Showing papers on "Dengue fever published in 1981"

Viraemia in patients with naturally acquired dengue infection.

Abstract: The magnitude and duration of dengue viraemia were studied in 153 patients with naturally acquired dengue infection in Jakarta, Indonesia. The duration of viraemia ranged from 2 to 12 days, but most patients had detectable circulating virus for 4-5 days. Accurate measurement of peak virus titres was not possible for many patients because of late admission to the hospital. Composite pictures of viraemia for each serotype, however, showed that many patients infected with dengue 1, 2, or 3 had circulating virus titres ranging from barely detectable to over 10(8) MID(50) per ml for 3-5 days. Virus titres in patients infected with dengue 4 were about 100-fold lower. Dengue haemagglutination-inhibition antibody titres of 80 or less had little effect on viraemia, but antibody titres of 160 or greater were associated with a decrease in virus isolation rate and in virus titre. The duration and magnitude of viraemia did not vary significantly with the severity of the disease and was only slightly higher in patients classified as primary dengue infections than in those classified as secondary infections. Measurement of viraemia in fatal dengue haemorrhagic fever (DHF) cases showed that these patients had significant quantities of circulating virus at the time of death.

Epidemic Dengue 3 in Central Java, Associated with Low Viremia in Man*

Abstract: An outbreak of dengue type 3 was studied in Central Java, Indonesia, in 1978. In contrast to previous dengue 3 epidemics in Central and East Java, this outbreak was less explosive, associated with mild illness, and low viremia. The dengue virus isolation rate from serologically confirmed patients was only 32% compared to 65% for an epidemic in Bantul a year earlier. Neither dengue hemagglutination-inhibition antibody titers nor day of illness on which specimens were collected accounted for this difference. These data suggest that some naturally occurring strains of dengue virus (endemic strains) are associated with low viremia and generally cause only mild illness in man.

Histocompatibility antigens and dengue hemorrhagic fever.

Abstract: Histocompatibility antigen (HLA) A and B typing on lymphocytes from 87 unrelated Thai children who had been hospitalized with dengue shock syndrome (DSS) and/or dengue hemorrhagic fever (DHF) was compared with that found in 138 controls who had not been hospitalized with clinical dengue infection. These data are presented as descriptive information; however, a statistical analysis was performed to identify potentially important relationships for future study. Several deviations (P less than 0.05) were detected in the distribution of four HLA-A and three HLA-B antigens. The prevalence of one HLA-A antigen and two HLA-B antigens appeared to relate to the development of DSS, with a positive association seen for HLA-A2 and HLA-B blank and a negative relationship for HLA-B13. These findings require confirmation, but they do suggest that genetic susceptibility may be important in the development of DHF/DSS and indicate that further broader studies of genetic markers might be rewarding.

The use of Toxorhynchites mosquitoes to detect and propagate dengue and other arboviruses.

Abstract: Both sexes of Toxorhynchites amboinensis, an unusually large, non-blood sucking mosquito, were found to be as susceptible to infection with each of the four types of dengue virus by intrathoracic inoculation as Aedes albopictus. Tx. amboinensis infected with dengue virus could be identified easily by fluorescent antibody staining of head squashes and had advantages of size, hardiness, and safety (for females) as compared with Ae. albopictus. Tx. amboinensis also were more susceptible to infection with Japanese and St. Louis encephalitis viruses than were Vero cell cultures and appeared useful for detection and propagation of other flaviviruses and arthropod-borne viruses of other taxonomic groups.

Dengue-2 vaccine: virological, immunological, and clinical responses of six yellow fever-immune recipients.

Abstract: Six male volunteers, previously immunized with yellow fever vaccine, were inoculated subcutaneously with a live, attenuated dengue-2 virus (PR-159/S-1) candidate vaccine. Five recipients developed viremia 8 or 9 days after vaccination, which lasted 1 to 10 days. The onset of viremia was followed by fever in three people, transient leukopenia in four, and an erythematous rash in one. One volunteer developed an oral temperature of 38.8 degrees C with headache, myalgia, fatigue, and photophobia suggestive of mild dengue fever. All five viremic volunteers developed fourfold or greater rises in serum neutralizing antibody. The sixth volunteer, who had a low titer of preexisting dengue-2 neutralizing antibody, had no viremia, no symptoms, and a modest rise in hemagglutination inhibiting antibody. Virus isolates obtained from plasma retained the small-plaque and temperature-sensitive growth characteristics of the vaccine virus in vitro. In this study, the vaccine virus genetically stable and immunogenic and seemed sufficiently attenuated for additional testing in humans.

