Evaluation of Platelets as Predictive Parameters in Dengue Fever

Dengue is an arboviral disease and occurs in tropical countries where over 2.5 billion people are at risk of infection. Each year an estimated 100 million cases of dengue fever (DF) occur and between 2.5 and 5 lakh cases of dengue hemorrhagic fever (DHF) are reported to WHO. Severe thrombocytopenia and increased vascular permeability are two major characteristics of DHF. A study was conducted to note the relationship between the platelet counts and severity of the disease in pediatric cases of dengue fever. Platelet counts were found to be predictive as well as recovery parameter of DF/DHF/DSS.     

Characteristic of Dengue Disease in Taiwan: 2002�C2007

Taiwan''s dengue outbreaks have a unique type of transmission: starting by import from abroad in early summer, spreading out locally, and ending in the winter. This pattern repeats every year. Most of the dengue patients are adults, with dengue fever peaking in the 50–54 year age range, and dengue hemorrhagic fever in the 60–64 year age range. Two patterns of dengue infection were found: DENV-2 in 2002 with 74% of secondary infection in contrast to non-DENV-2 (DENV-1 or DENV-3) in 2004–2007 with ~70% of primary infection. Secondary dengue virus infection increases disease morbidity, but not mortality in adults. The active serological surveillance shows two-thirds of the dengue-infected adults are symptomatic post infection. The Taiwanese experience of adult dengue should be valuable for countries or areas where, although dengue is not endemic, the Aedes aegypti vector exists and dengue virus can be introduced by travelers.     

Serum cortisol in dengue and dengue hemorrhagic fever: is there any clinical implication?

Dengue is an important mosquito-borne viral infection. This infection can be seen in many tropical countries and caused many infectious cases annually. The biochemical profile change during infection is very interesting. Here, the authors studied on a rarely mentioned parameter, serum cortisol. The levels of serum cortisol in the cases with dengue and dengue hemorrhagic fever were studied, reported and discussed.     

Vaccination against mosquito borne viral infections: current status

Mosquito borne infectious diseases are among important group of diseases worldwide. Vaccination is available for some tropical mosquito-borne diseases, especially for Japanese encephalitis virus infection and yellow fever. There are also several attempts to develop new vaccines for the other mosquito-borne diseases such as malaria, dengue infection and West Nile virus infection. In this article, the author reviews the issues on vaccination of some important tropical mosquito borne infectious diseases.     

Trends in imported chikungunya virus infections in Germany, 2006-2009

Chikungunya virus (CHIKV) has been previously reported in many African and Asian areas, but it recently reemerged strongly in countries bordering the Indian Ocean as well as caused an outbreak in northern Italy. In Germany, where potential CHIKV vectors are not yet established, CHIKV infection is mandatorily notifiable. Cases reported from 2006 through 2009 were analyzed for travel characteristics and demographic factors. 152 cases of symptomatic CHIKV infection were notified. Both sexes were affected, with a median age of 46 years. Over the years, countries of infection largely followed the outbreaks reported from various travel destinations. India and the Maldives were the countries of infection most frequently named. In Sri Lanka, India, and Thailand, which are also frequently named countries of infection for dengue virus, the median age of CHIKV-affected patients was higher than that of dengue fever patients. Taking traveler numbers into consideration, risk of CHIKV infection was higher in the Seychelles and Mauritius than in Thailand and India. Even though substantial underdiagnosis is suspected, this assessment of CHIKV importation to Germany offers valuable information about the details of travel-associated cases. Between 17 and 53 notified cases per year signify that CHIKV would be occasionally available for local transmission in Germany once a vector becomes present. Although CHIKV most often causes a comparatively mild disease, the high median age of notified cases and the higher age than dengue patients support more severe disease courses in older adults. Travelers to all CHIKV endemic areas should protect against mosquito bites. In Germany, CHIKV surveillance will be continued to monitor ongoing importation of the virus and to detect early potential autochthonous cases.     

Dengue and dengue hemorrhagic fever in Latin America and the Caribbean

Four serotypes of dengue viruses produce dengue fever, dengue hemorrhagic fever, and dengue shock syndrome. They are the most important arbovirus infections of humans, in terms of both morbidity and mortality, constituting one of the most rapidly expanding and re-emerging infectious disease problems in Latin America. In less than 20 years, the region has transformed itself from hypoendemic to hyperendemic, while serotype circulation in most countries has gone from none or single to multiple. Changes in endemicity have coincided with the emergence and increasing incidence of the severer forms of dengue infection. This article reviews the clinical presentations of these diseases. Health care providers who see patients in or returning from areas of Latin America, the Caribbean, and other tropical areas must consider dengue in the differential diagnosis of patients presenting with compatible symptoms, and must be knowledgeable in the current management of this important disease.     

