How the United States lost the war against West Nile



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In July 2000, a mosquito control expert searched a New Hampshire marsh for mosquitoes likely to carry West Nile.
Photo: Getty Images

For a brief moment at the turn of the millennium, few things could have frightened the average New Yorker more than the words "West Nile", the name given to the virus transmitted by a mosquito that started in 1999 to kill birds and the very first times in the United States

Two decades later, the worst fears of West Nile hysteria did not materialize. The initial outbreak in New York, which infected at least 59 people and killed seven, was not the work of bioterrorists. There has never been a massive outbreak of West Nile virus that has arrived every summer on deadly wings, like a clock, and thousands of people have died horribly after having the brains infected and cooked from top to bottom. .

But despite efforts to cleanse and monitor mosquitoes, the virus has thrived exceptionally well here. Discovered for the first time in Uganda in 1937, it is the most widespread mosquito-borne disease in the United States. Cases are regularly observed in the 48 landlocked states. Along the way, it has periodically decimated populations of birds and horses, sickened at least 50,000 people (millions of people were probably infected, but only a minority experience symptoms), caused neurological diseases devastating 25,000 people and killing more than 2,000 people. And scientists have termed the arrival of West Nile in the United States as one of the world's most important events in arbovirology ("arbo", spread by an insect or arthopod), which happened at during the last two centuries.

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In honor of West Nile's 20th anniversary in the United States, Gizmodo interviewed Laura Kramer, director of the Arbovirus Laboratory of the State of New York State Department of Health. Kramer is one of many experts who contributed to a retrospective on West Nile published today in the Journal of Medical Entomology. She was also one of the first scientists recruited by the local government to establish a West Nile virus surveillance team, following the first documented cases in the summer of 1999. The following conversation was modified and condensed for more clarity.

Gizmodo: As a permanent resident of New York City, the arrival of West Nile that year was one of the first really scary news events I could remember growing up. But what about researchers and field scientists who have tried to study and contain it?

Kramer: At first, the idea that West Nile was in the United States was a bit like "what!", Because it was originally thought to be encephalitis from St. Louis, but St. Louis did not do not kill birds. It took a little time to solve this problem, but not very long.

I have never felt scared. I had questions. It was alarming that this virus could come to the United States, but the big question was whether it would last? You know, will it go through the winter? And if he succeeds, will he be able to establish himself? And if it settles, what will happen in the southern states where the transmission season is much longer? I think when you're in the middle of that, you're not scared. You just have these questions. What do we have to do? How can we accomplish it? Let's go.

Gizmodo: In the end, the virus spread to the east, south and finally everywhere, thanks to the help of Culex mosquitoes. Have we ever had a chance to contain it at first?

Kramer: For a zoonotic disease, once you have a receptive environment, sensitive hosts, and favorable weather conditions, it's really hard to contain it. I think they did everything they could have done. You know, they sprayed a lot in areas where West Nile had been identified, like in Queens. But once it has entered the birds – and there are so many susceptible bird species, over 300, I think – every bird could play a role in the survival of the virus.

Oh yes, no. It's out of the bag … The activity level can go up and down from one year to the next, but it can not be eradicated.

In retrospect, they could have paid more attention to birds that die earlier. But it's not a CDC affair, it's the USDA. The birds were dying, but people did not think about public health. And I do not think most people have noticed that birds died early. So maybe if it had been noticed earlier, then an early sputtering could have stopped it much sooner. But I do not know – it would have been difficult.

Gizmodo: What do you think could be the most enduring legacy of the West Nile?

Kramer: I think we learned a lot from West Nile. West Nile also prepared us for Zika. The Zika virus is not present in the country and it's a completely different virus, but having a stronger public health infrastructure than we've put in place allowed us to do very quickly Zika screening tests.

I also think that it taught us that we needed to have a global perspective to be on the lookout for invasive viruses and other pathogens. And not just pathogens, but mosquitoes. Culex pipiens was an invasive species; It has been introduced in the United States. West Nile also highlighted the lesson of the unique health concept, that we must pay attention not only to human diseases, but to animal health. And that taught us that there should be open communication between laboratories and other scientists. This has certainly increased communication between veterinarians and public health practitioners, and veterinarians have sometimes been left behind in the past.

The other great lesson to remember is the complexity of these pathological cycles: it's not just about the virus, it's not about birds, it's about mosquitoes. There are different species of mosquitoes and, even within the same species, there are differences of population. Similarly with the virus, West Nile has more than one lineage, and the lineage that has come here has evolved. It was very well adapted when he came, but it's still evolve and adapt more.

Gizmodo: It sounds like you're saying that we do not have the tools, even today, to eradicate West Nile in this country.

Kramer: Oh yes no. That's out of the bag. It's enzootic [the animal equivalent of an endemic disease in people] in wildlife, birds, mosquitoes. The level of activity can go up and down from year to year, but it can not be eradicated. Even though mosquito control was really 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 there are enough birds, enough new birds and likely to maintain it.

What we need to do is maintain the public health infrastructure, which we need to do for many reasons other than West Nile, as for tick-borne diseases and others invasive diseases. And I think the monitoring has really improved. It's faster and we can do more specific tests. But I also think we need to rethink the way we watch.

Part of that thinking is going on right now, with all the new technologies that we have. We must be able to see things we are not looking for. Right now, we only test what we know is here – and that's good, we can track the activity of what is here. But if something else happens and we miss it at first, because we only do very specific tests, we will be in the same boat with the next invasive virus.

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