Enviro-headline of the year?
It’s a fatal infection without an effective treatment, and one that strikes in a decidedly gruesome manner: An amoebic organism lurking in water is inadvertently inhaled during a swim on a hot summer’s day. From there, it travels through the nasal passage and into the brain, where it multiplies, devours one’s cerebral fluid and gray matter, and almost invariably causes death.
These “brain-eating amoebas” — known to doctors and scientists as Naegleria fowleri, or N. fowleri — aren’t believed to kill often. In the US, researchers estimate that between three and eight people die from N. fowleri disease, commonly referred to as PAM (primary amebic meningoencephalitis) each year. But that might not be the case for long. In recent years, N. fowleri has popped up in unexpected locations, which some experts suggest is a sign that warmer waters — caused by brutal summer heat waves and rising temperatures across the country — are catalyzing their spread.
How are human and animal diseases in general affected by the climate becoming “wilder, wetter and warmer?” New research shows that ticks have spread over larger geographical areas in Norway and that climate and environmental changes, access to host animals and demography affect tick distribution in Norway. Furthermore, local climatic conditions can have a decisive influence on the ability of the tick to spread dangerous viruses. The climate can also play a role in the spread of gastrointestinal infections.
The effects of climate changes are the easiest to detect and are probably most pronounced near the geographical distribution limits of the infection or for the vector which carries the infection.
Ticks are champions at spreading diseases, expanding in both poor countries and rich ones, and delivering an extraordinary menagerie of bacteria, protozoans, and viruses. In a 2010 report on the dangers of ticks, the Institute of Medicine, the health arm of the National Academy of Sciences, declared the animals, with what sounds almost like admiration, “the Swiss Army knife of disease vectors.”
IT’S STARTLING to look at the graphs of tick-borne diseases over the past few decades. They’re mostly going in the wrong direction. The research on Lyme disease is fairly recent, sparked in the mid-1970s after a cluster of children around Lyme developed fever and aches. They were diagnosed with juvenile arthritis—a peculiar diagnosis for so many children in one place. Their parents searched for an explanation, and eventually Allan Steere, a doctor at Yale, figured out that they suffered from an infectious disease. The fact that they all came from a rural part of the state suggested that an insect or some other animal had delivered the infection. In 1982, Willy Burgdorfer, an entomologist with the National Institute of Allergy and Infectious Diseases, discovered corkscrew-shaped bacteria in black-legged ticks from Long Island. He exposed the bacteria to serum from people with Lyme disease and discovered that their antibodies swarmed around the microbes. That was a sign that these bacteria—which would later be named Borrelia burgdorferi after him—were the cause of Lyme disease.
Since Burgdorfer’s discovery, Lyme disease has spread relentlessly. New York and other northeastern states started recording new infections in the eighties. In the Midwest, Lyme disease came to light around the same time in Wisconsin and began radiating out from there. Today it can be found as far west as California, as far south as Virginia, and to the north across the border into Canada. Each year, 38,000 people in the United States are diagnosed with the condition. The list of symptoms includes fever, aches, fatigue, and, if left untreated for a length of time, arthritis, heart arrhythmia, and neurological damage. Lyme disease is rarely fatal.
These diseases are caused by viruses, bacteria and parasites, and affect more than one billion people, mainly in the tropics, where the most vulnerable developing world populations are concentrated.
But the map of tropical diseases like malaria, Chagas’ disease, sleeping sickness, leishmaniasis, schistosomiasis and dengue fever, is starting to change.
Tropical diseases transmitted by vectors like mosquitoes, flies, ticks or snails are directly affected by conditions in the ecosystems they inhabit, such as changes in humidity, water levels, temperature or rainfall, experts explain.
“Global warming is ‘tropicalising’ subtropical regions; rising temperatures could bring an explosion of parasite and insect vectors that are expanding into North America, the Southern Cone of South America, Australia and New Zealand,” Costa Nery said.
One sign of this, said the president of the SBMT, is the spread of leishmaniasis in Europe by travelling persons and dogs. He explained that the disease, which is endemic in southern Europe, could continue to spread northward if temperatures keep rising.
At the same time, climate variation in the tropics and its effects on the frequency of flooding and drought “could also modify the dynamic of the transmission of diseases,” with the emergence of vectors that alter the population’s immunity and resistance.
"The number of West Nile virus cases in the U.S. jumped dramatically in one week, increasing to 1,118, with 41 deaths, the Centers for Disease Control and Prevention said today.
The report marks a substantial increase from last week’s tally of 693 cases and 26 deaths.
Approximately 75% of the cases have been in five states: Texas, Mississippi, Louisiana, South Dakota and Oklahoma, the CDC says.
Texas has been hardest hit, accounting for almost half of all cases.”
Tuberculosis outbreak has claimed 13 lives and sickened nearly 100 people. Local news outlets in Florida are mentioning the closure, but are giving weak coverage.
Fantastic read: “Mosquitoes and NIMBYism" at The New Yorker.