Regression models for disease prevalence with diagnostic tests on pools of serum samples

Whether the aim is to diagnose individuals or estimate prevalence, many epidemiological studies have demonstrated the successful use of tests on pooled sera. These tests detect whether at least one sample in the pool is positive. Although originally designed to reduce diagnostic costs, testing pools also lowers false positive and negative rates in low prevalence settings and yields more precise prevalence estimates. Current methods are aimed at estimating the average population risk from diagnostic tests on pools. In this article, we extend the original class of risk estimators to adjust for covariates recorded on individual pool members. Maximum likelihood theory provides a flexible estimation method that handles different covariate values in the pool, different pool sizes, and errors in test results. In special cases, software for generalized linear models can be used. Pool design has a strong impact on precision and cost efficiency, with covariate-homogeneous pools carrying the largest amount of information. We perform joint pool and sample size calculations using information from individual contributors to the pool and show that a good design can severely reduce cost and yet increase precision. The methods are illustrated using data from a Kenyan surveillance study of HIV. Compared to individual testing, age-homogeneous, optimal-sized pools of average size seven reduce cost to 44% of the original price with virtually no loss in precision.

Impact of universal varicella vaccination on 1-year-olds in Uruguay: 1997-2005

OBJECTIVE

Varicella vaccination was introduced at the end of 1999 into the Uruguayan immunisation schedule for children aged 12 months. Varilrix (Oka strain; GlaxoSmithKline Biologicals) has been the only vaccine used since then and coverage has been estimated to exceed 90% since the start of the universal varicella vaccination programme. We assessed the impact of the Uruguayan varicella vaccination programme during 2005, 6 years after its introduction.

METHODS

Information on hospitalisations was collected from the main paediatric referral hospital and information on medical consultations for varicella was collected from two private health insurance systems in Montevideo. The proportion of hospitalisations due to varicella and the proportion of ambulatory visits for varicella since the introduction of the vaccine were compared between 1999 and 2005 and 1997 and 1999 in the following age groups: <1 year, 1-4 years, 5-9 years and 10-14 years.

RESULTS

By 2005, the proportion of hospitalisations due to varicella among children, was reduced by 81% overall and by 63%, 94%, 73% and 62% in the <1, 1-4, 5-9 and 10-14 years age groups, respectively. The incidence of ambulatory visits for varicella among children was reduced by 87% overall and by 80%, 97%, 81% and 65% in the <1, 1-4, 5-9 and 10-14 years age groups, respectively.

CONCLUSIONS

The burden of varicella has decreased substantially in Uruguayan children since the introduction of the varicella vaccination, including those groups outside the recommended vaccination age. It is expected to decrease further as more cohorts of children are vaccinated and herd immunity increases.

Enhancing vaccine safety surveillance: a capture-recapture analysis of intussusception after rotavirus vaccination

The Vaccine Adverse Event Reporting System (VAERS) is the passive reporting system for postmarketing surveillance of vaccine safety in the United States. The proportion of cases of an adverse event after vaccination that are reported to VAERS (i.e., VAERS reporting completeness) is mostly unknown. Therefore, the risk of such an event cannot be derived from VAERS only. To study whether its reporting sensitivity and risks could be estimated, VAERS was linked to data from a case-control and a retrospective cohort study in a capture-recapture analysis of intussusception after rotavirus vaccination (RV). Cases of intussusception after RV were selected from the common time frame (December 1998 through June 1999) and the common geographic area (19 states) of the three sources. Matching occurred on birth date, gender, state, date of vaccination, and date of diagnosis. Thirty-five matches were identified among a total of 84 cases. The estimated VAERS reporting completeness was 47%. The relative risks of intussusception in the periods 3-7 and 8-14 days after RV (relative risk = 22.7 and 4.4, respectively) were comparable with those reported in the two studies. Linkage of VAERS to complimentary data sources may permit more timely postmarketing assessment of vaccine safety.

