Clinical predictors of dengue fever co-infected with leptospirosis among patients admitted for dengue fever - a pilot study.

BACKGROUND: Dengue and leptospirosis infections are currently two major endemics in Malaysia. Owing to the overlapping clinical symptoms between both the diseases, frequent misdiagnosis and confusion of treatment occurs. As a solution, the present work initiated a pilot study to investigate the incidence related to co-infection of leptospirosis among dengue patients. This enables the identification of more parameters to predict the occurrence of co-infection. METHOD: Two hundred sixty eight serum specimens collected from patients that were diagnosed for dengue fever were confirmed for dengue virus serotyping by real-time polymerase chain reaction. Clinical, laboratory and demographic data were extracted from the hospital database to identify patients with confirmed leptospirosis infection among the dengue patients. Thus, frequency of co-infection was calculated and association of the dataset with dengue-leptospirosis co-infection was statistically determined. RESULTS: The frequency of dengue co-infection with leptospirosis was 4.1%. Male has higher preponderance of developing the co-infection and end result of shock as clinical symptom is more likely present among co-infected cases. It is also noteworthy that, DENV 1 is the common dengue serotype among all cases identified as dengue-leptospirosis co-infection in this study. CONCLUSION: The increasing incidence of leptospirosis among dengue infected patients has posed the need to precisely identify the presence of co-infection for the betterment of treatment without mistakenly ruling out either one of them. Thus, anticipating the possible clinical symptoms and laboratory results of dengue-leptospirosis co-infection is essential.

Cellular proteome alterations in response to enterovirus 71 and coxsackievirus A16 infections in neuronal and intestinal cell lines.

Hand, foot and mouth disease is mainly caused by enterovirus A71 (EV-A71) and coxsackievirus A16 (CV-A16), but EV-A71 is also associated with severe neurological complications. Host factors may contribute to the different clinical outcomes of EV-A71 and CV-A16 infections. A neurovirulent EV-A71 strain (EV-A71/UH1) from a fatal case, a non-neurovirulent EV-A71 strain (EV-A71/Sha66) and a CV-A16 strain (CV-A16/22159) from cases of uncomplicated HFMD were used. Replication of the viruses in SK-N-MC (neuronal) and HT-29 (intestinal) cell lines correlated with the severity of clinical disease associated with each virus. EV-A71/UH1 showed the greatest replication in neuronal cells. In HT-29 cells, both EV-A71 strains replicated well, but CV-A16/22159 showed no effective replication. The proteomes of mock and infected SK-N-MC and HT-29 cell lines were compared by 2D-SDS-PAGE. The differentially expressed proteins were identified by MALDI-TOF/TOF analysis. There were 46 and 44 differentially expressed proteins identified from SK-N-MC and HT-29 cells, respectively, categorized under apoptosis, stress, cytoskeletal, energy metabolism proteins and others. Western blot validation showed that EV-A71/UH1 and CV-A16 also differentially induced proteins involved in viral RNA translation and host cell stress responses in neuronal and intestinal cell lines.

Genotypic and phenotypic characterization of Chikungunya virus of different genotypes from Malaysia.

BACKGROUND: Mosquito-borne Chikungunya virus (CHIKV) has recently re-emerged globally. The epidemic East/Central/South African (ECSA) strains have spread for the first time to Asia, which previously only had endemic Asian strains. In Malaysia, the ECSA strain caused an extensive nationwide outbreak in 2008, while the Asian strains only caused limited outbreaks prior to this. To gain insight into these observed epidemiological differences, we compared genotypic and phenotypic characteristics of CHIKV of Asian and ECSA genotypes isolated in Malaysia. METHODS AND FINDINGS: CHIKV of Asian and ECSA genotypes were isolated from patients during outbreaks in Bagan Panchor in 2006, and Johor in 2008. Sequencing of the CHIKV strains revealed 96.8% amino acid similarity, including an unusual 7 residue deletion in the nsP3 protein of the Asian strain. CHIKV replication in cells and Aedes mosquitoes was measured by virus titration. There were no differences in mammalian cell lines. The ECSA strain reached significantly higher titres in Ae. albopictus cells (C6/36). Both CHIKV strains infected Ae. albopictus mosquitoes at a higher rate than Ae. aegypti, but when compared to each other, the ECSA strain had much higher midgut infection and replication, and salivary gland dissemination, while the Asian strain infected Ae. aegypti at higher rates. CONCLUSIONS: The greater ability of the ECSA strain to replicate in Ae. albopictus may explain why it spread far more quickly and extensively in humans in Malaysia than the Asian strain ever did, particularly in rural areas where Ae. albopictus predominates. Intergenotypic genetic differences were found at E1, E2, and nsP3 sites previously reported to be determinants of host adaptability in alphaviruses. Transmission of CHIKV in humans is influenced by virus strain and vector species, which has implications for regions with more than one circulating CHIKV genotype and Aedes species.

Chikungunya virus of Asian and Central/East African genotypes in Malaysia.

BACKGROUND: Chikungunya virus (CHIKV) of the Central/East African genotype has caused large outbreaks worldwide in recent years. In Malaysia, limited CHIKV outbreaks of the endemic Asian and imported Central/East African genotypes were reported in 1998 and 2006. Since April 2008, an unprecedented nationwide outbreak has affected Malaysia. OBJECTIVE: To study the molecular epidemiology of the current Malaysian CHIKV outbreak, and to evaluate cross-neutralisation activity of serum from infected patients against isolates of Asian and Central/East African genotypes. STUDY DESIGN: Serum samples were collected from 83 patients presenting in 2008, and tested with PCR for the E1 gene, virus isolation, and for IgM. Phylogenetic analysis was performed on partial E1 gene sequences of 837bp length. Convalescent serum from the current outbreak and Bagan Panchor outbreak (Asian genotype, 2006) were tested for cross-neutralising activity against representative strains from each outbreak. RESULTS: CHIKV was confirmed in 34 patients (41.0%). The current outbreak strain has the A226V mutation in the E1 structural protein, and grouped with Central/East African isolates from recent global outbreaks. Serum cross-neutralisation activity against both Central/East African and Asian genotypes was observed at titres from 40 to 1280. CONCLUSIONS: The CHIKV strain causing the largest Malaysian outbreak is of the Central/East African genotype. The presence of the A226V mutation, which enhances transmissibility of CHIKV by Aedes albopictus, may explain the extensive spread especially in rural areas. Serum cross-neutralisation of different genotypes may aid potential vaccines and limit the effect of future outbreaks.