DENGUE GUI DELINES FOR DIAGNOSIS,TREATMENT,PREVENTION AND CONTRO

Tiêu chảy - Dengue is the most rapidly spreading mosquitoborne viral disease in the world - Some 1.8 billion (more than 70%) of the population at risk for dengue worldwide live in member states of the WHO South-East Asia Region and Western Pacific Region - Symptomatic dengue virus infections were grouped into three categories: undifferentiated fever, dengue fever (DF) and dengue haemorrhagic fever (DHF) - DHF was further classified into four severity grades, with grades III and IV being defined as dengue shock syndrome - Dengue virus (DEN) is a small single-stranded RNA virus comprising four distinct serotypes (DEN-1 to 4) - Flavivirus, family Flaviviridae - The genome is cleaved by host and viral proteases in three structural proteins (capsid, C, prM, the precursor of membrane, M, protein and envelope, E) and seven nonstructural proteins (NS) - Ae aegypti has been found as far north as 45 0N, but such invasions have occurred during warmer months and the mosquitoes have not survived the winters Also, because of lower temperatures, Ae aegypti is relatively uncommon above 1000 metres - incubation period of 10 days Critical phase - Usually on days 3–7 of illness - an increase in capillary permeability in parallel with increasing haematocrit levels may occur - The period of clinically significant plasma leakage usually lasts 24–48 hours - Progressive leukopenia (3) followed by a rapid decrease in platelet count usually precedes plasma leakage - Shock occurs when a critical volume of plasma is lost through leakage - It is often preceded by warning signs Recovery phase - 48–72 hours - General well-being improves, appetite returns, gastrointestinal symptoms abate, haemodynamic status stabilizes and diuresis ensues Some patients may have a rash of “isles of white in the sea of red” (9) Some may experience generalized pruritus Bradycardia and electrocardiographic changes are common during this stage - White blood cell count usually starts to rise soon after defervescence - platelet count is typically later than that of white blood cell count Primary infection - flavivirus or immunized with a flavivirus vaccine (e.g for yellow fever, Japanese encephalitis, tick-borne encephalitis) Primary infection - the virus can be detected in serum, plasma, circulating blood cells and other tissues for 4–5 days - IgM antibodies detectable in 50% of patients by days 3-5 after onset of illness, increasing to 80% by day and 99% by day 10 - IgM levels peak about two weeks after the onset of symptoms and then decline generally to undetectable levels over 2–3 months - Anti-dengue serum IgG is generally detectable at low titres at the end of the first week of illness, increasing slowly thereafter, with serum IgG still detectable after several months, and probably even for life secondary dengue infection - Previously been infected by a dengue virus, or sometimes after non-dengue flavivirus vaccination or infection - dominant immunoglobulin isotype is IgG which is detectable at high levels, even in the acute phase, and persists for periods lasting from 10 months to life - Early convalescent stage IgM levels are significantly lower in secondary infections than in primary ones and may be undetectable in some cases, depending on the test used - RT-PCR methods varies from 80% to 100% and depends on the region of the genome targeted by the primers, the approach ... billion (more than 70%) of the population at risk for dengue worldwide live in member states of the WHO South-East Asia Region and Western Pacific Region - Symptomatic dengue virus infections were