Serodiagnosis of asymptomatic dengue infection

Dengue virus(DENV) is a mosquito-transmitted virus that is expanding across the world,The incidence of dengue infection,especially severe disease,has been increasing,DENV consist of 4 serotypes of single stranded RNA viruses(D1-D4) in the genus Flavivirus,family Flaviviridae,Majority of dengue infections are asymptomatic cases,which cause difficulty in disease control and are important in dengue surveillance,There is still no gold standard to diagnose asymptomatic dengue infection,Plaque reduction neutralization test(PRNT) has been developed for many purposes such as immunological study,clinical study,vaccine trial and is currently the most sensitive and specific method for serological surveillance,However,PRNT shows some degree of cross reaction among different dengue serotypes especially secondary dengue infection cases and to other flaviviruses,Moreover,various modification since the beginning make PRNT lack of inter-laboratory standardization which is an important issue,This paper discusses the important of asymptomatic dengue infection and its diagnostic method.

Scenario of dengue infection & its control in Pakistan: An up-date and way forward

Dengue fever is one of the major health problems in tropical and subtropical areas throughout the world. The causative agent of dengue fever is the dengue virus which is an enveloped single stranded RNA virus belongs to the family Flaviviridae and has five distinct serotypes(DENV-1,DENV-2, DENV-3, DENV-4 and DENV-5). Dengue virus is transmitted to human via bite of Aedes aegypti and Aedes albopictus mosquitoes. The clinical symptoms of dengue fever ranging from mild to severe form as dengue hemorrhagic fever and dengue shock syndrome. Pakistan is dengue endemic since 1994 but from 2006, Pakistan faced the worst condition regarding dengue in which thousands of people affected by the disease and hundreds of people lost their lives. DENV-2, DENV-3 and DENV-1 are the prevalent serotypes in Pakistan. Common diagnostic techniques are being used in Pakistan such as enzyme-linked immunosorbent assay,polymerase chain reaction and rapid diagnostic tests, while differential diagnosis, limitations of diagnostic methods and poor health care system are the real challenges in dengue diagnosis.Favorable climatic conditions, unplanned urbanization, travelling etc., are major factors responsible for dengue epidemics in Pakistan. This presentation provides update about dengue circumstances in Pakistan and also describes the way how to improve dengue situation in Pakistan.

Asymptomatic dengue infection in adults of major cities of Pakistan

Objective: To determine the asymptomatic dengue infection in adults of Pakistani population.Methods: This study was conducted in five major cities(Islamabad, Karachi, Lahore,Multan, and Peshawar) of Pakistan.A total of 5 230 adults aged 18 years and above without a history of dengue fever at any point in their life were enrolled from participating laboratories.Those who were confirmed for dengue previously were excluded.Of the total, 62.6%(n = 3 276) were male with an average age of 34.6 years.Participants were briefed about the objectives of the study, and written consent was obtained to perform dengue Ig G test using enzyme linked immunosorbent assay.The brief information related to age, gender and area was also taken on proforma.Results: Overall 32.3%(n = 1 691) was having asymptomatic dengue infection which was 67.5%(n = 756) in Karachi followed by 39.1%(n = 391) in Islamabad, 29.9%(n =316) in Lahore and 21%(n = 228) in Peshawar and none from Multan.More males were affected with asymptomatic dengue infection than females.The asymptomatic dengue infection was significantly higher in different cities; however, there was no significant difference with respect to age groups.Conclusions: The asymptomatic dengue infection is higher in cities i.e.Karachi,Islamabad and Lahore which are at risk of developing secondary dengue infections.There is a need of awareness among the public about secondary dengue infection.

