In the study, published in the Feb. 15 issue of The Journal of Infectious Diseases, now available online, Jared Baeten and colleagues from the United States and Kenya collected detailed sexual data from a group of male Kenyan truckers and, using statistical models, developed infectivity measures that estimate the per-sexual-act probability of HIV transmission. The study is the first to calculate the probability of infection for men who have multiple, concurrent heterosexual partners, which was found to be significantly higher than infectivity rates calculated in the past from studies of monogamous couples. Their results may help explain the rapid spread of HIV in settings where circumcision is not common and multiple sexual partnerships are.
Between 1993 and 1997, 745 male employees of trucking companies based in Mombasa, Kenya were followed for the study. Initially they were evaluated for circumcision status and HIV-negativity. Over the length of the study the men were asked to give information concerning the number of sexual encounters with three different partner types–wives, casual partners, and prostitutes–and were screened for HIV and other sexually transmitted infections. At the end of the study the probability of infection was calculated using a statistical model that incorporated published data to estimate the rates of HIV infection among the three types of sexual partners.
For the men in the study, the overall probably of becoming HIV-infected following a single act of intercourse was calculated to be .0063, or one in 160. Uncircumcised men had a more than two-fold increased risk of infection per sexual act compared with circumcised men–one in 80 versus one in 200. Read more »
Tags: account, act, addition, Africa, analysis, behavior, circumcised men, circumcision, circumcision status, difference, Diseases, end, estimate, evidence, Feb, group, heterosexual, heterosexual partners, HIV, hiv infection risk, hiv transmission, HIV-infected, HIV-negativity, HIV-positive, infection, Infectious, infectious diseases, infectivity, information, intercourse, issue, Jared Baeten, Journal, journal of infectious diseases, Kenya, Kenyan, length, model, Mombasa, negativity, number, online, order, other sexually transmitted infections, overall, partner, partner types, past, prevention, probability, prostitutes, rate, result, risk, Sex, sexual act, sexual behavior, sexual encounters, sexual partners, spread, statistical model, statistical models, status, study, transmission, truckers, trucking, trucking companies, Uncircumcised, uncircumcised men, United States, virus
Posted in medicalmatrix | February 13, 2010 | 
Comments (0)
Background
Anemia, like a fever, is a symptom of disease that requires investigation to determine the underlying etiology. Often, practicing physicians overlook mild anemia. This is similar to failing to seek the etiology of a fever. The purpose of this article is to provide a method of determining the etiology of an anemia.
Anemia is strictly defined as a decrease in red blood cell (RBC) mass. Methods for measuring RBC mass are time consuming, are expensive, and usually require transfusion of radiolabeled erythrocytes. Thus, in practice, anemia is usually discovered and quantified by measurement of the RBC count, hemoglobin (Hb) concentration, and hematocrit (Hct). These values should be interpreted cautiously because they are concentrations affected by changes in plasma volume. For example, dehydration elevates these values, and increased plasma volume in pregnancy can diminish them without affecting the RBC mass.
Pathophysiology
Erythroid precursors develop in bone marrow at rates usually determined by the requirement for sufficient circulating Hb to oxygenate tissues adequately. Erythroid precursors differentiate sequentially from stem cells to progenitor cells to erythroblasts to normoblasts in a process requiring growth factors and cytokines. This process of differentiation requires several days. Normally, erythroid precursors are released into circulation as reticulocytes.