Unusual cutaneous lesions in two patients with visceral leishmaniasis and HIV infection

Two HIV infected patients with visceral leishmaniasis and unusual cutaneous lesions are described. The first patient developed linear brown macules containing Leishmania parasites on the fingers and palms of the hands. This patient never received highly active antiretroviral treatment and the visceral leishmaniasis could not be cured even with liposomal amphotericin. In the second patient, Leishmania parasites were present in a skin biopsy of a fibrous histiocytoma. After completing visceral leishmaniasis treatment, a discrete elevation of one of his tattoos was seen. A biopsy specimen of this tattoo revealed Leishmania amastigotes. In this patient the visceral leishmaniasis was finally cured with meglumine antimoniate, followed by pentacarinat isothianate as maintenance therapy in conjunction with highly active antiretroviral treatment.

Reliability of the glenoid plane

HYPOTHESIS

The purpose of this study was to investigate the 3-dimensional (3-D) orientation of the glenoid and scapular planes. Different definitions of the glenoid plane were used and different planes measured, and we hypothesed that the 3-D plane with the least variation would be best to define the most reliable glenoid plane.

METHODS

We studied 150 CT scans from nonpathological shoulders from patients between 18 and 80. The scapular plane and 5 different glenoid planes were determined: inferior, anterior, posterior, superior, and neutral. All plane versions and inclination angles were measured. Because all examinations were done in a standardized position to the coronal, sagittal, and transverse planes of the body, the scapular plane could be defined versus the coronal, sagittal, and transverse planes of the body.

RESULTS

The version (mean, 3.76) of the inferior glenoid plane showed a significantly lower standard deviation than the version of the anterior (P < .001), posterior (P=.001), and superior (P=.001) glenoid plane (ANOVA). For inclination all planes have a similar variance. The scapular plane was different between gender (P=.022) and correlated with age.

CONCLUSION

This study showed that the retroversion of the inferior glenoid is reasonably constant. The osseous anthropometry of the inferior glenoid can offer a reproducible point of reference to be used in prosthetic surgery of the shoulder.

Lens-sparing vitrectomy with perfluorocarbon liquid for the primary treatment of giant retinal tears

PURPOSE

To evaluate the surgical success of vitrectomy without initial lensectomy in the primary treatment of retinal detachment associated with giant tears without proliferative vitreoretinopathy.

METHODS

Thirty-four consecutive phakic eyes with idiopathic giant retinal tears underwent vitrectomy, injection of perfluorocarbon liquid, endolaser, and gas tamponade. Encircling scleral buckling was performed in 14 of 34 patients. Preoperative visual acuity ranged from 20/25 to hand motions. Giant tear size ranged from 90 degrees to 330 degrees. Follow-up ranged from 10 to 64 months.

RESULTS

Anatomic retinal re-attachment was achieved intraoperatively in all eyes. The re-operation rate was 14% for eyes that underwent scleral buckling with the initial vitrectomy and 45% in eyes without primary scleral buckling. In 59% of eyes with cataract formation, 32% underwent cataract surgery with or without intraocular lens implantation. Best-corrected final visual acuity ranged from 20/15 to 20/400.

CONCLUSION

Most phakic eyes with giant retinal tear not associated with proliferative vitreoretinopathy can be re-attached successfully with initial preservation of the lens.

Neurological manifestations of acute posterior multifocal placoid pigment epitheliopathy

BACKGROUND

Acute posterior multifocal placoid pigment epitheliopathy (APMPPE) is a chorioretinal disease that causes acute visual symptoms with characteristic fundus findings. Although this entity has been associated with a variety of neurological complications, it has received little attention in the neurological literature. We wanted to emphasize the spectrum of neurological involvement, in particular the occurrence and management of strokes in patients with APMPPE.

CASE DESCRIPTIONS

We report three patients with APMPPE and neurological disease. All three presented with marked visual disturbances and headaches. One patient developed recurrent strokes involving different vascular territories of the brain and required immunosuppressive treatment for presumed cerebral vasculitis. The other two patients had cerebrospinal fluid pleocytosis and persistent headaches but recovered spontaneously. The review of the literature demonstrates a particular pattern of neurological complications in a subgroup of patients with APMPPE.

CONCLUSIONS

APMPPE should be considered among the causes of stroke and aseptic meningitis in young adults. The diagnosis is critically dependent on a thorough ophthalmologic examination. Severe neurological complications are difficult to predict at the onset of the ophthalmologic disease. The patients should be monitored closely. If investigations suggest cerebral vasculitis, immunosuppressive treatment may be helpful to prevent recurrences.

