I love microbiology and blogging about it can be tricky sometimes. I mean, it is not difficult to ramble about microorganism and all but to make it interesting and at the same time educational, people have to think and be creative in terms of the way we presented our articles and all, I'm sure with time, I will get the hang of it. So, shark attack, nothing terrifies me other than knowing you can get bitten anytime while swimming or floating in the vast sea while looking at the blue sky. Sharks usually give signs or warning before they were attacking their prey but since they were a better swimmer, by the time we escape, rarely we could do so without a wound or two.
While searching for my article's material today, I stumbled upon an article published in the LiveScience regarding a 42 years old man who was attacked by a 2 metres bull shark while swimming in the Gulf of Mexico, approximately 200 metres from the shore. He can be considered lucky as he was able to escape the shark bite after being helped by his friends and Sherriff's deputy who was around in that particular area at that time but unlike the other survivor of shark's attack, he was infected by a bacteria known as Vibrio vulnificus. Trust me when I said, you wanna know if you are infected with this particular bacteria as soon as possible or it can be fatal.
In 2016, Ricci et al published a paper which analysed the incidence of shark attack around the globe and they concluded that most attacks took place in North America. From the beginning of the 1900s to 2016, the number of reports related to shark attack can be totalled up to 5034 with a mortality rate of 22%. There has been a few characteristics/factors that might influence the survival rate of the victims but the majority of the attacks involved either upper or lower limbs. It should be noted that even though the number of cases seems to be increasing year by year but so do victims' survival rates. This can be attributed to how quick those victims were treated (first aid), availability of helping hands and how quickly they can be transferred to the nearest medical facility.
There are three species of shark out of the 400 which can be considered lethal and attributable to the increased morbidity rate; they are:
- Great white shark
- Tiger shark
- Bull shark
Although in records, tiger shark did less attack than the great white shark, according to Ricci, whether or not you were attacked by a tiger shark contributes greatly to your chance of survival. Unlike any other shark species, tiger sharks often hunt at night, they were nocturnal apex predators which would eat anything and everything (even garbage). Pollution has caused a significant damage to the sea and at the same time to the species of tiger sharks. Often, by slicing a dead tiger shark, we can find various kind of garbage in their stomach that has been disposed of by us, humans. Currently, they were listed as one of the shark species that is threatened with extinction due to pollution and finning; shark fins might be delicious but it does no good to their own survival.
Vibrio Vulnificus
Now, let's turn our attention to the man of the hour, the bacteria which has been considered as the flesh-eating type swimming freely mainly in the coastal area, the Vibrio vulnificus. I know that this particular organism rarely credited for its role in any of the gastrointestinal diseases and food poisoning, but it does a gruesome and severe infection of the wound of the healthy people (you can imagine how would it fare with someone who is immunocompromised) and seldom, causing fatal septicemia among people who have reduced immunity or people who have multiple comorbidities.
There are no pathognomonic feature which could have suggested that people were infected by this particular microorganism but if a medical doctor is able to get a good history, any contact with sea water might have been the possible window of opportunity for such infection. People will usually develop some kind of bullous skin lesion along with other constitutional symptoms which might have suggested infection such as chills, fever, nausea vomiting and worst, hypotension. Diagnosing such infection can be tricky as the symptoms could have explained other kind of infection but the rate of wound break down and quickly it spread can be the most important clue; it's a flesh-eating disease anyway.
Sharks' attack often caused a huge open wound/s that could have been the entry point for infection and since Vibrio vulnificus are abundant in the sea water especially at the coastal area, a lot of them could have entered and caused severe inflammatory reaction and infection. Obviously, the main priority for us when attending people who got bitten by a shark is to stop the bleeding but the patient should have been transferred to the nearest medical care centre for further assessment and management to avoid further complication. People could have lost their limbs to the shark attack but very few of them lose their limbs to this bacteria. Amputation can be one of the most effective but the least acceptable to prevent the infection from spreading.
In October 2016, a 67 years old man died after he was diagnosed with necrotising fasciitis (flesh-eating diseases) caused by the Vibrio vulnificus. The man was not bitten by the raging sea monster (the shark) but he swam around while having a cut at his left leg which can be equivalent to inviting the bacteria to enter and infect his systems; well the bacteria did that. He felt an unusual pain at his left leg and found that they were necrotic. The leg was then amputated but unfortunately, they underestimated the site to which the bacteria have been causing infection. Despite the amputation, the infection spread through his body and four days later, he died of septicemia.
I know people like to hang around the ocean, swimming, floating and all but you have to ensure that you were healthy enough to do so. In the cause of the 67 years old man, the infection can be that severe due to the fact that he was an elderly so his immune system can be that good compared to a young adult. The infection will start off at the skin, spreading through the dermis and once it enters the bloodstream, poof, your mortality rate rose to 50%. Although it seems severe, people rarely come to the point that they have to juggle between life and death when infected by this bacteria.
Most people presented with the gastrointestinal system after they accidentally drank some seawater (or intentionally) which could have the same presentation with people who were having a food poisoning symptoms; it's relatively normal and self-limiting; hydration is an important factor for recovery. The Centres For Disease Control (CDC) has estimated that among 80,000 people who were infected, 100 of them died as a result of complications (septic shock, mainly). The recommendation proposed by the CDC for people to protect themselves from getting such infection would be the same as any other gastrointestinal diseases except for a few details:
- Avoid getting in contact with seawater if you have open wounds
- Cover yourself with a waterproof bandage if you have to perform any activities that involved dipping in the seawater
- Avoid drinking from the seawater
- Ensure that you cook your shellfish well
References: [1], [2], [3], [4], [5], [6]
All images were taken from Pixabay
Images: [1], [2], [3], [4], [5], [6]
