Showing papers on "Dengue fever published in 1975"

Arthropod-borne viral infections of man in Nigeria, 1964-1970.

Abstract: During the years 1964 to 1970, 171 arboviruses of 15 different types were isolated from humans in Nigeria. Isolation rates were highest in 1969, and lowest in 1965 and 1967. Monthly arbovirus activity was highest in the rainy season months of June, July and August and lowest in the dry months of January and February. Viruses were isolated from all age groups, with the majority from children one to four years old. The viruses isolated in largest numbers were chikungunya and yellow fever, which caused epidemics in 1969, and dengue types 1 and 2 and Tataguine, which are endemic in Ibadan. Bwamba virus was isolated in 1964 and 1969, and Bunyamwera group viruses were encountered for the first time in 1969. Other viruses recovered less frequently were Zika, Igbo-Ora (an agent related to o'nyong-nyong), two viruses related to the Uganda mosquito virus Ug MP 359, Dugbe, Thogoto, Lebombo and Shuni. Several of these are new agents and have not previously been isolated from man. Clinical details are presented where available.

The relative resistance of dengue-immune monkeys to yellow fever virus.

Abstract: Dengue-immune rhesus monkeys were challenged with a South American and two African strains of yellow fever virus. Levels of viremia were reduced as compared with control nonimmunized monkeys. The results support the hypothesis that immunity to dengue in a human population acts as a barrier to establishment of yellow fever in that population.

Epidemiological features of dengue and chikungunya infections in Burma.

Abstract: A serological survey for antibody to dengue and chikungunya was carried out in all 14 divisions and states and 2 border towns in Burma during 1973-74. Dengue HI antibody prevalence rate of less than 10% was observed in Arakan and Shan States, 10 to 30% in the Irrawaddy, Pegu, Mandalay Divisions and Kachin, Mon and Karen States, 31 to 60% in Sagaing Division, and over 60% in Rangoon, Magwe and Tenasserim Divisions. Similarly, chikungunya HI antibody prevalence rate of less than 10% was observed in Arakan State, 10 to 30% in the Irrawaddy, Pegu, Mandalay and Sagaing Divisions and Kachin State, 31 to 60% in Rangoon Division and Mon State. Both dengue and chikungunya antibodies were detected where Aedes aegypti mosquitoes were prevalent but the antibody prevalent rates were not directly proportional to the premises index. No HI antibody to dengue nor chikungunya was detected in Aedes aegypti free hilly areas, Chin and Kayah States, but was detected in the Shan State, Dengue and chikungunya infections were observed both in rural and urban populations. Dengue and chikungunya infections affected all socioeconomic classes in Rangoon equally but in Mandalay high socioeconomic class was nearly 3 times less affected than lower socioeconomic class. The infrequencies of dengue and chikungunya infections were observed to be 2 to 3 times higher in residents of Rangoon City than those of other towns. In Rangoon the antibody prevalence rates to dengue increased progressively with age while in other towns no appreciable increase in rates with age was observed. Both sexes were equally affected. This study provides strong circumstantial evidence that dengue and chikungunya viruses are highly and widely distributed throughout Burma, and that new outbreaks of haemorrhagic fever could occur in previously free areas following introduction of dengue viruses into populations previously exposed to one type of dengue.

A lipid inhibitor of dengue virus in human colostrum and milk; with a note on the absence of anti-dengue secretory antibody

Abstract: Neutralizing activity against dengue virus types 1--4 was observed in milk samples from 5 non-immune and 29 dengue immune women. Anti-dengue activity in milk and colostrum was found only in the lipid component. The inhibitory activity is directed against the virus and not cell surfaces. When immunoglobulin types IgM,IgA, IgG were isolated from colostrum from dengue immune women, no antibody activity was found. Anti-dengue activity in human milk did not decrease over a period of ten months after delivery.

