title: Outbreak of viral hemorrhagic fever caused by dengue virus type 3 in Al-Mukalla, Yemen.
abstract: BACKGROUND
  Investigations 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.
  
  
  METHODS
  From 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.
  
  
  RESULTS
  Of 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.
  
  
  CONCLUSIONS
  DENV-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.
authors.affiliation: Department of Medicine, Faculty of Medicine, King Abdulaziz University, PO Box 80215, Jeddah 21589, Saudi Arabia. tmadani@kau.edu.sa
authors.forename: Tariq A
authors.initials: TA
authors.lastname: Madani
authors.forename: El-Tayeb M E
authors.initials: el-TM
authors.lastname: Abuelzein
authors.forename: Hussein M S
authors.initials: HM
authors.lastname: Al-Bar
authors.forename: Esam I
authors.initials: EI
authors.lastname: Azhar
authors.forename: Moujahed
authors.initials: M
authors.lastname: Kao
authors.forename: Haj O
authors.initials: HO
authors.lastname: Alshoeb
authors.forename: Alabd R
authors.initials: AR
authors.lastname: Bamoosa
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000818:Animals; D000914:Antibodies, Viral / Q000097:blood; D002648:Child; D002675:Child, Preschool; D015331:Cohort Studies; D003716:Dengue Virus / Q000235:genetics / Q000302:isolation & purification*; D004196:Disease Outbreaks; D005260:Female; D015511:Goat Diseases / Q000453:epidemiology / Q000821:virology; D006041:Goats; D006801:Humans; D008297:Male; D008875:Middle Aged; D012367:RNA, Viral / Q000032:analysis / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D019595:Severe Dengue / Q000175:diagnosis / Q000453:epidemiology* / Q000821:virology*; D012756:Sheep; D012757:Sheep Diseases / Q000453:epidemiology / Q000821:virology; D015006:Yemen / Q000453:epidemiology; D015047:Zoonoses / Q000453:epidemiology / Q000821:virology
chemical_list: D000914:Antibodies, Viral; D012367:RNA, Viral