Transmission of MERS-coronavirus in household contacts.

BACKGROUND: Strategies to contain the Middle East respiratory syndrome coronavirus (MERS-CoV) depend on knowledge of the rate of human-to-human transmission, including subclinical infections. A lack of serologic tools has hindered targeted studies of transmission. METHODS: We studied 26 index patients with MERS-CoV infection and their 280 household contacts. The median time from the onset of symptoms in index patients to the latest blood sampling in contact patients was 17.5 days (range, 5 to 216; mean, 34.4). Probable cases of secondary transmission were identified on the basis of reactivity in two reverse-transcriptase-polymerase-chain-reaction (RT-PCR) assays with independent RNA extraction from throat swabs or reactivity on enzyme-linked immunosorbent assay against MERS-CoV S1 antigen, supported by reactivity on recombinant S-protein immunofluorescence and demonstration of neutralization of more than 50% of the infectious virus seed dose on plaque-reduction neutralization testing. RESULTS: Among the 280 household contacts of the 26 index patients, there were 12 probable cases of secondary transmission (4%; 95% confidence interval, 2 to 7). Of these cases, 7 were identified by means of RT-PCR, all in samples obtained within 14 days after the onset of symptoms in index patients, and 5 were identified by means of serologic analysis, all in samples obtained 13 days or more after symptom onset in index patients. Probable cases of secondary transmission occurred in 6 of 26 clusters (23%). Serologic results in contacts who were sampled 13 days or more after exposure were similar to overall study results for combined RT-PCR and serologic testing. CONCLUSIONS: The rate of secondary transmission among household contacts of patients with MERS-CoV infection has been approximately 5%. Our data provide insight into the rate of subclinical transmission of MERS-CoV in the home.

Clinical profile and outcome of hospitalized patients during first outbreak of dengue in Makkah, Saudi Arabia.

OBJECTIVE: To describe clinical profile of patients with dengue virus infection hospitalized at a single center during the first outbreak of dengue in Makkah, Saudi Arabia from April to July 2004. METHODS: Clinical information and laboratory abnormalities of patients with suspected dengue infection were collected by a standardized data collection sheet and review of medical records. Dengue virus infection was confirmed by a positive IgM capture ELISA or RT-PCR. RESULTS: Of the 160 clinically suspected patients, 91 were confirmed (64 by IgM ELISA, 14 by RT-PCR and 13 by both) to have dengue virus infection. Dengue serotypes 2 and 3 were identified in 19 and 4 patients respectively. Most patients were young adults with median age of 26 (range=6-94) years and male:female ratio of 1.5:1. The common symptoms were fever (100%), malaise (83%), musculoskeletal pain (81%), headache (75%), nausea (69%), vomiting (65%) and abdominal pain (48%). According to World Health Organization (WHO) classification (10 patients were excluded due to lack of serial hematocrits), 75 (93%) had dengue fever (DF) and 6 (7%) had dengue hemorrhagic fever (DHF). Only one patient with DHF was in pediatric age group. Twenty-one patients (5 with DHF and 16 with DF) developed one or more clinical complications that included bleeding (14), shock (4), seizures (3), acute renal failure (2), meningo-encephalitis (1), and secondary bacterial infection (1). Only one patient with shock had dengue shock syndrome (DSS) by WHO classification. Development of clinical complications was significantly associated with absence of musculoskeletal pain (p-value=0.03), lower platelet counts (p-value=0.03) and higher serum aspartate aminotransferase levels (p-value=0.04). The median duration of symptoms and hospitalization was 8 days (range=3-18) and 4 days (range=1-10) respectively. No mortality was noted. CONCLUSION: Occurrence of dengue virus infection in Makkah, Saudi Arabia is documented. Continued surveillance and effective vector control programs are warranted due to unique population dynamics of Makkah that receives millions of pilgrims annually from all over the world.