Tag Archives: Tropical diseases

Health

‘Super’ Disease-Carrying Mosquitoes Detected in Asia

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An Aedes aegypti mosquito.
Image: Shutterstock (Shutterstock)

Researchers in Japan say they’ve discovered “super” resistant mosquitoes in Asia. In a study published this week, they detail finding populations of Aedes aegypti mosquitoes—a common disease vector—in Vietnam and Cambodia carrying several mutations believed to confer strong protection against the most widely used insecticides. The discovery should merit urgent action to prevent these mutations from spreading globally, they argue.

A. aegypti mosquitoes are one of the most prolific sources of human misery in the world, thanks in part to the wide assortment of germs they can transmit to us. These mosquito-borne diseases include yellow fever, dengue, Zika, and chikungunya, to name a few. The global presence of A. aegypti (along with a related species, A. albopictus) and the diseases they spread has expanded in recent years. Many experts expect their range to only grow wider over the coming decades as the climate continues to warm, including throughout the southern and eastern parts of the United States. So these new findings, published Wednesday in Science Advances, might add yet another concern to an already serious problem.

The research was led by scientists from Japan’s National Institute of Infectious Diseases, the country’s equivalent to the National Institute of Allergy and Infectious Diseases (NIAID) in the U.S. They studied samples of A. aegypti mosquitoes recently collected throughout Asia, looking specifically for mutations in their voltage-gated sodium channel gene. Some mutations in this gene, called knockdown mutations, can help mosquitos and other insects survive exposure to pyrethroids, a class of chemicals commonly used to control insect populations. To test whether any of the mutations found by the researchers truly protected the mosquitos, they also compared their survival rates against the insecticides to non-resistant mosquitoes in the lab.

The team ultimately identified 10 previously unknown substrains of A. aegypti mosquitoes that seemed to carry one or more of these knockdown mutations. One novel mutation in particular, called a L982W substitution, was found in over 78% of mosquitoes from both countries. And in a specific area of Cambodia, about 90% of mosquitoes carried one of two pairs of mutations that were identified as especially troubling.

Lab experiments also found that these combination mutation-carrying mosquitoes were much harder to kill, with “substantially higher levels of pyrethroid resistance than any other field population ever reported,” the team wrote. In the title of their paper, they describe their results as the “discovery of super-insecticide-resistant dengue mosquitoes in Asia.”

Other studies in recent years have found evidence of growing pyrethroid resistance among A. aegypti mosquitoes in Asia and the Americas, both in the lab and the real world. And the new study is the latest in the team’s ongoing research project to understand pyrethroid resistance in A. aegypti globally. They say it’s the first to try unraveling the molecular mechanisms that have led to these mutations emerging, particularly in the mosquitos from Cambodia.

There are developing non-insecticide technologies that might someday better keep mosquitoes in check, such as sterile insect techniques that sabotage the population from within, but none of these interventions are expected to see widespread use soon. There is also a newer class of insecticides, called neonicotinoids, that’s beginning to be deployed more often against mosquitoes. But these chemicals are controversial due to their damaging effects on important insect pollinators, and there are already signs that mosquitoes have begun to adapt to them as well. There are also no highly effective and/or low-cost vaccines and treatments for the most common diseases that these mosquitos spread, especially dengue.

All of this means that pyrethroids will remain a widely used tool against A. aegypti mosquitoes for the time being. Given that, much more has to be done to keep these worrying mutations from spreading around the world before it’s too late. The L982W mutation hasn’t been found in mosquitoes outside of Vietnam and Cambodia yet, for instance. But “it may be spreading to other areas of Asia, which can cause an unprecedentedly serious threat to the control of dengue fever as well as other Aedes-borne infectious diseases,” the researchers warn.

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Health

What to Know About Dengue, the Deadly Disease Showing Up in Arizona

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Photo: Thammanoon Khamchalee (Shutterstock)

An Arizona resident recently contracted the mosquito-borne disease known as dengue, and the dengue virus has been detected in mosquitoes in the area. Dengue, normally associated with tropical countries, may be spreading in Arizona for the first time.

It’s not the first time dengue has shown up in the United States, but we don’t usually get local transmission of the disease in the 48 contiguous states. Florida has had at least three local cases of dengue this year, and has had several local outbreaks in recent years, with the largest being 66 cases in 2010. (Before 2009, there had been no cases since 1934, Outbreak News Today reports.) Dengue is common in several U.S. territories, including Puerto Rico, American Samoa, and the U.S. Virgin Islands.

So how big a deal is dengue, and what should you know about it? Let’s look at the facts.

How bad is dengue?