Placental Passage of Antibodies to Dengue Virus in Persons Living in a Region of Hyperendemic Dengue Virus Infection

Abstract: Maternal and umbilical cord levels of antibodies to dengue 2 and 3 viruses were compared in 54 matched pairs of specimens from subjects in the Dominican Republic. Dengue infection appeared to be hyperendemic; pregnant women experienced a 6% weekly infection rate. Titers of antibody to dengue 2 and 3 viruses were considerably higher in cord sera than in maternal sera (P smaller than 0.001 and P smaller 0.01, respectively), especially when maternal levels were low. When maternal and cord sera were compared at equal titers of dengue 2 virus, heterotypic antibodies to dengue 1 and St. Louis encephalitis viruses were higher in the cord. These findings could not be directly related to the higher levels of IgG found in cord sera or to the presence of elevated concentrations of IgM. It is concluded that antibody with increased cross-reactivity preferentially crosses the placenta. The presence of such cross-reactive antibody does not appear to sensitize infants to dengue hemorrhagic fever/shock syndrome.

Arbovirus infections in Sarawak, October 1968–February 1970: Human serological studies in a Land Dyak Village

Abstract: 449 human sera collected in a Land Dyak village were tested for antibodies to 11 arboviruses. Japanese encephalitis and dengue virus antibodies were particularly prevalent. The rates of infection with these viruses were estimated to be 5-2% per annum for Japanese encephalitis, 8-8% for dengue 1 and 4-3% for dengue 2. Chikungunya virus antibodies were quite common with an annual infection rate of the order of 5% per annum. Infections with other Group A and B and Bunyamwera group viruses were generally at a low level.

The effect of dengue virus infection on the clinical sequelae of Japanese encephalitis: a one year follow-up study in Thailand.

Abstract: In order to determine if prior dengue virus infection reduces the severity of Japanese encephalitis (JE), we examined 127 patients hospitalized during the 1970 JE epidemic in the Chiangmai and Lampang Valleys of northern Thailand. Patients were studied during the first 30 days after onset of JE; 120 of these patients were examined one year later for residual neurologic sequelae. About 21% of patients had serological evidence of a prior dengue virus infection. Morbidity and mortality in patients with and without prior dengue virus experience were compared. These comparisons were made within two age groups to exclude differences due to age alone;

Dengue Virus Plaque Formation on Microplate Cultures and Its Application to Virus Neutralization

Abstract: Discussion and SummaryDengue virus plaque formation on BHK-21 cell micro-plate cultures was described. The clear plaques were visible usually 5 days after incubation in a CO2 incubator at 37°. The cells cultured in a 3-oz bottle were sufficient to prepare two microculture plates which were usually ready for use after 1-2 days of cultivation in the CO2 incubator at 37°. The overall procedures were easy and of economic advantage.It is to be stated in this connection that the affinity of dengue viruses to tissue culture cells is not necessarily high, so that the cell culture systems suitable for dengue virus plaquing have so far been limited; and even in such suitable systems the formation of clear plaques takes a much longer time of incubation than for other kinds of arbo-viruses in general. Some of the difficulties regarding this matter have been overcome by the techniques reported here.By use of the microplate cultures, in combination with the transfer-plates reported by previous investigators (8), dengue...

A review of the evidence in retrospect for a rickettsial etiology in Bullis fever.

Abstract: The authors have presented evidence through work done 25-30 years ago for the rickettsial etiology of Bullis fever, a forgotten epidemic which occurred with over a 1,000 cases among World War II troops in training at Camp Bullis, Texas. Rickettsiae were recovered from blood and lymph nodes of patients and from ticks, Amblyomma americanum, collected in the area. All patients gave a history of tick-bites. The human and tick strains of rickettsiae, carried in chick embryo culture and in animal passage, were found to produce the characteristic syndrome of Bullis fever in human volunteers inoculated with either strain, indicating identity and specificity of infection. Wildlife in the area was found to support the stages in the life cycle of A. americanum. Deer were implicated as supporting the most abundant adult tick population, the stage which attacks man. Serologic studies eliminated othe rickettsial diseases, Colorado tick fever, dengue and many other diseases. The name Rickettsia texiana is suggested for the hitherto un-named member of the rickettsia group of organisms.

Dengue haemorrhagic fever in Burma.

