INFECTIOUS DISEASE AND PRECAUTIONS

Infectious Disease and Precautions



Infectious Disease and Precautions

Dengue Fever

It is a serious disease caused by a virus transmitted by the mosquito “Aedes Aegypti”. It is usually of a short duration, and the patient has no complications, however, the patient may develop a severe form of the disease known as dengue hemorrhagic fever. Dengue is a severe infection of tropical countries, characterized by biphasic fever, arthralgia (pain in joints) and myalgia (pain in muscles), exanthema (eruption in skin), leukopenia (decreased number of white blood cells) and often haemorrhage (rupturing of blood arteries) (Martina, Koraka, & Osterhaus, 2009, pp 564 - 81).

The disease occurs in two forms: classic dengue and dengue hemorrhagic fever. The incubation period lasts 3 - 15 days. Disease begins intensely with a fever with a temperature rise to 39 - 41 ° C (Wang, Sung, Tsai, Kao, & King, 2002, pp 4472 - 4478). Common symptoms include swelling and redness in small joints, nausea and vomiting. However, at later stages, lack of white blood cells, decrease in platelets count, sever headache and other symptoms appear (Neo, & Lam, 2009, pp 66 - 77).

The Nature of the Micro-organism

The virus belonging to the family “Togaviridae” and genus “Flavivirus” causes Dengue Fever. It has 4 to 6 serotypes, and each serotype is capable of getting the person seriously ill (Leitmeyer, Vaughn, Watts, Ramos, & Hesse, 1999, pp 4738 - 4747).

Dengue Virus - Structure

Dengue viral particle is spherical and measures between 40 and 60 nm in diameter. It has a shell composed of protein (E-protein, mostly, and M-protein) that entirely covers the surface of the virus. A membrane covers the spherical capsid, which consists of a viral protein (C protein) and two surface proteins (M-protein and E-protein) (Zeng, Falgout, & Markoff, 1998, pp 7510 - 7522).

A circular symmetry polyhedral nucleocapsid protects the genetic material. The core diameter of the virus is 25-30 nm, while between the envelope and the nucleocapsid is a lipid bilayer. The host's cell membrane derives the lipid bilayer (Pijlman, Funk, & Kondratieva, 2008, pp 579 - 91). The genome composes of a single molecule of linear single stranded ribonucleic acid (RNA), which is a large molecule of 11,000 bases of RNA. The RNA has a two-layer lipid membrane of phosphor-lipids and cholesterol. It is the size of the “virion” of 40 - 45 nm in diameter (Jones, Burgner, Groesch, Post & Kuhn, 2003, pp 7143 - 7149).

Dengue Virus - Motility

The motility, or ability to move spontaneously and independently, is relatively low for the Dengue Virus because it lacks projections like that of other micro-organisms. It does not have a tail like Euglena nor does it possess projections like that of an amoeba (Gubler, 1998, pp 480 - 96).

Dengue Virus - Preferred Environment

Dengue Virus, like all other viruses, cannot sustain outside a living cell. It is impossible for the Dengue Virus to survive outside a living cell and thus, it prefers staying in a living organism where it can reproduce and ...