Articles on Medical Diseases and Conditions

Entries Tagged ‘Rickettsial Infections’

Other Rickettsial Diseases

Bartonellosis (Oroya fever or Carrion’s disease) is caused by the rickettsial organism Bartonella bacilliformis and occurs only in Andean mountain regions of South America. The vector is the sandfly Phlebotomus (species). The organism is related to Rochalimaea quintana, the rickettsial etiology of trench fever and therefore is also related to Rochalimaea henselae, one of the […]

Rickettsial Diseases

The rickettsiae to some extent resemble small bacteria but are not stained with Gram stain and cannot be cultured on artificial media. These organisms are spread only by insect vectors that have fed on blood from a patient with the disease, not from personal contact with a patient. Blood cultures can sometimes isolate and identify […]

Vincent’s Angina

Vincent’s angina (Vincent’s infection) is an infection of the mouth caused by an interesting synergistic group of organisms, including anaerobic streptococci, a fusiform gram-negative bacillus, and a spirochete. Gram-stained smears demonstrating all three organisms are usually sufficient for diagnosis.


Leptospirosis is caused by several species of Leptospira organisms found most often in rats but sometimes present in some farm animals and in some cats and dogs (presumably from rat-transmitted infection). Transmission is most often through accidental contact with water contaminated by infected rat urine. Those most at risk are sewer workers and slaughterhouse employees, […]

Lyme Disease

Lyme disease is caused by the spirochete Borrelia burgdorferi by means of several tick vectors, the principal one in the Northeast and North Central United States being the deer tick Ixodes dammini and in the Pacific Coast states, Ixodes pacificus, the Western black-legged tick (both morphologically “hard” ticks). The three major affected areas in the […]

Congenital Syphilis

It has been estimated that 75% of infants born from mothers with active syphilitic infection will become infected in utero. Of those infected about one third will be symptomatic in the neonatal period and two thirds will have some symptoms within the first 2 years of life. However, it appears that the majority of patients […]

Effect of Therapy on Test Results

Studies before 1990 indicated that if patients with their first syphilitic infection in the primary or secondary stage were given adequate treatment, an elevated VDRL titer would decline (on the average) 2 dilutions (fourfold) by 3 months and 3 dilutions by 6 months. The rate of decline was said to be faster when the pretreatment […]

Selection of Tests

The selection of tests for syphilis is dictated by the clinical situation. If the patient has possible primary syphilis, a dark-field examination would be helpful, although it is becoming difficult to find laboratories with the necessary equipment and laboratorians with sufficient expertise. If the dark-field test result is negative or cannot be performed, an FTA-ABS […]

Sensitivity and Specificity of Syphilis Tests

Studies have been done in which duplicate samples from known syphilitic patients in various stages of their disease and also from normal persons were sent to various laboratories. Besides this, many reports have appeared from laboratories all over the world comparing one test with another in various clinical stages of syphilis, in nonsyphilitic diseases, and […]

Specific Treponema Pallidum Tests

Treponema pallidum immobilization (TPI) test. Syphilitic spirochetes can grow in rabbits. Nelson devised a Treponema pallidum immobilization (TPI) test in which syphilitic spirochetes are incubated with the patient’s serum. If specific antisyphilitic antibody is present, it will attack the spirochetes and immobilize them, causing them to stop moving when viewed under the microscope. This involves […]