In a short time in the early millennium, few things may have frightened the average New Yorker more than the words "West Nile," the name given to the mosquito-borne virus that in 1999, began killing birds and eventually people for the first time in the US
Two decades later, the worst fears caused by hysteria in the West Nile did not come to pass. The initial epidemic in New York, which infected at least 59 people and killed 7 people, was not the work of bioterrorists. There have never been mass outbreaks of West Nile arriving on deadly wings like a watch every summer, nor have people of horror died from infecting their brains and cooking from the inside out.
But despite the specialized efforts to spread mosquitoes and surveillance, the virus has flourished extremely well here. First discovered in Uganda in 1937, it is now the most common mosquito-borne disease in the United States, with cases regularly observed in all 48 non-outdoor countries. Along the way, he periodically downgraded bird and horse populations, sickened at least 50,000 people (millions of people were probably infected, but only a minority experienced symptoms), caused devastating neurological disease in 25,000 people and killed over 2,000. And scientists have called the arrival of the West Nile in the US one of the most important events in the world of arbovirology ("arbo", which means insect or arthropod spread), which has happened in the last two centuries.
In recognition of West Nile's 20th anniversary in the US, Gizmodo interviews Laura Kramer, director of the Arbovirus Laboratory at the New York State Department of Health Kramer is one of many experts, though if for a West Nile retrospective published today in the Journal of Medical Entomology, she was also one of the first scientists brought in by the local authority to set up a West Nile monitoring team after the initial cases documented in the summer of 1999. The following talk
Gizmodo: As a lifelong resident of New York, the arrival of West Nile that year was one of the first truly frightening news events that I can remember witnessing. growing up. But what was it about researchers and scientists on the ground trying to study and contain them?
Kramer: At first, the idea that West Nile was here in the US was kind of like "what !?" because the initial thought was that it was St. Louis encephalitis, but St. Louis doesn't kill birds. So it took a little while to deal with it, but not very long.
I have never been afraid. I had questions. It was disturbing that this virus could come to the US, but the big question then was, would it continue? Do you know, will it succeed in winter? And if it succeeds, will it succeed in establishing itself? And if it does, what happens when it reaches the southern states, where there is a much longer transmission season? I think when you're in the middle, you have no fear. You just have these questions. What do we have to do? How can we achieve it? Let's get there.
Gizmodo: Eventually the virus spread to the east, south, and eventually everywhere, with the help of Culex mosquitoes. Have we ever had a chance to contain it in the beginning?
Kramer: For zoonotic disease, once you have a susceptible environment, susceptible hosts and suitable meteorological conditions, it is really difficult to contain it. I think they did everything they could. You know, they sprayed heavily in areas where West Nile was identified, for example in Queens. But after it has appeared in birds – and there are so many species of birds that are susceptible, I think they are over 300 – any bird could play a role in maintaining the virus.
Oh, yes, no. Out of the bag … Activity levels can go up and down from year to year, but they can't be uprooted.
In retrospect, they could pay more attention to birds that died earlier. But it's not the CDC, it's the USDA. The birds were dying, but people were not thinking about public health. And I don't think most people have noticed that birds die early. So maybe if this was noticed earlier, then spraying early could have stopped it much earlier. But I don't know – it would have been difficult.
Gizmodo: What do you think may be West Nile's lasting legacy?
Kramer: And I think we learned a lot from West Nile. One thing the West Nile did was prepare us for Zika. Not that Zika is in the country and it's a completely different virus, but having a healthier public health infrastructure that helped us, we started testing for Zika very quickly.
I also think it taught us that we need to have a global perspective to be on the lookout for invasive viruses and other pathogens. And not just pathogens, but mosquitoes. Culex pipiens is an invasive species; it was brought to the US, West Nile also really brought the lesson of the concept of sole health, where we have to pay attention not only to human diseases, but also to animal health. And this has taught us that we need to maintain open communication between laboratories and other scientists. This has definitely enhanced communication between veterinarians and public health practitioners, and sometimes veterinarians have been left aside.
The other major lesson is about the complexity of these disease cycles – that it's not just the virus, or just the birds, or just the mosquitoes. There are different types of mosquitoes and even within one species there are differences in populations. Like the virus, the West Nile has more than one lineage, and the lineage that came here has evolved. It was very well adapted when it came, but it is still evolving and adapting further.
Gizmodo: You seem to be saying that we don't have the tools even today to root West Nile in this country.
Kramer: Oh, no, no. He came out of the bag. It is enzootic [the animal equivalent of an endemic disease in people] in the wild, birds, mosquitoes. The level of activity can grow up and down from year to year, but it cannot be eliminated. Even if you had a mosquito control that is truly innovative, something like using Wolbachia [a bacteria that’s been used in other mosquito species to keep them from hosting and spreading diseases like Zika and dengue] every year has enough birds, enough new birds that are susceptible and could continue to do so.
What we have to do is maintain a public health infrastructure that we have to do for many reasons besides West Nile, such as tick borne diseases and other invasive diseases. And I think supervision has really improved. It's faster and we can do more specific tests. But I also think we need to rethink the way we conduct surveillance.
Part of that thought is happening now with all the new technology we have. We need to be able to see things we are not looking for. At the moment we are testing only what we know is here – and this is good, we can monitor the activity of what is here. But if something else comes in and we miss it again, since we're just doing this very specific testing, we'll be in the same boat with the next invasive virus.