Dengue hemorrhagic fever accompanied by encephalopathy in Jakarta.

Abstract: Forty one cases of dengue hemorrhagic fever, confirmed by viral isolation, accompanied by neurological signs compatible to the diagnosis of acute encephalopathy were observed in 3 University Hospitals in Jakarta during the period November 1975 to December 1977. Two of these children showed typical signs and symptoms of Reye's syndrome confirmed by liver biopsy.

Infection of young adult mice with dengue virus type 2

Abstract: Young adult female mice, five to six weeks old, were injected intraperitoneally with 2·5 × 106·3 LD50 of dengue-2 virus, New Guinea C strain. The mice were killed on day 1, 2, 3, 4, 5, 6, 7, 10, 14, 21, 28 and 35 respectively. By means of the immunofluorescent antibody technique, viral antigen appeared as irregular granules in the reticuloendothelial cells of liver, lymph nodes and spleen of infected mice on the first day after inoculation and then diminished. From the fifth to sixth day of infection dengue antigen appeared again as homogeneous staining in the cytoplasm of single or groups of mononuclear cells in the lymphatic sinuses only. Later, by the third week of infection, dengue antigen could be seen in the mononuclear cells located in the marginal zone of lymphoid follicle of the spleen, the pattern of staining changing to bright spherical granules. At the same time, the deposition of immune complexes (composed of dengue antigen, mouse gamma and β1C globulin) could be seen in the renal glomeruli of infected mice. Serum antibody to dengue virus was found at low levels, being maximal on the 14th day after infection. Dengue virus was not isolated from the sera or from the infected organs. Granulomatous inflammation developed in lymph nodes and liver of mice infected with dengue virus and in mice inoculated with normal mouse brain suspension. Proliferative glomerular lesion was observed on day 14 after inoculation without definite abnormal urine findings.

Dengue in the Seychelles

Abstract: Epidemics of dengue-like illness occurred in the Seychelles from December 1976 to April 1977 and from December 1978 to January 1979. Dengue 2 virus was isolated from individuals who had been in the Seychelles in 1977. From February to April 1979, sera were collected from outpatients in Mahe, Seychelles, who had not previously been hospitalized with a dengue-like illness. Results of neutralization tests with these sera indicated that prevalence rates for the four dengue viruses were between 81% and 91.8% and that dengue 2 was the most probable etiological agent in the epidemics. In addition, antibodies to chikungunya (8.7%) and Sindbis (7.4%) viruses were found, providing, for the first time, evidence of the presence of these two alphaviruses in the Seychelles.

Arbovirus Infections among Laboratory Personnel in Ibadan, Nigeria*

Abstract: Laboratory-acquired infections encountered between 1963 and 1977 among personnel of the Virus Research Laboratory, Ibadan, Nigeria, are reported. Two cases of chikungunya infection occurred and one each with Dugbe, Wesselsbron, and dengue viruses. In each case, virus was isolated or development of antibody demonstrated. Among virus and two each to chikungunya and Rift Valley fever viruses, without experiencing any clinically recognized disease.

Antibody‐mediated infection of macrophages and macrophage‐like cell lines with 17D‐yellow fever virus

Abstract: The 17D vaccine strain of yellow fever virus (17D-YF) produces a safe human arboviral infection that can provide antisera of well-defined specificity under chronologically defined conditions. We studied 17D-YF growth in human peripheral blood macrophages and in two continuous Fc receptor-bearing, macrophage-like cell lines, P388D1 of mouse origin and U937 of human origin. Cells were infected with virus in the presence or absence of antibody to 17D-YF and to two related flaviviruses, St. Louis encephalitis (SLE) and dengue 2 (D2V). The virus 17D-YF grew in the three cell types when infection was established without antibody; viral yields were increased by addition of antibody to 17D-YF, SLE, and D2V. Increased titers of virus were accompanied by an increased number of infected cells by immunofluorescent assay. Enhancing activity was present in the IgG but not the IgM fractions of immune sera. Infection without cytopathic effect was observed in U937.

