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...

Immunization Prophylaxis

In active immunization, the immune system is stimulated by administration of vaccines to develop a disease-specific immunity. Table 1.12 lists the vaccine groups used in active immunization. Table 1.13 shows as an example the vaccination schedule recommended by the Advisory Committee on Immunization Practices of the USA (www.cdc.gov nip). Recommended adult immunization schedules by age group and by medical conditions are also available in the National Immunization Program...

HIV replication

HIV can infect T4 lymphocytes and other cells bearing the CD4 marker on their surface. The CD4 molecule is the main receptor for HIV, or more precisely for its gp120 Fig. 8.14 . In addition, either the chemokine receptor CCR5 macro-phage-tropic R5 HIV strains or CXCR4 T cell-tropic X4 strains is used as a core-ceptor. Persons with homozygotic missing CCR5 are highly resistant to HIV infection. A number of other coreceptors are also active depending on the viral strain involved. HIV is then...

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...

Basic Principles of Medical Microbiology and Immunology

General Aspects of Medical Microbiology 4 Subcellular Infectious Entities 4 Prokaryotic and Eukaryotic Microorganisms 4 5 7 Basic Terminology of Infectiology 8 Determinants of Bacterial Pathogenicity and Virulence 8 11 Strategies against Nonspecific Immunity 12 Strategies against Specific Immunity 13 Regulation of Bacterial Virulence 18 The Genetics of Bacterial Pathogenicity 20 Nonspecific Defense Mechanisms 21 Specific Defense Mechanisms 23 Defects in Immune Defenses 24 Immune Defects...

Chlamydia psittaci Ornithosis Psittacosis

The natural hosts of C. psittaci are birds. This species causes infections of the respiratory organs, the intestinal tract, the genital tract, and the conjunctiva of parrots and other birds. Humans are infected by inhalation of dust from bird excrements containing the pathogens, more rarely by inhalation of infectious aerosols. After an incubation period of one to three weeks, ornithosis presents with fever, headache, and a pneumonia that often takes an...

Borrelia that Cause Relapsing Fevers

Borrelia Giemsa Stain

The genus Borrelia belongs to the family Spir-ochaetaceae. The body louseborne epidemic form of relapsing fever is caused by the species B. recurrentis. The endemic form, transmitted by various tick species, can be caused by any of a number of species at least 15 , the most important being B. duttonii and B. hermsii. Morphology and culture. Borreliae are highly motile spirochetes with three to eight windings, 0.3-0.6 im wide, and 8-18 im in length. They propel...

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...

Pediculus humanus capitis Head Louse

Oval body, length 2.2-4.0 mm, morphology very similar to the body louse. Nits are 0.5-0.8 mm long. Localization is mainly in the hair on the head, occasionally also on other hairy areas of the head or upper body. The nits are glued to the base of the hair near the skin. Duration of development from nit to adult is 17 days. The lifespan of adults on human host about one month, survival off host at room temperature is for up to one week. Occurrence and epidemiology. Occurs...

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

Porphyrin Test Haemophilus

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 ,...

Streptococcus pneumoniae Pneumococci

Pneumococ Gram Stain

Pneumococci are Gram-positive, oval to lancet-shaped cocci that usually occur in pairs or short chains Fig. 4.5a . The cells are surrounded by a thick capsule. When cultured on blood agar, S. pneumoniae develop a-hemolytic colonies with a mucoid smooth, shiny appearance hence S form, Fig. 4.5b . Mutants without capsules produce colonies with a rough surface R form . Antigen structure. Pneumococci are classified in 90 different serovars based on the fine chemical...

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....