Moujahed Kao

Outbreak of viral hemorrhagic fever caused by dengue virus type 3 in Al-Mukalla, Yemen

BackgroundInvestigations were conducted by the authors to explore an outbreak of viral hemorrhagic fever (VHF) reported in 2010 from Al-Mukalla city, the capital of Hadramout in Yemen.MethodsFrom 15–17 June 2010, the outbreak investigation period, specimens were obtained within 7 days after onset of illness of 18 acutely ill patients hospitalized with VHF and 15 household asymptomatic contacts of 6 acute cases. Additionally, 189 stored sera taken from acutely ill patients with suspected VHF hospitalized in the preceding 12 months were obtained from the Ministry of Health of Yemen. Thus, a total of 222 human specimens were collected; 207 specimens from acute cases and 15 specimens from contacts. All samples were tested with RT-PCR for dengue (DENV), Alkhumra (ALKV), Rift Valley Fever (RVFV), Yellow Fever (YFV), and Chikungunya (CHIKV) viruses. Samples were also tested for DENV IgM, IgG, and NS1-antigen. Medical records of patients were reviewed and demographic, clinical, and laboratory data was collected.ResultsOf 207 patients tested, 181 (87.4%) patients were confirmed to have acute dengue with positive dengue NS1-antigen (97 patients, 46.9%) and/or IgM (163 patients, 78.7%). Of the 181 patients with confirmed dengue, 100 (55.2%) patients were IgG-positive. DENV RNA was detected in 2 (1%) patients with acute symptoms; both samples were molecularly typed as DENV type 3. No other VHF viruses were detected. For the 15 contacts tested, RT-PCR tests for the five viruses were negative, one contact was dengue IgM positive, and another one was dengue IgG positive. Of the 181 confirmed dengue patients, 120 (66.3%) patients were males and the median age was 24 years. The most common manifestations included fever (100%), headache (94.5%), backache (93.4%), malaise (88.4%), arthralgia (85.1%), myalgia (82.3%), bone pain (77.9%), and leukopenia (76.2%). Two (1.1%) patients died.ConclusionsDENV-3 was confirmed to be the cause of an outbreak of VHF in Al-Mukalla. It is important to use both IgM and NS1-antigen tests to confirm acute dengue particularly under the adverse field conditions, where proper storage and transportation of specimens are missing, which substantially reduce the sensitivity of the RT-PCR for detecting DENV RNA.

Successful propagation of Alkhumra (misnamed as Alkhurma) virus in C6/36 mosquito cells

Epidemiological data suggest that Alkhumra (misnamed as Alkhurma) virus (ALKV) is transmitted from livestock animals to humans by direct contact with animals or by the mosquito bites, but not by ticks. To assess the ability of the virus to replicate in mosquito cells, serum and plasma of seven acutely febrile patients with clinically suspected ALKV infection reported in Najran, Saudi Arabia in 2009 were inoculated onto Aedes albopictus mosquito cells (C6/36) and directly examined with ALKV-RNA-specific real time RT-PCR as well as indirect immunfluorescence assay (IFA) using ALKV-specific polyclonal antibodies. The isolated virus was titrated in the mammalian rhesus monkey kidney cells (LLC-MK2). Five of the seven specimens were RT-PCR- and culture-positive demonstrating cytopathic effects in the form of cell rounding and aggregation appearing on day 3 post inoculation with syncytia eventually appearing on day 8 post inoculation. Identification of ALKV-RNA in the cell culture was confirmed with RT-PCR and IFA. The virus titre was 3.2×10(6) tissue culture infective dose 50 (TCID(50)) per mL. Three more viral passages were successfully made in the C6/36 cells. This is the first description of propagation of ALKV in mosquito cells.

Alkhumra, Not Alkhurma, Is the Correct Name of the New Hemorrhagic Fever Flavivirus Identified in Saudi Arabia