Geographic Aedes aegypti strains and dengue-2 virus: Susceptibility, ability to transmit to vertebrate and transovarial transmission

Abstract: Summary Relations between dengue-2 virus (New Guinea C strain) and its most common vector, Aedes aegypti , were investigated in 5 geographical strains of mosquitoes originating from endemic areas for dengue fever. Four strains were recently collected from regions with high (Hanoi strain, Vietnam), rather high (Guadeloupe strain, Carribean), low (Lagos strain, Nigeria), or no incidence for dengue virus (Kari strain, Upper Volta). The fifth strain was colonized in the laboratory for several years (Queensland strain, Australia). Following infection by intrathoracic inoculation, the susceptibility of the strains to dengue-2 virus, their ability to transmit the virus to suckling mice (SM) by bite and the possibility of transovarial transmission were compared. The virus replicated in the 5 strains at the same rate averaging 4.1 log 10 PFU/mosquito, and the 50% mosquito infection dose was similar for each strain (0.001 PFU). The ability of infected females to transmit the virus to SM by bites varied from 37 to 56% according to the strain. Transovarial transmission was demonstrated in 4 strains. The Kari strain from non-endemic region did not transmit the virus. The minimal filial infection rate was rather low ranging from 0.3 to 1.2‰ Infected progeny of both sexes were detected only in the first or second ovarian cycle from eggs ovoposited between the 14th and the 16th day post inoculation of parent females.

In vitro virulence marker: growth of dengue-2 virus in human leukocyte suspension cultures.

Abstract: We wished to find a simple, biologically relevant method to evaluate the virulence of dengue viruses for human beings. Since cells of mononuclear phagocyte lineage may be important sites of dengue infection in primates, we evaluated the permissiveness of these cells to dengue virus as a correlate of virus virulence. Two wild-type, large-plaque, monkey-virulent dengue-2 virus strains and two small-plaque, monkey-avirulent dengue-2 virus strains were evaluated for their ability to replicate in human peripheral blood leukocyte cultures supplemented with enhancing antibody. One of the small-plaque strains was demonstrated to have reduced virulence for man. Wild-type dengue-2 viruses replicated readily in peripheral blood leukocyte suspension cultures, whereas small-plaque dengue-2 strains did not. Differences between our data and results obtained by other workers employing adherent peripheral blood leukocytes are discussed. Antibody-enhanced growth of dengue virus in suspension cultures of human peripheral blood leukocytes gives promise of being a simple in vitro system for characterizing dengue virus virulence.

Surveillance of dengue hemorrhagic fever cases in Thailand.

Abstract: A long-term surveillance system is necessary for planning and evaluation of hemorrhagic fever control Dry blood collection and using one dengue 2 antigen have been proved to be an efficient method to detect low and high level of HI antibody, determined to prove dengue infection. The percentage of dengue infection serologically proved from cases reported throughout a 3 year study was 52%. Dengue infected cases were reported outside epidemic period with lowest incidence in January. The majority of dengue proven cases occur at age 6 years. For chikungunya infection, studied in Bangkok metropolis and in this study in 72 provinces shows similar result indicating that chikungunya virus shows no significance in clinical and laboratory study in the surveillance programme. This study provides definite information for the planning and evaluation of hemorrhagic fever control.

Isolation and identification of dengue viruses by combined use of C6/36 cells and the immune adherence hemagglutination test.

Abstract: Dengue viruses were isolated in a mosquito cell clone, C6/36, and their serotypes were identified by the immune adherence hemagglutination (IAHA) test. Even when viruses were not cytopathogenic, the IAHA test detected virus growth in the cells.

Factors Affecting Syncytial Development in Aedes Pseudoscutellaris Cells by Dengue Viruses

Abstract: Several factors that were suspected of affecting the development of syncytia in cultured Aedes pseudoscutellaris cells inoculated with dengue viruses were studied. The results indicated that fresh media (less than 1 week old), low cell density at inoculation (2.8 x 10(5) cells/cm2), and low cell passage level (less than 52 passages) favored the development of syncytia. All three types (1, 2, and 3) of dengue viruses tested could be isolated from human sera by Aedes pseudoscutellaris cell culture by using syncytial development as an indicator, but the isolation rate was lower than that obtained by using intrathoracically inoculated Aedes aegypti mosquitoes.

