Dengue infections in the Philippines: clinical and virological findings in 517 hospitalized patients

Genetic Diversity and Dispersal of DENGUE Virus among Three Main Island Groups of the Philippines during 2015-2017

Dengue has been one of the major public health concerns in the Philippines for more than a century. The annual dengue case burden has been increasing in recent years, exceeding 200,000 in 2015 and 2019. However, there is limited information on the molecular epidemiology of dengue in the Philippines. We, therefore, conducted a study to understand the genetic composition and dispersal of DENV in the Philippines from 2015 to 2017 under UNITEDengue. Our analyses included 377 envelope (E) gene sequences of all 4 serotypes obtained from infections in 3 main island groups (Luzon, Visayas, and Mindanao) of the Philippines. The findings showed that the overall diversity of DENV was generally low. DENV-1 was relatively more diverse than the other serotypes. Virus dispersal was evident among the three main island groups, but each island group demonstrated a distinct genotype composition. These observations suggested that the intensity of virus dispersal was not substantive enough to maintain a uniform heterogeneity among island groups so that each island group behaved as an independent epidemiological unit. The analyses suggested Luzon as one of the major sources of DENV emergence and CAR, Calabarzon, and CARAGA as important hubs of virus dispersal in the Philippines. Our findings highlight the importance of virus surveillance and molecular epidemiological analyses to gain deep insights into virus diversity, lineage dominance, and dispersal patterns that could assist in understanding the epidemiology and transmission risk of dengue in endemic regions.

Dengue Hemorrhagic Fever: A State-of-the-Art Review Focused in Pulmonary Involvement

Dengue fever is an arboviral disease transmitted to humans through the bites of infected female Aedes mosquitoes. Dengue virus is a member of the Flaviviridae family, and human infection can be caused by any of the four antigenically distinct serotypes (DENV 1–4). The infection has become recognized as the most important and prevalent arboviral disease in humans, endemic in almost 100 countries worldwide. Nearly 3 billion people live in areas with transmission risk. Autochthonous transmission of the virus in previously disease-free areas, increased incidence in endemic areas, and epidemic resurgence in controlled regions could increase the risk of contracting more severe forms of the disease, such as dengue hemorrhagic fever (DHF)/dengue shock syndrome (DSS). Symptomatic dengue virus infection can present with a wide range of clinical manifestations, from mild fever to life-threatening DSS. Thoracic complications may manifest as pleural effusion, pneumonitis, non-cardiogenic pulmonary edema, and hemorrhage/hemoptysis. No vaccine is currently available and no specific treatment for dengue fever exists, but prevention and prompt management of complications in patients with DHF can help reduce mortality. This review describes the main clinical, pathological, and imaging findings of thoracic involvement in DHF.

Characterization of dengue virus infections in a sample of patients suggests unique clinical, immunological, and virological profiles that impact on the diagnosis of dengue and dengue hemorrhagic fever

Dengue virus (DENV) infections are increasing with respect to incidence and severity in the Central Province of Sri Lanka. The objective of this study was to define the clinical, immunological, and virological profiles of patients admitted to the General Hospital, Kandy with clinically apparent dengue. Demographic, clinical, hematological parameters, liver enzymes (ALT and AST), and blood samples were collected from 292 patients with fever <5 days post onset and fulfilling the WHO criteria for the diagnosis of dengue fever/dengue hemorrhagic fever (DF/DHF). Samples were analyzed for, anti-DENV IgM, IgG, and DENV nucleic acid. Myalgia was the commonest complaint by 65% of the patients. Packed cell volume was >45% in 27% of the patients while 42.12% had reduced platelets and 62.67% had reduced white blood cell counts. In contrast to other studies, positive tourniquet test (PTT) and petechiae were not major indicators of DENV infection or severity of the disease. Clinical profiles were significantly different between DF and DHF/DSS and showed many similarities to that reported elsewhere. Altogether, 43 patients (14.73%) were viremic as detected by RT-PCR; 181 patients (62%) were positive for anti-DENV IgM, and 245 (84%) patients were positive for anti-DENV IgG. In combination, anti-DENV IgM and RT-PCR assays detected 224 (77.5%) of DENV infected cases, thus improving the DENV diagnosis rate. Hence, the diagnostic utility of PTT, anti-DENV IgM/IgG serology, or RT-PCR used alone in the early phase of illness is low in Sri Lanka but the diagnostic value can be improved by a combination of serology and RT-PCR. J. Med. Virol. 88:1703-1710, 2016. © 2016 Wiley Periodicals, Inc.