Abstract: Although sporadic from 1965 to 1969, a major outbreak of dengue haemorrhagic fever (DHF) occurred for the first time in Rangoon in 1970. Since then the disease has occurred every year in Rangoon and is now observed to be expanding to other urban areas in the country. The clinical diagnosis of DHF was confused by concurrent outbreaks of influenza A in 1971 and influenza A and B in 1972. A laboratory study of 3,447 clinically diagnosed haemorrhagic fever cases showed that 1643 cases (47.8%) were due to dengue and chikungunya, 296 (8.6%) to influenza A, 85(2.5%) to influenza B, 12(0.3%) to measles and 1411(40.8%) were of unknown aetiology during the 5 year period 1970-1974. Ae. aegypti mosquitoes are widely distributed in the country up to and including 900 meters above sea level but breeding is not found above that altitude. The absolute larval population which is highest in July as well as landing rate correlated with the peak incidence of DHF cases.

Prevalence of antibodies to arboviruses in Egypt. Results of a serologic survey among 1,113 university students.

Abstract: A serologic survey was carried out to demonstrate the present distribution of antibodies to certain arboviruses in Egypt. An examination of serum specimens from 1,113 male university students from different localities of Egypt showed that West Nile, phlebotomus fever, and Sindbis viruses are endemic, having overall prevalence rates of 50%, 23%, and 6%. The geographic distribution of West Nile and Sindbis viruses was identical, and dissimilar to that of the ecologically different phlebotomus fever virus. The prevalence of West Nile and Sindbis viruses has decreased from that reported 10 to 15 years ago, whereas that of phlebotomus fever remained unchanged. No antibodies were detected to eastern equine encephalomyelitis, western equine encephalomyelitis, or Bunyamwera virus. Only four serum samples (0.3%) were positive for dengue 1 virus.

Changes in the tissues of the immune system in dengue haemorrhagic fever.

Abstract: A total of 100 post-mortems were done on patients clinically diagnosed as dengue haemorrhagic fever from Rangoon Children's Hospital. Histopathological changes in bone marrow, thymus, spleen, lymph nodes and other associated tissues of the immune system were analysed and correlated with the clinical picture and serology results. The major changes in cases with a positive serology result for secondary dengue infection consist of hypoplasia of the bone marrow, acute atrophy and wasting of the thymus, atrophy and depletion of cells in the periarterial lymphatic sheaths of the spleen and the paracortical areas of the lymph nodes. The tissues affected are the thymus-dependent areas of the spleen and lymph nodes, and the thymus itself. Thymus-independent areas of the secondary lymphatic tissues are also affected but to a lesser extent. The pathological observations suggest that immunodepression may be an integral part of the pathophysiology of dengue haemorrhagic fever.

Indirect fluorescent antibody technic for demonstration of serum antibody in dengue hemorrhagic fever cases.

Abstract: One hundred eighty-three sera from two groups of children with dengue hemorrhagic fever and 37 control sera were examined for antibody against dengue virus by an indirect immunofluorescent method. When the reciprocal titer of 16 or higher was used as the diagnostic level, positive tests could be obtained in 80% of Group I and 100% of Group II sera after 3--6 days of fever. Positive tests were obtained in 100% of both groups after the first week of fever. There was no false-positive among the control sera. Preparation of the antigen is relatively easy, and the antigen may be stored for at least 3 months. The immunofluorescent method is rapid and simple, and is recommended for routine detection of serum antibody in dengue hemorrhagic fever.

Arbovirus studies in two towns in western state of Nigeria.

Abstract: Three hundred and fifty-one persons were tested for HI antibody to arbovirus Groups A, B and Ingwavuma viruses in Ilesha and Oshogbo, two towns in western Nigeria. Chikungunya accouted for most Group A infections (39%). Antibodies to Group B virus were distributed as follows: Dengue 22%, Yellow Fever 25%, West Nile 28% and Wesselsbron 30%. Few sera 5% were positive to Ingwavuma. No virus was isolated from 188 blood specimens processed for virus isolation.

