The Influenza (Flu) Virus. Next to the common cold, influenza or "the flu" is perhaps the most familiar respiratory infection in the world. In the United States alone, approximately 25 to 50 million people contract influenza each year. The symptoms of the flu are similar to those of the common cold, but tend to be more severe.
Biology and Replication of Cytomegalovirus Edward S. Mocarski, Jr HUMAN CYTOMEGALOVIRUS (CMV, human herpesvirus 5), is a ubiquitous human pathogen causing a broad range of clinical illness.1-3 CMV resides latent in the host after primary infection, a hallmark of all herpes viruses, possibly in kidney tissues or lymphocytes.
Dengue virus causes dengue fever. Common names for dengue fever include breakbone fever and dandy fever; dengue hemorrhagic fever ([DHF] and dengue shock syndrome (DSS) are the severe forms. Dengue is found in tropical and sub-tropical climates worldwide, mostly in urban and semi-urban areas.
Marburg virus is a hemorrhagic fever virus of the Filoviridae family of viruses and a member of the species Marburg marburgvirus, genus Marburgvirus. Marburg virus (MARV) causes Marburg virus disease in humans and nonhuman primates, a form of viral hemorrhagic fever.
Herpes simplex viruses 1 and 2 (HSV-1 and HSV-2) are two members of the herpes virus family, Herpesviridae, that infect humans. Both HSV-1 (which produces most cold sores) and HSV-2 (which produces most genital herpes) are ubiquitous and contagious.
Are Viruses Living or Nonliving? Scientists have long sought to uncover the structure and function of viruses. Viruses are unique in that they have been classified as both living and nonliving at various points in the history of biology. Viruses are particles that are capable of causing a number of diseases including cancer.
Viruses are found in almost every ecosystem on Earth and are the most numerous type of biological entity. The study of viruses is known as virology, a sub-speciality of microbiology. While not inside an infected cell or in the process of infecting a cell, viruses exist in the form of independent particles.
A viral infection is a proliferation of a harmful virus inside the body. Viruses cannot reproduce without the assistance of a host. Viruses infect a host by introducing their genetic material into the cells and hijacking the cell's internal machinery to make more virus particles.
Viral infections are contagious for varying periods of time depending on the virus. An incubation period refers to the time between exposure to a virus (or other pathogen) and the emergence of symptoms. The contagious period of a virus is not necessarily the same as the incubation period.