DIVE DRY WITH DR. BILL #750: FROM US TO THEM!
Many of you are probably aware that some diseases can be transmitted from animals to humans. HIV/AIDS is just one example of this. This disease is caused by a virus originating in non-human primates. It spread to humans beginning in the early 20th century, possibly as a result of bushmeat hunting and consumption.
Ebola is another terrible disease caused by a virus that has jumped the species barrier from primates, fruit bats, antelope and porcupines to humans. A less virulent example is the transmission of swine flu from pigs to humans. Hmm, I wonder if our island's feral pigs were infected? Other examples include avian or bird flu and rabies.
Until recently scientists were not aware that disease transmission can occur from humans to other critters. One such example caught my attention recently while watching an episode of the TV documentary series "Changing Seas." One segment focused on the work of Dr. Kathryn Sutherland of Rollins College in Florida.
Dr. Sutherland has been investigating the serious decline of elkhorn coral (Acropora palmata) off the coast of southern Florida. Since the mid-1990s, about 90% of the once healthy coral species has disappeared. It was determined that a disease known commonly as "white pox" was a major contributing factor. The disease got its name from the white patches of dead coral, representing areas where the tissue had died leaving the white calcium carbonate skeleton.
In 2002 Dr. Sutherland isolated the pathogen responsible, Serratia marcescens, a bacterium commonly found in the digestive tract of humans and other animals. Possible sources of this bacterium include human fecal matter from septic tanks, sewage outfalls, marine birds and fish. However the rapid degradation of the coral beginning in the mid-1990s suggests humans as a primary contributor. DNA and other research studies by Dr. Sutherland also support this.
An additional factor making this coral disease so virulent is the increase in water temperature. Scientists have found that warmer water often enhances the spread of harmful pathogens while diminishing those that are important in the physiology of the animal. Many who have dived tropical waters are aware that pathogens are more abundant there and infection a more likely possibility.
Some scientists have proposed a new name for the disease, acroporid serratiosis, but that's much harder to say. White pox disease is highly contagious on elkhorn coral reefs. This allows for rapid spread of the disease once it reaches a site. In addition, the dead portions of the coral serve as anchor points for algae to grow on the coral head. This can further stress the invertebrate.
These coral generally reproduce by fragmentation. Following a natural disturbance such as a hurricane, the individual fragments can grow and restore the reef. However, white pox disease often destroys the vast majority of elkhorn coral at a site. Therefore, it is dead coral that gets fragmented and little to no new coral heads are formed.
Having spent way too much time in a hospital last year due to multiple infections, I try to avoid them whenever possible. Of course my two granddaughters bring them to me on occasion. I bought 50 surgical masks in anticipation of warding off infections during my chemo sessions. Unfortunately for the elkhorn coral, a surgical mask would do them no good. The answer is better sewage treatment to eliminate the introduction of this bacterium into southeast Florida waters.
© 2018 Dr. Bill Bushing. For the entire archived set of over 750 "Dive Dry" columns, visit my website Star Thrower Educational Multimedia (S.T.E.M.) Home Page
Image caption: Elkhorn coral (courtesy of Wikipedia Commons)
Many of you are probably aware that some diseases can be transmitted from animals to humans. HIV/AIDS is just one example of this. This disease is caused by a virus originating in non-human primates. It spread to humans beginning in the early 20th century, possibly as a result of bushmeat hunting and consumption.
Ebola is another terrible disease caused by a virus that has jumped the species barrier from primates, fruit bats, antelope and porcupines to humans. A less virulent example is the transmission of swine flu from pigs to humans. Hmm, I wonder if our island's feral pigs were infected? Other examples include avian or bird flu and rabies.
Until recently scientists were not aware that disease transmission can occur from humans to other critters. One such example caught my attention recently while watching an episode of the TV documentary series "Changing Seas." One segment focused on the work of Dr. Kathryn Sutherland of Rollins College in Florida.
Dr. Sutherland has been investigating the serious decline of elkhorn coral (Acropora palmata) off the coast of southern Florida. Since the mid-1990s, about 90% of the once healthy coral species has disappeared. It was determined that a disease known commonly as "white pox" was a major contributing factor. The disease got its name from the white patches of dead coral, representing areas where the tissue had died leaving the white calcium carbonate skeleton.
In 2002 Dr. Sutherland isolated the pathogen responsible, Serratia marcescens, a bacterium commonly found in the digestive tract of humans and other animals. Possible sources of this bacterium include human fecal matter from septic tanks, sewage outfalls, marine birds and fish. However the rapid degradation of the coral beginning in the mid-1990s suggests humans as a primary contributor. DNA and other research studies by Dr. Sutherland also support this.
An additional factor making this coral disease so virulent is the increase in water temperature. Scientists have found that warmer water often enhances the spread of harmful pathogens while diminishing those that are important in the physiology of the animal. Many who have dived tropical waters are aware that pathogens are more abundant there and infection a more likely possibility.
Some scientists have proposed a new name for the disease, acroporid serratiosis, but that's much harder to say. White pox disease is highly contagious on elkhorn coral reefs. This allows for rapid spread of the disease once it reaches a site. In addition, the dead portions of the coral serve as anchor points for algae to grow on the coral head. This can further stress the invertebrate.
These coral generally reproduce by fragmentation. Following a natural disturbance such as a hurricane, the individual fragments can grow and restore the reef. However, white pox disease often destroys the vast majority of elkhorn coral at a site. Therefore, it is dead coral that gets fragmented and little to no new coral heads are formed.
Having spent way too much time in a hospital last year due to multiple infections, I try to avoid them whenever possible. Of course my two granddaughters bring them to me on occasion. I bought 50 surgical masks in anticipation of warding off infections during my chemo sessions. Unfortunately for the elkhorn coral, a surgical mask would do them no good. The answer is better sewage treatment to eliminate the introduction of this bacterium into southeast Florida waters.
© 2018 Dr. Bill Bushing. For the entire archived set of over 750 "Dive Dry" columns, visit my website Star Thrower Educational Multimedia (S.T.E.M.) Home Page
Image caption: Elkhorn coral (courtesy of Wikipedia Commons)
