Dr Peter Hotez gestured at three tires dumped on the weed-ravaged, litter-strewn roadside by a boarded-up house on Worms Street.
To Hotez they were more than an eyesore – they signified a potential health hazard, the perfect breeding ground for mosquitoes that could spread the Zika virus.
The World Health Organization has warned that the virus is spreading “explosively” through the Americas, with one estimate that there could be as many as 4m infections across the continent over the next year.
At a special briefing in Geneva on Thursday, Margaret Chan, the WHO director general warned it was a threat of “alarming proportions”. Hotez, an eminent scientist and researcher who is dean of the National School of Tropical Medicine at Baylor College of Medicine, agrees.
“I’m quite convinced it’s going to be all over the Caribbean within the next few weeks. And then, where’s next?” he said. “Where we’re standing here in the Gulf Coast… Pretty much all of the Gulf Coast cities are vulnerable but Houston is the largest.”
It is less than 15 minutes’ drive from Hotez’s office in the world’s biggest medical complex to the Fifth Ward, a historic, mostly African American quarter just northeast of downtown Houston.
When he hears experts assert that Zika is unlikely to spread significantly in the US, his response is: go to the Fifth Ward and look around.
Broken window screens lie discarded a few feet away from the tires. A block away, more tires, a sofa, armchairs, drawers and a colorful variety of other household waste were piled in the street.
A rooster crowed somewhere, barely audible above the drone of the traffic barrelling through on the nearby knot of elevated freeways. It was a grey, damp morning. The streets had not yet fully drained from the overnight rain. In some sodden nooks it seemed doubtful they ever would.
“I could show you dozens of neighborhoods like this in south-east Texas, along the Gulf Coast,” said Hotez. “What we have is dilapidated housing, inadequate or absent window screens, standing water, poor drainage, which are going to allow the mosquitoes to breed, and then the classic piece to this is the discarded tires along the side of the road. Aedes mosquitoes love discarded tires filled with water.”
Reports emerged this week that two people in Virginia and Arkansas who had traveled abroad had tested positive for the virus, which is spread when infected mosquitoes bite people. The most common symptoms are mild but it can be transmitted from pregnant mothers to babies.
Since the first cases of local transmission in Brazil were reported last May it has spread to about two-dozen countries and territories in the Americas and been linked to brain damage in thousands of newborns.
Last week health officials said that Brazil has reported 3,893 suspected cases of microcephaly, a birth defect where babies have abnormally small heads.
Earlier this month the US Centers for Disease Control and Prevention (CDC) said that a baby born in Hawaii to a mother who had lived in Brazil is the first US-born child with microcephaly linked to Zika, while a Houston-area woman who travelled to El Salvador was diagnosed with the virus.
The CDC recommends that pregnant women “consider postponing travel to any area where Zika virus transmission is ongoing” – a list of 22 countries and territories across Latin America and the Caribbean. The WHO expects Zika to spread everywhere in the Americas except Canada and Chile, where the climate is unfavourable to the main culprits for transmission, Aedes aegypti mosquitoes.
Aedes bites during the day, surprising those who assume they only need to wear repellant in the evenings. It enjoys entering houses, where it is safe from street-spraying treatments of the kind that routinely take place in Texas cities. And it has called the state home for years, passing on diseases such as dengue fever, which can be fatal.
In recent years, US media has exhaustively covered the spread of The West Nile virus, transmitted by Culex mosquitoes. In 2014 there were 379 human cases and six deaths in Texas, according to state statistics.
But other tropical diseases have also been spreading in the region – sometimes with lethal consequences. A 2013 study showed that dengue has also been spreading unnoticed in Houston for years.
In 2014, Chikungunya, which can cause severe joint pain, was also found in Austin and Houston. Chagas disease, carried by bloodthirsty “kissing bugs” and capable of causing sudden death decades after the initial infection, is a concern in Texas. So is cutaneous leishmaniasis, a skin infection spread by sand flies.
For a man who spends his days immersed in these and other scary diseases on his doorstep, Hotez has a remarkably cheerful personality. But he is worried about the latest trends.
“I think we are seeing something very unusual in the western hemisphere. What we’ve seen is dengue fever, which hadn’t been in the Americas for a long time, reintroduced in the eighties and now dengue is all throughout South America, Central America, and then moving into the Gulf Coast,” he said.
“Chikungunya virus was never here and was then introduced in 2013 and spread like wildfire across the Americas and now Zika. The question is, what’s going on? What are the factors that are accounting for this?”
In his view: travel – caused by mass migration or specific events such as 2014’s World Cup in Brazil; unimmunised populations; climate change; warmer weather thanks to El Nino; and poverty. Above all, poverty.
Like the kind in the Fifth Ward, so close to the shiny skyscrapers of the fourth biggest city in the world’s richest nation. In 2013 the median household income was below $19,000 .
Tropical diseases thrive in neglected areas of the humid southern US but many residents do not have access to air conditioning and good healthcare. The debilitating effects of undiagnosed or untreated illnesses can make it hard to hold down a job or prosper at school.
Studies have found that deprived Houston neighbourhoods are more likely to be affected by West Nile than prosperous ones.
“What we have in this part of Houston is the perfect storm to allow Zika virus to flourish here,” said Hotez. “We have both major species of mosquitoes that transmit Zika virus and then we have the critical other piece, the warm weather that’s going to start in the spring months, April and May, going into the summer, and then all of the environmental degradation and poverty. All of that’s going to mix together and I think that’s going to make the Gulf Coast susceptible to Zika.”
Waiting for a bus, Lewis, a 63-year-old who recently moved to the neighborhood, said he had heard about Zika. “I do worry about that,” he said. Another man whose front porch was almost obscured by trash on the sidewalk said that he had seen the news on TV but was not too bothered about the local mosquitoes - they are simply a fact of life. “They bite sometimes,” he said.
Hotez, though, is calling for action rather than waiting for confirmation that local mosquitoes are spreading the disease. “We have to start screening all women who are pregnant. That’s not what the CDC guidelines say, but I think if I were an obstetrician practicing in this area I would want to know if my patient who’s just become pregnant could be affected by Zika,” he said.
“I think what we have to do now, public health authorities in Texas at the local, state and federal level, is assume Zika’s going to hit now in the coming weeks and take steps accordingly.”
One of the alarming aspects of Zika, he said, is uncertainty, since its most devastating impact is often not seen until infected mothers give birth. All the more reason to be proactive: developing strategies, raising awareness – and removing tires.
“We can’t wait nine months to see if there’s a disaster,” he said.