Emerging of dengue infection after big flood in Thailand:a concern

Editor,dengue is an important tropical borne mosquito infection.This infection is very common in Southeast Asia especially for Thailand and nearby country.There are several factors that lead to the emerging of dengue infection.Here, the author presents the interesting observation on emerging of dengue infection after big flood in Thailand.In mid 2010.big flood occurs around Thailand.About 30%of total area of Thailand was occupied by water.Interestingly,a sharp increase of dengue prevalence was reported in many provinces.Up to 83%increasing of prevalence was noted by Thai Minister of Public Health(http://thairecent.com/Breaking/2010/695901/).

Monoclonal Antibody-Based Enzyme Immunoassay for Epidemiological Studies of Asymptomatic Dengue Infection

Dengue virus (DENV) is the world most prevalent mosquito-transmitted virus. The incidence of dengue infection has been increasing and most of the infected people are asymptomatic or have non specific febrile illness. Laboratory test is essential to confirm dengue infection in epidemiological studies. We developed an indirect ELISA test based on monoclonal immunoglobulin against all four DENV serotypes and evaluated the test for the diagnosis of asymptomatic dengue infection in paired annual serum samples. The indirect ELISA was found to have a sensitivity 87.5% and specificity 78.3% at optimized cut off. The results from indirect ELISA demonstrate an incidence of asymptomatic dengue infection from children aged 4 - 11 years in Ratchaburi province, Thailand (2006-2009). These findings indicate that the indirect ELISA is suitable for serodiagnosis and seroepidemiological studies of asymptomatic dengue infection.

Dengue hemorrhagic fever and the liver

Dengue hemorrhagic fever(DHF)is one of the most rapidly emerging infections of tropical and subtropical regions worldwide.It affects more rural and urban areas due to many factors,including climate change.Although most people with dengue viral infection are asymptomatic,approximately 25%experience a selflimited febrile illness with mild to moderate biochemical abnormalities.Severe dengue diseases develop in a small proportion of these patients,and the common organ involvement is the liver.The hepatocellular injury was found in 60%-90%of DHF patients manifested as hepatomegaly,jaundice,elevated aminotransferase enzymes,and critical condition as an acute liver failure(ALF).Even the incidence of ALF in DHF is very low(0.31%-1.1%),but it is associated with a relatively high mortality rate(20%-68.3%).The pathophysiology of liver injury in DHF included the direct cytopathic effect of the DENV causing hepatocytes apoptosis,immunemediated hepatocyte injury induced hepatitis,and cytokine storm.Hepatic hypoperfusion is another contributing factor in dengue shock syndrome.The reduction of morbidity and mortality in DHF with liver involvement is dependent on the early detection of warning signs before the development of ALF.

Dengue hemorrhagic fever and cardiac involvement

Dengue viral infection(DVI)is one of the world’s most significant viral infections spreading.Most of the patients have been asymptomatic,with relatively benign clinical manifestations and outcomes.However,a small number of patients have progressed to severe dengue diseases,including hemorrhage,multi-organ impairment,and increased vascular leakage causing hypovolemic shock,which can cause cardiovascular collapse and death.Numerous lines of evidence have demonstrated that DVI could also cause cardiac dysfunction,arrhythmias,and severe myocarditis.The treatment for dengue hemorrhagic fever(DHF)patients remains symptomatic and supportive,with close monitoring of hemodynamic status.The contributory role of cardiac dysfunction in DHF patients has potentially critical implications on the management.This review will address the current knowledge of cardiac involvement in DHF patients and the management strategy to reduce the fatality outcome.

Qualitative analysis for a Wolbachia infection model with diffusion

We consider a reaction-diffusion model which describes the spatial Wolbachia spread dynamics for a mixed population of infected and uninfected mosquitoes. By using linearization method, comparison principle and Leray-Schauder degree theory, we investigate the influence of diffusion on the Wolbachia infection dynamics.After identifying the system parameter regions in which diffusion alters the local stability of constant steadystates, we find sufficient conditions under which the system possesses inhomogeneous steady-states. Surprisingly,our mathematical analysis, with the help of numerical simulations, indicates that diffusion is able to lower the threshold value of the infection frequency over which Wolbachia can invade the whole population.