Reticulocytes remain in the circulation for approximately 1 day before reticulin is excised by reticuloendothelial cells with the delivery of the mature erythrocyte into circulation. The mature erythrocyte remains in circulation for about 120 days before being engulfed and destroyed by phagocytic cells of the reticuloendothelial system. Read more »
Tags: Abnormal, abnormality, absorption, access, addition, adulthood, African, age, AIDS, anemia, Arabians, area, aspirin, attemp, availability, average, Bleeding, blood, body, bone, bone marrow, bowel, calf, capability, care, Carefully, cell, Clinical, colon, color, contrast, Coumadin, decade, deficiency, deficient, dehydration, depletion, description, development, diet, difference, differentiation, disease, disorder, diverticula, document, donor, duration, equilibrium, erythrocyte, estimate, Etiology, examination, example, extent, factor, family, Fanconi, fault, food, gastrointestinal, Gram, growth factors, hair, Hbs, health, hematocrit, hemoglobin, Hemorrhoidal, hiatal, history, household, ice, incidence, inquiry, instance, investigation, iron, jaundice, life, loss, malaria, man, marrow, mass, meat, mild anemia, Morbidity, Mortality, mother, Neoplasia, nonsteroidal, northern Europe, NSAIDs, Obtain, occupation, part, Pathophysiology, patient, phagocytic cells, plasma volume, pregnancy, premenopausal, prescription, prevalence, quantity, Race, rate, RBC, red blood cell, rejection, replacement, reticulocytes, reticuloendothelial cells, reticuloendothelial system, Saudi, Severe, Sex, Sicilians, sickle, significance, Socioeconomic, splenectomy, standpoint, status, stem cells, symptom of disease, Symptoms, syndrome, tarry, thalassemia, tolerance, treatment, tumor, United States, urine, use, woman, Women, work, world
Posted in medicalmatrix | | Comments (0)
This article focuses on common bacterial infections in pregnancy and describes the manifestations of these infections and the therapies used to treat them.
Bacterial infections can affect pregnant women from implantation of the fertilized ovum through the time of delivery and peripartum period. They may also affect the fetus and newborn. Many women with these infections are asymptomatic, necessitating both a high degree of clinical awareness and adequate screening.
Grop B Streptococcus
Group B Streptococcus (GBS) is the most common cause of life-threatening infections in newborns; thus, GBS is the primary focus of any discussion about infections and pregnancy. Infections caused by GBS affect both mother and child. Since the emergence of this pathogen in the 1970s, the increased use of intrapartum prophylaxis has decreased the infection rate by 70%.
Etiology
Streptococcus agalactiae, or GBS, is a facultative, beta-hemolytic, fastidious, gram-positive coccus. GBS can be found as part of normal vaginal, rectal, and oral flora. The virulence of the organism depends largely on the polysaccharide capsule.
Transmission
Twenty to 25% of pregnant women are asymptomatic carriers of vaginal or rectal GBS. Intrapartum transmission occurs via ascending spread or at the time of delivery.
Clinical spectrum
Because only 0.5-1% of mothers who carry GBS develop signs and symptoms of disease, clinical diagnosis of GBS infection can be problematic.
In pregnant women, GBS is a cause of cystitis, amnionitis, endometritis, and stillbirth. Occasionally, GBS has caused endocarditis and meningitis in pregnant women, while, in postpartum women, GBS has been identified as a cause of urinary tract infections (UTIs) and pelvic abscesses. Read more »
Tags: abscesses, absorption, addition, alternative, Ampicillin, antenatal, antibody, Antitreponemal, assay, asymptomatic carriers, Avoid, azithromycin, bacteremia, benzathine, blood, care, Ceftriaxone, cervix, Chlamydia, choice, Clinical, clinical diagnosis, clinical spectrum, CNS, common bacterial infections, congenital, Consume, context, course, CSF, culture, cystitis, death, delivery, diagnose, diagnosis, disease, dose, drug, endometritis, equivalent, Erythromycin, Etiology, examination, failure, fetus, fever, fluorescent, focus, food, FTA-ABS, gbs, gestation, group b streptococcus, Herxheimer, HIV, increase, infection, intramuscular, Jarisch, labor, laboratory, lack, latent, lesion, life, lumbar, lymphadenopathy, material, maternal, meat, MHA-TP, microhemagglutination, milk, Morbidity, mother, mother and child, motile, neonatal, Neurosyphilis, nonpregnant, nontreponemal, ovum, pain, pallidum, patient, penicillin, plasmin, polysaccharide capsule, postpartum women, pregnancy, prenatal, preparation, preterm, prevention, prophylaxis, puncture, Rash, rate, reaction, reagin, Research, risk, Screening, screening group, seafood, Serological, show, site, spectrum, spilling, spirochete, stage, stillbirth, stool, streptococcus agalactiae, streptococcus group b, sulfamethoxazole, surveillance, symptom onset, Syphilis, test, testing, therapy, third, treatment, Treponema, treponemal, trimester, Trimethoprim, ulcer, United States, Untreated, urinary tract infections, uterine, vagina, VDRL, Venereal, virulence, visit, vulva, Wash, week, Women
Posted in medicalmatrix | | Comments (0)
Background
Intracranial abscesses are uncommon, serious, life-threatening infections. They include brain abscess and subdural or extradural empyema and are classified according to the anatomical location or the etiologic agent. The term brain abscess is used in this article to represent all types of intracranial abscesses.
