Browsing by Author "Fujii, Y."

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Analysis of effects of meteorological factors on dengue incidence in Sri Lanka using time series data
(Public Library of Science, 2013) Goto, K.; Kumarendran, B.; Mettananda, S.; Gunasekara, D.; Fujii, Y.; Kaneko, S.
In tropical and subtropical regions of eastern and South-eastern Asia, dengue fever (DF) and dengue hemorrhagic fever (DHF) outbreaks occur frequently. Previous studies indicate an association between meteorological variables and dengue incidence using time series analyses. The impacts of meteorological changes can affect dengue outbreak. However, difficulties in collecting detailed time series data in developing countries have led to common use of monthly data in most previous studies. In addition, time series analyses are often limited to one area because of the difficulty in collecting meteorological and dengue incidence data in multiple areas. To gain better understanding, we examined the effects of meteorological factors on dengue incidence in three geographically distinct areas (Ratnapura, Colombo, and Anuradhapura) of Sri Lanka by time series analysis of weekly data. The weekly average maximum temperature and total rainfall and the total number of dengue cases from 2005 to 2011 (7 years) were used as time series data in this study. Subsequently, time series analyses were performed on the basis of ordinary least squares regression analysis followed by the vector autoregressive model (VAR). In conclusion, weekly average maximum temperatures and the weekly total rainfall did not significantly affect dengue incidence in three geographically different areas of Sri Lanka. However, the weekly total rainfall slightly influenced dengue incidence in the cities of Colombo and Anuradhapura. Copyright: 2013 Goto et al.
Detection of Dengue Co Infections Using a Novel Single Tube Multiplex Reverse Transcription Polymerase Chain Reaction.
(In: Proceedings of the International Postgraduate Research Conference 2017 (IPRC – 2017), Faculty of Graduate Studies, University of Kelaniya, Sri Lanka., 2017) Jayathilake, E.K.S.; Jayarathne, J.A.J.C.; Muhandiramlage, T.P.; Fujii, Y.; Gunasekara, K.A.D.C.
Co-infection in individuals by more than one Dengue Virus (DENV) serotype has been reported in regions where multiple serotypes co-circulate. Co-infections can be detected using Polymerase Chain Reaction (PCR). Semi-nested multiplex PCR with Lanciotti’s primers is a widely used PCR method for serotyping DENV and it has also been used for detecting coinfections. Despite of being widely used, Lanciotti’s method may be sub-optimal in detecting co-infections as overlapping primer targets will create a bias in the amplification of the serotype with a low viral load. This could lead to underreporting of co-infections. Nine new non- overlapping primers were designed to independently amplify each serotype with minimal competition between primers to their target.In mixed infections, novel PCR assay exhibited higher sensitivity in detecting the minor serotype compared to Lanciotti’s method. The new method can also detect all four serotypes in viral RNA isolated from viral cultures and patient samples in a single tube multiplex PCR. This enables rapid and cost-effective serotyping with improved sensitivity indetection ofco-infections in clinical samples.
Detection of Leishmania donovani DNA within field-caught Phlebotomine Sand Flies (Diptera: Psychodidae) in three cutaneous leishmaniasis endemic foci of Kurunegala District, Sri Lanka
(Hindawi Pub. Corp., 2021) Wijerathna, T.; Gunathilaka, N.; Gunawardena, K.; Fujii, Y.; Gunasekara, D.
ABSTRACT: Leishmaniasis is a parasitic infection transmitted through the bite of female phlebotomine sand flies. Microscopy is the gold standard to detect parasites within the sand flies and for vector incrimination. However, molecular-based detection has become more popular nowadays in the identification of Leishmania parasites since it provides detection and species identification simultaneously with no need of laborious procedures. The entomological surveys were conducted monthly from May to October 2017 using standard entomological techniques. Field-caught sand flies were identified to the species level followed by DNA extraction. The polymerase chain reaction (PCR) was performed using species-specific primers to detect Leishmania donovani parasites. A total of 1,662 sand flies were encountered from the entomological surveys, and the majority of them were Phlebotomus argentipes (n = 1517; 91.27%), while others were Sergentomyia punjabiensis (n = 140; 8.72%). Leishmania donovani parasite DNA was detected only from P. argentipes (2.3%; n = 2). The detection of Leishmania DNA in P. argentipes suggests the possible role of this species as a vector for leishmaniasis in Sri Lanka.
Prevalence of NS-1 Status of Clinically Suspected Dengue Patients in a Selected Out-Patient Setting
(Faculty of Graduate Studies, University of Kelaniya, Sri Lanka, 2016) Kodikara, K.; Jayathilake, S.; Kumarasinghe, B.; Muhandiramlage, T.; Gunesakera, D.; Fujii, Y.
Dengue infection is one of the rapidly emerging arboviral infections in the world. It is a cause of significant morbidity and mortality especially in developing countries. Although most dengue infections are asymptomatic, dengue fever can be manifested with or without complications. Early diagnosis of dengue is important both clinicians and the patients, where appropriate management of dengue patients reduces both morbidity and mortality. Traditionally dengue infection is clinically suspected with full blood count aided by clinical features although dengue infection cannot be confirmed by either of these methods. Confirmatory tests for detection of the dengue virus are by virus isolation or by nucleic acid detection. which are not suitable for routine diagnosis. NS-1 rapid antigen test has become available for early detection of dengue NS1 antigen, which can be performed at the point of care. Estimate the prevalence of NS1 positivity in dengue suspected patients with acute febrile illness in a selected study setting Blood samples from clinically suspected patients within the first five days of fever were sent for NS1 diagnosis to the molecular laboratory in the department of Biochemistry Faculty of Medicine Ragama. Clinical diagnosis was made by a medical officer. Serum was used for the NS1 diagnosis using Inbios Diagnostic kit (USA). 22.2% of samples were tested positive for NS-1 antigen in a total of 54 samples collected. There were 53.7% males. 9.2% patients were below 10 years of age, 37% patients between 11-20 years of age, 20.3% patients between 21-30 years and 31.4% patients above 31 years of age. 30 % of patients between 11-20 years were NS-1 positive. 36.3 % of patients between 21-30 years of age and 11.7% patients above 31 years of age were also NS-1 positive. NS-1 antigen prevalence was highest among patients between the ages of 11-30 years. Initial clinical assessment of dengue infections is of low specificity as the disease manifests as an undifferentiated febrile illness. Therefore, the inclusion of an antigen test will improve the specificity of diagnosis in a similar out-patient setting which will enable clinicians to make decisions on the further management of the condition.