Article from July, 2013


It has been said that good things come in small packages but the opposite can be true on travel and in remote areas.  The biggest killers in tropical areas are actually mosquitoes who spread tiny deadly organisms responsible for malaria, dengue, and yellow fever.  Even though these diseases affect millions, greater lurking dangers relate to pandemic viral outbreaks.  Three pandemics within the 20th century have killed tens of millions.  With recent news of new bird flu strains and a novel virus arising in the Middle East, concerns in the medical and business communities have been ratcheted up.  Public confusion warrants an update for our readers.

Viruses are small, complex, very efficient infectious agents.  Millions of types make them the most abundant biological organisms on earth, infecting animals, plants, bacteria, and fungi.  They are much smaller than a cell and have no cellular characteristics except genes.  Surrounding the genetic material is a membrane envelope containing various proteins which function to attach to and invade cells.  Once in the cell, the virus corrupts the host cell metabolism to reproduce and escape to infect other cells.

Viruses have either RNA or DNA genes.  Most DNA viruses have a double strand as do humans (picture a railroad track) while most RNA viruses are single-stranded (half a railroad track split down the middle).  Viruses mutate frequently and can acquire traits to allow more rapid spread or resistance to medication.  DNA viruses usually require mutations in both complementary sites of the gene strand to change but the one-stranded RNA only needs mutation at one site to change viral behavior.  The rapid mutation of RNA viruses causing colds is the reason you have to get a shot every flu season.

Influenza is an RNA-viral infection of birds and mammals.  Influenza-like illnesses like the common cold and the 24-hour “stomach flu” are mistakenly called “flu” but caused by other RNA viruses.  Viruses usually stay within their host but occasionally, an animal virus can mutate to infect humans with dire consequences.  Severe acute respiratory syndrome (SARS) is a coronavirus infection (not a flu) that arose from bats in 2002 and spread to 37 countries in a few months killing 10% of those infected before being contained.

Flu viruses are named by their H protein (17 subtypes known) and N protein (9 subtypes known).  New strains emerge when a flu acquires the ability to spread to humans or when a human virus picks up new genes from an animal or bird flu.  The real problem occurs if the virus develops the ability to transfer between humans like SARS did.

Recently we have been lucky.  An avian flu H5N1 emerged in the 1990s with over 600 cases and 60 percent fatality rate in the last decade.  Despite periodic outbursts including one currently, it has not been able to transmit between humans.  A flu that combined swine, avian, and human genes emerged in 2009 and spread between people but fortunately this H1N1 swine flu has a low mortality rate.  One that is being watched closely emerged in eastern China recently.  H7N9 avian flu has killed about 20 percent of those infected but unlike H5N1, birds are not very sick so there is no warning in the community.  Ominously, it possesses traits that suggest an easier spread to man and may be resistant to medication.  Close proximity to birds in a live market or handling of poultry have been highly associated with both H5N1 and H7N9.  Two other flu strains, H7N1 in South African ostriches and H7N3 in Mexican poultry have not jumped to humans yet but are under close scrutiny.

Other viral diseases besides flu are of serious concern.  Five strains of coronavirus including SARS are known to infect man.  A sixth strain has now emerged from the Middle East, primarily in Saudi Arabia, but 3 cases appeared in London after travel to that area.  This deadly Middle East Respiratory Syndrome coronavirus (MERS-CoV) has killed two thirds of those infected though likely not due to direct human transmission.  Camels have been implicated but not proven as the animal host.  There have been over 60 cases reported at the time of this printing over the year since April 2012.

Other deadly viruses but with low risk for most travelers include Nipah virus in Bangladesh which originated in Malaysia, has bat reservoirs, and is associated with unpasteurized date palm juice.  Lassa Hemorrhagic Fever, similar to Ebola, is found in West African grains stores and can transmit from human to human.

Advice.  If you are traveling to an area of reported dangerous viral diseases, stay away from live birds and undercooked poultry.  Avoid live markets with birds.  Wash hands regularly or use hand sanitizer.  Masks will not help.  If you develop a fever within thirty days of traveling to an area known for flu or other viral diseases, report to health authorities quickly.  There have been no travel restrictions to these areas as of this printing.


This article was published in The Explorers Journal


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