Reflecting on Summer 2019, the news was full of stories of changing waters and an increase in different organisms inhabiting oceans, lakes, and other bodies of water. Two of these organisms in particular received attention and caused wide-spread fear; however, it is important to distinguish them. Flesh-eating bacteria and cyanobacteria often get confused by the public, but these two bacteria are unique in very noticeable ways.
Vibrio bacteria is the main culprit in the flesh-eating bacteria outbreak seen every summer. There are different species of vibrio bacteria and each causes their own kind of illness called vibriosis. According to the Center for Disease Control and Prevention (CDC), 80% of vibriosis infections occur between the months of May and October when water temperatures are warmer. The CDC also estimates that there are about 80,000 cases of vibriosis each year. Vibriosis is often contracted by eating undercooked or raw shellfish, but people can also become infected by swimming with an open wound.
Flesh-eating bacteria is as terrible as it sounds; however, this bacteria does not only attack the skin. Vibriosis usually causes gastrointestinal problems, with symptoms such as abdominal cramping, vomiting, and diarrhea. For skin infections, red and inflamed blisters often appear. In severe instances, the infection can become necrotizing, in which case amputation is required and the infection can proceed rapidly to death. Although necrotizing fasciitis is rare compared to other forms of the infection, all types of vibriosis cases are increasing in number.
This bacteria has historically remained in the Gulf of Mexico and along the southeast coast of the United States in more tropical waters, but this past summer, cases were found as far up as the New England shoreline. Before 2017, Cooper University Hospital in New Jersey had witnessed only one case of flesh-eating vibriosis in eight years. In 2017 and 2018, that number increased to five. Scientists believe the increase is due to warmer ocean temperatures, which allows the bacteria to survive farther north during the summer. For bacteria once limited to equatorial habitats, warmer oceans are increasing the habitat range of this organism and also increasing the potential public health danger.
Cyanobacteria, on the other hand, is a different type of organism, and it manifests itself in different ways. Cyanobacteria colonies lead to algal blooms. Algal blooms form for a variety of reasons, such as an increase in nutrients, warmer water temperatures, and still water conditions. The main culprit is eutrophication, or nutrient over-enrichment, which is a naturally occurring phenomenon as a result of lake and river sediments, but is mostly caused by the overuse of phosphorus and nitrogen by human activity. These activities include runoff from fertilized agricultural farms and lawns, deforestation, and sewage effluent.
While there are natural algal blooms in both fresh and saltwater environments, algal blooms have increased in both frequency and intensity in recent years. What makes algal blooms so dangerous is that the cyanobacteria accumulate toxins when multiplying, then these toxins are released when the colonies die. These toxins harm people when ingested, targeting specific areas such as the nervous system, liver, and kidneys. Because of the health risks, algal blooms force drinking water restrictions and shutdowns of recreational swimming areas. In the past summer, the algae bloom in Lake Erie was among the most toxic and dense ever recorded. More than 11 million people depend on Lake Erie for drinking water, but many fear tap water and choose bottled water instead. Scientists believe these increasingly severe blooms in Lake Erie are caused by both agricultural runoff and warming waters.
Although these two phenomena are distinct, both negatively impact human and ecosystem health. Water becomes unsafe to drink and swim in, habitats are altered, and human health is at risk. As water temperatures continue to rise due to climate change, occurrences of both flesh-eating bacteria and algal blooms will rise as well. It is important that the public stays informed of flesh-eating bacteria and cyanobacteria as occurrences escalate and spread to new cities and towns and pose environmental and public health issues.
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