Kristen A. Weigle

Assessment by meta-analysis of PCR for diagnosis of smear-negative pulmonary tuberculosis.

ABSTRACT We conducted a meta-analysis to assess the performance of PCR for the diagnosis of smear-negative pulmonary tuberculosis (SPT) and to identify factors that account for differences in the diagnostic accuracy of different studies. Studies published before February 2002 were included if sensitivity and specificity of PCR in smear-negative respiratory or gastric-aspirate specimens could be calculated. Analysis was conducted by using summary receiver operating characteristics models. Sensitivity and specificity ranged from 9 to 100% and from 25 to 100%, respectively. Fewer than 40% of the 50 studies reported results by number of patients, reported clinical characteristics of patients, or used as a reference standard combined culture and clinical criteria. Studies that included bronchial specimens showed higher accuracy than studies that evaluated only sputum specimens or included gastric aspirates. Studies that did not report that tests were applied blindly showed higher accuracy than those reporting blind testing. Increased sensitivity due to the use of DNA purification methods was associated with decreased specificity. Studies published after 1995, using Amplicor or dUTP-UNG, were associated with an increase in specificity at the expense of lower sensitivity. We concluded that PCR is not consistently accurate enough to be routinely recommended for the diagnosis of SPT. However, PCR of bronchial specimens could be useful in highly suspicious SPT cases. Studies not reporting blind testing are likely to overestimate accuracy of PCR. Future evaluation of PCR accuracy should be conducted by patient and type of respiratory specimen, blindly, by using a reference standard that combines culture and clinical criteria and addresses the issue of how patient characteristics affect PCR accuracy.

PCR-Based Diagnosis of Acute and Chronic Cutaneous Leishmaniasis Caused by Leishmania (Viannia)

ABSTRACT We evaluated PCR methods for diagnosis of acute and chronic cutaneous leishmaniasis (CL) in an area of Colombia where Leishmania (Viannia) is endemic. The PCR method specifically amplified whole linearized minicircle kinetoplast DNA (kDNA) of the Leishmania subgenus Viannia from biopsy lysates. PCR products were detected in agarose gels. For 255 acute cases, this PCR method had greater sensitivity (75.7%) than each conventional method, i.e., microscopic examination of Giemsa-stained lesion scraping (46.7%), biopsy culture (55.3%), aspirate culture (46.3%), and the conventional methods combined (70.2%). Among 44 cases of chronic CL, amplification of biopsy DNA was more sensitive (45.5%) than the individual (4.5 to 27.7%) and combined (27.3%) conventional methods. The detection of kDNA in biopsies from chronic lesions was enhanced by a chemiluminescent dot blot hybridization, which produced a sensitivity of 65.8% when alone and 90.9% when in combination with DNA extraction of biopsy lysates (P < 0.001). Three biopsies from 84 skin lesions of other etiologies were falsely positive by PCR (specificity, 96.4%). PCR detected kDNA more frequently in biopsies (detection level, 83.9%) than in aspirates (74.7%) from 103 cases of acute CL. Among aspirates from 53 chronic cases of CL, the alternative methods, DNA extraction and hybridization, increased sensitivity from 41.5 to 56.6% (P > 0.05). This enhanced PCR method in chronic biopsies was so much more sensitive than conventional methods that it should be considered the preferred diagnostic method for chronic CL. These findings support the appropriate incorporation of PCR into diagnostic strategies for cutaneous leishmaniasis.

Recurrent lesions in human Leishmania braziliensis infection - reactivation or reinfection?

Strains of Leishmania braziliensis subspecies isolated from initial and recurrent lesions in 24 patients from the Pacific coast of Colombia were examined for distinguishing polymorphisms by enzyme electrophoresis, restriction endonuclease analysis of kDNA, and molecular karyotyping of nuclear DNA. Recurrent strains from 12 patients (50%) were identical to the initially infecting strain by all methods of characterisation. Phenotypic and genotypic identity, together with clinical data, support endogenous reactivation as the mechanisms of recurrent disease in these 12 patients. 5 of the 24 (22%) recurrent strains differed from the initial strain by all methods. The remaining 7 strain pairs, not separated by enzyme polymorphisms, showed differing schizodeme and/or karyotype profiles. Patients whose recurrent lesions were caused by strains different from those causing the initial lesions had a significantly longer disease-free interval than patients whose lesions were caused by identical strains. Recurrent lesions occurred further from initial lesions in the former than in the latter group. Exogenous reinfection is the most plausible explanation for recurrences due to disparate organisms. These findings have important implications for both treatment evaluation and vaccination strategies for American tegumentary leishmaniasis.

