Dengue, the commonest arbovirus infection worldwide, has become a serious public health concern. As of today the geographic distribution of dengue has crossed more than 100 countries worldwide. The World Health Organisation has estimated that more than 2.5 billion people are at risk of dengue infection.
Dengue is a mosquito borne viral disease mostly reported in tropical or subtropical areas. In the context of Nepal, the dengue incidence has increased rapidly in recent years due to expansion of vectors (Aedes aegypti and Aedes albopictus) and Fewer cases being imported from the movement of people from the affected regions mostly of India.
Transmission of Dengue:
Dengue is transmitted primarily by the bite of a female Aedes aegypti mosquito. The mosquito is highly anthropophilic in nature and gets attracted to humans rather than other animals. This specific mosquito has short and frequent biting behaviour, prefers to rest indoors and bites usually during day time. Its peak biting periods are early in the morning and before dusk in the evening.
The Aedes aegypti mosquito has a specific arc on the thorax region, ornamented with white stripes and spots on its body and appendages except wings.
Once infected, humans are the main carriers and multipliers of the virus, serving as the source of virus for the uninfected mosquitoes.
Incubation period varies from 3-14 days .
Clinical features :
Dengue viral infection usually shows mild symptoms of fever and flu-like features. Dengue infections are primarily categorised into two main types.
1. Dengue fever
2. Dengue hemorrhagic fever
Dengue Fever:
The illness starts from 2-7 days of infection. The most common symptoms of Dengue fever are:
- High Fever(102 – 105 *C)
- Aches and Pain: Headache ,Pain behind the eyeball, Muscle pain, Joint pain
- Loss of appetite
- Nausea and Vomiting
- Abdominal discomfort
- Dehydration
- Swollen glands
- Electrolyte imbalance
- Skin rashes etc
Dengue hemorrhagic fever:
This is the severe/critical form of dengue viral infection. People with past history of dengue infection are prone to develop severe forms of dengue. Infants and pregnant women are also at higher risk of developing dengue hemorrhagic fever.
Symptoms of dengue hemorrhagic fever usually start within 24-48 hours of infection. The common symptoms are”
- Leukopenia and thrombocytopenia: Significant decrease in white blood cells and platelets leads to leakage of plasma.
- Hemorrhagic stage: Decrease in platelets leads to internal bleeding i.e. Abdominal bleeding ,Blood in urine/stool/vomit, Bleeding from nose and gums.
In a severe form of Dengue, organ impairment may occur such as Hepatitis, encephalitis or myocarditis.
Diagnosis:
Mortality from dengue can be reduced to almost zero by implementing timely, appropriate clinical management, which involves early clinical and laboratory diagnosis.
A successful clinical outcome requires efficient and early diagnosis of cases provided by accurate differential diagnosis, rapid laboratory assessment/confirmation, and early response to severe disease.
Diagnostic tests such as Complete blood cell count, Detection of viral nucleic acid, detection of viral antigen and antibodies can help in diagnosis of dengue infection. In Vitro diagnostic test kits are easily available for identification.
Prevention and control:
Dengue mortality can be reduced by implementing early case detection and appropriate management of severe cases; reorienting health services to identify early cases and manage dengue outbreaks effectively.
Control of dengue vectors can be done mainly by source reduction: the elimination of containers that are favourable sites for oviposition and development of the aquatic stages. Insecticides can be sprayed on the surface of stagnant water to kill the aquatic stages of mosquito.
The availability of a safe, efficacious and cost-effective vaccine would significantly alter the concept for dengue prevention. Some live- attenuated vaccines going through different stages of clinical trials which might be available for the public in near future.
Contact Details:
Medical laboratory scientist , Medical Microbiologist: Ajit Neupane
Phone no. +9779849287570
Facebook: https://www.facebook.com/aziyt.neupane
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