Herpes simplex Virus HSV

Pathogen, pathogenesis, and clinical picture. The viral genome codes for about 90 proteins, categorized as immediate early (regulatory functions), early (DNA synthesis), and late (structural) proteins. Herpes simplex viruses are classified in types 1 and 2, which differ both serologically and biologically (host-cell spectrum, replication temperature). Initial infection with herpes simplex type 1 usually occurs in early childhood. The portal of entry is normally the oral mucosa (oral type) and...

Clostridium botulinum Botulism

Foodborne botulism is not an infection, but rather an intoxication, that is, the toxin is ingested with food. Infant botulism involves ingestion of spores and wound botulism results from infection of a wound. Toxin. The very strong botulinum neurotoxin is a heat-labile protein. Seven toxigenic types are differentiated, each of which produces an immunologi-cally distinct form of botulinum toxin. Types A, B, and E cause poisoning in humans. The toxin is a metalloprotease that catalyzes the...

Borrelia burgdorferi Lyme Disease

Microbiology Borrelia Burgdorferi

The etiology of an increase in the incidence of acute cases of arthritis among youths in the Lyme area of Connecticut in 1977 was at first unclear. The illness was termed Lyme arthritis. It was not until 1981 that hitherto unknown borreliae were found to be responsible for the disease. They were classified as B. burgdorferi in 1984 after their discoverer. Analysis of the genome of various isolates has recently resulted in a proposal to sub-classify B. burgdorferi sensu lato in...

Sarcoptes scabiei

Causative agent of scabies the itch, sarcoptic itch Infestation with Sarcoptes scabiei var. hominis causes human scabies, a condition characterized by pronounced pruritus, epidermal mite burrows, nodules, and pustules. Transmission is person to person. Various mite species that parasitize animals may also infest the human skin without reproducing, causing the symptoms of pseudoscabies. Occurrence. Scabies caused by Sarcoptes scabiei var. hominis does not occur frequently in Europe, although...

Primary Immune Response

Primary Immune Response

Fig. 2.11 Regulation of T-cell activation is controlled by multiple signals, including costimulatory signals Signal 2 . Stimulation of the T cell via the T-cell receptor TCR Signal 1 activates a tyrosine kinase, which in turn activates phospholipase C PLC . PLC splits phosphatidylinositol bisphosphate PIP2 into inositol trispho-sphate IP3 and diacyl glycerol DAG . IP3 releases Ca2 from intracellular depots, whilst DAG activates protein kinase C PKC . Together, Ca2 and PKC induce and activate...

Human Herpesvirus HHV

Vaccinia Replication Factories

HHV 8 has recently been identified as a decisive cofactor in induction of Kaposi sarcoma. The classic, sporadic form of this malignancy was described in 1872 in the Mediterranean area. It also occurs following organ transplantations and is a significant cause of death in AIDS patients 12 . The contribution of HHV 8 to the pathogenesis of Kaposi sarcoma appears to lie in dysregulation of cytokine and hormone production. In transplantation-association Kaposi sarcoma...

Wuchereria bancrofti and Brugia species

Wuchereria Bancrofti Life Stages

Causative agents of lymphatic filariosis Parasites and occurrence. About 120 million people in 80 countries suffer from lymphatic filariosis caused by Wuchereria bancrofti or Brugia species one-third each in India and Africa, the rest in southern Asia, the Pacific region, and South America , and 1.1 billion people are at infection risk WHO, 2000 . Table 10.4 . Humans are the only natural final hosts of W. bancrofti and the most widely disseminated Brugia strains. There are, however, other...

Haemophilus influenzae

Haemophilus Satellite Cells

Hemophilic bacteria are so designated because they require growth factors contained in blood. The most important human pathogen in this genus is H. influenzae. Other Haemophilus species either infect only animals or are found in the normal human mucosal flora. These latter include H. parainfluenzae, H. hemolyticus, H. segnis, H. aphrophilus, and H. paraphrophilus. These species can cause infections on occasion. Morphology and culture. Haemophilus are small length 1.0-1.5 im, width 0.3 im ,...

Toxoplasma gondii

Toxoplasma Cell Stages

Toxoplasma gondii is the causative agent of a zoonosis that occurs worldwide with high prevalences up to 80 depending on region and age . Humans are infected by ingesting oocysts excreted by the definitive hosts cats or by eating unprocessed meat containing Toxoplasma cysts. If a women contracts toxoplasmosis for the first time during pregnancy, diaplacental transmission of the pathogen to the fetus is possible with potential severe consequences for example malformations, eye damage, clinical...

Polio Vaccines Pros and Cons

The dead or inactivated vaccine has the advantage of a long stability period and practically foolproof application safety. The disadvantages of this vaccine form are its high cost, the requirement for three injections and weaker or at least shorter-lived protection than is provided by the attenuated form. Work is ongoing on development of enhanced eIPV vaccines of this type. The advantages of the live vaccine are its oral application route, low price and high level of efficiency. One...

Cutaneous Mycoses

Trichophyton Schoenleinii

Dermatophytes Dermatomycoses or Dermatophytoses Dermatophytes are fungi that infect tissues containing plenty of keratin skin, hair, nails . Classification. Dermatophytes are classified in three genera Trichophyton with the important species T. mentagrophytes, T. rubrum, T. schoenleinii, T. tonsurans Microsporum M. audouinii, M. canis, M. gypseum and Epidermophyton E. floccosum . Some dermatophyte species are anthropophilic, others zoophilic. The natural habitat of the geophilic species M....