NATURAL HISTORY, CLINICAL EVOLUTION AND THE HOST-PARASITE INTERACTION IN NEW WORLD CUTANEOUS LEISHMANIASIS

I n the New World, human diseases caused by the genus Leishmania are widespread, ranging from southern Texas to Northern Argentina and the Caribbean Islands. This review will address the natural history of the Leishmania that primarily affect skin and upper respiratory mucosa of humans. This group of diseases will be referred to as American cutaneous leishmaniasis (ACL). ACL is produced by a group of genetically related species, each of which has characteristic manifestations and areas of endemnicity (Table 1)le3; however, none of the clinical manifestations is unique to a particular species, because there is considerable overlap between clinical spectrums. Likewise, in a given locale several Leishmania species may be transmittede4 All the listed species can cause simple cutaneous lesions. Mucosal lesions are mostly characteristic of the Leishmania subgenus Viannia, particularly L. (V.) braziliensis and L. V. panamensis, but have also been caused by LO’.) guyanensis’ and L. (L.1 amazonesis.6 Diffuse cutaneous leishmaniasis (DCL) is a rare form of leishmaniasis caused by I,. (L.) mexicana in the United States, Mexican, Central American, and Caribbean regions and by L. (L.) anzazonensis and L. iL.1 zlenezuelensis in South America.7*g These species more frequently cause simple cutaneous leisl~maniasis.y8’0 L. (L.) mexicana is also associated with chronic lesions of the external ear (chiclero’s ulcer?’ in the Yucatan peninsula of Mexico. Despite these well recognized associations between Leishmania subspecies and clinical manifestations, anecdotal reports indicate that Leishmania species occasionally produce clinical manifestations beyond their recognized spectrum.‘2-‘4 The reasons why a given Leishmarda will produce differing manifestations in a different host or setting is not completely understood.

Racial and Ethnic Disparities in Influenza Vaccination Among Elderly Adults

AbstractOBJECTIVES: To examine whether access to care factors account for racial/ethnic disparities in influenza vaccination among elderly adults in the United States. DESIGN: Indicators of access to care (predisposing, enabling, environmental/system, and health need) derived from Andersen’s behavioral model were identified in the National Health Interview Survey questionnaire. The relationship of these indicators to influenza vaccination and race/ethnicity was assessed with multiple logistic regression models. MAIN RESULTS: Significant differences in vaccination were observed between non-Hispanic (NH) whites (66%) and Hispanics (50%, P<.001) and between NH whites (66%) and NH blacks (46%, P<.001). Controlling for predisposing and enabling access to care indicators, education, marital status, regular source of care, and number of doctor visits, reduced the prevalence odds ratios (POR) comparing Hispanics to non-Hispanic whites from 1.89 to 1.27. For NH blacks, controlling for access to care indicators changed the POR only from 2.24 (95% CI, 1.9 to 2.7) to 1.93 (95% CI, 1.6 to 2.4). CONCLUSIONS: This study confirmed the existence of sizable racial/ethnic differences in influenza vaccination among elderly adults. These disparities were only partially explained by differences in indicators of access to care, especially among non-Hispanic blacks for whom large disparities remained. Factors not available in the National Health Interview Survey, such as patient attitudes and provider performance, should be investigated as possible explanations for the racial/ethnic disparity in influenza vaccination among non-Hispanic blacks.

Seroepidemiological survey of hepatitis B and C virus infections in Ghanaian children

The seroprevalences of hepatitis B virus (HBV) and hepatitis C virus (HCV) markers were evaluated in a random sample of 803 children attending school in Ashanti‐Akim North district in Ghana in order to gain a better understanding of transmission patterns of these viruses, particularly horizontal transmission of HBV. This rural district is typical of 70% of the Ghanaian population. The overall seroprevalence of at least one marker of HBV infection was 61.2%, with rates increasing from 48% to 80% between the ages of 6–18 years (P < 0.001). The overall HBsAg seroprevalence was 15.8%, with the proportion of HBsAg positives amongst those with anti‐HBc increasing from 39.3% in 6–7‐year‐olds to 51.8% in 12–13‐year‐old. It appears that horizontal transmission during this age period was accompanied by a high rate of HBsAg carriage. Among those infected but not carriers, i.e., those HBsAg negative and anti‐HBc positive, >50% lacked detectable levels of anti‐HBs, an unusual pattern of convalescent immune response to HBV. The overall seroprevalence of anti‐HCV was 5.4% and did not differ significantly by age or gender. Anti‐HCV seroprevalence was not associated with the presence of any HBV marker. A better understanding of the unusually high prevalences of HBV and HCV infections demonstrated in this population is likely to influence vaccination and blood transfusion policies and to stimulate further evaluations of these infections and their vehicles of spread in highly endemic regions such as sub‐Saharan Africa.

