Issue 37

Bacterial and Viral Infections



This issue of Health Review looks at the differences between bacterial and
viral infections, and the role of the immune system in protecting the body
from the damage they may cause.   The importance of a healthy diet
and lifestyle can only be emphasized.



Treatment differences in bacteria and viruses



The main difference from a medical point of view is that antibiotics can
deal with bacteria but not viruses.  Years ago, if a doctor was consulted
for an infection, a swab would have been taken and sent to a laboratory for
a culture to be grown to identify the type of bacteria to enable the correct
type of antibiotic could be prescribed.  Nowadays in the fast ‘instant’
world, a broad spectrum antibiotic would be prescribed and tests only carried
out if the condition persisted, largely because the patient wants to be treated
‘now’, and the doctor has another person to see in a couple of minutes time. 
The consequences are that the number of antibiotics in the medical arsenal
is now very limited as a lot of people have become resistant to certain antibiotics.



Viruses are more difficult to deal with than bacteria.  Drugs have to
be designed to kill viruses without killing the cells that they have attached
themselves to.  Some antiviral drugs work by preventing the virus entering
cells in the first place or by interfering with its replication process. 
 



What are bacteria? (1)



The simple answer is germs!  Bacteria were discovered in the 17th century
after the invention of the microscope.  In the 19th century, Louis Pasteur
made a positive connection between bacteria and particular diseases. 
Bacteria are a group of single-celled microorganisms.  Some may cause
disease, these are known as pathogens.  However, others are necessary
for life, for example the lactic acid producing bacteria in the human gut
(see Probiotics issue).   Bacteria are found everywhere – air,
soil, food and water.  



There are three main groups of bacteria:



1. Cocci – sphere-shaped – associated with pneumonia, tonsillitis, meningitis,
toxic shock syndrome and skin disorders.

2. Bacilli – rod-shaped – associated with tuberculosis, whooping cough, tetanus,
typhoid, diphtheria, salmonellosis, Legionnaires’ disease and botulism.  

3. Spirilla – spiral-shaped – associated with syphilis and Lyme disease.

Bacteria that reside in the human body thrive in warm, moist conditions. 
Some are aerobic, meaning that they need oxygen to grow and multiply. 
These bacteria are commonly found on the skin or in the respiratory system. 
Anaerobic bacteria thrive where there is no oxygen, deep in wounds or tissue.



Most bacteria do not move around the body much, perhaps in natural currents
of air or fluid.  Bacteria such as salmonella are highly motile, moving
through fluid by using the action of their whip-like tails.  



Reproduction of bacteria takes place every twenty minutes in ideal conditions.
Each bacterium will divide into two cells; in six hours this can produce
250,000 bacteria!  Fortunately conditions are not always ‘ideal’.   
 



What are viruses? (1)



Most viruses are so small that they can only be seen with an electron microscope. 
About one half to one-hundredth the size of the smallest bacteria, viruses
are the smallest known type of infectious agent.  Viruses come in different
shapes and sizes, but they have the same basic simple structure.  Parasites
to living cells, viruses parasitize all life forms, outside the living cell
they are inert.  They are incapable of activities such as metabolism
or the internal processing of nutrients.  Not all viruses cause disease,
but many do.



Some of the most well known families of virus and examples of conditions
are:

Papoviruses         - Warts

Adenoviruses    - Respiratory and eye infections

Herpesviruses    - Cold sores, genital herpes, chickenpox,
herpes zoster      

                                  
(shingles), glandular fever

Picomaviruses    - Poliomyelitis, viral hepatitis type A,
respiratory infections

Togaviruses        - Yellow fever, dengue,
encephalitis

Orthomyxoviruses    - Influenza

Paramyxoviruses    - Mumps, measles

Coronaviruses    - Common cold

Arenaviruses        - Lassa fever

Rhabdoviruses    - Rabies

Retroviruses        - AIDS, degenerative brain
diseases, possibly types of cancer



Viruses replicate differently to bacteria.  A virus particle attaches
itself to, and then injects itself into a host cell.  The outer protein
shell of the virus breaks down and the viral nucleic acid (DNA or RNA) is
released.  The nucleic acid replicates itself, with new copies being
made from raw materials inside the host cell.  Each of the new copies
of the viral nucleic acid now is able to produce its own outer protein shell
making new virus particles; these are released in large numbers to start
the replication process all over again, and the weakened host cell may be
destroyed.



Most viruses are rapidly dealt with by the immune system.  Each mechanism
of the immune system may be involved in resisting a viral attack, including
white blood cells (macrophages) that engulf the viral particles, and antibody-producing
lymphocytes that protect cells against the virus or attack virally infected
cells.  Recovery from most viral infections usually occurs within a
few days or weeks, the immune system is often able to recognise the same
virus again making re-infection less severe.