April 2001, published with Charrel et al. [6] a paper describing the complete coding sequence of this virus, unfortunately mistakenly naming it Alkhurma not Alkhumra due to a transpositional typographical error where the ‘m’ and ‘r’ were reversed. The new name Alkhurma, erroneously now assigned to this virus in a number of other reports, refers to a small city, 280 kilometers from Alkhumra district in Jeddah and has had, to this point, nothing to do with this virus. All reported cases of ALKV identified to date in Saudi Arabia have been from Alkhumra/Jeddah, Makkah and more recently from Najran [4, 5] . (2) The authors erroneously cite that 37 suspected ALKV hemorrhagic fever cases, that included 20 laboratory-confirmed cases, were from Alkhumra district, south of Jeddah; the citation clearly described these cases as being from Makkah [4] . (3) The authors used the case definition for suspected ALKV infection developed by Madani without referring to the source [4] . (4) A comprehensive prospective epidemiological study in Najran for the period 2003–2009 published recently by us showed that only 3 (3.8%) out of 78 laboratory-confirmed cases of ALKV infection Sir, We have the following comments on the paper published by Alzahrani et al. [1] . (1) The authors claim that the virus was named Alkhurma because the first case was reported from the Alkhurma governorate. They cited a reference that actually did not mention Alkhurma city while it clearly mentioned that the first 6 cases were butchers from Jeddah where Alkhumra district and not Alkhurma city is located [2] . The original publication that reported those same cases also described them as being from Jeddah and not from Alkhurma city [3] . According to the official reports from the Ministry of Health of Saudi Arabia, the first 6 cases were indeed from ‘Alkhumra’ district, a southern district in Jeddah that has been the location of livestock marketplaces and slaughterhouses, the characteristic environmental risk factors for acquiring this virus [4, 5] . Following re-identification of the virus in Makkah by Madani in February 2001, the Ministry of Health circulated a memo to all health sectors to alert them of this new virus and tentatively referred to it as Alkhumra virus (ALKV) for the first time [4, 5] . Subsequently, in August 2001, Zaki (a non-Saudi virologist working in Saudi Arabia), who received the aforementioned memo from the Ministry of Health in Published online: March 19, 2012

Gastroenteritis attributable to rotavirus in hospitalized Saudi Arabian children in the period 2007-2008.

PURPOSE Rotavirus (RV) is a leading cause of severe gastroenteritis (GE) in children across the world. As there is a lack of epidemiological data for RV gastroenteritis (RVGE) in Saudi Arabia, this hospital-based study was designed to estimate the disease burden of RVGE and assess the prevalent RV types in Saudi children younger than 5 years of age. PATIENTS AND METHODS Children hospitalized for acute GE were enrolled at four pediatric referral hospitals in Saudi Arabia. The study was conducted from February 2007 to March 2008 and used the World Health Organizations generic protocol for RVGE surveillance. The Vesikari severity scale was used to assess the severity of RVGE. Stool samples were tested for RV using an enzyme-linked immunosorbent assay. Samples were further typed by reverse transcriptase-polymerase chain reaction and hybridization assay for determining the G and P types. RESULTS A total of 1,007 children were enrolled; the final analysis included 970 children, of whom 395 were RV positive, 568 were RV negative, and seven had unknown RV status. The proportion of RVGE among GE hospitalizations was 40.7% (95% confidence interval: 37.6-43.9). The highest percentage of RVGE hospitalizations (83.1%) was seen in children younger than 2 years of age. The highest proportion of RV among GE hospitalizations was in June 2007 with 57.1%. The most common RV types detected were G1P[8] (49.3%), G1G9P[8] (13.2%), and G9P[8] (9.6%). Before hospitalization, severe GE episodes occurred in 88.1% RV-positive and 79.6% RV-negative children. Overall, 94% children had recovered by the time they were discharged. Two children (one RV positive and one RV negative) died due to GE complications. CONCLUSION RVGE is responsible for a high proportion of hospitalizations in Saudi children younger than 5 years of age. Routine RV vaccination has therefore been introduced into the national immunization program and may help reduce the morbidity, mortality, and disease burden associated with RVGE in Saudi Arabia.

Propagation and titration of Alkhumra hemorrhagic fever virus in the brains of newborn Wistar rats

Alkhumra hemorrhagic fever virus (AHFV) is a novel flavivirus identified first in Saudi Arabia. In this study, successful propagation of AHFV in the brains of newborn Wistar rats is described and the median rat lethal dose (RLD50) is determined. AHFV-RNA-positive human sera diluted 1:10 were injected intracerebrally into 16, ≤24h old rats. Post-inoculation, the rats were observed daily for 30 days. Brains of moribund rats were tested for AHFV-RNA using RT-PCR and cultured in LLC-MK2 cells. The titer of the isolated virus was determined and expressed in median tissue culture infectious dose (TCID50). To determine the RLD50, AHFV brain suspension was 10-fold diluted serially and each dilution was inoculated in the cerebral hemispheres of 10 rats for a total of 90 rats. Three days post-inoculation, the rats developed tremor, irritability, convulsion, opisthotonus, and spastic paresis starting in the hind limbs and ascending to involve the whole body. All infected rats died within 3-7 days with histopathologically confirmed meningoencephalitis. AHFV-RNA was detected in the brains of all infected rats and the virus titer was 10(9.4) RLD50/ml. The virus titer in LLC-MK2 was 10(8.2) TCID50/ml. In conclusion, AHFV was propagated successfully to high titers in the brains of newborn Wistar rats.