Tataguine virus isolations from humans in Nigeria, 1971–1975

Abstract: Seven isolates of Tataguine virus were obtained from Nigerians between 1971 and 1975. All were from children less than five years old. The virus is more active in the early wet season. Clinical presentation is similar to malaria.

Quantitation of dengue precipitating antibody by inhibition countercurrent immunoelectrophoresis.

Abstract: The inhibition countercurrent immunoelectrophoresis test was employed to detect dengue virus antibody in patients' sera. Anti-dengue type 2 titers determined by inhibition countercurrent immunoelectrophoresis correlated well with hemagglutination inhibition titers. In secondary cases, more than fourfold increases in precipitating antibodies were observed. The control sera were negative except for sera from a few patients with systemic lupus erythematosus, which showed low titers. Simultaneous detection of dengue virus antigen and antibody in sera collected during the acute phase could confirm at least 90% of cases. This method is recommended as a routine technique to quantitate antibody in sera from suspected cases of dengue hemorrhagic fever.

Replication of dengue, yellow fever, St. Louis encephalitis and vesicular stomatitis viruses in a cell line (TRA-171) derived fromToxorhynchites amboinensis

Abstract: The replication of seven arboviruses in a cell line (TRA-171) derived from a nonhematophagous mosquito was studied. Four serotypes of laboratory adapted and three serotypes of unadapted dengue viruses replicated in the TRA-171 cell line, inducing syncytia. The sensitivity of TRA-171 cells to dengue virus infection was comparable to that ofAedes albopictus orA. pseudoscutellaris cells. Yellow fever, St. Louis encephalitis, and vesicular stomatitis viruses also replicated. All four serotypes of dengue viruses could be plaque assayed with TRA-171 cell cultures.

Lack of greater seroconversion of rhesus monkeys after subcutaneous inoculation of dengue type 2 live-virus vaccine combined with infection-enhancing antibodies.

Abstract: Four groups of six nonimmune male rhesus monkeys were inoculated subcutaneously with formulations of dengue type 2 vaccine virus DEN-2/S-1. Group A received 1.9 x 10(4) plaque-forming units of vaccine in normal human serum albumin diluent. Group B received the same dose combined with a dengue type 2-immune human serum diluted 1:1,600, beyond its neutralization endpoint of 1:300, but having an immune enhancement titer of 250,000. Groups C and D received 10-fold dilutions of these respective formulations. No migration-inhibitory factor was found when peripheral blood mononuclear leukocytes obtained on day 68 post-immunization from monkeys of all experimental groups were tested. No viremia was detected in any of the monkeys when sera taken on postvaccination days 1 through 12 were inoculated into adult Toxorhynchites amboinensis mosquitoes and LLC-MK2 cells. By day 89, four of the six monkeys had seroconverted by the neutralization test in each of groups A, B, and C, and three of five monkeys in group D (one monkey died from cardiac collapse after anesthesia) had seroconverted. Immune enhancement of dengue virus infection is known to occur in humans and monkeys circulating heterologous flavivirus antibodies. In this study, there was no enhancing effect when antibody was mixed with dengue type 2 vaccine virus and injected subcutaneously.

Evaluation of Toxorhynchites Splendens as a Bioassay Host for Dengue Viruses.

Abstract: : Toxorhynchites splendens, a non-hematophagous mosquito was evaluated as a bioassay host for the detection and propagation of dengue viruses. All dengue virus serotypes and strains attained titers in T. splendens comparable to those observed for 2 strains of Aedes aegypti. Peak virus titers occurred in Tx. splendens approximately 6 days postinoculation; however, specific fluorescence for all viruses was not observed in 100% of mosquito heads until 12 days postinoculation. A 100% correlation was noted between specific fluorescence in Tx. splendens heads and the recovery of virus from corresponding thorax-abdomens. The volume of inoculum tolerated by Tx. splendens was approximately 5 timers greater than that injected into Ae. aegypti. Thus, for a given volume of inoculum, the number of Tx. splendens required for virus assays was appreciably less than that needed for Ae. aegypti. The overall survival rate for Tx. splendens following intrathoracic inoculation with dengue viruses was 92%, compared to 41 and 42% for 2 strains of male Ae. aegypti. These findings imply that Tx. splendens would be more efficient than Ae. aegypti as a laboratory assay host for detecting dengue viruses in blood of infected patients and for use in experimental investigations. (Author)