Patterns of disease among adults hospitalized with dengue infections.

BACKGROUND: Recent years have seen an increase in dengue infections among adults in Sri Lanka, with similar trends seen in many other countries. Data on the natural history and outcome of dengue in adults are quite limited. AIM: To study clinical and laboratory findings in adult dengue patients hospitalized in Sri Lanka during a recent major dengue epidemic. DESIGN: Prospective observational study. METHODS: Clinical, laboratory and demographic information were collected from adult patients with confirmed dengue infections (n = 108) treated in a general medical ward in Sri Lanka from 24 April to 31 July 2004. RESULTS: There were 68 male and 40 female patients, mean age 26.6 years. Dengue fever (DF) was seen in 33 (30.6%) and dengue haemorrhagic fever (DHF) in 75 (69.4%). Of the 37 (34.3%) with primary dengue infections, 19 (51.4%) developed DF and 18 (48.6%) developed DHF. Overall, 42 patients (38.9%) had bleeding manifestations. These adults showed differences in clinical and laboratory findings, disease severity and mortality, compared to children seen during the same epidemic. Secondary dengue infections were significantly associated with development of severe disease (OR 5.0, 95%CI 1.9-13.5, p < 0.001). Mortality was 3.7%. DISCUSSION: Pooling data on adult dengue patients from different regions should help us to understand the natural history of disease in this group. It would also help in developing evidence-based treatment guidelines and allocating limited and scarce health resources. Our data contribute towards this goal.

An immunofluorescence assay for human antibodies to Ross River virus.

A rapid reliable immunofluorescence assay for antibodies to Ross River virus has been developed. Its particular benefit is in aiding a differential diagnosis to be made by rapid detection of IgM antibodies to this virus.

Comparison of PanBio Dengue Duo IgM and IgG capture ELISA and venture technologies dengue IgM and IgG dot blot.

BACKGROUND: A number of commercial ELISA for dengue diagnosis have recently become available, though direct comparison between these assays have not been published. OBJECTIVES: The Venture Technologies Dengue IgM and IgG Dot Blot assays and the PanBio Dengue Duo IgM and IgG Capture ELISA were compared. STUDY DESIGN: Paired sera from patients with dengue (n=20) and Japanese encephalitis (JE, n=10), and single sera from patients with typhoid (n=10), leptospirosis (n=10) and scrub typhus (n=10) were assayed according to the manufacturer's instructions. RESULTS: The Dot Blot IgM ELISA showed higher sensitivity than the PanBio IgM ELISA (100 vs. 95%), while the PanBio IgM ELISA showed higher specificity in JE (100 vs. 20%) and non-flavivirus infections (100 vs. 97%). Defining elevation of either IgM or IgG as a positive result, the Dot Blot and ELISA tests both showed 100% sensitivity in dengue infection, while the PanBio test showed superior specificity in JE (70 vs. 0%) and non-flavivirus infections (100 vs. 67%). CONCLUSIONS: Both assays are useful aids to the serological diagnosis of dengue infection. The clinical setting, user preference and local conditions will be important in determining which test is more appropriate.

Failure of a dengue 1 sub-unit vaccine to protect mice against a lethal dengue virus infection.

Mice immunized with DEN-1 pre-matrix protein produced antibody which reacted with dengue virus infected cells and intact virions but failed to neutralize virus in vitro or in vivo. Newborn mice passively immunized with anti-DEN-1 pre-matrix antibody also failed to survive intracerebral infection with 100 LD50 of any dengue virus serotype.

Effect on mice of infection during pregnancy with three Australian arboviruses.

Infection of pregnant mice with Ross River or Getah viruses after the establishment of a functional placenta resulted in fetal infection with these viruses. However, only with Ross River virus was there any significant fetal death. There was significant post-partum mortality in mice infected in utero with Ross River but not with Getah virus. In contrast, significant post-partum mortality occurred in Murray Valley encephalitis virus-infected mice despite the inability of the virus to cross the placenta. Infection of mice with Ross River, Getah, or Murray Valley encephalitis viruses before placentation had occurred (5th day post-conception) did not result in fetal infection although there was significant post-partum death in litters born to Ross River virus-infected mothers.

Characterization of Ross River viruses isolated from patients with polyarthritis in New Caledonia and Wallis and Futuna Islands.

Viruses isolated during 1979 and 1980 from patients with polyarthritis in New Caledonia and Wallis and Futuna Islands have been found to be more closely related to Ross River virus than any other regional Alphavirus. On the basis of virulence in suckling mice the majority of these isolates were found to be more closely related to the NB5092 strain of Ross River virus than to the prototype T48 strain.

Surveillance for Ross River virus infection using blood donors.

