Dengue – What you should know

Loop lifestyle brings information you should know about Dengue and Severe Dengue made available by the City Pharmacy group through their awareness program.

DENGUE is a mosquito-borne viral disease that has rapidly spread in all regions of WHO in recent years.

Dengue virus is transmitted by female mosquitoes mainly of the species Aedesaegypti, and to lesser extent.

 The disease is widespread throughout the tropics, with local variations in risk influenced by rainfall, temperature and unplanned rapid urbanization.

Severe dengue (also known as Dengue Haemorrhagic Fever) was first recognised in the 1950s during dengue epidemics in the Philippines and Thailand.

There are 4 distinct, but closely related, serotypes of the virus that cause dengue (DEN-1, DEN-2, DEN-3 and DEN-4).

Recovery from infection by one provides lifelong immunity against that particular serotype. However, cross immunity to the other serotypes after recovery is only partial and temporary. Subsequent infections by other serotypes increase the risk of developing severe dengue.

Transmission

The Aedesaegypti

Mosquito is the primary vector of dengue. The virus is transmitted to humans through the bites of infected female mosquitos. After virus incubation for 4-10 days, an infected mosquito is capable of transmitting the virus for the rest of its life.

Infected humans are the main carriers and multipliers of the virus, serving as a source of the virus for uninfected mosquitoes. Patients who are already infected with the dengue virus can transmit the infection (for 4-5 days; maximum 12) via Aedes mosquitos after their first symptoms appear.

The Aedesaegypti mosquito lives in urban habitats and breeds mostly in man-made containers.Unlike other mosquitos Ae.Aegyptiis a day-time feeder; its peak biting periods are early in the morning and in the evening before dusk. Female Ae.Aegypti bites multiple people during each feeding period.

Aedesalbopictus, a secondary dengue vector in Asia, has spread to North America and Europe largely due to the international trade in used tyres (a breeding habitat) and other goods (e.g. lucky bamboo). Ae.Albopictus is highly adaptive and, therefore, can survive in cooler temperature. Its spread is due to tolerance to temperatures below freezing, hibernation, and ability to shelter in microhabitats.

Characteristics

Dengue fever is a severe, flu-like illness that affects infants, young children and adults, but seldom causes death.

Dengue should be suspected when a high fever (40C/104 F) is accompanied by 2 of the following symptoms;

• Severe headache
• Pain behind the eyes
• Muscle and Joint pains
• Nausea
• Vomiting
• Swollen glands or rash
• Symptoms usually last for 2-7 days, after an incubation period of 4-10 days after the bite from an infected mosquito

 Severe dengue is a potentially deadly complication due to;

• plasma leaking,
• fluid accumulation,
• respiratory distress,
• severe bleeding or
• organ impairment
• warning occurs 3-7 days after the first symptoms in conjunction with a decrease in temperature (below 38 C/100F) and include;

• severe abdominal pain
• persistent vomiting
• rapid breathing
• bleeding gums
• fatigue
• restlessness
• blood in vomit

The next 24-48 hours of the critical stage can be lethal; proper medical care is needed to avoid complications and risk of death.

Treatment

There is no specific treatment for dengue fever.

For severe dengue, medical care by physicians and nurses experienced with the effects and progression of the disease can save lives- decreasing mortality rates from more than 20% to less than 1%. Maintenance of the patient’s body fluid volume is critical to severe dengue care.

Immunization

There is no vaccine to protect against dengue. However, major progress has been made in developing a vaccine against dengue/ severe dengue.

Prevention and control

At present, the only method to control or prevent the transmission of dengue virus is to combat mosquitoes through;

• preventing mosquitoes from accessing egg-laying habitats by environmental management and modification;
• disposing of solid waste properly and removing artificial man-made habitats;
• covering, emptying and cleaning of domestic water storage containers on a weekly basis;
• applying appropriate insecticides to water storage outdoor containers;
• using of personal household protection such as window screens, long-sleeved clothes, insecticide treated materials, coils, and vaporizers;
• improving community participation and mobilization for sustained vector control;
• applying insecticides as space spraying during outbreaks as one of the emergency vector-control measures;
• active monitoring and surveillance of vectors should be carried out to determine effectiveness of control interventions.

Key Facts

• Dengue is a mosquito-borne viral infection.
• The infection causes flu-like illness, and occasionally develops into a potentially lethal complication called severe dengue.
• The global incidence of dengue has grown dramatically in recent decades.
• About half of the world’s population is now at risk.
• Dengue is found in tropical and sub-tropical climates worldwide, mostly in urban and semi-urban areas.
• Severe dengue is a leading cause of serious illness and death among children in some Asian and Latin American countries.
• There is no specific treatment for dengue/severe dengue, but early detection and access to proper medical care lowers fatality dates below 1%.
• Dengue prevention and control solely depends on effective vector control measures.