Recurrence of blackwater fever: triggering of relapses by different antimalarials

Five cases of blackwater fever (BWF) are described, all of whom had a history of recent quinine therapy. In two cases a second haemolytic crisis was induced by halofantrine, in one case also a third. Increasing frequency of this syndrome with its dramatic clinical presentation is to be expected as imported P. falciparum infection, parasite resistance to chloroquine and the use of quinine and other related antimalarials become more frequent.

Acute Schistosomiasis in Travelers Returning From Mali

Acute schistosomiasis or "Katayama syndrome" occurs in previously uninfected persons 3-6 weeks after exposure to cercaria-infested water.1,2 Many outbreaks among tourists have been reported.3-11 Such outbreaks occur because tourists are bathing or swimming in waters thought by tourist organizations to be bilharzial free. Imported schistosomiasis acquired in the Dogon country in Mali, West Africa, was first demonstrated in 1989 in three Spanish travelers;3 in 1991, an outbreak was described among Dutch travelers.7 In 1993, we investigated a similar outbreak among European and American travelers returning from the same area.

Pooling sera to reduce the cost of HIV surveillance: a feasibility study in a rural Kenyan district

Seroprevalence studies are crucial in HIV control programs but too expensive at district level. We evaluated the applicability of pooling sera and how it can reduce cost and affect accuracy at district level. 740 samples collected from antenatal clinic attendants for a sentinel survey in a rural Kenyan district were screened individually and in pools of 10. The seroprevalence when measured individually was 7.30%, while the calculated seroprevalence from pooled testing was 7.49%. Pooling was practicable and reduced costs by 62% for a marginal loss of accuracy. It is a useful tool in increasing the affordability of surveillance at district level. A pool size of 8 would have resulted in optimal cost reduction at minimal loss of accuracy.

The "automatic mode switch" function in successive generations of minute ventilation sensing dual chamber rate responsive pacemakers

Automatic mode switch (AMS) from DDDR to VVIR pacing is a new algorithm, in response to paroxysmal atrial tachyarrhythmias. With the 5603 Programmer, the AMS in the Meta DDDR 1250 and 1250H (Telectronics Pacings Systems, Inc.) operates when VA is shorter than the adaptable PVARP. With the 9600 Programmer, an atrial protection interval can be defined after the PVARP. The latest generation, Meta DDDR 1254, initiates AMS when 5 or 11 heart cycles are > 150, 175, or 200 beats/min. From 1990 to 1993, 61 patients, mean age 61 years, received a Meta DDDR: in 24 a 1250, in 12 a 1250H and in the remaining 25 a 1254 model. Indication for pacing was heart block in 39, sick sinus syndrome in 15, the combination in 6, and hypertrophic obstructive cardiomyopathy in 1. Paroxysmal atrial tachyarrhythmias were present in 43. All patients had routine pacemaker surveillance, including 52 Holter recordings. In 32 patients, periods of atrial tachyarrhythmias were observed, with proper AMS to VVIR, except during short periods of 2:1 block for atrial flutter in 4. In two others, undersensing of the atrial arrhythmia disturbed correct AMS. With the 1250 and 1250H model, AMS was observed on several occasions during sinus rate accelerations in ten patients. This was never seen with the 1254 devices. Final programmation was VVIR in 2 (chronic atrial fibrillation), AAI in 1 (fracture of the ventricular lead), VDDR in 1 (atrial pacing during atrial fibrillation), DDD in 5, and DDDR in 53, 48 of whom had AMS programmed on.(ABSTRACT TRUNCATED AT 250 WORDS)

Rocking-horse phenomenon of the glenoid component: the importance of inclination

BACKGROUND

Abnormal glenoid version positioning has been recognized as a cause of glenoid component failure caused by the rocking horse phenomenon. In contrast, the importance of the glenoid inclination has not been investigated.

MATERIALS AND METHODS

The computed tomography scans of 152 healthy shoulders were evaluated. A virtual glenoid component was positioned in 2 different planes: the maximum circular plane (MCP) and the inferior circle plane (ICP). The MCP was defined by the best fitting circle of the most superior point of the glenoid and 2 points at the lower glenoid rim. The ICP was defined by the best fitting circle on the rim of the inferior quadrants. The inclination of both planes was measured as the intersection with the scapular plane. We defined the force vector of the rotator force couple and calculated the magnitude of the shear force vector on a virtual glenoid component in both planes during glenohumeral abduction.