Intracranial abscesses can originate from infection of contiguous structures (eg, otitis media, dental infection, mastoiditis, sinusitis) secondary to hematogenous spread from a remote site (especially in patients with cyanotic congenital heart disease), after skull trauma or surgery, and, rarely, following meningitis. In at least 15% of cases, no source can be identified.
In recent years, the complex array of etiologic agents that cause brain abscess has become better understood.
Pathophysiology
Brain abscess is caused by intracranial inflammation with subsequent abscess formation. In at least 15% of cases, the source of the infection is unknown (cryptogenic). Infection may enter the intracranial compartment directly or indirectly via 3 routes.
Contiguous suppurative focus (45-50% of cases)
Direct extension may occur through necrotic areas of osteomyelitis in the posterior wall of the frontal sinus, as well as through the sphenoid and ethmoid sinuses.This direct route of intracranial extension is more commonly associated with chronic otitic infection and mastoiditis than with sinusitis. Odontogenic infections can spread to the intracranial space via direct extension or a hematogenous route. Contiguous spread could extend to various sites in the central nervous system, causing cavernous sinus thrombosis; retrograde meningitis; and epidural, subdural, and brain abscess. Read more »
Tags: abdominal, abscess formation, abscesses, administration, age, agent, AIDS, array, artery, article, availability, Background, body, brain, brain abscess, cause, cavernous sinus thrombosis, central nervous system, cerebellum, Chronic, Clinical, compartment, complication, congenital, congenital heart disease, contamination, Contiguous, contiguous structures, course, decrease, dental infection, diagnosis, dilatation, disease, distribution, drug, dural, emergence, emissary veins, empyema, entry, epidural, esophageal, ethmoid, ethmoid sinuses, etiologic agent, etiologic agents, evidence, exacerbation, extension, extradural, focus, formation, fracture, Frequency, frontal sinus, fulmi, fulminant, fungal, Haemophilus, heart, Hematogenous, history, HIV, hospital, imaging, indolent, infection, inflammation, influenzae, injection, International, Intracranial, introduction, life, lobe, location, lung, mode, Morbidity, Mortality, MRI, mucosa, mucosal, necrotic areas, network, neutropenia, Odontogenic, odontogenic infections, osteomyelitis, paranasal, Pathophysiology, posterior, prevalence, problem, rate, resul, retrograde, route, Rupture, seed, sequelae, Sex, shrapnel, site, skin, skull, source, space, sphenoid, spread, structure, subdural, surgery, system, term, Thrombophlebitis, transplantation, trauma, United States, use, vaccine, vasculature, wall, world
Posted in medicalmatrix | | Comments (0)
Background
Acute rheumatic fever (ARF) is an autoimmune inflammatory process that develops as a sequela of streptococcal infection. ARF has extremely variable manifestations and remains a clinical syndrome for which no specific diagnostic test exists. Persons who have experienced an episode of ARF are predisposed to recurrence following subsequent (rheumatogenic) group A streptococcal infections. The most significant complication of ARF is rheumatic heart disease, which usually occurs after repeated bouts of acute illness.
