8/8/2019 Infectious Diseases-Dr.mohammad Suliman- 15102010

1/2

Infectious Diseases (known as Infectology)

The Human Immune System maintains the human body

In harmony with all the environmental elements .It is the firstdefense line to protect the body against an aggressive environment

that continuously attacks it for survival .

Among these aggressive elements ,infectious agents are of majorimportance sometimes, their incidence on body functioning

determines the bodys existence .

If the battle results in a balanced outcome, a healthy condition

can be maintained ;otherwise, where microbial agents overcome

the immunologic barrier ,a condition known as infection presents .

Infections are within the scope of Infectology, a science that studiesThe pathologies induced by infections agents, and the treatments for them .

During the last years ,great progress has been made through the

development of new diagnostic and therapeutic tools .However ,a great number of themysteries that render Infectology an exciting field of study still remain unexplained.

The respiratory tract as a route of infection

The respiratory tract is one of the most common routes of entry of infectious agentsIn the body . With a ventilation of 6 litres per minute ,a total of nearly 10,000

Microorganisms per day ,is estimated to enter the lung .Immunodepressed conditions

May lead to life risk due to unimportant infections .

Viruses are a common cause of airway damage and can also effect the pulmonaryParenchyma .Damage may involve upper airway or lower airway ,where lungs are

involved, the illness is known as pneumonitis in order to distinguish it from lobarPneumonia ,which is caused by bacteria .

Respiratory viral infections.

Common cold-rhinitis, or called acute rhinitis;Nasal mucosa gets inflamed and mucus discharge increases significantly .

Common cold is caused by viruses, the most common of which are rhinovirus,influenza

virus ,myxovirus, paramyxovirus and adenovirus .

8/8/2019 Infectious Diseases-Dr.mohammad Suliman- 15102010

2/2

Pathogenesis of rhinovirus infection ;

When a person is affected by viral rhinitis ,the virus replicates in the lining epithelium

and after this , degenerate epithelial cells are exfoliated .The mucosa is edematous andcongestive and infiltrated by neutrophils and lymphocytes .Once the process is stopped ,

epithelial cells regenerate .

About 70% of conditions presenting throat inflammation are caused by viruses.Rhinovirus as well as other upper respiratory tract viruses get in touch with defensive

barriers formed by the oropharyngeal lymphoid tissue ,and this is the reason why the

mucosa looks inflamed and eritematous .Among the bacterial agents that can cause pharyngitis ,Group A S. pyogens is the most

common and clinically important one since it can result in complications. Streptococcal

and viral pharyngitis being very difficult to distinguish one from the other ,laboratory

tests are of material importance for differential diagnosis .Streptococcal pharyngotonsillitis is clinically important because it causes frequent

complications .Bacteria such as streptococcus pyogenes have certain structures known to

determine pathogenicity which enable them to cause infections .This bacterial and

secretion factors that enable colony formation in the host .Acute rheumatic fever .

Rheumatic fever refers to an acute systemic inflammatory process that frequently followsa pharyngeal condition caused by Group A streptococci infection.

Repeated attacks of this type of cocci can damage the valves .

Pathogenic mechanisms of rheumatic fever include expansion of T-lymphocytes that can

show a reaction to autoantigens .Thus ,cardiac valves seem to be damaged in this way .Acute poststreptococcal glomerulonephritis

Acute glomerulonephritis refers to an immunocomplex-mediated illness that

is..continue next time .Dr.mohammad Suleiman .

;A

dr.Mohammad- Suleiman

Medics Index Member

www.medicsindex.com

http://medicsorg.tripod.com/drmohammadsuleiman.htm

http://www.medicsindex.com/http://medicsorg.tripod.com/drmohammadsuleiman.htmhttp://www.medicsindex.com/http://medicsorg.tripod.com/drmohammadsuleiman.htm