Seroprevalence and seroincidence of Norwalk-like virus infection among Brazilian infants and children

To determine the importance of Norwalk‐like viruses (NLVs) as pediatric pathogens in a developing country, the seroprevalence and seroincidence of this group of viruses in a cohort of children less than 4 years of age in an urban shantytown in northeastern Brazil was examined. Serum samples were collected approximately every 6 months from 135 children who were surveyed three times each week for diarrhea and vomiting. NLV IgG was measured by an enzyme immunosorbent assay (EIA) with recombinant Norwalk virus capsid protein. Overall NLV seroprevalence was 71%, and the overall NLV seroconversion rate was 0.7 seroconversions per child‐year. The highest age‐specific NLV seroconversion rate (0.8 seroconversions per child‐year) was observed in the 13–24‐month age group. For all study children, the incidence of diarrhea and vomiting was significantly greater (P < 0.01) during time periods spanned by serum pairs that indicated NLV seroconversion compared with time periods without NLV seroconversion. However, NLV seroconversion was not associated with gastrointestinal symptoms during the first year of life. J. Med. Virol. 61:117–124, 2000.

Evaluación de la respuesta de isotipos de inmunoglobulina especifica a Leishmania en leishmaniasis tegumentaria Americana

Leishmania-specific immunoglobulin subclass response was evaluated in 133 patients infected with Leishmania braziliensis. The indirect immunofluorescent antibody test (IFAT) was employed with amastigotes of L. mexicana amazonensis as antigen. Among the 133 sera obtained at consultation fo rdiagnosis of active lesions, IgM was detected in 54 following absorption with Staphylococcus aureus Cowan strain I, and in 5 sera prior to absorption. IgM reactive with Leishmania antigen was only found in sera from patients whose lesions had envolved over past two months or less. Leishmania-specific IgG was detected in all sera prior to absorption. Sera obtained at the time of recurrence of after complete healing of lesions presented only specific IgC. The combined use of the Montenegro skin test and specific IgM increased the sensitivity of immunodiagnostic methods in patients with lesions of less than 2 months duration. Normal control volunteers were negative for specific IgM and unreactive to Montenegro skin testin. Among 16 patients with non-leishmanial lesion, 3 with sporotrichosis showed IgG reactive with Leishmania; none, including 4 with lesions of less than two months duration, showed specific IgM. We conclude that in patients infected with L. brasiliensis the presence of specific IgG and IgM is associated with the time of lesion evolution and the primary or recurrent nature of the lesions. In addition, the combined use of IgM titer and Montenegro reactivity is of potential utility in the diagnosis of early lesions.Leishmania-specific immunoglobulin subclass response was evaluated in 133 patients infected with Leishmania braziliensis. The indirect immunofluorescent antibody test (IFAT) was employed with amastigotes of L. mexicana amazonensis as antigen. Among the 133 sera obtained at consultation fo rdiagnosis of active lesions, IgM was detected in 54 following absorption with Staphylococcus aureus Cowan strain I, and in 5 sera prior to absorption. IgM reactive with Leishmania antigen was only found in sera from patients whose lesions had envolved over past two months or less. Leishmania-specific IgG was detected in all sera prior to absorption. Sera obtained at the time of recurrence of after complete healing of lesions presented only specific IgC. The combined use of the Montenegro skin test and specific IgM increased the sensitivity of immunodiagnostic methods in patients with lesions of less than 2 months duration. Normal control volunteers were negative for specific IgM and unreactive to Montenegro skin testin. Among 16 patients with non-leishmanial lesion, 3 with sporotrichosis showed IgG reactive with Leishmania; none, including 4 with lesions of less than two months duration, showed specific IgM. We conclude that in patients infected with L. brasiliensis the presence of specific IgG and IgM is associated with the time of lesion evolution and the primary or recurrent nature of the lesions. In addition, the combined use of IgM titer and Montenegro reactivity is of potential utility in the diagnosis of early lesions.Leishmania-specific immunoglobulin subclass response was evaluated in 133 patients infected with Leishmania braziliensis. The indirect immunofluorescent antibody test (IFAT) was employed with amastigotes of L. mexicana amazonensis as antigen. Among the 133 sera obtained at consultation for diagnosis of active lesions, IgM was detected in 54 following absorption with Staphylococcus aureus Cowan strain I, and in 5 sera prior to absorption. IgM reactive with Leishmania antigen was only found in sera from patients whose lesions had evolved over the past two months or less. Leishmania-specific IgG was detected in all sera prior to absorption. Sera obtained at the time of recurrence or after complete healing of lesions presented only specific IgG. The combined use of the Montenegro skin test and specific IgM increased the sensitivity of immunodiagnostic methods in patients with lesions of less than 2 months duration. Normal control volunteers were negative for specific IgM and unreactive to Montenegro skin testing. Among 16 patients with non-leishmanial lesions, 3 with sporotrichosis showed IgG reactive with Leishmania; none, including 4 with lesions of less than two months duration, showed specific IgM. We conclude that in patients infected with L. braziliensis the presence of specific IgG and IgM is associated with the time of lesion evolution and the primary or recurrent nature of the lesions. In addition, the combined use of IgM titer and Montenegro reactivity is of potential utility in the diagnosis of early lesions.