Laboratory-confirmed Dengue in Children in Three Regional Hospitals in the Philippines in 2009-2010

BACKGROUND

The burden of dengue is high in the Philippines but the prevalence of confirmed cases is unknown, and the disease is subject to underreporting because surveillance of suspected cases is passive. We conducted a prospective epidemiological study to estimate the proportion of laboratory-confirmed dengue among clinically suspected hospitalized cases in the pediatric wards of 3 regional hospitals in the Philippines and to describe the clinical and laboratory features, age distributions, case fatality rates and serotype distributions of these hospitalized cases.

METHODS

Patients ≤18 years and hospitalized for suspected dengue were included if they had an axillary temperature ≥38°C for 2-7 days and 2 or more dengue-associated symptoms. Dengue infection was confirmed in acute blood samples by serotype-specific reverse transcription-polymerase chain reaction and IgM immunoassay.

RESULTS

We confirmed dengue infection in 1809 (86.1%) cases of 2103 suspected cases between November 2009 and November 2010. The 6- to 10-year-old age group had the highest proportion of cases overall (36.7%). Fever, anorexia, myalgia, abdominal pain and headache were the most common symptoms at admission. Hemorrhagic manifestations, signs of plasma leakage, thrombocytopenia and leucopenia were all significantly more common in confirmed than in nonconfirmed cases. Most cases (76.5%) developed dengue hemorrhagic fever or dengue shock syndrome, and the overall case fatality rate was 0.94%. Distributions of all 4 virus serotypes varied at each hospital.

CONCLUSIONS

The clinical burden of pediatric dengue continues to be substantial in the Philippines. Most hospitalized cases of suspected pediatric dengue can be laboratory confirmed and most develop severe disease.

HLA-A*33:01 as protective allele for severe dengue in a population of Filipino children

Dengue virus infection is a leading cause of morbidity among children in the Philippines in recent years. In order to investigate the association of HLA Class I and II alleles and dengue disease severity in a cohort of Filipino children, we performed a case control study in 2 hospitals in Metro Manila from June 2008 to December 2009. A total of 250 laboratory confirmed dengue patients and 300 healthy individuals aged 5 to 15 years old were typed for HLA-A, B and DRB1 alleles. The frequency of HLA-A*33:01 was significantly decreased in severe dengue (DHF/ DSS; Pc = 0.0016)) and DSS (Pc = 0.0032) compared to the background population. These findings support a previous study that this allele may confer protection against the severe form of dengue and provide the first evidence of HLA association with dengue in the Philippines. Future studies should be directed in investigating the possible mechanisms of protection.

Dengue infection in children and adolescents: clinical profile in a reference hospital in northeast Brazil

INTRODUCTION

This study aimed to describe the clinical spectrum of dengue in children and adolescents from a hyperendemic region who were admitted for hospitalization.

METHODS

A retrospective study was conducted on patients diagnosed with dengue infection upon admission to a reference center in Fortaleza, Brazil.

RESULTS

Of the 84 patients included, 42 underwent confirmatory testing. The main symptoms were fever, abdominal pain and vomiting. The median level of serum aspartate aminotransferase was 143.5±128mg/dL.

CONCLUSIONS

A peculiar clinical profile was evident among children and adolescents with dengue infection in a reference center in northeast Brazil, including gastrointestinal symptoms and liver involvement.

Disease severity and mortality caused by dengue in a Dominican pediatric population

Millions are infected with dengue yearly. We evaluated the epidemiological and clinical characteristics of pediatric patients infected with dengue in the Dominican Republic. The applicability of World Health Organization (WHO) warning signs for predicting severe dengue and mortality was also studied. This study was a cross-sectional retrospective review of patients with a clinical diagnosis of dengue. Univariate and multivariate analyses were performed to evaluate characteristics associated with severity and mortality. The study included 796 subjects: 288 subjects were classified as dengue, 290 subjects had alarm signs, and 207 subjects were classified as severe dengue. Common findings included thrombocytopenia (96%), abdominal pain (71%), and vomiting (59%). The most important factors associated with severe dengue were rash (P < 0.01), severe thrombocytopenia (P < 0.01), and anemia (P < 0.01). These signs and symptoms were also associated with mortality. This study validates the current WHO warning signs of severity. Rash and severe thrombocytopenia may be early warning signs and need additional study.

