Since 2010, the Tarai region has seen a dengue outbreak every monsoon. It seems the outbreak could be on the move from the Tarai region and into the city. This month alone, three cases of dengue have been reported in the valley. This spread is not surprising because of two reasons
: a migrant population with the disease, and the abundant supply of the particular vector (carrier) mosquitoes. Dengue
is pronounced “dengi” with the u being silent.
Dengue is the most widely distributed mosquito-borne viral illness, affecting an estimated 100 million people worldwide each year. Forty per cent (2.5 billion) of the world’s population is estimated to be at risk for infection. After biting an infected person, vector mosquitos transmit the disease to a healthy person with another bite.
Because of the open border with India, many migrant Nepali and Indian labourers with the disease enter parts of Nepal, including Kathmandu, where it was hardly known to be present.
Dengue fever originated from Africa during the slave trade in the 15th through 19th centuries. It spread into Asia through commercial exchanges in the 18th and 19th centuries.
Importantly, different species of mosquitoes transmit different diseases. So, the mosquito that transmits malaria will not transmit dengue. Mosquitoes that transmit dengue are called aedes aegypti, while the female anopheles transmits malaria. But the dengue mosquito is generally a city dweller, unlike the malaria mosquito which is usually rural based. The aedes aeygpti is also an efficient vector for Chikungunya and yellow fever viruses.
Any patient sufferomg from a fever, particularly if there is a rash, should be considered for the diagnosis of dengue.
For most people, the fever, headache, eye pain and joint aches associated with dengue subsides in a week’s time. Severe pain on eye movement can be a key symptom for diagnosis as well. But doctors can treat only the symptoms in dengue because there is no specific antidote.
Most people with dengue will recover, but for some severe cases it causes leaky capillaries that lead to shock. It is impossible to predict who will become critically ill and who will have an uneventful recovery from dengue.
The World Health Organisation however has listed some warning signs of severe dengue, such as persistent vomiting, abdominal pain, fluid accumulation, excessive lethargy or restlessness and increase in haemoglobin (which carries iron and oxygen ) in the face of decreasing platelets, which help to clot blood.
Unfortunately, there is no commercially available dengue vaccine although there are candidate vaccines in initial stages. For prevention, use mosquito repellents (like odomas or DEET) and wear full length clothing even during the day because the dengue mosquito is a day-time mosquito. The malaria mosquito is active at night. In addition, turn over watering cans and pails after use so that the dengue mosquito does not breed in them.
It is hard to predict how severely the population will be affected this summer. Indeed the ability to predict epidemics and to put in place the public health and clinical needs to deal with large outbreaks would be a major advance. However, it is clearly a good idea to take precautions and avoid mosquito bites.
Dengue Fever, Buddha Basnyat
Beware of Vectors, Buddha Basnyat
Dengue Ke Ho?, Buddha Basnyat