Usefulness of the electrocardiogram in diagnosing mechanisms of tachycardia.

The electrocardiogram, despite its simplistic technological composition, remains a valuable tool in the diagnosis of pediatric arrythmias. In this article the characteristic features of different tachycardias are reviewed.

US policy for disease control among imported nonhuman primates.

In 1990, in response to the occurrence of Ebola virus (subsequently identified as subtype Reston) infection among cynomolgus monkeys imported from the Philippines, the United States implemented strict disease control measures for handling nonhuman primates during transit and quarantine and initiated importer facility compliance inspections. Disease control measures emphasized protection of workers from exposure, use of containment facilities and procedures, measures to prevent spread of infection among animals, and laboratory testing of animals that die or become ill during quarantine. From 1991-1995, no outbreaks of filovirus infection occurred, and only one other disease outbreak (caused by Mycobacterium species) was recognized. In April 1996, Ebola virus (subtype Reston) infection was identified in another group of cynomolgus monkeys imported from the Philippines. The disease control measures implemented since the first Ebola virus (subtype Reston) outbreak appeared to work well. Currently, the 27 registered importer facilities import approximately 8500 nonhuman primates annually, and mortality rates are <1.0%. Importer facilities receive regular inspections, and compliance with disease control measures and disease reporting is excellent.

Tuberculosis among foreign-born persons in Los Angeles County, 1992-1994.

OBJECTIVES: To describe the epidemiology of foreign-born tuberculosis (TB) cases in Los Angeles County and to evaluate current TB screening and follow-up of immigrants and refugees (I&R) to the USA. DESIGN: Retrospective analysis of the Los Angeles County TB registry between October 1992 and December 1994. We matched all cases who entered the USA during fiscal year 1993 (FY93) with a database from the tracking system of I&R with suspected TB. RESULTS: Foreign-born persons accounted for 64% of all reported TB cases. Half were born in Mexico or Central America. Standardized incidence rates were 3-5 times higher than those of US-born persons for Mexicans and Central Americans, 6-7 times higher for North-east Asians, and 10-15 times higher for South-east Asians. Among foreign-born cases who arrived during FY93, 5% of the Mexicans and Central Americans, 48% of the North-east Asians and 67% of the South-east Asians were registered by the tracking system. CONCLUSION: Mexicans and Central Americans accounted for the majority of cases but had a lower incidence of TB than Asians. The current screening procedures identify a large proportion of cases among recently arrived South-east Asians, but contribute little to the control of TB among Mexicans and Central Americans.

Overseas screening for tuberculosis in immigrants and refugees to the United States: current status.

The number of reported cases of tuberculosis (TB) in foreign-born persons in the United States during 1995 was 8,042, 36% of the national total. The overseas screening of immigrants and refugee visa applicants, which relies on a chest radiograph and smear microscopy, is designed to identify future U.S. residents who have active TB or who are at high risk for TB. In this commentary, we summarize current policies and review retrospective evaluations of the screening system currently in place. The system appears to detect most persons who have active TB at the time of screening. However, active TB is actually diagnosed in < 15% of persons who are identified by screening as having suspected TB and who are evaluated in the United States. To improve the system, more sensitive and specific techniques as well as improved means of data transmission to state and local health departments are needed.

Tuberculosis screening for immigrants and refugees. Diagnostic outcomes in the state of Hawaii.