Gender differences in response to the Multitest CMI skin test in the general population

BACKGROUND Previous studies of gender differences in response to the Multitest CMI skin test have produced conflicting results. OBJECTIVE To determine whether gender is associated with response to the Multitest CMI skin test. METHODS Two-hundred ninety-seven adults, aged 18 to 64 years, recruited originally for a study of the immune effects associated with living near a hazardous waste site containing primarily organochlorine pesticides, underwent a skin test using the Multitest CMI skin test. Six of seven antigens were tested: tetanus toxoid, diphtheria toxoid, Candida, Tricophyton, Streptococcus, and Proteus. The tuberculin antigen was excluded. Lymphocyte function was also evaluated in vitro using standardized methods of mitogen stimulation with phytohemaglutinin (PHA), concanavalin A (CON-A), and pokeweed mitogen. RESULTS The frequency of positive responses to the skin tests was significantly (P < .001) higher among males (80.4%) than among females (55.7%). Males were more likely than females to respond to all six antigens tested (P < .05). The mean diameter of positive skin test measurements for males statistically significantly (P < .05) exceeded female responses for tetanus and diphtheria. Although not statistically significant, male response size exceeded that of females for all other antigens except Trycophyton. Controlling for age, race, smoking, income, and plasma DDE levels did not change these results. Skin test positivity was not associated with mitogen stimulation assay results overall or within gender groups. CONCLUSION Significant gender differences in response to the Multitest CMI skin test could limit its use as a marker of anergy in general population studies.

SELECTION AND USE OF VACCINES FOR HEALTHCARE WORKERS

Exposure to multiple infectious agents with the potential for disease acquisition is a well-recognized risk for healthcare workers (HCWs) .1-15 Important infectious risks may be classified by their route of transmission and include airborne (eg, tuberculosis, influenza, varicella, measles), droplet (eg, pertussis, meningococcal infection, respiratory syncytial virus), skin contact (eg, ectoparasites, Herpes simplex, colonization with methicillin-resistant Staphylococcus aureus); contact with feces (eg, salmonellosis, hepatitis A virus [HAAT], cryptosporidiosis); and parenteral or mucosal exposure to blood or contaminated body fluids (eg, hepatitis B, hepatitis C, human immunodeficiency virus). Minimizing the risk of disease acquisition is based on strict adherence to three key recommended interventions: handwashing,16 rapid institution of appropriate isolation precautions for patients with known or suspected communicable diseases,17 and appropriate immunizations. Other important occupational health interventions include an accessible health service; periodic tuberculin skin tests; evaluation of ill employees with potential communicable diseases, with appropriate treatment and work restrictions; evaluation of employees following infectious disease exposures for postexposure prophylaxis and work restrictions; and education of employees, focusing on general infection control guidelines in addition to Occupational Safety and Health Administration