Over the past few days, patients diagnosed with dengue fever have been visiting the outpatient department of Sukraraj Tropical and Infectious Disease Hospital (STIDH). These patients had been infected either in India or Malaysia, where dengue has broken out. Mosquitoes, namely Aedes agypti and Aedes albopictus, are responsible for person to person transmission of dengue virus, which are known to exist in Kathmandu and other parts of the country.In Nepal, every year, dengue fever has been observed during post-monsoon season. Dengue virus can be transmitted for seven days after the first onset of symptoms. Patients, particularly from India, are returning to Nepal immediately after the diagnosis of dengue, posing a significant risk for transmission and outbreak of dengue fever in Kathmandu, the most densely populated area of Nepal.
Fever, severe muscle and joint pain, pain behind the eye, nausea and vomiting and rashes appearing few days after the onset of fever are the early signs and symptoms of dengue. This is known as classic dengue fever (DF) and usually lasts for four to seven days. Nosebleed, gum bleed, black stool, blood in the urine and vomit are collectively known as "dengue hemorrhagic fever" (DHF) and is considered as serious illness. It may be associated with fluid accumulation in the abdomen and around the lungs and lasts about 24 to 48 hours, also known as "critical phase".
This may progress into the state of shock called Dengue Shock Syndrome (DSS). During the 2010 dengue outbreak, our research study showed that nearly 10 percent of the dengue-infected patients developed DHF, while DSS was found in less than one percent. Previously, most of the dengue patients presumably had been misdiagnosed with typhoid fever and treated accordingly. There are persuasive evidences that dengue patients can be co-infected with other infectious diseases and therefore, inevitably misdiagnosed as other infections such as chikungunya fever, typhoid fever, malaria, leptospirosis, if not included in the differential diagnosis.
Clinical signs and symptoms of dengue fever are similar to other infectious diseases, and hence laboratory test is a must. PCR, antigen test (NS1), antibody test (ELISA) and rapid diagnostic tests (RDTs) are commonly used to diagnose dengue fever worldwide. In addition to this, platelet count, white blood cell count, hematocrit, serum albumin, liver function test are other laboratory parameters useful in diagnosis and predicting disease progression.
Neither physicians nor patients are interested in identifying the cause of diseases. As a result, many newly emerging diseases including dengue fever are being underreported in many parts of the country. Chest x-ray and ultrasonography are useful in predicting disease outcome and guiding physicians for treatment.
So far, specific treatment for dengue is not available. Treatment for patient with classical dengue can be done at home but requires supervision of the infectious disease specialists, as it is difficult to predict when DHF or DSS is likely to develop, especially during secondary dengue infection with another serotype. In Nepal, all four dengue serotypes have been identified. A preliminary report in India has suggested that dengue serotype 2 and 4 are responsible for the current outbreak. Thus, it would not be surprising if these serotypes were reported in the days to come in Nepal.
Serotype 2 and 4 are considered to cause severe disease in humans. However, it is not known or documented whether these serotypes are capable of causing severe disease in the Nepali population as reported elsewhere. It is unfortunate that vaccine against dengue virus is currently not available. For this reason, the best way to prevent the disease is to avoid being bitten by the infected mosquitoes.
Aedes mosquito that carry dengue virus primarily bite during the daytime, especially early morning and in the afternoon hours before sunset. It can be found in water containers such as flowerpots, water storages containers, discarded tires, tins cans etc. People in Kathmandu have been facing inadequate and intermittent piped water supplies, forcing them to store water in containers and tankers, which create favorable conditions for mosquito breeding.
Hospital itself can be a source of infection, putting healthcare workers at higher risk of exposure to dengue virus; for example, it can be transmitted when a mosquito bites a hospitalized patient with dengue fever and then to a health care provider. Several hospitals in India have been found to be breeding places in and around their premises. In many countries, dengue patients remain under mosquito nets while being treated in hospitals even in the daytime. Although, this method has never been comprehended in Nepal in the past, it can significantly reduce risk exposure to dengue virus. Thus, it can be brought into discussions amongst decision makers about the feasibility of implementing this method in Nepal.
Government has to take the initiative in implementing a number of preventive measures as a campaign against dengue in Kathmandu and other parts of the country where dengue has been reported. A public private partnership could be one of the options to improve dengue control at the local level. Several studies have pointed out that using pesticide alone for killing adult mosquito or its larvae might not be effective in controlling dengue vectors. Public health education and active involvement of the local stakeholders can allow a more efficient response to dengue epidemics.
Dengue virus is a relatively new disease for Kathmandu. Majority of patients so far have been treated without further complications, possibly because of primary dengue infections (first time infection). Nevertheless, patients with secondary dengue virus infections often lead to DHF or DSS, which cannot be precluded in the days to come. Dengue is expected to become an epidemic. There is a need to prepare immediate, mid- and long-term dengue control strategies based on national or international experiences to overcome the constant threats of dengue epidemic.
The author is a Medical Officer and Research Coordinator at Sukraraj Tropical & Infectious Disease Hospital
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