The effectiveness of the required overseas tuberculosis (TB) screening for immigrants and refugees to the United States has not been evaluated since new guidelines were introduced in 1991. Using data from the Hawaii State TB register for 1992-1993, patient records, and data from the U.S. government notifications of suspect TB among aliens, we determined the percentage of persons either classified as having active TB (B1), inactive TB (B2), or considered "normal" overseas, who were evaluated and subsequently diagnosed with active TB within 1 yr of arrival in the United States. Of the 124 TB cases among immigrants and refugees evaluated within 1 yr of arrival, 78 (63%) had been classified overseas as B1, 17 (14%) as B2, and 29 (23%) as "normal." The proportion of TB cases diagnosed after arrival in the United States was 14.0% for B1s and 2.1% for B2s. This proportion decreased with increasing age. A positive skin test was a strong predictor (OR: 10.7; 95% CI: 1.4-80.1) of culture-confirmed TB. These data document that immigrants and refugees with B1 and B2 TB status have a high prevalence of active TB. They should be promptly evaluated after arrival in the United States to determine the need for curative or preventive therapy.

Surveillance for pneumonic plague in the United States during an international emergency: a model for control of imported emerging diseases.

In September 1994, in response to a reported epidemic of plague in India, the Centers for Disease Control and Prevention (CDC) enhanced surveillance in the United States for imported pneumonic plague. Plague information materials were rapidly developed and distributed to U.S. public health officials by electronic mail, facsimile, and expedited publication. Information was also provided to medical practitioners and the public by recorded telephone messages and facsimile transmission. Existing quarantine protocols were modified to effect active surveillance for imported plague cases at U.S. airports. Private physicians and state and local health departments were relied on in a passive surveillance system to identify travelers with suspected plague not detected at airports. From September 27 to October 27, the surveillance system identified 13 persons with suspected plague; no case was confirmed. This coordinated response to an international health emergency may serve as a model for detecting other emerging diseases and preventing their importation.

Influenza--United States, 1988-89.

PROBLEM/CONDITION: CDC monitors the emergence and spread of new influenza virus variants and the impact of influenza on morbidity and mortality annually from October through May. REPORTING PERIOD COVERED: This report covers United States influenza surveillance conducted from October 1988 through May 1989. DESCRIPTION OF SYSTEM: Weekly reports from the vital statistics offices of 121 cities provided an index of influenza's impact on mortality; 58 WHO collaborating laboratories reported weekly identification of influenza viruses; weekly morbidity reports were received both from the state and territorial epidemiologists and from 153 sentinel family practice physicians. Nonsystematic reports of outbreaks and unusual illnesses were received throughout the year. RESULTS: During the 1988-89 influenza season, influenza A (H1N1) and B viruses were identified in the United States with essentially equal frequency overall, although both regional and temporal patterns of predominance shifted over the course of the season. Throughout the season increases in the indices of influenza morbidity in regions where influenza B predominated. Only 7% of identified viruses were influenza A (H3N2), but not isolations of this subtype increased as the season waned and it subsequently predominated during the 1989-90 season. During the 1988-89 season outbreaks in nursing homes were reported in association with influenza B and A (H3N2), but not influenza A (H1N1). INTERPRETATION: The alternating temporal and geographic predominance of influenza strains A (H1N1) and B during the 1988-89 season emphasizes the importance of continual attention to regional viral strain surveillance, since amantadine is effective only for treatment and prophylaxis of influenza A. ACTIONS TAKEN: Weekly interim analyses of surveillance data produced throughout the season allow physicians and public health officials to make informed choices regarding appropriate use of amantadine. CDC's annual surveillance allows the observed viral variants to be assessed as candidates for inclusion as components in vaccines used in subsequent influenza seasons.

Influenza--United States, 1989-90 and 1990-91 seasons.

During the 1989-90 influenza season, 98% of all influenza viruses isolated in the United States and reported to CDC were influenza A. Almost all those that were antigenically characterized were similar to influenza A/Shanghai/11/87(H3N2), a component of the 1989-90 influenza vaccine. Regional and widespread influenza activity began to be reported in late December 1989, peaked in mid-January 1990, and declined rapidly through early April 1990. Most of the outbreaks reported to CDC were among nursing-home residents. Considerable influenza-associated mortality was reflected in the percentage of deaths due to pneumonia and influenza (P&I) reported through the CDC 121 Cities Surveillance System from early January through early April. More than 80% of all reported P&I deaths were among persons greater than or equal to 65 years. In contrast to the predominance of influenza A during 1989-90, during the 1990-91 influenza season 86% of all influenza virus isolations reported were influenza B. Widespread influenza activity was reported from mid-January through April 1991, with regional activity extending into May. Outbreaks were reported primarily among schoolchildren, and no evidence of excess influenza-associated mortality was found. Almost all the influenza B isolates tested were related to influenza B/Yamagata/16/88, a component of the 1990-91 influenza vaccine, but were antigenically closer to B/Panama/45/90, a minor variant.

