Dengue Haemorrhagic Fever in the South of Vietnam during 1975-1992 and Its Control Strategy

The incidence of dengue (DEN) virus infection in Vietnam has increased dramatically in the past 30 years. From 1960 up to now, the number of dengue haemorrhagic fever (DHF) cases has been continuing to increase and recorded as the greatest one in Southeast Asia and the Western Pacific Regions. DHF was endemic in South Vietnam and 30-380 cases/100,000 population were reported annually. Major epidemics have occurred in a 3-4 years frequency, as in 1975, 1978-1979, 1983 and 1987. The 1987 outbreak was the largest one with 83,905 cases and 904 deaths. DHF epidemics usually took place from June to November every year. The peak transmission was recorded in July-August and September, coinciding with the rainy season and the breeding period of Aedes aegypti. The majority of confirmed cases was children of 5-6 year-old-group, in which there was no sex difference. In the virological surveillance in Ho Chi Minh City and in some surrounding provinces, several DEN virus strains were isolated from patients\u27 blood as well as from the mosquitoes. In the 1987 DHF outbreak, DEN-2 was the dominant sero-type (90.5%). But from 1990 the epidemic sero-type has changed, DEN-1 was introduced and was continuing to grow-up (58%). Then in 1992 outbreak, the DEN-2 was reintroduced, from 26.3% in 1991 has increased to 41.4%. Serological investigation of healthy persons in 12/17 southern provinces had demonstrated that there were relatively wide circulations of DEN, Japanese encephalitis (JE) and chikungunya (Chik) viruses and the endemic strains of DEN were found different in some studied areas. There had been augmentation of primary infection rate and decrease of the susceptibility rate in children prior to the DHF epidemic. Seven JE virus strains were isolated from dengue fever (DF) patients\u27 blood. This fact has introduced as a new concept in the isolation of JE virus. In the final pant of the report, the authors stressed on the "Active surveillance" as a new strategy for controlling the DHF epidemic in South Vietnam. The goal of this active surveillance is to have early warning and predictive capability for epidemic dengue, based on serological and clinical surveillance. Because dengue cases were detected in January-February of every year, so the base line is: when first cases of DF/DHF were detected, it needs to be promptly implemented the larval control and insecticide must be sprayed around the patient\u27s houses. But now almost Provincial Centers of Hygiene and Epidemiology often waited and when big DHF epidemic had already occurred, they started to implement its control measures, so it is too late to control the DHF outbreak

Current Situation of Japanese Encephalitis in the South of Vietnam, 1976-1992

Cases of "Acute Encephalitis Syndrome (AES)" and deaths were reported annually in all 17 provinces in the South of Vietnam. The highest morbidity of 936 patients was recorded in 1980, while highest mortality of 339 deaths in 1977. The lowest figures of morbidity was 197 cases in 1990 and lowest mortality was 34 deaths in 1985. Sporadic cases were reported throughout the year but small outbreaks with low peaks were seen in February and July annually. Twenty five strains of Japanese encephalitis (JE) virus were isolated during 1978-1992: 8 from patients\u27 blood, 5 from cerebrospinal fluid (CSF), 9 from Culex quinquefasciatus, 3 from Aedes aegypti. Serologically confirmed JE cases were not many, because most of the human sera sent to us for testing were used for differential diagnosis of pernicious malaria. The anti-JE antibody prevalence among healthy human in 11/17 provinces was found to be extremely high, especially in adults. The antibody positive rate among swine to JE was found to be high: 82% with GMT 65.2 in 189 sera taken at My Tho-Tien Giang province in March 1978 and 77.4% with GMT 49.7 in 261 sera taken in the vicinity of Ho Chi Minh City in September 1992. From the above data, the Southern part of Vietnam is an endemo-epidemic area of JE virus infection

Elevated Levels of Cell-Free Circulating DNA in Patients with Acute Dengue Virus Infection

BACKGROUND: Apoptosis is thought to play a role in the pathogenesis of severe dengue and the release of cell-free DNA into the circulatory system in several medical conditions. Therefore, we investigated circulating DNA as a potential biomarker for severe dengue. METHODS AND FINDINGS: A direct fluorometric degradation assay using PicoGreen was performed to quantify cell-free DNA from patient plasma. Circulating DNA levels were significantly higher in patients with dengue virus infection than with other febrile illnesses and healthy controls. Remarkably, the increase of DNA levels correlated with the severity of dengue. Additionally, multivariate logistic regression analysis showed that circulating DNA levels independently correlated with dengue shock syndrome. CONCLUSIONS: Circulating DNA levels were increased in dengue patients and correlated with dengue severity. Additional studies are required to show the benefits of this biomarker in early dengue diagnosis and for the prognosis of shock complication