Case Report: Fatal Staphylococcal Infection following Classic Dengue Fever

Dengue represents an important public health issue in many tropical areas, leading to high morbidity and the employment of substantial health resources. Even though the number of fatalities related to dengue is unknown, several reports warn about the potential occurrence of severe infections and even death. The clinical spectrum of dengue is highly variable, ranging from a mild flu-like syndrome to severe disease, with shock and hemorrhage. The occurrence of bacterial superinfection, or coinfection, in patients with dengue has been noted by some authors, but the available information comes from anecdotic reports. In this study, we show the clinical and anatomopathological data of a patient infected with dengue, who subsequently died of acute multi-organic failure related to Staphylococcus aureus infection. The autopsy revealed a severe disseminated staphylococcal disease and confirmed dengue infection.     

Isolated Bell's palsy – An unusual presentation of dengue infection

Dengue fever is a very common arthropod – borne infection in tropical countries. Neurological complications in dengue fever are relatively uncommon and among these, isolated cranial neuropathies have been reported only very rarely. We present an unusual neurological complication of Bell's palsy (lower motor neuron 7 th nerve palsy) associated with dengue infection. To the best of our knowledge, there have been very few documented cases of Flavivirus causing isolated Bell's palsy.     

Economic impact of dengue illness in the Americas

The growing burden of dengue in endemic countries and outbreaks in previously unaffected countries stress the need to assess the economic impact of this disease. This paper synthesizes existing studies to calculate the economic burden of dengue illness in the Americas from a societal perspective. Major data sources include national case reporting data from 2000 to 2007, prospective cost of illness studies, and analyses quantifying underreporting in national routine surveillance systems. Dengue illness in the Americas was estimated to cost $2.1 billion per year on average (in 2010 US dollars), with a range of $1-4 billion in sensitivity analyses and substantial year to year variation. The results highlight the substantial economic burden from dengue in the Americas. The burden for dengue exceeds that from other viral illnesses, such as human papillomavirus (HPV) or rotavirus. Because this study does not include some components (e.g., vector control), it may still underestimate total economic consequences of dengue.     

Cross-protective immunity can account for the alternating epidemic pattern of dengue virus serotypes circulating in Bangkok

Dengue virus, the causative agent of dengue fever and its more serious manifestation dengue hemorrhagic fever, is widespread throughout tropical and subtropical regions. The virus exists as four distinct serotypes, all of which have cocirculated in Bangkok for several decades with epidemic outbreaks occurring every 8-10 years. We analyze time-series data of monthly infection incidence, revealing a distinctive pattern with epidemics of serotypes 1, 2, and 3 occurring at approximately the same time and an isolated epidemic of serotype 4 occurring in the intervening years. Phylogenetic analysis of virus samples collected over the same period shows that clade replacement events are linked to the epidemic cycle and indicates that there is an interserotypic immune reaction. Using an epidemic model with stochastic seasonal forcing showing 8- to 10-year epidemic oscillations, we demonstrate that moderate cross-protective immunity gives rise to persistent out-of-phase oscillations similar to those observed in the data, but that strong or weak cross-protection or cross-enhancement only produces in-phase patterns. This behavior suggests that the epidemic pattern observed in Bangkok is the result of cross-protective immunity and may be significantly altered by changes in the interserotypic immune reaction.     

Immunodominant T-cell responses to dengue virus NS3 are associated with DHF

Dengue infections are increasing at an alarming rate in many tropical and subtropical countries, where epidemics can put health care systems under extreme pressure. The more severe infections lead to dengue hemorrhagic fever (DHF), which can be life threatening. A variety of viral and host factors have been associated with the severity of dengue infections. Because secondary dengue infection is more commonly associated with DHF than primary infections, the acquired immune response to dengue, both B cells and T cells have been implicated. In this study, we set out to study T-cell responses across the entire dengue virus proteome and to see whether these were related to disease severity in a cohort of dengue-infected children from Thailand. Robust responses were observed in most infected individuals against most viral proteins. Responses to NS3 were the most frequent, and there was a very strong association between the magnitude of the response and disease severity. Furthermore, in DHF, cytokine-high CD107a-negative cells predominated.     