Illness in hemodialysis patients after exposure to chloramine contaminated dialysate.

In September 1987, patients at an outpatient dialysis center were exposed to chloramine contaminated dialysate when the carbon filter in a recently modified water treatment system failed. Forty-one patients required transfusion to treat the resultant hemolytic anemia. Epidemiologic investigation demonstrated that the mortality rate among dialysis center patients increased during the 5 months after chloramine exposure when compared with the 12 months before chloramine exposure, but no deaths could be attributed to the exposure. Chloramine is commonly used as a disinfectant in municipal water supplies, and has previously been reported to cause hemolytic anemia in patients undergoing dialysis. Hemodialysis centers in cities that use chloramine in water supplies must design water treatment systems with adequate means for removing chloramine and must monitor processed water closely to ensure that chloramine contamination does not occur. Dialysis centers that make changes in their water processing systems should evaluate all components of the system before changes are made, and must ensure that after modifications are made, processed water meets the standards set by the Association for Advancement of Medical Instrumentation.

Swine influenza virus infections. Transmission from ill pigs to humans at a Wisconsin agricultural fair and subsequent probable person-to-person transmission.

In September 1988, a previously healthy 32-year-old pregnant woman was hospitalized for pneumonia and died 8 days later. The only pathogen detected was an influenza virus antigenically related to the swine influenza virus (SIV). Four days before illness onset, the patient visited a county fair swine exhibition where there was widespread influenzalike illness among the swine. To detect other persons who were possibly infected by contact with the ill swine, we measured serum SIV hemagglutination-inhibition antibody titer in 25 swine exhibitors who were 9 to 19 years old. Nineteen (76%) had SIV hemagglutination-inhibition titers of 20 or greater. Antibody was undetectable in serum samples from 25 swine exhibitors from a neighboring county. Additional studies suggest that one to three health care personnel who had contact with the patient developed influenzalike illnesses with laboratory evidence of SIV infection. An outbreak of apparent SIV infection in swine resulted in multiple human infections, and, although no recognized community outbreak resulted, there was evidence of virus transmission from the patient to health care personnel.

Sepsis associated with transfusion of red cells contaminated with Yersinia enterocolitica.

Between April 1987 and May 1989, the Centers for Disease Control investigated seven cases of transfusion-associated Yersinia enterocolitica sepsis; four were caused by organisms of serotype O:3, and one each was caused by organisms of serotype O:1,2,3; O:5,27; and O:20. All seven recipients developed septic shock after receiving units of red cells (RBCs) contaminated with Y. enterocolitica; five recipients died. The cases occurred in seven states and were unrelated. There was no evidence for contamination of the RBC units during processing. Six of the seven donors had serologic evidence of recent Y. enterocolitica infection, and it is hypothesized that these donors had asymptomatic bacteremia when they donated the implicated blood. Four of the seven donors reported gastrointestinal illness in the 4 weeks before blood donation, and one donor became ill on the day he donated blood. Y. enterocolitica grows well at 4 degrees C and in the presence of dextrose and iron. If blood is contaminated at the time of collection, storage of the RBCs at 4 degrees C provides an ideal environment for bacterial growth and endotoxin production. These cases demonstrate the need for careful evaluation of patients with transfusion reactions for possible sepsis and suggest a need to screen prospective blood donors for mild gastrointestinal illness, including those illnesses not requiring physician evaluation or medication.

