What is dengue virus ?
Dengue fever virus also called break bone fever virus is an RNA virus of the family Flaviviridae and genus Flavivirus.Other viruses which share the same genus include Yellow fever virus,west nile virus,japanese encephalitis virus,tick borne encephalitis virus, and others.
The dengue virus genome contains about 11,000 nucleotide bases which form the three different types of proteins which build the virus particle.And other seven proteins make are used for the replication of the virus.
The virus has five strains or stereotypes,the first four are called DENV-1,DENV-2,DENV-3 and DENV-4 and the fifth one.The differences among these strains is ofcourse by their capability to bind with a group of products that have adaptive immunity.[i.e by their antigenicity.]
The first record in history of the disease comes from a Chinese medical encyclopedia from the Jin Dynasty.But the most laudable reports of this epidemic of the disease comes from the 1779 and 1780 across Asia,Africa,and north america.In 1906 the disease was shown to be transmitted via Aedes mosquito. The virus infects 50-528 million people world wide and about 20,000 deaths.It is common in 110 countries.
what is the pathology of the virus ?
Dengue is vector borne virus [i.e mosquito.] Symptoms commence after 3-14 days after infection.High fever,headache,muscle and joint pain (hence termed as breakbone fever),vomiting and a characterstic skin rash.The progression of the disease has a febrile,critical and recovery phases.
The febrile phase includes a high fever over 40′ c with a headache and pain lasting for 2-7 days. As fever resolves the critical phase commences, here there is a leakage of plasma from blood vessels which may result in fluid accumulation in the chest wall and abdominal cavity here decreased fluid in the patients system.The recovery phase happens with the reabsorbtion of the leaked fluid from the systems.Hence,fluid overload may affect the brain and result in decreased consciousness or seizures.Dengue fever affects several bodily systems including the brain,heart and the liver.
The primary transmitters of this virus are Aedes aegypti and other Aedes species.These mosquitoes exist between latitudes of 35′ north and 35′ south on an elevation of 3,300ft.They bite during early morning as well as in the evenings. Similar to malaria humans are primary hosts of the virus when the female mosquito takes a blood meal from a patient in the febrile phase of the disease 2-10 day, it becomes infected and the virus infects the cells lining its gut , then on from the 8th to the 10th days later the salivary gland of the mosquito gets infected.Hence,releasing the virus into another non-infected human via a bite.The virus can also be transmitted via blood transfusions,organ donations,and vertical transmissions.
what is the treatment or prevention ?
As with malaria, and Zika the prevention mechanism is to erradicate stagnant water used by Aedes mosquito to lay its egg.Inaddition,insecticides and biological control can be utilized.Using mosquito repellant,mosquito nets, and fully covering dresses can be used as a personal prevention measure.
When we come to treatment there is no vaccine present currently.But a partially effective vaccine produced by Sanofi called Dengvaxia is 60% effective.Maintaining a proper fluid balance or oral rehydration is important.Paracetamol is used to reduce fever and pain.Blood transfusion maybe initiated in those patients with low heamatocrit.Finally in the recovery period fluid adminstration is discontinued inorder to stop fluid overload in the circulatory system.The fatality rate is 1-5 % and less than one with accurate treatment.Those patients with low blood pressure are the one at high risk for death.That is why hydration is emphasized as discussed above.