World Health Organization response to hantavirus

Interview with Maria van Kerkhove, World Health Organization

Part of the show Hantavirus outbreak: cruising for a biological bruising

We are going to get the latest on the outbreak now. Maria van Kerkhove is the head of the emerging diseases and zoonosis unit at the World Health Organization, and she's been telling Chris Smith about the response…

Maria - First of all, I'm going to say thanks for having me on your show because I always love doing this show with you. It's been 10 days since we first became aware of what we now know are cases of hantavirus on this cruise ship. In the last 10 days, there has been a highly organised choreographed outbreak investigation to understand, you know, who is infected with incredible laboratory support from South Africa, from Dakar, from the Netherlands, from Switzerland. I mean, incredible quick diagnostics and sequencing to track an unfolding cluster of hantavirus is associated with a cruise ship, which started in Argentina and moved up the coast of Africa. And over the course of these last 10 days, there have been 11 cases that have been identified. Nine of these are confirmed, two of them are probable. We've had, unfortunately, three deaths. We have had the ship dock in the Canary Islands with massive efforts from Spain, the Netherlands, and all of this coordinated by WHO of repatriated passengers and crew back to their home countries where active follow-up is taking place to monitor them for signs and symptoms, for the laboratory testing, all in an effort to contain. And I think it's really important to stress that this is not a COVID situation. The story is not over, but a lot of actions have taken place to actually minimise the impact of hantavirus on this cruise ship.

Chris - Do we have a source yet?

Maria - Our current working hypothesis is that the first two cases, who were a couple, who unfortunately died prior to them getting on the ship, they were in Argentina, and they had gone on some birdwatching tours in Argentina and Chile and Uruguay. And in these areas, there are rodents that carry hantavirus, that carry the Andes virus in particular. And our working hypothesis, because we know the incubation period can be quite long, up to six weeks, we think they were infected, one of them at least, certainly the first case, but perhaps both, off of the ship. And given that they boarded the ship in Argentina and they went on this cruise, there was potentially some human-to-human transmission, particularly to the ship's doctor, who is in isolation in the Netherlands and I understand stable, which is good news, to another crew member who was a guide, and to some others. So we're really trying to better understand what happened on the ship in terms of what types of contacts actually resulted in transmission. But our working hypothesis is that it started prior to the ship's departure in Argentina on the 1st of April, and that over the course of the last month or so, there was some limited human-to-human transmission on the ship.

Chris - When do we think the infectivity period for a case is? In other words, when a person becomes a potential threat to someone else?

Maria - When they are symptomatic. However, there may be a two-day period beforehand, where there could be some transmission.But this is very, very different than COVID, like we've said before.

Chris - Given that window, how many people then are you currently considering as possible contacts slash incubatees that we need to follow up or at least have on the list?

Maria - So we are actively working with all of the countries that had nationalities on board, and people who have come into contact with passengers when they were off the ship. So there's a detailed, detailed list of individuals. Certainly our characterisation of anyone on the ship, passengers and crew, we treat them as high risk contacts, which means we are recommending a 42-day period of active follow-up and quarantine either in a dedicated facility or at home. And what we mean by active follow-up is daily checks of their health, that they are not in contact with other people. If anyone develops symptoms, they should be isolated immediately and medically cared for.So there are people that we are following, the passengers and crew on the ship, so that's the 147 that were there, the people that disembarked in St. Helena, the people who were on the flight, the medical attendants in South Africa. So it's not a huge number of people, but it is a concentrated list, and we do have excellent people in the countries that are following each of these people up.

Chris -And is this a tried and tested method, asking people to self-monitor at home as long as they stay asymptomatic, and obviously you escalate accordingly after that? Do we know that's a reliable and safe way to manage a situation like this?

Maria - We'd actually prefer more of an active follow-up, which can be done in person, it can be done by phone, but really to follow these individuals for that 42-day period, which has been decided that the last point of exposure was on May 10th. So that actually brings us up to June 21st, if I'm not mistaken. Certainly people, if they are asymptomatic, can self-monitor, and I think in this situation there's so much attention to it that they will oblige. But remember, not all countries are the same. If people are in self-quarantine or in quarantine in a facility, they need to be cared for, they need to be given food, they need to be given water, they need to be respected, we don't want people losing their jobs, we don't want any stigma associated with this. It's just really just trying to take a precautionary principled approach to limiting any further spread. But we rely on the medical authorities in all of these countries to actively monitor and follow up each of these individuals.

Chris - So there's no obligation on some of these individuals to actually comply?

Maria - We give our recommendations and we work with the countries to set the policies in the countries, and not every country is doing the same thing in terms of their follow-up.

Chris - One infectious diseases physician has suggested that there's a line in the sand of about May 19th, because based on the incubation period we've seen for the other cases so far, if we're going to get tertiary cases, so we've got the first person who gave it to these second people, if these second people have given it to anybody else, they ought to be manifesting by then.  So if we don't see cases at that point, does that give us a lot more reassurance? Does that make us feel even more comfortable? 

Maria - I think the numbers may fluctuate in the next couple of days. Certainly, even in the last 24 hours, people that have gone home, there will be serology that will be done.  So I think the numbers will change a little bit. What I feel confident in is the management of all of these individuals and the active follow-up now. So, I think if we do see additional cases, it doesn't mean that the situation is out of control. It just means that laboratory testing is underway, people will get medical care. We haven't had any more deaths. And while we have had three deaths that are tragic, we haven't had any further deaths among the confirmed cases or anywhere else. And I think that is a good sign. The people who are in ICU in the Netherlands and in South Africa, in Switzerland are doing well. So that to me is incredibly encouraging.  But our work is not over. So, we're working with the governments to make sure that we're getting regular feedback on all of the contacts. Anyone who develops symptoms needs to be immediately notified. And I think we should wait until June to understand the full extent of this. But I am confident in how everything has been managed. Can we guarantee? Of course not.  But I am confident in how countries, how seriously they have taken this, their obligations to care for the people involved and to make sure that they take all of the precautions to limit any potential further spread.