RESULTS

The inclination of the component positioned in the MCP averaged 95° (range, 84°-108°) and for the ICP averaged 111° (range, 94°-126°). A significant reduction in shear forces was calculated for the glenoid component in the ICP vs the MCP: 98% reduction in 60° of abduction to 49% reduction in 90° of abduction.

CONCLUSION

Shear forces are significantly higher when the glenoid component is positioned in the MCP compared with the ICP, and this is more pronounced in early abduction. Positioning the glenoid component in the inferior circle might reduce the risk of a rocking horse phenomenon.

Identification of Streptococcus pneumoniae in hospital-acquired pneumonia in adults

Hospital-acquired pneumonia (HAP) is often more severe and life-threatening than community-acquired pneumonia (CAP). The role of Streptococcus pneumoniae in CAP is well-understood, but its role in HAP is unclear. The objective of this study was to summarize the available literature on the prevalence of S. pneumoniae in HAP episodes. We searched MEDLINE for peer-reviewed articles on the microbiology of HAP in individuals aged ≥18 years, published between 2008 and 2018. We calculated pooled estimates of the prevalence of S. pneumoniae in episodes of HAP using a random-effects, inverse-variance-weighted meta-analysis. Forty-seven of 1908 articles met the inclusion criteria. Bacterial specimen isolation techniques for microbiologically defined HAP episodes included bronchoalveolar lavage, protective specimen brush, tracheobronchial aspirate and sputum, as well as blood culture. Culture was performed in all studies; five studies also used urine antigen detection (5/47; 10.6%). S. pneumoniae was identified in 5.1% (95% confidence interval (CI): 3.8-6.6%) of microbiologically defined HAP episodes (N = 20), with 5.4% (95% CI: 4.3-6.7%, N = 29) in ventilator-associated HAP and 6.0% (95% CI: 4.1-8.8%, N = 6) in non-ventilator-associated HAP. S. pneumoniae was identified in 5.3% (95% CI: 4.5-6.3%) of HAP occurring in the intensive care unit (ICU, N = 41) and in 5.6% (95% CI: 3.3-9.5%, N = 5) outside the ICU. A higher proportion of early-onset HAP (10.3%; 95% CI: 8.3-12.8%, N = 16) identified S. pneumoniae as compared with late-onset HAP (3.3%; 95% CI: 2.5-4.4%, N = 16). In conclusion, S. pneumoniae was identified by culture in 5.1% of microbiologically defined HAP episodes. The importance of HAP as part of the disease burden caused by S. pneumoniae merits further research.

Immunity to tetanus is protective against the development of multiple sclerosis

Following allegations that Hepatitis B vaccination causes or triggers multiple sclerosis (MS), several epidemiological studies have been conducted to evaluate the association between MS and vaccination. In one study conducted in the US, a significant protective effect on the development of MS was observed for tetanus immunization. We reviewed the medical literature and found two additional recent studies, as well as several older studies, which also observed a significant protective effect of tetanus immunization on the development or progression of MS. Furthermore, decreased humoral and cellular immunity to tetanus toxoid has been observed among MS patients. We postulate that naturally acquired or vaccine-induced immunity to tetanus has a protective effect against the development and progression of MS. We also postulate that this link to tetanus is in part responsible for the gender, age, geographic and socio-economic distribution of MS, as well as its pattern among migrants. The biological basis for this protective effect could be an unspecific boost of bystander suppression of auto-immunity as shown for other infections. Our hypothesis can be tested in several ways. The simplest approach would be to compare tetanus exposure and MS occurrence on a population level. Stronger support would come from the re-analysis of previous studies that have information at the individual level on both tetanus exposure, whether induced or natural, and on the development of MS. Laboratory evidence could be sought by testing the effect of tetanus toxoid on experimental allergic encephalomyelitis, the experimental animal model of MS.

Histoplasma capsulatum infection in three AIDS patients living in Africa

Three AIDS patients are reported, 2 European and 1 African. All 3 developed Histoplasma capsulatum infection while living in Africa. Two developed a pulmonary infiltrate, and 2 had skin lesions. One patient was successfully treated with itraconazole, 400 mg daily; in a second patient, itraconazole was partially successful; the third patient was lost to follow-up before adequate treatment could be started. Histoplasma infection is probably an often undiagnosed complication in African AIDS patients.