About 75% of people who are infected with dengue won’t have noticeable symptoms. Statistically, 25% will get sick, 5% will get severe dengue, and 0.01% die from it.

It’s worth noting that you’re more likely to get severe dengue if you have had dengue before. There are four types of the dengue virus, so in theory you can get it four times in your life. But if you’ve had one type, and then contract another, that second infection carries a higher risk than the first of progressing to severe dengue.

Symptoms of an ordinary dengue infection may include nausea, vomiting, a rash, or muscle or joint pain. There may be a sensation of pain behind the eyes. The illness typically lasts between two and seven days. During this time, the CDC says, you should rest and you may take acetaminophen (Tylenol), but not aspirin or ibuprofen.

Symptoms of severe dengue can include belly pain or tenderness, bleeding from the nose or gums, blood in the vomit or stool, vomiting more than three times in 24 hours, or feeling unusually tired or irritable. If you have these signs, seek medical care right away.

How does dengue spread?

Dengue is caused by a virus, and that virus is transmitted by mosquitoes. Not all mosquitoes can transmit it, though. It requires Aedes aegypti or Aedes albopictus mosquitoes. These mosquitoes bite during the day as well as at night, and they can breed in small containers of standing water. Both species are more common in the southern U.S. than in northern areas.

(The little brown mosquitoes that live in more northern areas and bite more often at night are Culex mosquitoes, which do not transmit dengue. They can transmit West Nile virus, though.)

For a mosquito to give you dengue, it would have to bite someone with dengue, and then later bite you. If this happens in a given area, it’s considered local transmission of dengue. People can contract dengue while traveling and then bring it home, which accounts for most cases of dengue in the continental U.S.

How to avoid getting dengue

The main way to protect yourself from dengue is by protecting yourself from mosquito bites, and you can also help to protect your community by making sure the mosquitoes don’t have places to breed.

Mosquitoes will lay their eggs in stagnant water. This can include items like garbage cans and tires that fill with rain water, sources of water like dog bowls and birdbaths, and puddles that form on the ground or in tarps. Drain these items regularly if you can’t prevent them from filling up in the first place. (For example, if your dog has an outdoor water dish, make sure to empty it twice a week.)

To protect yourself from bites, the CDC recommends using an effective insect repellent (such as one containing DEET), wearing long-sleeved shirts and long pants where possible, and using window screens to keep mosquitoes out of the home.

There is a vaccine against dengue that is currently approved for children aged 9 to 16 who live in areas where dengue is common. It is not approved for people who are just traveling to those places.

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Health

The Dengue Virus Has Been Found in Arizona

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Aedes aegypti mosquitos, the primary vector of dengue, seen at a lab of the Institute of Biomedical Sciences of the Sao Paulo University, on January 8, 2016 in Sao Paulo, Brazil
Photo: Nelson Ameida/AFP (Getty Images)

A dangerous viral disease transmitted by mosquitoes has seemingly landed in Arizona. Earlier this week, health officials reported that a Maricopa County resident recently contracted dengue, while routine surveillance has found traces of the dengue virus in at least one nearby mosquito population. These discoveries suggest that the infection could be spreading locally in the state for the first time, though the investigation is still ongoing.

Maricopa County Department of Public Health (MCDPH) officials announced the human case of dengue on Monday, though no other details about the patient were provided. They also reported that the Maricopa County Environmental Services Department had detected the virus last month in samples taken from a mosquito trap in a neighborhood of the county. Though there have been cases of dengue reported in Arizona before, they’ve been found in people who likely caught it while recently traveling to countries where the disease is endemic. But given the surveillance data, officials say, it’s possible that this is the first locally transmitted case of dengue to be reported in the county and the state as a whole.

“While previous dengue cases in Maricopa County have been related to travel to countries where dengue commonly occurs, it is important to understand if others could have been exposed or if this is an isolated incident,” said Nick Staab, medical epidemiologist, in a statement released by the MCDPH. “This is in addition to our routine investigations of anyone suspected to have dengue or other mosquito-borne diseases.”

Dengue is spread by bites from infected mosquitoes. Most infected people will experience no illness, but about one in every four will develop flu-like symptoms, according to the Centers for Disease Control and Prevention. About one in every 20 people will develop severe dengue, which can lead to life-threatening complications like internal bleeding and shock. There are four major serotypes of the virus, and surviving infection from one type does not provide immunity to the others. In fact, it actually raises the risk of severe dengue should you ever catch another type of the virus.

