Dengue Fever

INTRODUCTION 

Dengue is a viral infection, of an endemic-epidemic nature, spread by mosquitoes of the genus Aedes, particularly by Aedes aegypti. Dengue virus (DENV) is a member of the Flaviviridae family, which consist of tick-borne encephalitis virus (TBEV), Japanese encephalitis virus (JEV), West Nile virus (WNV) and yellow fever virus. Dengue virus infection may be asymptomatic, may cause a self-limited febrile disease identified as dengue fever (DF), or in a small ratio of cases, may affect in a life-threatening syndrome, the so-called dengue hemorrhagic fever/dengue shock syndrome (DHF/DSS). In South- East Asia, dengue disease remains to be a major challenge to public health which is an arthropod-borne viral hemorrhagic fever.

Serotypes of dengue virus

DENV-1, DENV-2, DENV-3, DENV-4 are four serotypes of dengue fever virus. Entirely four strains can cause the full illness. Infection with one of the four serotypes can produce enduring protection to that serotype but only short period defense against the other. On secondary infection the severe difficulty may happen particularly when someone before visible to serotype DENV-1 then exposed to serotype DENV-2 or serotype DENV-3, or if someone formerly exposed to type DENV-3 then gets DENV-2. 

Infection 

The course of infection can be separated into three phases: 

  • Febrile, 
  • Critical 
  • Recovery

Frequently high fever occurs in the febrile phase associated with generalized pain, headache and fever often over 40 °C (104 °F); this generally continues 2 to 7 days. Throughout this phase, a rash arises in about 50-80% of the patients with indications. It occurs in the first or second day of symptoms as flushed skin, or later in the development of infection (days 4-7), it may seem as a measles-like rash. In some causes at this stage petechiae may also appear caused by broken capillaries, particular mild bleeding from nose and mucous membrane of mouth can also happen. In nature the illness itself is classically breaking, biphasic and then recurring for one or two days though there is wide difference in this pattern. 

In certain patients, the infection may continue to a critical stage, in which there is determination of the high fever and characteristically continues for 1 to 2 days. In this stage there may be increased capillary permeability and leakage, which may cause substantial accumulation of fluid in the abdominal cavity and chest. This disorder may lead to reduction of fluid from the circulation and decreased blood supply to vital organs. Through this stage, severe bleeding, particularly from the gastrointestinal tract and organ dysfunction can also occur. In all cases of dengue, dengue shock syndrome and dengue hemorrhagic fever happen in less than 5%, but those patients are at high risk who have formerly been ill with other serotypes of dengue virus. 

In the recovery phase restoration of those fluid occur which had leaked into the bloodstream. This frequently last 2 to 3 days. The upgrading in dengue fever is often remarkable, but there may be a slow heart rate and severe itching. Fluid overload condition may occur at this point, if it disturbs the brain, a reduced level of consciousness or seizures may occur. 

Symptoms

DF is an acute illness of sudden onset with symptoms such a headache, fever, fatigue, sever muscle and joint pain, enlarged glands (lymphadenopathy), and rash. Dengue hemorrhagic fever is a separate disease, caused by dengue virus but much more severe symptoms than DF, so DF should not be confused with DHF. 

Diagnosis

Different laboratory tests are used to diagnose dengue fever. Detection can do by viral antigen detection or specific antibodies, nucleic acid detection by PCR, virus isolation in cell cultures. More exact methods are virus isolation in cell cultures and nucleic acid detection than antigen detection, but because of their cost these tests are not generally used. In the early phases of the infection all tests may be negative. 

Virus definite serum immunoglobulin, IgM, is developed within 5 days of onset of infection while IgG consequently developed within 14 to 17 days. IgM, IgG assays are diagnosis tests while CBC is a good monitoring test. It is very significant that CBC should be performed every day. If lymphocytosis with increase in atypical lymphocytes and platelets less than 100,000/cμmm are seen, then it means that within next 24 hours patient is upcoming in critical state and he should be taken care of. Platelet transfusion is suggested for only those with severe bleeding. There are no definite treatments for dengue fever. 

Well-recognized features of DF are thrombocytopenia, Leukocytopenia and elevation of AST or LDH. Common difficulty of dengue virus infection is liver damage with increased of aminotransferases and reactive hepatitis. Patients have higher levels of AST and ALT with dengue than those patients with non-dengue febrile disorders. 

Dengue infection treatment

Dengue infection have no specific treatment. In dengue infection it is important to take pain killers such as acetaminophen (such as Panadol, Tylenol), take plenty of juices, rest and contact the doctor as soon as possible. It is important to avoid aspirin. 

Epidemiology

Every year it is expected that 2.5 billion individuals are at risk of evolving DF, and that 50 million people actually become ill. About 100 cases of DF are stated per year, according the Infectious Disease Law, this number is increasing. 

Around 975 million of whom living in urban zones in tropical and sub-tropical countries in Southeast Asia, the pacific and Americas. Transmission similarly arises in Africa and the Eastern Mediterranean, and rural populations are progressively being affected. Every year more than 50 million infections are assessed, including 500,000 hospitalizations for dengue hemorrhagic fever, mostly among children, with the incident death rate above 5% in some areas. 

Incidence of Dengue in Pakistan is growing since 1994 and is flattering a significant public health problem. Its occurrence is growing quickly and mainly affecting the old age group. Approximately 700 cases of definite Dengue fever have been described across Pakistan this year. The Dengue investigation cell of Pakistan government has established that 696 people have been ill since August of the last year. Fumigation and dengue consciousness campaigns are in action in earlier years, but it is clear that not sufficient has been completed in Pakistan to control and eliminate this disease.

The signs in children are frequently related to common cold and gastroenteritis, but more vulnerable to severe problems. Unexpected beginning with rash, high fever, and headache, backbone, muscle and joint pains are the characteristics symptoms of dengue fever. Hemorrhagic indications are also common and may range from mild to severe. The break-bone fever name of dengue fever is occupied from the accompanying muscle and joint pains. 

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