That said, some viruses are quite devious and able to ‘hide’ or even dodge
away from the immune system (herpes for example).  The AIDS virus is
different again; it weakens the immune system, leaving the body open to opportunistic
infections.  



Treatment of viral infections depends on prevention, in the form of vaccines
to fight viruses and prevent them spreading; or on alleviating the symptoms
or having a sufficiently healthy immune system to cope.  



Common factors in transport of bacteria and viruses



Both bacteria and viruses can enter the body by breathing in droplets that
have been sneezed, coughed or breathed out by an infected person; or they
can be swallowed in food or liquid; or passed on to through genito-urinary
contact with an infected person during sex; or may enter the skin through
a wound, bite, or sting.   



Nutrition and Health



Changes to the diet and the use of food supplements may be very useful for
supporting immune health.  A compromised immune system works harder
to keep healthy and the need for certain nutrients increases, for example,
antioxidants including the trace elements selenium (2) and zinc, and the
B complex vitamins.  Deficiency of folic acid may impair immune function,
while vitamins B2 and B6 are involved in antibody formation (3).



Vitamin C is fundamental to immune health and research has shown that during
an infection, levels of this nutrient may become depleted (4).  A regular
intake of 1000mg vitamin C a day may help to reduce the duration of the common
cold and the severity of symptoms (5).



Vitamin A has been shown to benefit many immune processes, including enhancement
of white blood cell function and increased antibody response (6).

 

Zinc is an essential mineral for immune function and a minor deficiency may
have serious effects on all aspects of the immune system.  People who
suffer frequent infections or those who do not eat zinc-rich foods (meat,
fish, shellfish, cheese, eggs, pulses and seeds) may wish to supplement with
zinc.  



Co Q 10 has an antioxidant effect and directly stimulates the formation of
antibodies and white blood cells (7).

 

Vitamin E deficiency may result in poor immune function, it appears to enhance
both antibody and cell-mediated immunity (8).



Herbs and the immune system



Many herbs have anti-bacterial and/or anti-viral activity.  Research
is continuing to reveal more of these life-saving properties in plants.



Aged Garlic Extract possesses potent anti-viral (9) and anti-bacterial activity
(10). Scientific studies have shown that it stimulates various facets of
the immune system.  It is particularly useful during the winter when
colds and flu are more prevalent.      

Echinacea is a herb, which is used traditionally as an immune stimulant. 
The herb contains useful antibacterial and antiviral compounds that stimulate
the production of white blood cells, thereby helping to reduce the body’s
susceptibility to infection (11).



Compounds contained in liquorice are documented for their ability to exert
anti-viral and anti-bacterial activity (12).

Cat’s Claw has been shown to enhance the immune system by increasing the
production of white blood cells and specifically T4 lymphocyte.  These
are involved in fighting foreign substances and in antibody production, potentially
blocking the advances of many viral illnesses (13).



St. John’s wort also has some antibacterial activity especially against the
Streptococcus aureus bacterium and studies have shown the herb to exert anti-viral
activity against certain viruses (12).  

 

Factors that influence the immune system



Certain factors can affect immune system efficiency including nutritional
status, age, gender, race, some drugs, radiation, alcohol intake, hereditary
factors, fatigue and stress.  Origin, gender or genetic make-up cannot
be changed, but we can take control of other aspects of our lives to ensure
that the immune system does not become compromised.  



Safeguarding intakes of essential nutrients, getting regular exercise and
limiting consumption of alcohol and sugar are just four steps that can strengthen
the immune system to fight invading bacteria and viruses to help the body
stay healthy.   



References:



1.  “BMA Complete Family Health Encyclopaedia”, Ed. Dr. T. Smith. 1996.
DK.

2.  Clin Sci (Lond). 2000 May; 98 (5):593-9.

3.  Int Jnl of Alt & Comp Med, Jan 1997; 15: 29-32.

4.  Ann Nutr Metab, 1997, 41; 6:344-352.

5.  Adv.Ther. 2002 May-June; 19 (3): 151-9.

6. R.D. Semba, “Vitamin A, Immunity, and Infection,” Clin Inf Dis 19 
(1994): 489-99.

7. Biochem Biophys Res Commun, 1993, 193; 1:88-92.  

8. P. Dowd and R. Heatley, “The Influence of Under nutrition on Immunity,”
Clin Sci 66 (1984); 343-8.  

9. Fed. Proc. 1987, 46; 3:441.

10.  Kokai Tokkyo Koho, Japanese Patent HI-252276.

11.   “Herbal Medicines, a Guide for Healthcare Professionals”,
C Newall & L Anderson, Pharmaceutical Press. 1996.

12.  “The Healing Power of Herbs”, M Murray N. D.  Prima, 1995.


13.  Phytomedicine. 2001 Jul; 8(4):267-74.