Though dengue is most common in the hottest and most humid areas of the world, it’s become remarkably widespread in recent decades, with the virus now believed to be endemic in over 100 countries, according to the World Health Organization. Many experts fear that climate change will allow dengue and similar viruses to become a local problem in previously unaffected parts of the world, like much of Europe and the United States. Notably, two of the best known vectors of dengue, Aedes aegypti and Aedes albopictus mosquitoes, can now be found throughout much of the Southern and Eastern U.S. during their peak seasons, though it’s still not clear whether these populations could sustain the widespread local transmission of dengue and other viruses yet.

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For the time being, Maricopa officials are planning to go door to door in the area, armed with mosquito prevention kits and tests that should be able to detect whether any residents have been infected with dengue in the past several months.

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Health

A Man’s Seizures Turned Out to Be Caused by Dead Tapeworms in His Brain

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A close-up look at the scolex, or head, of a fully mature pork tapeworm. Interestingly enough, cysticercosis is what happens when the tapeworms don’t get the chance to become adults.
Image: Roberto J. Galindo/Wikimedia Commons

Coming down with seizures would be a scary experience no matter what, but for one unfortunate man, that experience was compounded by the discovery that dead tapeworm cysts lodged in his brain for decades were the root cause. Thankfully, his seizures were treated successfully, and the man seems to have made a recovery in the years since.

Doctors in Massachusetts described the patient’s case in a paper out last week in the New England Journal of Medicine. According to the report, which included his wife’s testimony, the 38-year-old man had fallen out of his bed at 4 a.m. He then began shaking and speaking gibberish. When police and emergency medical services arrived, he was “combative and disoriented” and initially refused to go to the hospital in an ambulance. On his way to the emergency room, he experienced a two-minute-long seizure and was given a sedative commonly used for seizures.

The man had no history of underlying health problems, and, according to his family, he had been completely fine the day before. Once doctors were able to run CT and MRI scans of his brain, though, the likely culprit of his illness was found: calcified and long-since-dead larval tapeworm cysts. Doctors then concluded that he had a relatively rare form of infestation from the pork tapeworm (Taenia solium), known as neurocysticercosis.

A pork tapeworm infestation can broadly manifest in two ways. If we ingest tapeworms found in pork or other undercooked meat that have matured a bit into cysts, these cysts will migrate to our intestines and bloom into full-blown adult tapeworms—uncomfortably long, weight-loss-inducing parasites. These worms will produce eggs that get pooped out and potentially find their way back to other animals like pigs, so that the cycle can start all over again.

But if another human or even the same infected human then ingests these eggs, the new generation of worms reaches a dead end and can only mature into their cyst form of life. Unfortunately, the nightmare doesn’t end there, because these cysts can still wreck havoc wherever they end up. When they get stuck in the brain, they can cause pressure and trigger inflammation that leads to all sorts of neurological symptoms, including seizures and even death. But it can take years or decades following infestation for symptoms to show up, often only after the worm cysts die (adult tapeworms can live up to 30 years in a host; cysts have a shorter lifespan of around five years). Sometimes, the cysts and the trouble they cause can be confused for a brain tumor.

Locally acquired tapeworm infestations are rare in the U.S. but remain very common in developing countries. And the doctors’ best guess is that their patient first played host to these worms at least 20 years ago in his native home of Guatemala, before he migrated to the U.S.

Following treatment with anti-seizure medication and steroids, the man’s condition (including the swelling around the lesions in his brain) improved enough that he was discharged from the hospital by day five. Though the cysts can sometimes be removed surgically or treated with antiparasitics if they’re still alive, that’s often not possible or needed, and patients who have had seizures will instead be given long-term medication to manage or prevent them in the future, as was the case here. Luckily, follow-up visits three years later have found that the man hasn’t had any episodes of seizure since and that he remains in good health.

While neurocysticercosis is relatively rare here, it’s one of the leading causes of seizures that show up in adulthood worldwide. Even in the U.S., about 1,000 people are hospitalized as a result every year. Cysticercosis in general is considered a neglected tropical disease, and according to the Centers for Disease Control and Prevention, there is currently “little being done to monitor, prevent, or identify and treat neurocysticercosis.”

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Entertainment

Coachella capitulates, reverses mandatory vaccination policy

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What’s that? Oh, no, these people won’t need to be vaccinated, despite overwhelming proof that it’s the best way to reduce hospitalizations from COVID-19.
Photo: Presley Ann (Getty Images)

Despite vaccinations being a fairly simple, uncomplicated method of preventing harm that has been employed for decades to keep polio, measles, diphtheria, hepatitis, and more dangerously infectious and potentially fatal illnesses from ravaging our public schools (among other places), Coachella has looked at the evidence and said, “Nah, bro, we’re all good.”