Serologic examination of birds from the area of Southern Moravia for the presence of antibodies against arboviruses of the groups alfa, flavo, Bunyamwera supergroup, and the virus Yaba 1-Lednice 110. I. Domestic fowls.

Abstract: 196 geese, 141 ducks, and 100 hens from 9 localities of the South Moravian region (District of Breclav) were examined by means of the haemagglutination-inhibition test (HIT) for the presence of antibodies against 12 arbovirus antigens of the groups Alfavirus (Western Equine Encephalitis (WEE), Eastern Equine Encephalitis (EEE), Semliki, Sindbis, Chikungunya, O'nyong-nyong), Flavovirus (Tick-borne Encephalitis (TBE), Dengue and West Nile Virus (WN), Bunyamwera Supergroup (Tahna and Beta Calovo), and the Yaba 1-Lednice 110 Virus. In tested fowls antibodies were mostly found against Yaba 1-Lednice 110 Virus, namely 3.6% in geese and 17.7% in ducks. Antibodies against Calovo Virus were found in only 1 of the tested ducks. All sera of hens were negative. Antibodies against arboviruses of the Alfa-and Flavovirus groups were not detected.

A sero-epidemiologic survey on arbovirus in Wuvulu Island.

Abstract: The authors present here the results of a serological survey on arbovirus infections, which was conducted on 116 out of 505 inhibitants of Wuvulu island, the westernmost island of the Bismarck archipelago, located 260 km north of Wewak, Papua-New Guinea. The islanders are divided in two communities of unequal size: the Wuvulian themselves, who are Micronesians, and the coconut workers who are Melanesians coming from the Sepik district. In addition to the presence of a group A virus, this survey shows a recent infection in the Melanesians by Dengue type 2 virus, probably during the 1971-72 epidemic. The virus did not reach Wuvulu island, as shown by negative results observed in the micronesian sera. A better knowledge of the potential dengue mosquito vectors would be useful in order to define the risk of an eventual introduction of the virus on the remote island.

Sensitivity of rapid plaque assay method of dengue viruses.

Abstract: The sensitivity of the hemadsorption-negative plaque test for the infectivity assay of dengue virus type 2 was compared with those of other methods such as conventional plaque test, intracranial inoculation technique of suckling or weanling mice and intrathoracical inocu- lation technique of Aedes aegypti. The results indicated that the infectivity of the virus can be rapidly and reliably assayed by this method and the sensitivity of the method is higher than that of suckling or weanling mice intracranial inoculation technique, although about 5-fold less sensitive than that of intrathoracical inoculation technique of Aedes aegypti. Physicochemical, biochemical and growth characteristices of mouse brain passaged dengue viruses have been extensively studied. However, many problems still remain un- clear, especially on the pathogenicity of the virus and the pathogenesis of dengue hemorrha- gic fever. One of the main reasons of the slow progress in these fields might be due to the lack of adequate virus growth system and rapid assay method of the infectivity of the virus in tissue culture. Various assay methods of the virus in tissue culture system have been repor- ted (1, 2, 3, 4, 6, 12, 14, 16) previously, but they, in general, take long incubation peri- ods to obtain the results and are less susceptible than 2 to 3-day-old suckling mouse intra- cranial inoculation method.

Dengue virus replication in cultures of peripheral blood leukocytes during the course of dengue haemorrhagic fever.

Abstract: A preliminary study was made of the ability of cultured human peripheral blood leukocytes (PBL) to support dengue 2 infection. Leukocyte donors, children hospitalized with primary (one case) or secondary dengue infections (12 cases), were studied during the acute and convalescent stages of illness. D2 virus replication occurred infrequently in PBL cultures obtained from children before the 10th day after onset of symptoms (2/23 samples), but frequently thereafter (8/13 samples). The absence of virus permissive cells during the acute stage of illness might be explained by several different mechanisms, including the possibility that permissive PBL are exhausted as the result of a severe dengue infection. An unexpected finding was the appearance of dengue hemagglutination-inhibition antibodies in cultures of PBL obtained from children during the acute stage of secondary dengue infections.