[Intra-alveolar hemorrhage associated with dengue and leptospirosis]

The intra-alveolar hemorrhage syndrome is defined by the presence of red cells in the alveolar lumen and can lead to acute respiratory failure. Among the infectious etiologies of this syndrome, leptospirosis is a common cause, whereas in dengue, the intra-alveolar hemorrhage is exceptional. We report a patient aged 46 years, with no particular history, who presented a clinical picture involving acute respiratory failure, hemoptysis, bilateral alveolar images and anemia. The intra-alveolar hemorrhage has been authenticated by bronchoalveolar lavage. The etiological showed infection by both dengue and leptospirosis.

Multicentre prospective study on dengue classification in four South-east Asian and three Latin American countries

OBJECTIVE

To evaluate the existing WHO dengue classification across all age groups and a wide geographical range and to develop a revised evidence-based classification that would better reflect clinical severity.

METHODS

We followed suspected dengue cases daily in seven countries across South-east Asia and Latin America and then categorised them into one of three intervention groups describing disease severity according to the overall level of medical and nursing support required. Using a pre-defined analysis plan, we explored the clinical and laboratory profiles characteristic of these intervention categories and presented the most promising options for a revised classification scheme to an independent group of WHO dengue experts for consideration. Potential warning signs were also evaluated by comparing contemporaneous data of patients who progressed to severe disease with the data of those who did not.

RESULTS

A total of 2259 patients were recruited during 2006-2007 and 230 (13%) of the 1734 laboratory-confirmed patients required major intervention. Applying the existing WHO system, 47/210 (22%) of patients with shock did not fulfil all the criteria for dengue haemorrhagic fever. However, no three-tier revision adequately described the different severity groups either. Inclusion of readily discernible complications (shock/severe vascular leakage and/or severe bleeding and/or severe organ dysfunction) was necessary to devise a system that identified patients requiring major intervention with sufficient sensitivity and specificity to be practically useful. Only a small number of subjects (5%) progressed to severe disease while under observation; several warning signs were identified, but much larger studies are necessary to fully characterize features associated with disease progression.

CONCLUSIONS

Based on these results, a revised classification system comprised of two entities, 'Dengue' and 'Severe Dengue', was proposed and has now been incorporated into the new WHO guidelines.

The history and evolution of human dengue emergence

Dengue viruses (DENV) are the most important human arboviral pathogens. Transmission in tropical and subtropical regions of the world includes a sylvatic, enzootic cycle between nonhuman primates and arboreal mosquitoes of the genus Aedes, and an urban, endemic/epidemic cycle principally between Aedes aegypti, a mosquito that exploits peridomestic water containers as its larval habitats, and human reservoir hosts that are preferred for blood feeding. Genetic studies suggest that all four serotypes of endemic/epidemic DENV evolved independently from ancestral, sylvatic viruses and subsequently became both ecologically and evolutionarily distinct. The independent evolution of these four serotypes was accompanied by the expansion of the sylvatic progenitors' host range in Asia to new vectors and hosts, which probably occurred gradually over a period of several hundred years. Although many emerging viral pathogens adapt to human replication and transmission, the available evidence indicates that adaptation to humans is probably not a necessary component of sylvatic DENV emergence. These findings imply that the sylvatic DENV cycles in Asia and West Africa will remain a potential source of re-emergence. Sustained urban vector control programs and/or human vaccination will be required to control DEN because the enzootic vectors and primate reservoir hosts are not amenable to interventions.

Dengue viruses can infect human primary lung epithelia as well as lung carcinoma cells, and can also induce the secretion of IL-6 and RANTES

Dengue viruses (DENV) are herein demonstrated for the first time as being able to infect and replicate in human primary lung epithelium and various lung cancer cell lines. The detection of dengue virus particles and viral negative strand RNA synthesis in the cell, in conjunction with the release of viral progenies in culture supernatants, support the notion that lung cells are susceptible to dengue virus infection. The replication efficiency of DENV in lung cancer cells from high to low is: DEN-2 (dengue virus type-2), DEN-3, DEN-4 and DEN-1. Moreover, the susceptibility of the six lung cancer cell lines to DEN-2 infection is: SW1573>A549>H1435; H23; H520; Bes2B. DEN-2 infection significantly increased the expression levels of IL-6 and RANTES in four of the six lung cancer cell lines, which is consistent with the high expression levels of these molecules in DHF/DSS patients. IL-6 expression induced by DEN-2 infection was NF-kappaB dependent. In summary, our results indicate that lung epithelial cell is a possible target of dengue viruses and IL-6 and RANTES may play pivotal roles in lung related immuno-pathogenesis.