The festival equivalent of the fraternity brother who gets sent to pick up booze for the Friday night party and instead ends up doing lines on the back of a toilet seat in Vegas, Coachella, has reversed course on its mandatory vaccination requirement for the April 2022 event.

Variety reports the move to switch from its previously announced plan to require vaccination against COVID-19 comes as a surprise, for the primary reason that there’s no real sensible explanation. Tickets have been sold out for months, so it’s not like the vaccine mandate was hurting attendance.

Weirder still, the festival didn’t announce the change in policy via its main accounts on Instagram or Twitter (the latter’s most recent post, from August, still states vaccines are required for attendance). Instead, it was posted as a soon-to-vanish IG story:

After seeing first-hand the low transmission data and successful implementation of safety protocols at our other festivals this past month, we feel confident we can update our health policy to allow for:

Negative Covid-19 test taken within 72 hours of the event

OR

Proof of full vaccination.

Even Variety calls out how weird that method of quietly announcing the shift in policy looks, noting that, “in the music world, Instagram stories are usually used by artists for insider-fan announcements, not by major concert promoters for serious health-policy updates.”

Given that coronavirus has proven nothing if not resilient, why make such a belated shift in what was apparently a wholly unproblematic and science-based decision that didn’t impact sales in the slightest? Could there possibly be some major artists performing who have refused to get the vaccine, thereby making the festival look hypocritical if it went ahead with their bookings while keeping the vaccination requirement? Cynicism, thy name is history.

Instead, by rolling the dice on negative tests, the festival is going to hope nobody contracts it while in attendance, and subsequently dies horribly when a simple vaccine shot could’ve saved their life. That’s optimistic! And after all, why not be optimistic? Surely, if nothing else, the past couple years have demonstrated that things always get better whenever we hope they will. This might sound like hectoring. It is. Get vaccinated. 

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Health

Canada Fines 2 Idiots $20,000 for Faking Their Vaccine Status

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Photo: Eva Hambach / AFP) (Getty Images)

It’s one thing to refuse to get vaccinated against covid-19 or tested for the virus—precautions that are, unfortunately, not mandatory in many parts of the world—but it’s another thing to blatantly lie to authorities about it, especially when you’re visiting another country.

Canadian authorities announced that they recently busted two idiots traveling from the U.S. to Toronto for failing to comply with entry requirements. According to a news release from the Public Health Agency of Canada, the travelers provided false information related to proof of vaccination credentials and pre-departure tests. In addition, they also failed to stay in government-authorized accommodations, which is a requirement for people who are not vaccinated, and carry out covid-19 arrival tests.

The travelers, who arrived in Toronto the week of July 18, received eight fines and will have to pay $19,720 each.

“The Government of Canada will continue to investigate incidents reported and will not hesitate to take enforcement action where it is warranted to protect the health of Canadians from the further spread of COVID-19 and its variants of concern,” the Public Health Agency of Canada said in the release.

While that may sound like a hefty chunk of cash, the travelers could have been fined a lot more and even faced prison time. Canadian authorities say that travelers violating any quarantine or isolation instructions given by a screening or quarantine officer upon entry to the country could face $5,000 in fines for each day they break the rules or for each violation. More serious penalties can lead to six months in prison and/or $750,000 in fines.

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Under current Canadian travel regulations, fully vaccinated Canadians and permanent residents no longer must spend time in quarantine when they enter the country. The regulation also applies to fully vaccinated foreign nationals that have an exemption to enter the country. (Non-essential travel by foreigners will not be allowed until August 9). However, to be able to opt out of quarantine, travelers must present documents that prove their vaccination status and upload them to the ArriveCAN app.

Travelers who aren’t vaccinated like the two in this case are required to stay in a government-approved hotel for three days, quarantine for 14 days, and carry out covid-19 tests before their flight’s departure, after their flight’s arrival, and eight days later, CTV News explained.

“All travellers arriving in Canada are obligated by Canadian law to respond truthfully to all questions,” the Public Health Agency of Canada said. “Providing false information and/or documents to a Government of Canada official upon entry to Canada or making false statements or presenting fraudulent documents, such as vaccination credentials, is a serious offence and may result in fines and/or criminal charges.”

All in all, lying to authorities is a bad idea. On a related note, it also seems like it would take more work. Think about it. Presumably the two travelers in question had to forge authentic-looking documents. It’s much easier to just get vaccinated and get tested instead of going through all that hassle. And while we’re on the subject of wasting time, just imagine how the travelers’ trip turned out after being caught with their pants on fire.

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