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Isolation of Japanese encephalitis virus from Culex sitiens mosquitoes in Selangor, Malaysia

Vythilingam I, Oda K, Tsuchie H, Mahadevan S, Vijayamalar B

J Am Mosq Control Assoc, 1994 Jun;10(2 Pt 1):228-9.
PMID: 8965071

Isolation of Japanese encephalitis virus (JEV) from mosquitoes in Sabak Bernam, Selangor, Malaysia, was attempted. An aliquot of homogenate from each pool of mosquitoes, 50 per tube, was inoculated into Aedes albopictus clone C6/36 cells for virus isolation. Each cell culture was tested for the presence of viral antigen by immunoperoxidase staining using an anti-JEV polyclonal antibody. Out of 4 Culex sitiens mosquito pools, 2 pools were positive for JEV by cell culture. Presence of JEV genome in the cell cultures for Cx. sitiens was confirmed by using reverse transcriptase-polymerase chain reaction and JEV-specific primers. This is the first report on the isolation of JEV from Cx. sitiens.
Type-3 dengue viruses responsible for the dengue epidemic in Malaysia during 1993-1994

Kobayashi N, Thayan R, Sugimoto C, Oda K, Saat Z, Vijayamalar B, et al.

Am J Trop Med Hyg, 1999 Jun;60(6):904-9.
PMID: 10403318

To characterize the dengue epidemic that recently occurred in Malaysia, we sequenced cDNAs from nine 1993-1994 dengue virus type-3 (DEN-3) isolates in Malaysia (DEN-3 was the most common type in Malaysia during this period). Nucleic acid sequences (720 nucleotides in length) from the nine isolates, encompassing the precursor of membrane protein (preM) and membrane (M) protein genes and part of the envelope (E) protein gene were aligned with various reference DEN-3 sequences to generate a neighbor-joining phylogenetic tree. According to the constructed tree, the nine Malaysian isolates were grouped into subtype II, which comprises Thai isolates from 1962 to 1987. Five earlier DEN-3 virus Malaysian isolates from 1974 to 1981 belonged to subtype I. The present data indicate that the recent dengue epidemic in Malaysia was due to the introduction of DEN-3 viruses previously endemic to Thailand.
Fulltext Comparison of sequences of E/NS1 gene junction of dengue type 3 virus following culture subpassage in C6/36 cells to study the possible occurrence of mutations

Thayan R, Morita K, Vijayamalar B, Zainah S, Chew TK, Oda K, et al.

Southeast Asian J. Trop. Med. Public Health, 1997 Jun;28(2):380-6.
PMID: 9444025

The aim of this study was to determine whether mutations could occur in the dengue virus genome following three subpassages of the virus in a mosquito cell line. This was done because sources of virus isolates used for sequencing studies are usually maintained in cell lines rather than in patients' sera. Therefore it must be assured that no mutation occurred during the passaging. For this purpose, sequencing was carried out using the polymerase chain reaction (PCR) products of the envelope/non-structural protein 1 junction region (280 nucleotides) of dengue type 3 virus. Sequence data were compared between the virus from a patient's serum against the virus subpassaged three times in the C6/36 cell line. We found that the sequence data of the virus from serum was identical to the virus that was subpassaged three times in C6/36 cell line.
Isolation of Japanese encephalitis virus from mosquitoes collected in Sabak Bernam, Selangor, Malaysia in 1992

Vythilingam I, Oda K, Chew TK, Mahadevan S, Vijayamalar B, Morita K, et al.

J Am Mosq Control Assoc, 1995 Mar;11(1):94-8.
PMID: 7616198

Detection and isolation of Japanese encephalitis (JE) virus were attempted from female mosquitoes collected in Kampong Pasir Panjang, Sabak Bernam, Selangor, from May to November 1992. A total of 7,400 mosquitoes consisting of 12 species in 148 pools were processed and inoculated into Aedes albopictus clone C6/36 cell cultures. Of these, 26 pools showed the presence of viral antigens in the infected C6/36 cells by specific immunoperoxidase staining using an anti-JE virus polyclonal antibody. Presence of JE virus genome was confirmed in the infected culture fluid for 16 pools by using reverse transcriptase-polymerase chain reaction and JE virus-specific primers. Of these, 3 pools were from Culex tritaeniorhynchus, 4 from Culex vishnui, 3 from Culex bitaeniorhynchus, 2 from Culex sitiens, one from Aedes species, and 3 from Culex species. Isolation of JE virus from Cx. sitiens, Cx. bitaeniorhynchus, and Aedes sp. (Aedes butleri and Ae. albopictus) is reported for the first time in Malaysia.
Genetic study of Japanese encephalitis viruses isolated in Malaysia

Tsuchie H, Oda K, Vythilingam I, Thayan R, Vijayamalar B, Sinniah M, et al.

Jpn. J. Med. Sci. Biol., 1994 Apr;47(2):101-7.
PMID: 7853748

Two hundred and forty nucleotides from the pre-M gene region of 10 Japanese encephalitis (JE) virus strains isolated in Malaysia in 1992 were sequenced and compared with the other JE virus strains from different geographic areas in Asia. Our JE virus strains belong to the largest genotypic group that includes strains isolated in temperate regions such as Japan, China, and Taiwan. Our Malaysian JE virus strains differed in 32 nucleotides (13.3%) from WTP/70/22 strain isolated from Malaysia in 1970, which belonged to another distinct genotypic group.
Abundance, parity, and Japanese encephalitis virus infection of mosquitoes (Diptera:Culicidae) in Sepang District, Malaysia

Vythilingam I, Oda K, Mahadevan S, Abdullah G, Thim CS, Hong CC, et al.