Classifying dengue: a review of the difficulties in using the WHO case classification for dengue haemorrhagic fever

BACKGROUND

The current World Health Organisation (WHO) classification of dengue includes two distinct entities: dengue fever (DF) and dengue haemorrhagic fever (DHF)/dengue shock syndrome; it is largely based on pediatric cases in Southeast Asia. Dengue has extended to different tropical areas and older age groups. Variations from the original description of dengue manifestations are being reported.

OBJECTIVES

To analyse the experience of clinicians in using the dengue case classification and identify challenges in applying the criteria in routine clinical practice.

METHOD

Systematic literature review of post-1975 English-language publications on dengue classification.

RESULTS

Thirty-seven papers were reviewed. Several studies had strictly applied all four WHO criteria in DHF cases; however, most clinicians reported difficulties in meeting all four criteria and used a modified classification. The positive tourniquet test representing the minimum requirement of a haemorrhagic manifestation did not distinguish between DHF and DF. In cases of DHF thrombocytopenia was observed in 8.6-96%, plasma leakage in 6-95% and haemorrhagic manifestations in 22-93%. The low sensitivity of classifying DHF could be due to failure to repeat the tests or physical examinations at the appropriate time, early intravenous fluid therapy, and lack of adequate resources in an epidemic situation and perhaps a considerable overlap of clinical manifestations in the different dengue entities.

CONCLUSION

A prospective multi-centre study across dengue endemic regions, age groups and the health care system is required which describes the clinical presentation of dengue including simple laboratory parameters in order to review and if necessary modify the current dengue classification.

Pulmonary hemorrhage syndrome associated with an autochthonous case of dengue hemorrhagic fever

Dengue fever is a major public health problem worldwide. Dengue hemorrhagic fever, a much rarer form of the disease, occurs when a person previously infected with dengue is re-infected with a different viral serotype. In recent years the infection rates of dengue and both clinical syndromes have increased along the United States-Mexico border. We present the case of a 61-year-old Laotian female who presented with a 1-week history of fever, altered mental status, oral ulceration, and rash. The patient developed diffuse pulmonary hemorrhage and anemia requiring multiple transfusions. She eventually sustained multi-organ system failure and expired. Both the titer data and serologies were consistent with the diagnosis of dengue hemorrhagic fever. We hypothesize that this syndrome was the result of re-infection occurring within the United States. This case is also unusual in that it is the second reported in the literature of pulmonary hemorrhages associated with dengue hemorrhagic fever.

Antibody-dependent enhancement of viral infection: molecular mechanisms and in vivo implications

Besides the common receptor/coreceptor-dependent mechanism of cellular attachment, some viruses rely on antiviral antibodies for their efficient entry into target cells. This mechanism, known as antibody-dependent enhancement (ADE) of viral infection, depends on the cross-linking of complexes of virus-antibody or virus-activated complement components through interaction with cellular molecules such as Fc receptors or complement receptors, leading to enhanced infection of susceptible cells. Recent studies have suggested that additional mechanisms underlie ADE: involvement of complement component C1q and its receptor (Ebola virus), antibody-mediated modulation of the interaction between viral protein and its coreceptor (human immunodeficiency virus) and suppression of cellular antiviral genes by the replication of viruses entering cells via ADE (Ross River virus). Since ADE is exploited by a variety of viruses and has been associated with disease exacerbation, it may have broad relevance to the pathogenesis of viral infection and antiviral strategies.

Isolation and partial characterization of dengue virus type 2 and 4 strains from dengue fever and dengue haemorrhagic fever patients from Mindanao, Republic of the Philippines

OBJECTIVE

Isolation of dengue virus from dengue fever and dengue haemorrhagic fever cases from Mindanao, Republic of the Philippines.

METHODS

12 patients with clinically suspected dengue fever (DF) or dengue haemorrhagic fever (DHF) presenting in four regional hospitals between August and September 1995 on Minadano were enrolled in the study. Dengue virus was isolated by inoculation of Vero/E6 or C6/36 cells with patient serum. IgM antibodies were measured using a commercial test system. Up to 454 bp of the capsid region and 240 bp of the E/NS1 gene junction of different viral isolates were sequenced and phylogenetically analyzed.

