Arboviridae: Types, Symptoms, and Complications

These are arthropod-borne viruses. There are some important types of arboviral virus which are very prevalent in India. The types are- 

• Bunyaviridae
• Togavirus:
  • Rubella virus
  • Chikungunya virus 
  • Eastern equine encephalitis 
  • Western equine encephalitis 
• Flavivirus
  • Japanese encephalitis
  • Yellow fever
  • Zika virus 
  • Dengue virus 

Bunyaviridae

• These viruses have 3 segments of RNA.
• This virus family consists of:
• Bunyavirus- It is also called California encephalitis and it is caused by the Aedes mosquito.

Phlebovirus

It is also called sand fly fever and it is spread by sand fly. It has one more variant which is called Rift Valley fever. These symptoms are fever, retinitis, and encephalitis. It is spread by the Aedes mosquito.

Nairovirus

It is called Crimean Congo Hemorrhagic fever. It is very prevalent in Gujarat. It is transmitted by Hard Tick. Animal-to-human and human-to-human transmissions are seen.

Hantavirus

It is spread by rodents. Hemorrhage can occur. It causes a disease called Hantan Renal syndrome in which Interstitial nephritis can occur. It can also lead to Hantan pulmonary syndrome in which Interstitial pneumonia-like clinical features can develop.

Also Read: Measles: Causes, Clinical Presentation, Risk Factors, Complications, Diagnosis, Treatment And Vaccinations

Toga virus

Rubella Virus

• It is also called German measles and it should not be confused with rubeola which is called measles.
• The mode of transmission of rubella is respiratory droplets and transplacental.
• The clinical features are different in respiratory droplet transmission and transplacental transmission.
• The Respiratory droplet transmission infective period is 14 to 21 days and it can lead to upper respiratory tract infection.
• The patient can develop Posterior auricular lymphadenopathy.
• The most common sign of German measles is rash. The rash lasts for 3 days and there is a special sign called Forschheimer’s spot on the palate.
• The transplacental transmission leads to Congenital Rubella Syndrome. The maximum malformations occur in the first trimester. The clinical features include Patent Ductus Arteriosus, Sensorineural hearing loss, cataracts, and Blueberry Muffin Syndrome. 
• The diagnosis is done by antigen and antibody testing. RT PCR is very helpful. For pregnant ladies increase in IgM antibodies indicates acute or current infection.
• Live attenuated vaccine is present in the market for use period it is contraindicated. It is contraindicated in immunocompromised individuals.

Chikungunya Virus

• It is spread by the Aedes Mosquito. 
• The infective period is five to six days.
• The clinical features are fever and migratory arthritis.
• The fever is biphasic fever and the arthritis mainly involves small joints.
• Chik sign positive: post chikungunya hyperpigmentation.
• Other symptoms are headache, myalgias, conjunctivitis, and maculopapular rash.
• Lymphadenopathy is also seen
• The diagnosis is done by antibody testing and RT PCR.
• Treatment is done by supportive care and the infection resolves within 7 to 10 days.
• Eastern equine encephalitis 
  • It is spread by the Aedes mosquito.
  • It has a very high mortality rate.
  • Western equine encephalitis
  • It is it is spread by culex mosquito.

Japanese Encephalitis

• The most important outbreak was in Gorakhpur UP.
• The Culex mosquito is the vector and pigs and humans are the hosts.
• The clinical features are initially there will be mild prodromal symptoms which can progress into acute encephalitis which has a long-term neurological deficit.
• The lab diagnosis are RT PCR of cerebrospinal fluid.
• Treatment is mainly symptomatic. 
• Live attenuated and inactivated vaccines are available for use.

Yellow Fever

• It is spread by the mosquito Aedes aegypti.
• The infective period is five to seven days.
• The clinical features include mild fever and myalgia. Faget’s sign is also seen in this patient.
• In severe cases, hemorrhagic manifestations like platelet dysfunction and hepatitis can occur.
• India is free from yellow fever because unvaccinated travelers coming from endemic zones to India are quarantined for six days.
• The diagnosis is done by serology.

Zika Virus

• Aedes mosquito is the vector.
• It is mainly spread from mother to child. Hoffbeauer cells of the placenta have the deposition of the Zika virus.
• The clinical features include fever, arthralgia, and rash video the patient can present with cardiovascular side effects and neural this is just like Guillain Barre syndrome.
• In transplacental transmission, the newborn baby will present with optic neuropathy and congenital glaucoma. Neurological problems like microcephaly and ventriculomegaly can be observed. 
• Diagnosis is done by RT PCR and antibody testing.

Dengue Virus

• Dengue is the most common mosquito-borne infection.
• In India, it is the most rapidly spreading disease and it is the most common arbovirus found in India.
• The vector is Aedes Mosquito.
• It has four serotypes (DEN1-DEN4) and DEN2 is the most dangerous.
• There is always the risk of having a more severe secondary dengue infection. This occurs because non-neutralizing antibodies from the first time will combine with the second-time infected serotype, this enhances the viral entry into the macrophages and leads to more replication.
• The clinical features of dengue fever are high fever which is also called break bone fever, watery eyes, frontal headache, posterior ocular pain, muscle and joint pains, and rashes.
• The Clinical features of dengue hemorrhagic fever are all features of dengue fever along with severe fall in platelet count (<1lac)  and platelet functional defects.
• There is one more serious manifestation of dengue is dengue shock syndrome. In this manifestation, features of dengue fever and dengue hemorrhagic fever occur along with shock features. The patient will go into shock and will require severe treatment.
• Lab diagnosis is done by PCR, NS-1 antigen, and IgM antibodies.
• The treatment is supportive in dengue fever but may require lots of fluids and platelet transfusion in DHF.
• Dengvaxia is the vaccine available in the market to protect against dengue serotypes 1-4.

Also Read: Fungal infections : Types, Causes, Risk Factors, Symptoms , Diagnosis and Treatment

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