J Med Entomol, 1997 May;34(3):257-62.
PMID: 9151487

A 2-yr study of Japanese encephalitis (JE) virus in Sepang District, Selangor, Malaysia, was carried out to identify the mosquito vectors and to determine their seasonal abundance, parity, and infection rates. In total, 81,889 mosquitoes belonging to 9 genera and > 50 species were identified from CDC trap collections augmented with dry ice during 1992 and 1993. Culex tritaeniorhynchus Giles and Culex gelidus Giles were the most abundant species, and both increased in numbers with increases in rainfall. Overall, 45 JE virus isolations were made from 7 species-Cx. tritaeniorhynchus (24), Cx. gelidus (12), Culex fuscocephala Theobald (2), Aedes butleri Theobald (4), Culex quinquefasciatus Say (1), Aedes lineatopennis Ludlow (1), and Aedes (Cancraedes) sp. (1). Based on elevated abundance and JE infection rates, Cx. tritaeniorhynchus appears to be the most important vector of JE virus in Sepang.
Fulltext Cross-sectional serosurvey for Japanese encephalitis specific antibody from animal sera in Malaysia 1993

Oda K, Igarashi A, Kheong CT, Hong CC, Vijayamalar B, Sinniah M, et al.

Southeast Asian J. Trop. Med. Public Health, 1996 Sep;27(3):463-70.
PMID: 9185254

Serum specimens were collected from 6 species of animals living in 9 states of Malaysia including Sabah, North Borneo in 1993. Antibodies against Japanese encephalitis (JE) virus in these sera were detected by means of hemagglutination-inhibition (HI) and neutralization (NT) tests. By HI test, 702 of 2,152 (32.6%) sera showed positive results. Higher positive rates were obtained by the NT test, in which 1,787 of 1,927 (92.7%) sera had antibodies against JE virus. All serum specimens with positive HI were confirmed as positive by the NT. Swine sera showed especially higher rates of antibody positive and higher antibody titers compared with other animals. These results suggest that JE infections are widely distributed among many animals of Malaysia, and pig is the most susceptible amplifier host for JE virus.
Genotypes of Japanese encephalitis virus isolated in three states in Malaysia

Tsuchie H, Oda K, Vythilingam I, Thayan R, Vijayamalar B, Sinniah M, et al.

Am J Trop Med Hyg, 1997 Feb;56(2):153-8.
PMID: 9080873

Two hundred forty nucleotides from the pre-membrane gene region of 12 Japanese encephalitis virus (JEV) strains isolated from three different regions of Malaysia from 1993 to 1994 were sequenced and compared with each other and with the JEV strains from different geographic areas in Asia. These 12 Malaysian isolates were classified into two genotypes. The four JEV strains isolated from Sarawak in 1994 and the four JEV strains isolated from Sepang, Selangor in 1993 were classified into one genotype that included earlier isolated strains from Malaysia (JE-827 from Sarawak in 1968 and WTP/70/22 from Kuala Lumpur in 1970). The four JEV strains from Ipoh, Perak in 1994 were classified into another genotype that included JEV strains isolated from northern Thailand and Cambodia. In an earlier report, 10 JEV strains from Sabak Bernam, Selangor in 1992 were classified into the largest genotype that included strains isolated in temperate regions such as Japan, China, and Taiwan. The data indicate that at least three genotypes of JEV have been circulating in Malaysia.
Workplace oral health promotion activities among community-aged care workers: A qualitative exploration

Bakri NN, Ferguson CA, Majeed S, Thomson WM, Oda K, Bartlett S, et al.

Community Dent Oral Epidemiol, 2023 Nov 10.
PMID: 37950336 DOI: 10.1111/cdoe.12924

BACKGROUND: The workplace is an ideal-and priority-setting for health promotion activities. Developing and implementing workplace health promotion interventions, including oral health promotion activities, can help create health-supporting workplace environments.
OBJECTIVE: To pilot workplace oral health promotion activities among staff working in the aged care sector, report their impact and explore participants' views on the factors that contribute to participation and effectiveness.
METHODS: This study comprised three phases: (i) the development and face validation of the resources, (ii) a 3-h educational session and (iii) five interview sessions with participants 4-6 weeks following the education session. The recorded interviews were transcribed verbatim and analysed thematically.
RESULTS: Eleven community-aged care workforce were invited to five feedback sessions. Ten participants were female and ranged in age from 18 to 64. All participants gave favourable comments about the content and delivery of the training session and accompanying resources. The participants felt that the benefits of WOHP include improved staff knowledge, awareness and oral care routine, the ability to share (and put into practice) the gained knowledge and information with their dependants, a lower risk of having poor oral health that adversely affects their well-being and work tasks, and potentially beneficial impacts on the organization's staff roster. Their attendance in the WOHP was facilitated by being paid to attend and scheduling the sessions during work time. Future WOHP suggestions include the possibility of a one-stop dental check-up at the workplace or staff dental care discounts from local dental practitioners and combining oral health with other health promotion activities.
CONCLUSIONS: Planning and implementing WOHP was deemed acceptable and feasible in this study context and successfully achieved short-term impacts among community-aged care workers. Appropriate times and locations, organizational arrangements and a variety of delivery options contributed to successful programme planning and implementation.