RESULTS

Virus could be isolated from seven patients, five isolates were typed as dengue virus type 2 and two as dengue virus type 4 by immunostaining with monoclonal antibodies or by RT/PCR. Phylogenetic analysis confirmed a close relationship of the dengue virus type 2 isolates with viruses isolated in the Philippines in 1983 and 1988.

CONCLUSION

As observed in studies from other parts of South East Asia, dengue virus type 2 was readily isolated from dengue haemorrhagic fever cases. Dengue virus type 2 and 4 circulate in Mindanao, Philippines, with dengue type 2 being responsible for most of our severe DF or DHF cases.

Prospective study of the duration and magnitude of viraemia in children hospitalised during the 1996-1997 dengue-2 outbreak in French Polynesia

The magnitude and duration of viraemia in children admitted to the hospital with dengue was studied during a dengue 2 outbreak in French Polynesia in 1996-1997. Forty-nine patients from whom at least 3 plasma samples were available were included in the study. Based on analysis of IgG-ELISA and haemagglutination inhibition assay, 21 of these were primary and 28 were secondary infections. According to World Health Organization criteria, 42 were dengue fever and 7 were dengue haemorrhagic fever. Virus was detectable by reverse transcription-PCR in all patients for at least the first 3 days of the onset of fever, but was never detected after the 6th day (mean duration = 4.4 days). Plasma virus titers ranged from 1.7-5.6 Log(10) TCID(50)/ml. A significant difference was not observed in the magnitude and duration of viraemia in patients with primary versus secondary infections. The severity of the illness, however, was correlated with both criteria.

Dengue haemorrhagic fever in adults: a prospective study of 110 cases

One hundred and ten adult patients hospitalized with dengue haemorrhagic fever (DHF) during the recent outbreak in North India were prospectively studied. Of these, 48 (43.6%) were grade I, 40 (36.4%) grade II, 10 (9.1%) grade III and 12 (10.9%) grade IV DHF. Dengue shock syndrome (DSS) was seen in 22 (20%) patients. Fever, headache, myalgias and arthralgias were the common symptoms seen in 100%, 80.9%, 76.2% and 52.3% patients, respectively. Spontaneous bleeding was seen in 62 patients (56.4%) with mucocutaneous bleeding being the most common (46 patients). Gastrointestinal bleeding was seen in 38 (34.5%) patients. In as many as 40 patients, the haemorrhagic manifestations occurred after the fever had come down. Fifty-five patients (50%) required platelet transfusions. Twelve patients died, giving a mortality rate of 10.9% in the present study. Prompt recognition and supportive treatment can be lifesaving.

Possible dengue sequential infection: dengue spread in a neighbourhood during the 1996/97 dengue-2 epidemic in French Polynesia

A DEN-2 epidemic occurred in French Polynesia from August 1996 to April 1997 after 7 years of DEN-3 circulation. The susceptible population constituted all expatriates and Polynesians under 21. In August 1996, two successive DEN-2 cases occurred in Teroma, a Tahitian neighbourhood close to the international airport of Tahiti. A serological prospective study of persons < 21 years living in Teroma was conducted. The study population was bled in September 1996, October 1996 and June 1997. Analysis of dengue spread in Teroma confirmed that dengue transmission occurs primarily in the house, thus vector control campaigns should incorporate focal insecticide spraying and systematic daily use of insecticide in houses. The evolution in time of the disease demonstrated that among a susceptible population, prevalence and incidence rates are related to the time of exposure, and consequently to age. Comparison of dengue incidence or dengue prevalence between populations therefore requires adjusted age rates. Most studies did not adjust for age, leading to the conclusion that DHF is more frequent during secondary than during primary dengue infection. Prospective studies taking into account the time of dengue exposure are necessary to confirm the sequential infection hypothesis.

Dengue fever with hemorrhagic manifestations in travellers returning to Quebec from Asia

Two cases of dengue fever with hemorrhagic manifestations were observed in 1990 and 1992 among travellers returning from Asia, while a third presented with classical dengue fever after the patient's first trip to an endemic region. All experienced rash, thrombocytopenia and coagulation disorders and had flavivirus serology consistent with exposure to dengue virus.