Prolonged monitoring for detection of symptomatic arrhythmias after slow pathway ablation in AV-nodal tachycardia

To study the incidence of symptoms and recurrences of AV-nodal re-entrant tachycardia (AVNT) after treatment with radio-frequency ablation of the slow pathway, event recording with transtelephonic transmission was performed for at least 3 weeks in 19 patients out of a series of 25. Follow-up with an implanted antitachycardia device was possible in two other patients, making the total number under continued surveillance 21/25. The period of monitoring was prolonged as complaints remained or became present after 1 month in eight patients. During a mean follow-up of 10 months, late recurrence of AVNT was observed in this way in 4/25 patients; they were submitted to a second procedure. Symptoms were present in many others and were explained by the recordings. Sinus tachycardia was recorded in three patients, intermittent AV-block of the first degree in another, and frequent atrial or ventricular premature beats in six patients. These minor arrhythmias tended to decrease over time. A coexistent atrial tachycardia was redetected in two patients. Thus, event recording is useful to distinguish recurrence of AVNT, sinus tachycardia, other types of supraventricular tachycardia, and atrial or ventricular premature beats, which all may be a reason of complaints during the first weeks after ablation. It provided a feeling of safety for symptomatic patients who often suffered from anxiety before the ablation.

Rhodococcus equi infection in 3 AIDS patients

Three cases of AIDS complicated by Rhodococcus equi infection are reported. At least one of the patients acquired his Rhodococcus infection in Africa. Despite the fact that the R. equi strains were susceptible to tetracycline, erythromycin, amikacin, co-trimoxazole, rifampicin and vancomycin, these antibiotics were clinically not successful. A clinical improvement was observed in only one patient during teicoplanin and imipenem-cilastatin treatment. Multicentre clinical trials are needed to determine the optimal treatment of R. equi infections in AIDS patients.

Safety of the Fiocruz ChAdOx COVID-19 vaccine used in a mass vaccination campaign in Botucatu, Brazil

INTRODUCTION

Brazil has been at the core of the COVID-19 pandemic, with the second-highest death toll worldwide. A mass vaccination campaign was initiated on May 16th, 2021, in Botucatu, Brazil, where two doses of ChadOx1-nCoV19 were offered 12 weeks apart to all 18-60- year-olds. This context offers a unique opportunity to study the vaccine safety during a mass campaign.

METHODS

The first and second doses of the vaccine were administered in May and August 2021, respectively. Emergency room (ER) and hospitalization records were obtained from the Hospital das Clínicas da Faculdade de Medicina de Botucatu for six weeks before and six weeks after the first and second doses, from 4 April to 19 September 2021. Diagnoses with COVID-19-related ICD codes were excluded to distinguish any trends resulting from the COVID-19 pandemic. ER and hospital visits during the two time periods were compared, including an ICD code comparison, to identify any changes in disease distributions. Data were scanned for a defined list of Adverse Events of Special Interest (AESIs), as presented by the Safety Platform for Emergency Vaccines.

RESULTS AND DISCUSSION

A total of 77,683 and 74,051 subjects received dose 1 and dose 2 of ChadOx1-nCoV19, respectively. Vaccination was well tolerated and not associated with any major safety concerns. Increases in ER visits 1 week following both doses were primarily seen in ICD codes related to non-serious side effects of the vaccine, including vaccination site pain and other local events. The neurological AESIs identified (2 of 3 cases of multiple sclerosis) were relapses of a pre-existing condition. One potentially serious hospitalization event for Bell's palsy had onset before vaccination with dose 1, in a patient who also had a viral infection of the central nervous system. There was no myocarditis, pericarditis cases, or vaccine-related increases in thromboembolic events.

A non-Hodgkin's lymphoma in a patient with HIV-2 infection

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Evaluation of two rapid hepatitis B surface antigen detection tests for screening in a blood bank

The sensitivity and specificity of two rapid, low cost latex agglutination HBsAg detection tests were compared to a EIA HBsAg detection test using serum samples from 371 pregnant women in Kajiado, a rural Kenyan district. The sensitivity of the latex agglutination tests when compared to the EIA was 70.6% and 61.8%, while specificity was 92.0% and 85.2% respectively for the same tests. In view of their low sensitivity these rapid tests are not suitable for screening blood in district hospitals.