Dengue is a viral disease transmitted by Aedes aegypti mosquitoes. It is caused by any one of four dengue virus serotypes. Symptoms include high fever, severe headache, and joint pains. While most cases resolve on their own, severe dengue can involve bleeding and organ impairment. Diagnosis is by blood tests detecting virus, antibodies, or antigens. There is no specific treatment, but symptoms can be relieved with rest and pain medication. Prevention focuses on mosquito control and personal protection measures.
2. • Dengue is fast emerging pandemic-prone viral disease in
many parts of the world. Dengue flourishes in urban poor
areas, suburbs and the countryside but also affects more
affluent neighbourhoods in tropical and subtropical countries.
• The dengue virus (DEN) comprises four distinct serotypes
(DEN-1, DEN-2, DEN-3 and DEN-4) which belong to the genus
Flavivirus, family Flaviviridae.
• Severe dengue previously known as dengue haemorrhagic
fever
• Also called as “Break bone fever”
3. TRANSMISSION
• The life cycle of dengue fever virus involves mosquito as a
transmitter (or vector) and humans as the main victim and
source of infection.
• Caused by Aedes aegypti Incubation: 3-14 days
• Affects only humans
4. PATHOGENESIS
• Dengue may be caused by any of the dengue viral serotypes. During the feeding of
mosquitoes, DENV is injected into the bloodstream, with spillover in the epidermis and
dermis, resulting in infection of immature Langerhans cells (epidermal dendritic cells) and
keratinocytes.
• Infected cells then migrate from site of infection to lymph nodes, replicates within cells of
the mononuclear phagocyte lineage (macrophages, monocytes, and B cells).
• The virus is disseminated through the lymphatic system. As a result of this primary viremia,
infection of mast cells, dendritic cells, and endothelial cells occurs.
• The incubation period of dengue infections is 7–10 days.
• A viraemic phase follows where the patient becomes febrile and infective. Thereafter, the
patient may either recover or progress to the leakage phase, leading to DHF and/or dengue
shock syndrome. Peak plasma viraemia correlates with the severity of dengue
infections. Differences in antibody, cytokine, and T-cell responses are seen among patients
with uncomplicated dengue fever or DHF/dengue shock syndrome. For clarity of
description, these will be described separately under the headings antibody responses,
cytokine responses, and cellular responses to the dengue virus.
• Generally, infection with one serotype confers future protective immunity against that
particular serotype but not against other serotypes. Furthermore, when infected for a
second time with a different serotype, a more severe infection may occur. This is due to a
phenomenon referred to as antibody dependent enhancement, where antibodies against
the first serotype enhance infection with the second serotype.
5. SYMPTOMS
FEBRILE PHASE
• Symptoms last for 2-7 days
• High grade fever
• Severe headache,
• Retrobulbar pain (pain behind eyes)
• Facial flushing (reddening of skin)
• Fatigue,
• nausea
• Skin erythema,
• skin rash
• arthralgia (Pain in back, limbs and joints)
• Lymphadenopathy
CRITICAL PHASE
• Defervescence
• Between 3-8 days, Progressive leukopenia ( low level of WBC)
• “Dengue hemorrhagic fever/ Dengue shock syndrome”
• Bleeding from nose, gums
• Severe case: Enlargement of liver
• Failure of circulatory system
• Blood vomit, Blood stool
6. DIAGNOSIS
• Based on Symptoms
• Blood test to check for the virus or antibodies
• Detection of Non structural protein antigen (NSI)
• Detection of IgM antibodies
• IgM ELISA
• Vector control
• Avoid travelling to tropical areas/ sub tropical areas in times of
outbreak
CONTROL
7. TREATMENT
• No specific medicine
• Use pain relievers with acetaminophen and avoid medicines with
aspirin, which could worsen bleeding.
• Take rest, drink plenty of fluids
• In 2019, the FDA approved a vaccine called Dengvaxia to help
prevent the disease from occurring in adolescents aged 9 to 16
who have already been infected by dengue.