Microbiology review - Research Paper Example

Some of these factors include the fact that the virus tends to disappear from the tissues of the severely ill patients, and thrives in patients who have been mildly affected (Halstead, 1965), while studies have been made on the tissues of the terminally ill patients (Halstead, 1965). Also, the virus does not reproduce in the effected tissues, but in healthy tissues that are often ignored during collection and isolation (Halstead, 1965). Despite these limitations, at least four different strains of the virus have been isolated, namely type 1, 2, 3, and 4 (Halstead, 1965).

The vector for the virus is the Aedes aegypti mosquito in most of the cases (Halstead, 1965). There are other species of the mosquitoes which might or might not serve as vectors, depending on the geographical location of the mosquito population and the dominance of the species (Halstead, 1965). Due to the nature of the vector, Dengue can also be refereed to as a mosquito-borne hemorrhagic fever (Halstead, 1965), however, this term is not preferred over Dengue fever (Halstead, 1965). Epidemiology: The recent technique is to divide the virus epidemiologically into three groups, depending on the types and degree of illnesses that it causes (Rico-Hesse, 2003).

If it remains dormant in the human host with almost negligible transmissibility, it can be termed as low-level virus (Rico-Hesse, 2003). If it causes Dengue fever only, it is a medium-level virus (Rico-Hesse, 2003). If it produces the more potent form of the disease, that is Dengue hemorrhagic fever and dengue shock syndrome, it is a high-level virus (Rico-Hesse, 2003). The potential of transmission and, hence, the epidemiology of the virus increases with the increase in the level (Rico-Hesse, 2003).

The factors for this increase could be the immunological and genetic disposition of the host, and the ability of the virus to replicate progressively in the vector (Rico-Hesse, 2003). The region of the world that is most prone to the epidemics of Dengue hemorrhagic fever and shock is Southeast Asia, affecting predominantly children (Ramos, Garcia, & Villaseca, 1993). However, the epidemics are not merely restricted to this region; some of the most significant outbreaks have been reported in Cuba, Venezuela, and Brazil (Ramos et al., 1993). Other countries or regions where the disease has been reported include Greece, South Africa_ Durbin, Formosa, Bengok, Vietnam, Malaysia, and Singapore (Halstead, 1965).

A recent outbreak, in 2004, was reported from Fuzhou, China (Yan et al., 2006). It is interesting to note that no cases have yet been reported from East Pakistan, Indonesia, and Burma (Halstead, 1965). Symptoms: A detailed study of the course of action of the virus and the symptoms of the disease and their causes is beyond the scope of this paper. However, an attempt will be made to succinctly present the course of the disease. Stage 1: The virus is contracted as a result of mosquito bite (Halstead, 1965).

This induces a period of viral replication and reproduction as a result of which the patient becomes febrile for three or four days (Halstead, 1965). There is extensive damage to the capillaries, more than is incurred in the usual viral infections (Halstead, 1965). Stage 2: Due to reasons not yet identified, there is extensive damage to the liver, more than there is in the other organs of the body (Halstead, 1965), although the toxic conditions in the body effect the