الفهرس 
Human Herpes Virus-7Only 14 pages are availabe for public view
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Abstract
Pityriasis rosea is an acute, inflammatory skin disease of unknown cause which occurs worldwide and in individuals of all races. It affects mainly adolescents and young adults in the second to fourth decade of life.
There is a widely held belief that PR is a viral infection. Many observations support this view, including seasonal variation, occasional constitutional symptoms, the characteristic course of the disease, and reported clustering in families or communities. However, the role of other organisms was also suggested such as spirochetes, streptococci and immunologic factors have been considered.
The aim of the present work was to study the possible role of HHV-7 in PR which was a matter of debate in different studies.
The present work included 20 cases of PR (17 classical PR, 3 PR inversa), 15 patients with healed PR and 15 control healthy subjects.
All groups were subjected to HHV-7 DNA detection in lesional, non-lesional, PBMC and plasma samples using n-PCR with specific primers for HHV-7 DNA sequence.
We found that 80% of patients group had positive result for HHV-7 DNA in their lesional tissues and 75% in the non-lesional tissues wheares non of the control and healed PR group were positive.
These results showed a highly significant statistical difference between the patients group and the healed group on one hand and patients group and control group on the other hand, as regards HHV-7 DNA detection in tissues.
Also, we found that 85% of the patients group had positive results for detection of HHV-7 DNA in their plasma samples whereas HHV-7 DNA was not detected in all plasma samples of the healed PR group and control group. These results showed a highly statistically significant difference on comparing patient group with healed PR group and control group.
HHV-7 DNA detection in blood samples showed no significant difference suggesting that HHV-7 DNA detection in tissues and plasma by n-PCR technique has a higher significance than detection in blood that require a quantitative assay for diagnosis of active HHV-7 replication.
All PR cases with prodromal symptoms were positive for HHV-7 DNA while PR cases without prodromal symptoms showed negative detection of HHV-7 DNA in different samples.
All recurrent PR cases were positive for HHV-7 DNA by n-PCR in different samples but quantitative viral assay in blood sample must be done.
Finally, our study found that the cause of recurrent PR may be due to reactivation of HHV-7.
In Conclusion:
The results of our study suggest that HHV-7 play; both in adults and in children an etiological role in PR. All cases of PR plasma showed a positive detection of HHV-7 DNA by n-PCR which represent a marker of active or productive infection while blood samples need further investigation (quantitative assay) to differentiate between latency (clinically silent) and active (clinically manifest) viral infection.