Survival and vehicular spread of human rotaviruses: possible relation to seasonality of outbreaks

In developing countries rotavirus infections account for nearly 6% of all diarrheal episodes and for 20% of diarrhea-associated deaths of young children. Even in industrialized countries rotavirus diarrhea in the young is among the leading causes of hospitalization. In temperate regions institutional outbreaks of the disease occur mainly in cold dry weather, whereas in tropical settings the seasonality is less well defined. Waterborne outbreaks of rotavirus gastroenteritis have been recorded; air, hands, fomities, and food may also act as vehicles for this infection. Rotaviruses can survive for weeks in potable and recreational waters and for at least 4 hours on human hands. In air and on nonporous inanimate surfaces, the survival of rotaviruses is favored by a relative humidity of less than or equal to 50% and viral infectivity can be retained for several days. Rotaviruses are relatively resistant to commonly used hard-surface disinfectants and hygienic hand-wash agents.     

DC-SIGN (CD209) Carbohydrate Recognition Domain Is Not Polymorphic in Dengue Virus-Infected Indonesian Patients

Dengue virus (DENV) infection is a significant burden in Indonesia and other tropical countries. DENV infection has a wide spectrum of clinical manifestations, i.e. asymptomatic, dengue fever, dengue hemorrhagic fever and dengue shock syndrome. The variety of clinical manifestations may be due to the diversity of genetic constitution of the host. The C-type lectin DC-SIGN (CD209) has been identified as the major dengue receptor on human dendritic cells. There are at least five polymorphisms in exon 5 and 6 of the DC-SIGN encoded gene which have been identified and recorded in dbSNP. The aim of this work is to measure the frequency of these polymorphisms among asymptomatic and hospitalized DENV-infected patients. We enrolled 23 hospitalized and 73 asymptomatic DENV-infected patients. Among the subjects, we performed PCR amplification and DNA direct seqencing for 23 hospitalized DENV-infected patients and 24 asymptomatic DENV-infected patients. The result showed that there were no polymorphic nucleotides in the CD209 encoded gene among the patients.     

Discriminable roles of Aedes aegypti and Aedes albopictus in establishment of dengue outbreaks in Taiwan

Aedes aegypti and Aedes albopictus were reported to be significant as vectors of dengue fever. In Taiwan, the latter is distributed throughout the island while the former appears only south of the Tropic of Cancer; i.e., 23.5° N. In the past decade, there were five outbreaks with over 1000 cases of dengue fever in Taiwan. Without exception, these outbreaks all occurred in the south where the two Aedes mosquitoes are sympartic. According to the Center for Disease Control of Taiwan, imported cases are thought to provide the seeds of dengue outbreaks every year. Mostly, the number of imported cases is greater in northern island, probably due to a larger population of travelers and imported workers from endemic countries. Looking at the example in 2002, northern, central, and southern parts of Taiwan reported 28, 11, and 13 imported cases, respectively. However, 54, 21, and 5309 total cases were confirmed in the corresponding regions over the entire year, indicating a significant skew of case distributions. A hypothesis is thus inspired that the existence of Ae. aegypti is a prerequisite to initiate a dengue outbreak, while participation of Ae. albopictus expands or maintains the scale until the de novo herd immunity reaches high level.     

Travel-Acquired Dengue Infection: Clinical Spectrum and Diagnostic Aspects

Background: Dengue fever is increasingly recognized in travelers returning from endemic areas with acute febrile illness; however, its true burden in nonendemic countries is unknown. Only few studies focus on clinical manifestations and serological findings in primarily nonimmune individuals. Patients and Methods: We analyzed the epidemiology, clinical manifestations and virological results in patients with imported acute dengue infection who presented at our travel clinic in Frankfurt am Main, Germany, between September 1998 and November 2000. An immunochromatographic test and an immunofluorescence assay were used for antibody testing. Results: Dengue fever was confirmed in 13 patients, thus being the second commonest tropical infection after malaria in patients with fever and a travel history to a tropical country (18 cases per 1,000 patient visits per year). Most patients had only spent a short time abroad, either in South Central or South East Asia or in the Caribbean. Conclusion: The clinical features considered typical for dengue were not always present. Antibody assays were typically negative early in the course of disease, with seroconversion occurring only after cessation of clinical symptoms. A high index of suspicion is needed in these patients who often present without typical features of dengue and whose early antibody tests may be negative. Received: January 20, 2002 · Revision accepted: March 15, 2002     

