- The 1918 influenza A H1N1 virus caused the worst pandemic
of influenza ever recorded[1]. This influenza was called then and now the
"Spanish Flu." The virus causing the Spanish Flu pandemic is
an Orthomyxovirus. The 1918 Type A H1N1 virus that killed between 20 to
40 million people worldwide is antigenically related to a "A/Swine/Iowa/30
(Sw/Iowa/30)" orthomyxovirus[2].
-
- The present "avian flu" virus, A/H5N1, of concern
because of its potential likelihood of causing a global influenza pandemic
has neuraminidase (N1) that is genetically related to the N1 of the 1918
A H1N1 "Spanish flu" virus[3]. However, the classic swine strain,
sw/Iowa/15/30, and the contemporary human viruses are not direct descendants
of the 1918 human pandemic strain, but did diverge from a common ancestral
virus around 1905. Furthermore, previous to this the above mammalian viruses
diverged from the lineage containing the avian viruses at about 1880[4].
In short, the A/H5N1 avian influenza virus and the A/H1N1 1918 "Spanish
Influenza" virus are related by common ancestor in their neuraminidase
structure.
-
- Relative to the hemaglutinin of A/H5N1, data appear to
suggest that A/H1N1 is a descendant of a common ancestor with A/H5N1, pointing
to an avian origin[5], perhaps in duck or chicken. In short, there exists
in A/H5N1 avian influenza, now infecting and killing humans in Thailand
and Vietnam and now showing evidence of possible human-to-human transmission
an orthomyxovirus/influenza virus that is quite similar to and genetically
related to the Spanish Flu of 1918.
-
- At this point under 100 persons have died from A/H5N1.
Data suggest a mortality rate of over 70% in infected humans to date[6,7].
Given the A/H1N1 Spanish influenza killed between 20 to 40 million people
worldwide in 1918 and given that A/H5N1 Avian influenza appears to be genetically
related to A/H1N1, there is cause for concern.
-
- In the last month thousands of people have been displaced
in Thailand resulting from the recent tsunami. "The south-western
coast of Thailand was particularly hit by the force of the tsunami. Almost
immediately, nearly 50,000 rescue workers were mobilized to look for survivors.
200 disease surveillance specialists have been deployed throughout the
affected areas, to strengthen disease surveillance in urgent efforts to
rapidly identify potential outbreaks. While no disease outbreaks have been
reported, an increase in isolated cases of diarrhoeal diseases have been
confirmed, indicating that sanitary conditions and access to safe drinking
water remains critical in displacement camps."[8]
-
- The above information is highlighted by this:
-
- "26 January 2004 Situation in Thailand
-
- The Ministry of Public Health in Thailand has today announced
laboratory confirmation of the country's third human case of H5N1 avian
influenza infection. The patient, who remains alive, is a 6-year-old child
from Sukhothai province.
-
- Health officials in Thailand have also confirmed the
death of a 6-year-old boy from Kanchanaburi province. The boy, whose infection
with the H5N1 strain was announced on Friday, died Sunday night. He had
been hospitalized in Bangkok with severe pneumonia and acute respiratory
distress syndrome."[9]
-
- There appears a high likelihood that A/H5N1 Avian influenza
is going to break out into the human population. Type A influenza viruses
are known for their ability to pick up genes, through antigenic drift and
pseudotyping, so to assist them in their ability to establish new hosts
and to become more efficient in infecting these newly acquired hosts.
-
- According to the CDC in Atlanta, "If these H5N1
viruses gain the ability for efficient and sustained transmission between
humans, there is little preexisting natural immunity to H5N1 in the human
population, and an influenza pandemic could result, with high rates of
illness and death. In addition, genetic sequencing of influenza A (H5N1)
virus samples from human cases in Vietnam and Thailand show resistance
to the antiviral medications amantadine and rimantadine, 2 of the medications
commonly used for treatment of influenza. This would leave 2 remaining
antiviral medications (oseltamavir and zanamavir) that should still be
effective against currently circulating strains of H5N1. Efforts to produce
a vaccine that would be effective against this strain of influenza A H5N1
are under way. Vaccine reference virus strains already have been made and
provided to manufacturers to produce pilot lots for human clinical trials
as well as to produce a larger quantity of H5N1 vaccine, but mass production
and availability of such a vaccine is some time off."[10]
-
- Notes:
-
- [1]
- http://www.ncbi.nlm.nih.gov/
-
- [2]
- http://www.ncbi.nlm.nih.gov/
-
- [3] Graphic
-
- [4]
- http://www.ncbi.nlm.nih.gov/
-
- [5] Graphic
-
- [6]
- http://www.ncbi.nlm.nih.gov/
- and
- http://www.ncbi.nlm.nih.gov/
-
- [7]
- http://www.ncbi.nlm.nih.gov/
-
- [8]
- http://www.who.int/
-
- [9]
- http://www.who.int/csr/
-
- [10]
- http://www.cdc.gov
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