likely die down, but it should serve as a warning that such events will keep occurring unless we invest in long-term surveillance and preparedness.
You mentioned surveillance gaps. Are you referring specifically to India or globally?
Globally. Of course, I speak more about India because I know the system better and care deeply about it. But the problem is worldwide.
For example, the United States has weakened parts of its public health surveillance infrastructure. The CDC divisions responsible for monitoring certain risks, including those associated with cruise ships, have reportedly been reduced.
When institutional systems weaken, vulnerabilities increase. Preparedness is built during peacetime, not during crises.
Finally, what about vaccines? We were told after COVID that mRNA platforms would allow rapid vaccine development for future outbreaks. Does that still hold true here?
The technology certainly exists. mRNA platforms can accelerate vaccine development significantly.
However, developing a vaccine is only part of the challenge. Testing it becomes difficult when dealing with viruses that cause only sporadic outbreaks. Conducting large human trials requires enough cases, and that may not always happen.
So, while vaccine technology is promising, I would not rely entirely on vaccines at this stage. Right now, the priority should be containing this outbreak through isolation, contact monitoring, and stronger surveillance systems. Otherwise, these kinds of outbreaks will continue to emerge unexpectedly.
