There is an ancient Greek saying: “Rain opens the window of Poets and door of Doctors.” There is ample evidence of the latter but discussion about the former is beyond the context of this article. During rainy season, many infectious diseases become more prevalent in our community and it is worth mentioning that dengue fever is one of the most feared and common infection. Fortunately, it is now well managed in expert hands.
Dengue, a viral fever but...
Dengue (pronounced DENgee) fever is usually a self-limiting viral disease, more specifically a type of viral hemorrhagic (can induce bleeding) fever. It is of importance to distinguish dengue fever from other viral fevers as it may lead to severe implications, though most cases are self-limiting.
Distinguishing features are severe bodyache, pain behind the eyes, pain in joints, rash that appears between fourth to seventh day of fever with a decreased platelet count.
Dengue fever is caused by dengue virus and it has been the most common arthropod-borne disease in our country for last decade. It is transmitted by Aedes mosquito. Dengue virus has four serotypes (subtype) DEN 1-4,of which DEN-2 and DEN-3 are more prevalent in Bangladesh. Among the South-East Asian countries, on epidemiological ground, Bangladesh lies on category-B of dengue prevalent areas. Infection with one type usually gives lifelong immunity or protection to that type, but only short-term immunity to the others.
In our country dengue usually surfaces during heavy monsoon (August-October), when breeding of the vector mosquito Aedes aegypti is abundant. These mosquitoes breed in fresh stagnant water, which is commonly found in flower tubs, pots, bottles. It even grows in stagnant accumulated water from air-conditioners, refrigerators. Hot and humid environment favours its transmission. Dengue mosquito usually bites during daytime.
Manifestations of dengue fever occur within 3-10 days of mosquito bite and may induce classical dengue fever, dengue hemorrhagic fever without shock, dengue hemorrhagic fever with shock (circulatory shutdown). Even dengue infections can be asymptomatic too. All ages and both sexes are susceptible to dengue fever. Typical symptoms include sudden onset of high fever, intense headache, severe muscle and joint pain (hence the term “break bone fever”), retro-orbital pain (pain behind the eye, more on eye movement), extreme weakness, depression. The fever is usually, but not inevitably followed by, a remission of a few hours to two days. Rash appears in 80% of the cases during remissions (fever free period) or during second febrile phase. If dengue hemorrhagic fever occurs there is bleeding manifestations which may involve skin, intestine, or can cause nasal and gum bleeding, depending on the bleeding manifestations and circulatory status (latter is assessed by blood pressure, pulse, urine output).
Investigations also play an important role in diagnosing dengue fever. Typical findings include: thrombocytopenia (low platelet count), increased hematocrit concentrations (concentrated red blood cell as fluid part of blood escapes vessel) and sometimes decreased white blood cell as well. Dengue antibody assay can be done eight days onward. Both thrombocytopenia and dengue antibody assay are useful in second week of disease. A new test, Dengue ns-1 Ag test, can detect dengue at the early stages but availability is limited.
Regarding management Dr Ahmedul Kabir, Associate Professor, Medicine Department of Dhaka Medical College said: “Management of dengue fever is supportive, consisting of fluid management and monitoring of platelet count and hematocrit. There is no proven benefit from antibiotic and steroid. Platelet transfusion is only needed if platelet count is less than 10,000mcl (normal count: 1,50,000-3,00,000mcl) or when there is active bleeding. Use of aspirin and intramuscular injections are strictly discouraged and are harmful. With this supportive treatment most of the cases are usually well-managed. The afebrile phase demands more attention than the febrile phase in case of dengue.”
It is always uttered that prevention is better than cure. Unfortunately, there is no vaccine available; we can minimise the risk by ensuring that our house and premises are not the breeding place of mosquitos and by putting up mosquito net while sleeping, specially at daytime. Otherwise a single mosquito during monsoon can make us feel the bone-breaking pain.