The number of clinical Ross River virus (RRV) infections (epidemic polyarthritis) each year in Australia continues to grow despite extensive vector control programs. There is a need, therefore, for a surveillance program that can give sufficient warning of outbreaks of the disease so that highly focused preventative measures may be undertaken. The ability of a surveillance program, based on voluntary Red Cross blood donations, to predict outbreaks of epidemic polyarthritis was evaluated. Anti-RRV IgM antibody was detected in significant numbers of blood donors from throughout the state of Queensland 6-9 weeks prior to an increase in the number of notified cases of epidemic polyarthritis. At a local level, significant numbers of anti-RRV IgM blood donors were detected in Brisbane in 1996 four weeks prior to an increase in the number of notified cases of epidemic polyarthritis. This system of surveillance is technically simple, rapid (results are obtained in 2-3 days), it samples the human population from throughout the state, and it gives timely warning of outbreaks of epidemic polyarthritis.

Risk factors in dengue shock syndrome.

Despite a growing body of evidence predominantly, but not exclusively, from Thailand suggesting that the risk of developing dengue shock syndrome (DSS) is greatest following an anamnestic dengue infection, particularly if the most recent infection was with dengue 2 virus, there continues to be debate about the justification for these claims. This report describes a five-year, prospective study in two townships (suburbs) in Yangon (Rangoon) Myanmar (Burma) in which attempts were made to confirm the data from an earlier prospective study in Thailand and to address some of the criticism of earlier studies. This investigation found the incidence of anamnestic dengue infections in DSS patients to be significantly higher than in the community from which they were drawn and a significantly higher risk of developing DSS following an anamnestic infection (particularly with dengue 2 virus) than following a primary infection with any serotype.

An epidemic of Ross River virus infection in Fiji, 1979.

An explosive epidemic of polyarthritis caused by Ross River virus occurred in the Fijian islands from April to June 1979. Serological results suggest there was a low level of Alphavirus activity throughout Fiji before April 1979, but that following the epidemic up to 90% of the residents of some communities had antibody to Ross River virus. The clinical and laboratory findings in patients from the Fijian outbreak were similar to those seen in Australian cases.

Ross River virus arthritis in Papua New Guinea.

In 1975 it was reported that antibodies to Ross River virus (RRV) were present in the sera of many population groups in Papua New Guinea. We describe here 3 cases of polyarthritis that occurred in Port Moresby, the capital of Papua New Guinea, during 1980-81 and in which the diagnosis of RRV infection was confirmed by serological tests, and 3 other cases in which serological tests suggested RRV infection but were not diagnostic. A possible case of fatal RRV encephalitis is also reported.

Development of a simple indirect enzyme-linked immunosorbent assay for the detection of immunoglobulin M antibody in serum from patients following an outbreak of chikungunya virus infection in Yangon, Myanmar.

During 1984, 1548 children were admitted to the Yangon [Rangoon] Children's Hospital in Myanmar [Burma] with haemorrhagic fever. No evidence of recent dengue infection was found in 577 of the 803 children from whom paired sera were obtained, raising the possibility of reappearance of Chikungunya virus infection in Myanmar. An enzyme-linked immunosorbent assay (ELISA) for the detection of anti-Chikungunya virus immunoglobulin M (IgM) antibody was prepared and standardized using only reagents which are commercially available or which could be prepared without the use of sophisticated equipment. While there was 90% agreement between haemagglutination inhibition (HI) tests and the IgM ELISA in the diagnosis of acute Chikungunya virus infections, 12 additional patients with stationary anti-Chikungunya virus HI antibody titres could be identified as having acute Chikungunya infections using the ELISA. Furthermore, the ELISA could identify twice as many patients (31/103) at the time of admission to hospital as the HI test (15/103). There was no false positive IgM reaction with the ELISA which could be attributed to the presence of rheumatoid factor. Using the test, 103 of a sample of 163 children who presented to the Yangon Children's Hospital with fever/haemorrhagic fever were diagnosed as Chikungunya patients, 4 had possible dual Chikungunya and dengue infections, 16 had dengue, 30 had neither Chikungunya nor dengue infections, and a definitive diagnosis could not be made for 10 patients. Routine use of the ELISA would alert authorities to future outbreaks of Chikungunya virus infection and avoid admission to hospital of patients with a non-life-threatening viral disease.

Viral-like characteristics of particle aggregates in a lymphoblastic cell line.