Complete Genome Sequencing and Genetic Characterization of Alkhumra Hemorrhagic Fever Virus Isolated from Najran, Saudi Arabia

Background: Alkhumra hemorrhagic fever virus (AHFV) is a newly described flavivirus first isolated in 1994-1995 from the Alkhumra district south of Jeddah, Saudi Arabia. Subsequently, the virus was also isolated from Makkah (2001-2003) and Najran (2008-2009), Saudi Arabia. Methods: The full-length genome of an AHFV strain isolated from patients in Najran (referred to as AHFV/997/NJ/09/SA) was PCR amplified and sequenced, and compared with the sequences of 18 other AHFV strains previously isolated from Jeddah and Makkah, dengue virus (DENV), Kyasanur forest disease virus (KFDV), Langat virus, Omsk hemorrhagic fever virus (OHFV), and tick-borne encephalitis virus (TBEV). Results: The RNA of the AHFV/997/NJ/09/SA strain was found to have 10,546 nucleotides encoding for a single 3,416-amino acid polyprotein, whereas the previously reported AHFV strains were composed of 10,685-10,749 nucleotides. The AHFV/997/NJ/09/SA strain showed about 99% homology with the previously reported AHFV strains. The KFDV, Langat virus, TBEV, and OHFV isolates formed a separate cluster with a variable homology. The most important variations were observed in the core protein and NS4a gene sequences of two AHFV isolates. Conclusion: The variation in the number of nucleotides and phylogenetic analysis with the other AHFV isolates could have resulted from recombination of circulating virus strains.

Superiority of the buffy coat over serum or plasma for the detection of Alkhumra virus RNA using real time RT-PCR

RT-PCR to detect Alkhumra virus (ALKV) RNA in plasma or serum has been the standard practice to confirm this infection in the first seven days of illness. In this study, RT-PCR detection of viral RNA from the plasma, serum, and buffy coat (BC) was compared to virus isolation. Plasma, serum, and BC were obtained from seven patients with clinically suspected ALKV infection in Najran, Saudi Arabia. Baby hamster kidney (BHK-21) and rhesus monkey kidney (LLC-MK2) cell culture monolayers were used for virus isolation. Real-time RT-PCR was used to confirm ALKV infection and to detect viral RNA directly from plasma, serum, and BC. ALKV was isolated from five of the seven patients. The virus was isolated from all three specimen types (plasma, serum, and BC) of the five confirmed patients. ALKV RNA was detected directly by RT-PCR in BC in all five (100%) culture-positive patients and in plasma or serum in only four (80%) of the five patients. Three of the five patients for whom ALKV RNA was detected in BC also had detectable viral RNA in plasma and serum. In the remaining two patients with detectable ALKV RNA in the BC, the plasma was positive but the serum was negative in one patient, whereas the serum was positive and the plasma was negative in the other patient. The use of real-time RT-PCR to detect ALKV RNA in the BC was superior to using plasma and serum and equivalent to virus isolation.

Virological diagnosis of dengue fever in Jeddah, Saudi Arabia: Comparison between RT-PCR and virus isolation in cell culture

A total of 233 serum samples were collected from patients presenting to King Abdulaziz University Hospital with suspected cases of Dengue Fever (DF) from 2006 to 2008. Dengue virus was successfully isolated from 70 samples by culture on C6/36 and LLC-MK2 cells; it was then detected by indirect immunofluorescence assay (IFA). The cytopathic effect (CPE) of dengue virus on C6/36 appeared in most of the samples within 1-4 days post-inoculation comparing to 7-12 days on LLC-MK2 cells, and this was characterized by the ability to induce syncytia and multinucleated giant cells. On the other hand, by using RT-PCR technique, 87 (37.3%) samples were positive. All 70 (30.4%) samples with positive cell culture results were detectable by RT-PCR in addition to 17 culture-negative samples were RT-PCR positive. Dengue virus type 1 (DENV-1) was the dominant serotype followed by DENV- 3 and DENV-2, while DENV-4 was not detected in tested samples. These results indicate that DENV-RNA detection by RT-PCR is more sensitive than virus isolation. We suggest that the high sensitivity coupled with the turnaround time, have made the RT-PCR a better choice as a routine test for DENV diagnosis. Key words: