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Background A periodic serosurvey of dengue seroprevalence is vital to determine the prevalence of dengue in countries where this disease is endemic. This study aimed to determine the prevalence of dengue immunoglobulin G (IgG) seropositivity among healthy Malaysian adults living in urban and rural areas. Methods A total of 2598 serum samples (1417 urban samples, 1181 rural samples) were randomly collected from adults ages 35–74 y. The presence of the dengue IgG antibody and neutralising antibodies to dengue virus (DENV) 1–4 was determined using enzyme-linked immunosorbent assay and the plaque reduction neutralisation test assay, respectively. Results The prevalence of dengue IgG seropositivity was 85.39% in urban areas and 83.48% in rural areas. The seropositivity increased with every 10-y increase in age. Ethnicity was associated with dengue seropositivity in urban areas but not in rural areas. The factors associated with dengue seropositivity were sex and working outdoors. In dengue IgG-positive serum samples, 98.39% of the samples had neutralising antibodies against DENV3, but only 70.97% of them had neutralising antibodies against DENV4. Conclusion The high seroprevalence of dengue found in urban and rural areas suggests that both urban and rural communities are vital for establishing and sustaining DENV transmission in Malaysia. [ABSTRACT FROM AUTHOR]

Background Dengue virus (DENV) infection-enhancing activity of pre-existing antibody has been suggested to be one of the factors responsible for the pathogenesis of the severe form of DENV infection, dengue haemorrhagic fever. Although studies of infection-enhancement activity using diluted serum sera are informative, infection-enhancement activity determined using undiluted sera may better reflect in vivo conditions. Methods We determined whether serum samples collected from dengue patients possessed the ability to enhance DENV infection without dilution using FcγR-expressing cells. Results Serum samples obtained at the early phase of secondary infection enhanced DENV infection without dilution. In contrast, sera obtained at the late stage of secondary infection demonstrated low levels or absence of infection-enhancing activity. Conclusion The results indicate that human sera obtained from patients with secondary infection possess the ability to enhance DENV infection without dilution, and suggest that antibody-dependent enhancement may occur in vivo during secondary DENV infection to infecting DENV serotypes. [ABSTRACT FROM PUBLISHER]

It has been reported that levels of viremia reflect the severity of illness in dengue virus infection. We assessed the levels of viremia in patients with primary and secondary infections, using 2 cell lines: FcγR-expressing BHK cells and FcγR-negative cells. In primary infection, virus titers were at similar levels between FcγR-expressing and FcγR-negative cells. In secondary infection, however, virus titers were ∼10 times higher in FcγR-expressing cells on days 1–6 when compared with FcγR-negative cells, indicating discrepancy in viremia titers between FcγR-expressing and FcγR-negative cells. The results suggest that dengue virus-antibody complexes with infectious capacity exist in patients with secondary infection, and these immune complexes can be detected by using FcγR-expressing cells. As it has been reported that principal target cells of dengue virus infection are FcγR-positive, monocyte/macrophage lineage cells, virus titers determined using FcγR-expressing cells may better reflect the actual viremic conditions in vivo. [ABSTRACT FROM PUBLISHER]

In July 2014, a Japanese traveller returning from Thailand was investigated for fever, headache, rash and conjunctivitis. Zika virus RNA was detected in his urine sample by real-time reverse transcription polymerase chain reaction. Serological tests showed cross reactivity of IgM against the dengue virus. Zika fever could be misdiagnosed or missed and should be considered in febrile patients with a rash, especially those returning from Thailand. [ABSTRACT FROM AUTHOR]

Dengue virus ( DENV) infection is a major health threat for travelers. We describe here a case of dengue virus serotype-3 ( DENV-3) infection in a traveler returning to Japan from the Republic of Benin. The isolated DENV-3 genotype 3 strain exhibited high sequence similarity to those from neighboring regions. [ABSTRACT FROM AUTHOR]

A response from the author of an article which discusses dengue fever differential diagnosis is presented.