Pathophysiology
ARF is characterized by nonsuppurative inflammatory lesions of the joints, heart, subcutaneous tissue, and central nervous system. An extensive literature search has shown that, at least in developed countries, rheumatic fever follows pharyngeal infection with rheumatogenic group A streptococci. The risk of developing rheumatic fever after an episode of streptococcal pharyngitis has been estimated at 0.3-3%. More recent investigations of rheumatic fever occurring in the aboriginal populations of Australia suggest that streptococcal skin infections might also be associated with the development of rheumatic fever. In Oceania and Hawaii, streptococcal strains that are not typically associated with rheumatic fever have been found to cause the disease.
Molecular mimicry accounts for the tissue injury that occurs in rheumatic fever. Both the humoral and cellular host defenses of a genetically vulnerable host are involved. In this process, the patient’s immune responses (both B- and T-cell mediated) are unable to distinguish between the invading microbe and certain host tissues.The resultant inflammation may persist well beyond the acute infection and produces the protean manifestations of rheumatic fever.
Frequency
United States
The incidence of ARF has declined markedly in the past 50 years in both the United States and Western Europe. Most Western physicians see only the late sequelae of rheumatic heart disease; the diagnosis of an acute case is usually reason enough for a ground rounds presentation. This remarkable decline of rheumatic fever likely reflects improved socioeconomic conditions, as well the decline in prevalence of the classically described rheumatogenic strains of group A streptococci.
Following two decades of almost total absence, a resurgence of ARF occurred in the 1980s among middle-class white children in Salt Lake City, Utah. Clusters were also reported in US Army and Navy training camps during the same period. These limited outbreaks were associated with mucoid rheumatogenic strains that were rarely seen in the preceding 20 years. Today, ARF remains a rarity in most of the United States, although Hawaii and American Samoa continue to see a significant number of cases, many of which are caused by streptococcal strains not usually associated with rheumatic fever in persons of Polynesian descent. Read more »
Tags: abdominal, aboriginal populations, acute case, acute illness, acute infection, acute rheumatic fever, adolescence, age, and, appearance, area, ARF, arthralgia, arthritis, attention, auscultation, bout, brain, breath, Carditis, Carey, central nervous system, Characteristic, chest, CHF, chorea, Clinical, cohort, Coombs, cough, damage, death, decrescendo, development, diagnosis, disability, disease, due, dyspnea, echocardiography, effusion, endocardium, enlargement, eruption, Erythema, Europe, evidence, evolution, exertion, failure, fair, family, featu, fever, flow, form, friction, ganglioside, gonococcal, group a streptococci, Hand, heart, history, host defenses, host tissues, incidence, infection, inflammation, inflammatory lesions, inflammatory process, involvement, Isolated, Jaccoud, Joint, laboratory, likelihood, literature search, locale, malaise, manifestation, marginatum, migratory, mimicry, mitral, murmur, Murmurs, myocardium, New Zealand, nocturnal, orthopnea, pain, patient, pattern, periarticular, pericardial, pericardium, pharyngitis, Physical, Polyarthritis, poststreptococcal, potential, predilection, predisposition, prevention, problem, process, puberty, rate, recall, Recurrent, regurgitation, Rheumatic, rheumatic heart disease, risk, rub, sequela, Severe, Sex, Sore, spine, streptococcal, streptococcal infections, streptococcal skin infections, streptococcal strains, Subcutaneous, subside, Sydenham, syndrome, tenderness, Tenosynovitis, throat, trunk, United States, valvular, variable manifestations, warmth, week, western physicians
Posted in medicalmatrix | | Comments (0)