A lymphoblastic cell line (K45) established from a child with acute lymphoblastic leukemia (ALL) is characterized by a profusion of intracytoplasmic particle aggregates (PA) similar in morphology to those occurring in fresh childhood ALL cells. The PA in K45 cells were examined for morphology and capacity for nucleic acid synthesis to test the hypothesis that they are identical to those in fresh ALL cells, and also to identify characteristics which might distinguish PA from cell organelles and which might determine if they are viral-like. In contrast to cell organelles, the PA in both K45 and ALL cells were found to be characterized by a localized thickening of the particle wall. Furthermore, autoradiography of K45 cells showed uptake by PA of 3H uridine rather than 3H thymidine indicating an RNA composition. The presence of PA in profusion was associated with, but preceded necrotic death of K45 cells. These combined features suggest that the PA in K45 and in ALL cells are identical, that they are distinct from cell organelles, are not formed as a consequence of the initiation of cell death and that, while their exact nature remains unknown, a viral origin cannot be excluded.

Natural killer (NK) cell activity against human gingival fibroblasts exposed to dental plaque extracts.

Natural killer (NK) cell activity against plaque pretreated human gingival fibroblasts and against the erythroblastoid cell line K562 also pretreated with plaque extract was studied. Supra- and subgingival plaque was collected and extracts prepared by sonication for 10 to 15 minutes at room temperature. The erythroblastoid cell line K562 was given in RPMI (1640) medium, and served as the control. Gingival fibroblasts were grown from an explant of human gingiva. The K562 cells and gingival fibroblasts were incubated in subcytotoxic doses of both supra- and subgingival plaque for 18 hours prior to the NK cell assay in serum free medium. Pretreatment of the K562 cells with both supra- and subgingival plaque was found to reduce NK cell activity. On the other hand pretreatment of the human gingival fibroblasts with plaque extracts seemed to increase their sensitivity to NK cell activity. This suggests that the plaque pretreatment leads to a cytopathic change in the fibroblasts making them more sensitive to NK cell activity, or alternatively that by binding to target cells, plaque modulates the ability of NK cells to bind to, and kill these cells. Nevertheless, these results indicate that NK cell activity could play a role in tissue destruction in chronic inflammatory periodontal disease.

Routine phenotyping of native and desialyzed alpha 2HS-glycoprotein from blood stains.

The application of a polyacrylamide gel isoelectric focusing (PAGIEF) and immunoblotting procedure for the identification of native alpha 2HS-glycoprotein (AHSG) in routine casework blood stains has produced reportable results on 57.2% of samples. This reporting rate is lower than that for group specific component (GC) (83.8%) and phosphoglucomutase (PGM 1) (72.8%) phenotyping of the same samples. Blood stain samples were desialyzed with 1 U/ml neuraminidase, overnight at room temperature prior to PAGIEF in gels containing pharmalyte pH 5-6 and 2.5 M urea. Simple AHSG patterns were developed by immunoblotting. This procedure was five times as sensitive as the native AHSG method and desialyzation was reproducible over a range of incubation times and neuraminidase concentrations. The application of the desialyzed AHSG analysis to routine casework samples has resulted in a significant increase in the number of reportable results (762 reported out of 1027 samples). This reporting rate (74.2%) compares favourably with that for GC (79.1%) and PGH 1 (69.6%) phenotyping of the same samples. The three AHSG alleles (AHSG*1, 2 and 3) are clearly resolved after sample desialyzation and separation in gels containing pharmalyte pH 5-6 and 2.5 M urea. The sensitivity of desialyzed AHSG phenotyping approaches that of GC and this technique is worthy of inclusion in blood stain screening protocols of forensic laboratories in regions where the population has a limited range of rare AHSG alleles.

Patterns of disease in Sri Lankan dengue patients.

BACKGROUND: Dengue is the most important mosquito borne viral infection in the world. Nearly 90% of infections occur in children. At present, prospective information on clinical and laboratory findings in South Asian children with dengue is generally lacking. AIM: To describe patterns of clinical disease in a cohort of children hospitalised with dengue during a major dengue epidemic in Sri Lanka. RESULTS: A total of 104 children were studied during a three month period. Eighteen had dengue fever (DF) and 86 had dengue haemorrhagic fever (DHF). Of those with DHF, 34, 23, 27, and 2 had DHF grade I, II, III, and IV respectively. Based on dengue serology testing, 13 of the DF patients had a primary infection and 5 had secondary dengue infections. In contrast, 68 of the children with DHF had secondary and 18 had primary dengue infections. Oral candidiasis was seen in 19 children. The odds ratio for children with secondary dengue infection to develop DHF was 9.8 (95% CI 3.1 to 31.2). CONCLUSION: Studies on patterns of paediatric dengue disease in different regions should help clinicians and health administrators make more informed and evidence based health planning decisions. It should also help towards mapping out dengue trends on a global scale. Oral candidiasis has not been previously documented in children suffering with acute dengue in Sri Lanka or elsewhere. Studying underlying reasons for this manifestation during future dengue epidemics may provide useful leads in understanding overall dengue pathogenesis.