الفهرس 
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Abstract
This study was conducted to trace the epidemiology of West Nile fever as a zoonotic viral disease transmitted by arthropod and its public health importance in Behera Province. For this purpose, the following points were investigated:
1. Serological detection of IgG against WNFV in equine.
2. Serological detection of IgG against WNFV in birds.
3. Serological detection of IgG against WNFV in human beings.
4. Detection of WNV RNA in mosquito pools by Real time RT-PCR.
1. Serological detection of IgG against WNFV in equine:
Fifty six equine blood samples including; horses (25) and donkeys (31) were collected from individually owned apparently healthy animals from Behera Province to be investigated for presence of antibodies against WNFV by ELISA test. It was found that the overall detection of WNFV IgG antibodies in all examined equine samples was 100% by ELISA.
2. Serological detection of IgG against WNFV in birds:
A total of 95 avian blood samples including; Ardeola ibis (55) and pigeon (40) were collected from apparently healthy birds from Behera Province to be investigated for presence of antibodies against WNFV by ELISA. It was recorded that the overall detection of WNFV IgG antibodies in all examined bird samples was 4.2 %. Concerning bird species, it was found that 4 out of 55 serum samples collected from Ardeola ibis were positive for the presence of WNFV IgG antibodies at the percentage of 7.2%. On contrary, all the examined serum samples of pigeons were found to be negative for the presence of WNFV IgG antibodies.
3. Serological detection of IgG against WNFV in human beings:
A total of 106 blood serum samples were collected from human beings from Behera Province; including apparently healthy individuals (40), febrile patients (45) and patients with clinical symptoms of meningitis (21). All serum samples were subjected to ELISA test for detection of WNFV IgG antibodies and found that the overall detection rate of WNFV IgG antibodies in the examined human samples was 58.5%.
The effect of health status on the frequency of detection of WNFV IgG antibodies was studied and revealed that 40% (16 out of 40) of apparently healthy individuals were found to be positive for presence of IgG against WNFV. In addition, 29 out of 45 FUO patients were found to be positive at the percentage of 64.4%. Finally, it was found that 17 out of 21 meningitis patients were found to be positive at the percentage of 80.9%.
The effects of gender and age groups on the frequency of detection of WNFV IgG antibodies in examined human beings samples were summarized under the following points:
• Detection of IgG antibodies against WNFV in examined serum samples of apparently healthy individuals in relation to gender indicated the significant differences (P < 0.01) in detection of IgG antibodies against WNFV in examined serum samples of apparently healthy males and females. The obtained results clarified that the higher detection rate of IgG against WNFV was observed in females (42.30 %) compared to the detection rate in males (35 %).
• Detection of IgG antibodies against WNFV in examined serum samples of apparently healthy individuals showed the significant differences (P < 0.01) in detection rate of IgG antibodies against WNFV in examined serum samples of apparently health individuals in relation to age groups. The higher detection rate of IgG was observed in age groups 40 - < 60 years (83.33 %) followed by age group 20- < 40 years (42.85 %), then age group 60 - < 80 years (37.5%) and the least detection rate of IgG was observed in age group 1 - < 20 years (16.66 %). These results cleared that the old age individuals are more susceptible to infection to with WNFV than young age individuals.
• Detection of IgG antibodies against WNFV in examined serum samples of FUO patients in relation to gender indicated the significant differences (P < 0.05) in detection of IgG antibodies against WNFV in examined serum samples of FUO in males and females. The results cleared that the higher detection rate of IgG was observed in females (64.70 %) than males (64.30 %).
• Detection of IgG antibodies against WNFV in examined serum samples of FUO patients cleared the significant differences (P < 0.01) in detection of IgG antibodies against WNFV in examined serum samples of FUO patients in relation to age groups. It was clear that the higher detection rate of IgG was observed in age groups 40 - < 60 years (83.33 %) followed by age group 20 - < 40 years (73.33 %), then the age group 1 - < 20 years (44.44 %). The obtained results cleared that the old age individuals suffered from FUO are more susceptible to WNFV infection than the young age individuals.
• Detection of IgG antibodies against WNFV in examined serum samples of meningitis patients in relation to gender showed the significant differences (P < 0.01) in detection of IgG antibodies against WNFV in examined serum samples of meningitis patients in males and females. It was found that the higher detection rate of IgG was observed in males (91.66 %) than in females (66.66 %). These results indicated that males suffered from meningitis are more susceptible to WNFV infection than females suffered from meningitis.
• Detection of IgG antibodies against WNFV in examined serum samples of meningitis patients showed the significant differences (P < 0.01) in detection of IgG antibodies against WNFV in examined serum samples of meningitis patients in relation to age groups. the obtained results revealed the higher detection rate of IgG was observed in age groups 60 - < 80 years and 1 - < 20 (100 %) followed by age group 20 - < 40 years (75 %) and the least detection rate was observed in the age group ranged from 40 – 60 years (33.33 %).
4. Detection of WNV RNA in mosquito pools by Real time RT-PCR:
A total of 943 mosquitoes (25 mosquitoes groups) were collected by CDC light trap from Behera Province. Mosquitoes were collected from the same places where animal and avian blood samples were obtained. Mosquitoes were identified according to genus into 25 mosquitoes’ pools formed of 943 mosquitoes. Each pool contains 25-50 mosquito of the same genus. All the collected mosquitoes in the study were of Culex species. These mosquitoes’ pools were subjected to Real time RT- PCR for detection of WNFV RNA and it was observed that all of the examined mosquitoes’ groups were negative for presence of the viral RNA.
Finally, the presence of WNFV antibodies in equine, bird and human sera indicates the circulation of WNFV in equine, birds and human beings in the study area. However, taking in consideration the complete lack of reports of clinical disease recently in the study area it appear more likely that these antibodies were due to a long standing infection that might have continued quietly smoldering in equine, birds and especially in human and may eventually flare up in an outbreak or epizootic form if favorable conditions prevail. Also, the seroprevelance studies in animals, birds and human are very necessary to obtain epidemiological data about the disease in Egypt.