Growth and endotoxin production of Yersinia enterocolitica and Enterobacter agglomerans in packed erythrocytes.

Since 1987, the Centers for Disease Control investigated six cases of transfusion-associated sepsis. All six patients developed septic shock after receiving units of packed erythrocytes (PRBCs) contaminated with Yersinia enterocolitica (five patients) and Enterobacter agglomerans (one patient); three of the blood recipients died. We studied the growth and endotoxin production of Y. enterocolitica and E. agglomerans in units of PRBCs stored at 4 degrees C for 60 days. When PRBCs were inoculated with 0.1 to 1.0 CFU of these organisms per ml, both Y. enterocolitica and E. agglomerans entered log-phase growth 2 to 3 weeks after inoculation; generation times were 15 and 22 h, respectively. Endotoxin was first detected at 3 weeks following inoculation, and the concentration paralleled the log phase of growth of the strains tested. These data show that prolonged storage of PRBCs at 4 degrees C provides conditions that allow these two organisms to grow and subsequently produce high concentrations of endotoxin.

Effect of pressure loading, volume loading and surgery on left ventricular chamber and myocardial stiffness in congenital heart disease, with a reevaluation of normal pediatric values.

This study assessed the effect of pressure load, volume load and surgery on left ventricular chamber stiffness (b) and myocardial stiffness (k). A normal range for chamber stiffness and myocardial stiffness was also established. A total of 44 patients were studied: 8 were control subjects, 12 had volume load and 24 had pressure load. At cardiac catheterization simultaneous high fidelity pressures (P) and left ventricular volumes (V) were obtained in one diastolic cycle. From the relation P = aVb, operant chamber stiffness (b) was estimated for each patient. Similarly, the relation between stress (sigma) and radius (B) was approximated by sigma = cBf and the myocardial stiffness (k) derived for each patient. Mean values for chamber or myocardial stiffness for the diagnostic groups were not significantly different but differed within the operative groups. Mean values for b and k were greater in the post-open heart surgery group than in the post-closed heart surgery or nonsurgical group. Although the mean values for chamber stiffness and myocardial stiffness for the diagnostic groups were not different, there were more abnormal patients in the pressure load group (9 of 24) than in the volume load group (2 of 8) when the normal range was obtained from the control group. Thus, left ventricular operant chamber and myocardial stiffness are often preserved with volume loading, less frequently with pressure loading and rarely after open heart surgery.

Clinical and echocardiographic evidence suggesting afterload reduction as a mechanism of action of tolazoline in neonatal hypoxemia.

The effect of tolazoline was assessed in 29 hypoxic neonates. Tolazoline was given in a bolus starting at 1 mg/kg and repeated or infused for 5-134 hours. A "good clinical response," defined as a rise in PaO2 of more than 20 mm Hg, was obtained in 23 (79%), 20 of this group were weaned from the respirator, and three died. Six infants did not respond initially and four died. Failure to respond to tolazoline or to be weaned from the ventilator was usually associated with severe additional pathology. Urine output (greater than 1 ml/kg/h) was adequate in most neonates during therapy. In those with preexisting oliguria (less than 1 ml/kg/h), output improved during therapy. Blood pressure monitoring showed a fall in blood pressure in 19 patients during tolazoline administration, but true hypotension only occurred in four; in seven there was no fall and in three there was a rise in blood pressure. Echocardiography was performed prior to therapy in 19 patients and repeated in 12 patients after 24 h. Additional "tracking" was performed at 10 min, 1 h, and 4 h in seven patients. Prior to therapy, right ventricular dysfunction was demonstrated by abnormal right ventricular systolic time intervals (RVSTIs) in 17 of the patients tested. A rapid improvement was evident during therapy especially with "tracking." Left ventricular dysfunction, assessed by left ventricular systolic time intervals (LVSTIs), ejection fraction (EF), shortening fraction (SF), and velocity of circumferential fiber shortening (VCF), was also evident prior to therapy and improved, though more gradually than the RVSTIs.(ABSTRACT TRUNCATED AT 250 WORDS)

Chlamydia pneumonia in infants: radiography in 125 cases.