Aedes aegypti vectorial capacity is determined by the infecting genotype of dengue virus

Dengue viruses causing severe, hemorrhagic disease have displaced less virulent strains in the Americas during the past three decades. The American (AM) genotype of dengue serotype 2 has been endemic in the Western Hemisphere and South Pacific, causing outbreaks of dengue fever (DF), but has not been linked to dengue hemorrhagic fever (DHF). The Southeast Asian (SEA) genotype of dengue was introduced into this hemisphere in 1981, has caused outbreaks with numerous cases of DHF, and has displaced the AM genotype in several countries. We investigated the effect of viral genotype on the potential for transmission by infecting Aedes aegypti mosquitoes collected in South Texas with six viruses, representing these two genotypes. Viral replication in the midgut was significantly higher in SEA-infected mosquitoes, and virus-specific proteins could be detected in salivary glands 7 days earlier in SEA- than AM-infected mosquitoes. This much earlier appearance of dengue virus in salivary glands resulted in an estimated 2- to 65-fold increase in the vectorial capacity of these mosquitoes for the viruses that can cause DHF. This may be one of the mechanisms through which more virulent flaviviruses spread and displace others globally.     

Laboratory-Based Surveillance and Molecular Characterization of Dengue Viruses in Taiwan, 2014

We present the results of a laboratory-based surveillance of dengue in Taiwan in 2014. A total of 240 imported dengue cases were identified. The patients had arrived from 16 countries, and Malaysia, Indonesia, the Philippines, and China were the most frequent importing countries. Phylogenetic analyses showed that genotype I of dengue virus type 1 (DENV-1) and the cosmopolitan genotype of DENV-2 were the predominant DENV strains circulating in southeast Asia. The 2014 dengue epidemic was the largest ever to occur in Taiwan since World War II, and there were 15,492 laboratory-confirmed indigenous dengue cases. Phylogenetic analysis showed that the explosive dengue epidemic in southern Taiwan was caused by a DENV-1 strain of genotype I imported from Indonesia. There were several possible causes of this outbreak, including delayed notification of the outbreak, limited staff and resources for control measures, abnormal weather conditions, and a serious gas pipeline explosion in the dengue hot spot areas in Kaohsiung City. However, the results of this surveillance indicated that both active and passive surveillance systems should be strengthened so appropriate public health measures can be taken promptly to prevent large-scale dengue outbreaks.     

An outbreak of dengue fever in rural areas of northern India

During the past few decades, epidemics of dengue fever are causing concern in several South-East Asian countries including India. The rural areas of Hissar district of Haryana state, situated about 170 km North-West of Delhi, experienced an outbreak of febrile illness during July-August 1996. A total of 13 villages in eight affected primary health centres reported fever cases. The clinical, epidemiological and entomological findings indicated that the present episode was due to dengue fever. The aetiological agent of the current outbreak, the DEN-2 virus, was isolated from 12 acute-phase sera specimens. Though, in the recent past outbreaks have been reported from the rural areas of southern and western India, the present episode is the first outbreak being reported from the rural areas of northern India. The increasing frequency of dengue fever outbreaks in rural areas of various Indian states reflects the changing life style of the rural population as a result of urbanization process and calls for a suitable prevention and control policy based on strengthened surveillance, appropriate health education to the community coupled with proper training of health personnel.     

Respiratory syncytial virus infection in tropical and developing countries

Little is known about the epidemiology of respiratory syncytial virus (RSV) infection in tropical and developing countries; the data currently available have been reviewed. In most studies, RSV was found to be the predominant viral cause of acute lower respiratory tract infections (ALRI) in childhood, being responsible for 27– 96% of hospitalised cases (mean 65%) in which a virus was found. RSV infection is seasonal in most countries; outbreaks occur most frequently in the cold season in areas with temperate and Mediterranean climates and in the wet season in tropical countries with seasonal rainfall. The situation on islands and in areas of the inner tropics with perennial high rainfall is less clear-cut. The age group mainly affected by RSV in developing countries is children under 6 months of age (mean 39% of hospital patients with RSV). RSV-ALRI is slightly more common in boys than in girls. Very little information is available about the mortality of children infected with RSV, the frequency of bacterial co-infection, or the incidence of further wheezing after RSV. Further studies on RSV should address these questions in more detail. RSV is an important pathogen in young children in tropical and developing countries and a frequent cause of hospital admission. Prevention of RSV infection by vaccination would have a significant impact on the incidence of ALRI in children in developing countries.