Dengue Causes, Treatment and Managment

Dengue

The dengue flavivirus is spread by the vector mosquito Aedes aegypti and is endemic in South-east Asia, India, Africa and the Americas. The incubation period following a mosquito bite is 2–7 days, with a prodrome of malaise and headache, followed by a morbilliform rash, arthralgia, pain on eye movement, headache, nausea, vomiting, lymphadenopathy and fever. The rash spreads centrifugally, spares the palms and the soles, and may desquamate on resolution. The disease is self-limiting but convalescence is slow. 

Dengue haemorrhagic fever and dengue shock syndrome: These more severe manifestations occasionally complicate infection: circulatory failure, features of a capillary leak syndrome, and disseminated intravascular coagulation (DIC) with haemorrhagic complications such as petechiae, ecchymoses, epistaxis, GI bleeding and multi-organ failure. Other complications include encephalitis, hepatitis and myocarditis. Case fatality with this aggressive disease may approach 10%.

Dengue

Investigations

Detection of a 4 × rise in anti-dengue IgG antibody titres.

Amplification of dengue RNA by PCR.

Management and prevention

Management is supportive, with treatment of haemorrhage, shock and pain as required. Insecticides that control mosquito levels help to limit transmission. Aspirin should be avoided and steroids are ineffective. There is currently no licensed vaccine.

Systemic viral infections without exanthem

Mumps

Mumps is a systemic viral infection causing swelling of the parotid glands. It is endemic worldwide and peaks at 5–9 yrs of age. Vaccination has reduced childhood incidence but, if incomplete, leads to outbreaks in young adults. Infection is by respiratory droplets.

Incubation lasts 15–24 days, and tender parotid swelling (bilateral in 75%) develops after a prodrome of pyrexia and headache. Diagnosis is clinical.

Complications

Epididymoorchitis: occurs in 25% of post-pubertal males, with testicular atrophy, although sterility is unlikely. Oophoritis is less common.

Mumps meningitis: complicates 10% of cases, with lymphocytes in CSF.

Encephalitis. 

Transient hearing loss and labyrinthitis: uncommon.

Spontaneous abortion.

Dengue Symtoms

Management

Analgesia for symptoms is sufficient. There is no evidence that corticosteroids are of value in orchitis. Mumps vaccine, given as part of MMR vaccine, has markedly reduced incidence and, if used widely, abolishes the epidemic pattern of disease.

Influenza

This is an acute systemic viral illness predominantly affecting the respiratory system, caused by influenza A or B viruses. Seasonal changes in haemagglutinin (H) and neuraminidase (N) glycoproteins allow the organism to evade natural immunity and cause outbreaks or epidemics of varying severity.

Clinical features

Influenza is highly infectious by respiratory droplet spray from the earliest stages of infection. Incubation is 1–3 days and onset is with fever, malaise, myalgia and cough. Viral or superadded bacterial pneumonia is an important complication. Myositis, myocarditis, pericarditis and encephalitis are rare complications. Management involves early diagnosis, scrupulous hand hygiene and infection control to limit spread by coughing and sneezing. Neuraminidase inhibitors such as oseltamivir (75 mg twice daily for 5 days) can reduce the severity of symptoms if started within 48 hrs of symptom onset.

Prevention involves seasonal vaccination of vulnerable groups, e.g. people over 65, the immunosuppressed and those with chronic illnesses. Avian influenza is the transmission of avian influenza A from sick poultry to humans, causing severe disease. Human–human spread is rare. Swine influenza, caused by a H1N1 strain infecting humans, spread around the world from Mexico in 2009.

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