Rising Cases of Dengue

Doctors in the Capital are reporting fevers due to common cold, flu, typhoid, sporadic cases of malaria, and the occasional case of scrub typhus, aside from dealing with cases of mosquito-borne dengue which are on the rise.

Dengue

Dengue is a mosquito-borne viral disease that has rapidly spread in all regions in recent years. Dengue virus is transmitted by female mosquitoes mainly of the species Aedes aegypti and, to a lesser extent, Ae. albopictus. These mosquitoes are also vectors of chikungunya, yellow fever and Zika viruses. Dengue is widespread throughout the tropics, with local variations in risk influenced by rainfall, temperature, relative humidity and unplanned rapid urbanization.

 

  • Dengue causes a wide spectrum of disease. This can range from subclinical disease (people may not know they are even infected) to severe flu-like symptoms in those infected.
  • Dengue is caused by a virus of the Flaviviridae family and there are four distinct, but closely related, serotypes of the virus that cause dengue (DENV-1, DENV-2, DENV-3 and DENV-4). Recovery from infection is believed to provide lifelong immunity against that serotype.

 

Signs and Symptoms

  • Dengue is a severe, flu-like illness that affects infants, young children and adults, but seldom causes death. Symptoms usually last for 2–7 days, after an incubation period of 4–10 days after the bite from an infected mosquito. The World Health Organization classifies dengue into 2 major categories: dengue (with / without warning signs) and severe dengue. The sub-classification of dengue with or without warning signs is designed to help health practitioners triage patients for hospital admission, ensuring close observation, and to minimise the risk of developing the more severe dengue.
  • Dengue should be suspected when a high fever (40°C/104°F) is accompanied by 2 of the following symptoms during the febrile phase: severe headache, pain behind the eyes, muscle and joint pains, nausea, vomiting, swollen glands, rash.

 

Vaccination Against Dengue

The first dengue vaccine, Dengvaxia® (CYD-TDV) developed by Sanofi Pasteur was licensed in December 2015 and has now been approved by regulatory authorities in 20 countries.

 

Vector Ecology

The Aedes aegypti mosquito is considered the primary vector of DENV. It lives in urban habitats and breeds mostly in man-made containers. Ae. Aegypti is a day-time feeder; its peak biting periods are early in the morning and in the evening before sunset  Female Ae. aegypti frequently feed multiple times between each egg-laying period.