الفهرس 
The red blood cellOnly 14 pages are availabe for public view
 |  | from | 159 |  |  |
| | | from | 159 | | |
Abstract
98
VI- Summary and Conclusions
Most of the infants and children attending outdoor clinics suffer from pyrexia
and infection which is commonly due to viral or bacterial agents. This study was
done in an attempt to assess whether these infections have an effect on blood
constituents. The immunization with attenuated measles virus was used as a model
of a mild and predictable viral illness. The study included 30 infants aged nine
months who attended to be vaccinated against measles according to the compulsory
vaccination schedule in Egypt.
Complete blood picture, serum iron and TIBC in addition to assessment of
phagocytic function of polymorphonuclear leukocytes were done for all infants
before vaccination. The same tests were done ten days later. The difference in
results was statistically analyzed.
Coulter counter model CBCs was used for determination of red blood cell
counts, total white cell counts, hematocrit, MCV (mean corpuscular volume), and
hemoglobin level. Differential leukocyte counts were made by spreading blood
films on slides which were stained by leishman stain and examined microscopically
under oil immersion lens. R,eticulocyte counts were estimated by staining viable
99
cells with brilliant cresyl blue stain and then spreading blood films on slides to be
examined by oil immersion lens. Platelets were counted in hemocytometer after
mixing blood with 1%ammonium oxalate solution. Iron and TIBC were determined
by colorimetric method (Kits provided by Boehringer Mannheim Diagnostica).
There was a significant reduction in hemoglobin concentration on the tenth
day after the administration of measles vaccine. There was also a significant
decrease in MCH (mean corpuscular hemoglobin) as well as in MCHC (mean
corpuscular hemoglobin concentration). On the other hand red blood cell count,
hematocrit, and MCV (mean corpuscular volume) showed no significant changes.
Serum iron level was significantly decreased while TIBC did not change.
These results mean that acute mild viral infection induces hematological
changes similar to the changes encountered in the anemia of chronic disease.
The mechanisms responsible for the development of the infection-related
anemia have not been defined. Low serum iron is most probably due to impaired
reutilization of iron. Among the reasons postulated as causes of this anemia is
defective red cell production due to decreased iron level,or impaired erythropoietin
effect on erythroid precursors. Increased red cell destruction may also be present
in acute infections leading to a rapid fall in hemoglobin. The reticulocytes showed
---~------
100
slight significant decline. This indicates failure of the marrow to meet the need
,f a slightly decreased red cell survival.
The anemia of infection resolves without hematinic therapy in presence of
idequate iron in the diet So, when an infant has a low or low normal hemoglobin
.oncentration, both the infection history and the dietary history will help m
leciding whether to start a therapeutic trial of iron.
In this study there was a significant decrease in platelet count on the tenth
lay after inoculation by measles vaccine which may be due to diminished platelet
sroduction. It is quite possible that this degree of platelet depression occurs
commonly during the incubation period of naturally occurring measles as well as
in many viral infections.
The development of reduction in hemoglobin concentration and decrease in
platelet count after vaccination with the live attenuated measles virus is not
deleterious to the infants and does not mean to abstain from vaccination or make
restrictions to its use.
,
101
Secondary bacterial infection is a frequent complication of viral infections.
This is due to impairment in immunity. Previous studies showed that the
chemotactic and bactericidal function of neutrophils is impaired in a variety of viral
infections and measles is one of them.
In this study phagocytic activity of polymorphonuclear leukocytes was
assessed by incubating the neutrophils with candida albicans for 30-45 minutes
after which films were spreaded and stained. then examined under the microscope
for cells phagocytosing candida.
There was no significant difference in total leukocytic count as well as the
differential count. As regards the function of neutrophils, the number of cells
phagocytosing candida did not show a significant difference on the tenth day of
vaccination comparable to the number before vaccination i.e. the
immuno-compromised state which is found in measles was shown in our study not
to occur after measles vaccination. This means that live attenuated measles vaccine
can be safely administered to healthy infants without the fear of secondary bacterial
infection.
----- ------------------ -_.-