Mohammed N. Al-Nasser

Prevalence of Intestinal Parasites in Saudi Children: a Community-based Study

A community-based study was undertaken to determine the prevalence and types of intestinal parasites in the pediatric population of Al-Baha region, Saudi Arabia. Stool samples were randomly collected from 19,939 children of whom 4208 (21.1%) were found to harbour intestinal parasites. The most affected age group was 5-9 years and the sex distribution was almost equal in all age groups. Specific prevalence rates were Giardia lamblia 9 per cent, entamoeba histolytica 5 per cent, Hymenolepis nana 2 per cent, and Enterobius vermicularis 2 per cent. The findings of this survey confirm the extremely complex nature of parasitic profile in developing communities, and indicate that relationships exist between cultural and ecological factors, sanitation, and observed pattern of intestinal parasites.

Visceral Leishmaniasis in Infancy and Childhood Epidemiology and Clinicopathological Study of 63 Cases in Al-Baha Province, Saudi Arabia

The epidemiology, clinicopathological features, and response to therapy of 63 Saudi patients with visceral leishmaniasis are described. The clinical features in our cases were similar to those described from Asir province, India, and Ethiopia, except for the presence of lymphadenopathy. Fever, hepatosplenomegaly, pancytopenia, and liver dysfunction were common findings. The unusual feature is the seasonal variation in the distribution of the disease. The response to sodium stibogluconate was excellent and the mortality rate was low (less than 1 per cent).

The clinical utility of molecular karyotyping for neurocognitive phenotypes in a consanguineous population

Purpose:Molecular karyotyping has rapidly become the test of choice in patients with neurocognitive phenotypes, but studies of its clinical utility have largely been limited to outbred populations. In consanguineous populations, single-gene recessive causes of neurocognitive phenotypes are expected to account for a relatively high percentage of cases, thus diminishing the yield of molecular karyotyping. The aim of this study was to test the clinical yield of molecular karyotyping in the highly consanguineous population of Saudi Arabia.Methods:We have reviewed the data of 584 patients with neurocognitive phenotypes (mainly referred from pediatric neurology clinics), all evaluated by a single clinical geneticist.Results:At least 21% of tested cases had chromosomal aberrations that are likely disease-causing. These changes include both known and novel deletion syndromes. The higher yield of molecular karyotyping in this study as compared with the commonly cited 11% can be explained by our ability to efficiently identify single-gene disorders, thus enriching the samples that underwent molecular karyotyping for de novo chromosomal aberrations. We show that we were able to identify a causal mutation in 37% of cases on a clinical basis with the help of autozygome analysis, thus bypassing the need for molecular karyotyping.Conclusion:Our study confirms the clinical utility of molecular karyotyping even in highly consanguineous populations.Genet Med 17 9, 719–725.

A Study on Herpes Simplex Encephalitis in 18 Children, Including 3 Relapses

Background: Herpes Simplex Virus (HSV) is the most common cause of acute sporadic focal encephalitis. Early Diagnosis is, therefore, crucial for predicting outcome. Improved laboratory technology and improved neuroimaging accessibility have enhanced our ability to diagnose this condition. Aims: To assess the reliability of different investigative tools in diagnosing and subsequent management of herpes simplex encephalitis (HSE); as well as the impact of infection and its relapse on the outcome of a cohort of 18 children evaluated during a period of 13 years. Methods: This combined prospective and retrospective study describes the clinical, laboratory, electroencephalographic and diagnostic imaging studies; and outcome in a cohort of 18 children with HSE over a period of 13 years. It also details the clinical and diagnostic features of 3 patients who relapsed. Results: The commonest initial presenting symptoms and signs were fever (100%), seizures (72%) irritability (50%) and weakness/hemiparesis (39%). Cerebrospinal fluid (CSF) pleocytosis was found in 62%, red blood cells (RBCs) >10x10 6 /L in 81% and raised proteins (>0.59g/L) in 52%. Examination for herpes simplex virus (HSV) by polymerase chain reaction (PCR) was positive in 50% (6/12). Electroencephalographic changes were universally abnormal (17/17; 100%) and periodic lateralization discharges (PLEDS) were seen in 35% (6/17). During the acute stage (days 1-8 from symptom onset), magnetic resonance imaging (MRI) revealed abnormalities in 91% (10/11), cranial computed tomography (CT) in 50% (5/10) and single photon emission computed tomography (SPECT), within 3days from onset of symptoms) had significant association with poor outcome (P = 0.002). Initial negative PCR results may become positive on subsequent CSF specimen. Conclusion: Diagnosis of HSE requires combined clinical, laboratory, electroencephalographic and neuroimaging studies. Negative results of PCR do not exclude the infection and should not interrupt the treatment. Early diagnosis and initiation of treatment minimize the devastating effect of HSE. Full course treatment with acyclovir for 21 days is also crucial for prognosis and prevention of subsequent relapse.