Hepatitis B virus (HBV) genotypes in a group of Sri Lankan patients with chronic infection

Hepatitis B infection causes a wide spectrum of liver diseases. Previous analyses of hepatitis B virus (HBV) genome have revealed eight HBV genotypes (A-H), with distinct geographical distribution worldwide. The epidemiology of HBV genotypes and their implications for natural history of disease progression and response to anti viral therapy have been increasingly recognized. This study was undertaken to determine the HBV genotypes in a group of Sri Lankan patients with chronic infection who presented for investigation prior to treatment. Genotypes were determined (2007-2009) in 25 patients with evidence of chronic HBV infection. A genotyping system based on multiplex-nested PCR using type-specific primers was employed in assigning genotypes A through F. Genotypes G and H were not determined. Among the 25 patients tested, genotypes B [9 (36%)], C [4 (16%)], D [3 (12%)], A [2 (8%)] and E [1 (4%)] were detected. There was a relatively high prevalence of mixed infections with genotypes B+C (3), A+D (1), and B+D (2), which overall constituted 24% of patients. Although this is a non-representative sample, HBV infections among this group of Sri Lankan patients were predominantly genotypes B, C and D.

A case of imported malaria: the first report of a Plasmodium malariae infection in Sri Lanka after 37 years.

We report a case of Plasmodium falciparum and P. malariae mixed infection in a patient who had been living in Malawi. This is the first case of P. malariae reported in Sri Lanka in 4 decades. The presence of both parasites was confirmed by microscopy and polymerase chain reaction (PCR). The history strongly indicated that the infection had been acquired from Malawi. The patient had liver dysfunction and a transient glomerulonephritis, both of which subsided with antimalarial treatment.

Chloroquine resistant falciparum malaria among security forces personnel in the Northern Province of Sri Lanka.

OBJECTIVE: To determine the occurrence and species distribution of malaria and the extent of chloroquine resistance among security forces personnel in a selected region of the Northern Province of Sri Lanka. DESIGN: A descriptive study. SETTING: Mannar District in the Northern Province. METHODS: Nine hundred and seventy five security personnel were screened for malaria by microscopy. Those who were positive were treated with chloroquine and were subjected to 28 day in vivo assay to determine chloroquine resistance. In vitro microtest assay was performed to determine the response of Plasmodium falciparum isolates to chloroquine in vitro. RESULTS: Of the 975 personnel screened, 181 (18.6%) were positive for malaria. P. falciparum was the predominant species (n = 125; 69.1%). The rest were due to P. vivax (n = 42; 23.2%) and mixed infections (n = 14; 7.7%). This was an inversion of the usual species distribution pattern in the country. In vivo assay revealed 38 (53.5%) P. falciparum infections as chloroquine resistant. Fifteen of 23 (65.2%) P. falciparum isolates showed evidence of resistance in vitro. None of the P. vivax infections showed evidence of chloroquine resistance. There was no significant difference in the severity of clinical disease between chloroquine resistant and sensitive infections at first presentation. Recrudescent P. falciparum infections had significantly lower mean parasite densities as well as lower clinical scores at recrudescence than at first presentation. CONCLUSION: Results demonstrate the high prevalence of malaria and chloroquine resistance in the study area and explains several contributory factors for this. There is an urgent need to review antimalarial drug policies in Sri Lanka.

A novel reverse transcriptase-polymerase chain reaction based-liquid hybridisation (RT-PCR-LH) assay for early diagnosis of dengue infection.

BACKGROUND: Early definitive laboratory diagnosis of dengue is difficult with the tests in routine use at present. OBJECTIVE: To develop a reverse transcriptase-polymerase chain reaction based liquid hybridisation (RT-PCR-LH) technique for the rapid and early diagnosis of dengue. RESEARCH DESIGN: RT-PCR products of the NS3 gene of dengue virus prototypes and of a few positive sera for dengue virus by culture, were allowed to hybridise in liquid phase with a mixture of dengue specific radiolabelled oligonucleotides. The products were separated by PAGE and visualised by autoradiography. 78 suspected dengue sera were also tested by RT-PCR-LH method, and by IgM-ELISA and HAI tests, for comparison. RESULTS: Two DNA bands (approximately equal to 470 bp and approximately equal to 455 bp) specific to dengue virus, were observed. RT-PCR-LH assay takes only 24 h. Of the 78 suspected dengue acute sera tested, 45/78 were positive by RT-PCR-LH, 31/78 were positive by IgM-ELISA, and 14/78 had a HAI titre > or = 2560. Duration of fever was known in 72 cases, and infection was detected by RT-PCR-LH in 11/22 of cases with < 5 d fever and by IgM-ELISA in 1/22. In cases with 5 to 15 d fever RT-PCR-LH and IgM-ELISA/HAI titre > or = 2560 detected infection in 30/50 and 27/50 respectively. The 10 sera which were negative by RT-PCR-LH, but were positive by either IgM-ELISA or HAI titre > or = 2560 were all > 5 d fever cases. RT-PCR-LH together with IgM-ELISA were capable of detecting dengue infection in 56/78 of the suspected cases. CONCLUSION: RT-PCR-LH assay developed in this study appears to have an advantage over other diagnostic techniques for the early detection of dengue.

Experiments in crossing two strains of Anopheles barbirostris van der Wulp 1884 (Diptera: Culicidae) in Thailand.

Crossing experiments between two strains of Anopheles (Anopheles) barbirostris from Chumphon and Chon Buri provinces in Thailand were done by induced copulation in order to determine the genetic relationship. On comparison of the F1 hybrids and those of their parent species as the control, there was a difference in the number of eggs laid, hatchability and viability. The low viability of the F1 hybrids with high larval and pupal mortalities, producing only a few F hybrids, and the fact that F1 hybrids' salivary chromosome showed asynapsis suggest there exists reproductive isolations between both strains. The data presented suggest that these two strains exhibit possible presence of a species complex in An. barbirostris.