Chlamydia trachomatis was recently discovered to be the causative organism in a distinctive afebrile pneumonia occurring in infants under 6 months of age. Experience with the first 125 cases seen at this hospital during a 3 1/2 year period is reported. Chest radiographs were reviewed of 2,273 infants in this age group with signs of lower respiratory tract infection. The first group comprised 148 patients admitted to the hospital. Chlamydia pneumonia was diagnosed in 41 cases. The second group of 2,125 infants was first seen in the outpatient department where 84 additional cases were detected. From this experience it was concluded that, although there are no radiographic findings specific for Chlamydia pneumonia, a combination of the clinical and radiographic findings strongly suggests the diagnosis before cultures and serum antibody titers are available. Important clinical features include age of onset at 2-14 weeks of age, cough, lack of fever, and elevated serum immunoglobulins. Most chest films show bilateral hyperexpansion and diffuse infiltrates with a variety of radiographic patterns including interstitial, reticular nodular, atelectasis, coalescence, and bronchopneumonia. Pleural effusion and lobar consolidation are not seen. The radiographic changes often suggest a more serious illness than that observed clinically. Radiographic features are described in detail.

Clinical characteristics of the afebrile pneumonia associated with Chlamydia trachomatis infection in infants less than 6 months of age.

Respiratory tract colonization with Chlamydia trachomatis commonly occurs in natally acquired chlamydial infection and is sometimes associated with a chronic, afebrile pneumonia that has relatively distinctive clinical characteristics. To further define the frequency and clinical characteristics of lower respiratory tract disease associated with C trachomatis, we grouped 56 infants aged less than 6 months with afebrile pneumonia according to nasopharyngeal shedding of Chlamydia and viruses and compared their illnesses. Forty-one (73%) were positive for C trachomatis (23 had C trachomatis only, while 18 had C trachomatis plus a virus [cytomegalovirus, respiratory synctial virus, adenovirus, rhinovirus, or enterovirus]), and 15 were C trachomatis negative (nine had a virus only, and six had neither C trachomatis nor virus). The 41 infants with C trachomatis alone or C trachomatis plus a virus were similar clinically and differed significantly from other infants in several ways: (1) onset of symptoms before 8 weeks of age; (2) gradually worsening symptoms; (3) presentation for care at 4 to 11 weeks of age; (4) presence of conjunctivitis and ear abnormalities; (5) chest roentgenograms showing bilateral, symmetrical, interstitial infiltrates and hyperexpansion; (6) peripheral blood eosinophils greater than or equal to 300/cu mm; and (7) elevated values for serum immunoglobulins M, G, and A. Pediatrics 63:192--197, 1979, Chlamydia trachomatis, pneumonia, afebrile pneumonia, interstitial pneumonia.

Treatment of chlamydial pneumonia of infancy.

Infants with untreated chlamydial pneumonia shed Chlamydia trachomatis and are symptomatic for may weeks. We used sulfisoxazole, 150 mg/kg/day, or erythromycin ethyl succinate, 40 mg/kg/day, for approximately 14 days to treat 32 patients with chlamydial pneumonia of infancy, and observed them for nasopharyngeal shedding of C trachomatis and changing clinical status. All infants stopped shedding chlamydiae soon after treatment was started. After treatment, three of the 25 infants tested again became culture positive (but did not have clinical relapse). All infants improved clinically. In 24 (83%) of 29 infants, where the onset of improvement could be times, improvement began within seven days of starting treatment. Progression to complete recovery was observed in 27 of 28 infants examined between two weeks and two months of treatment completion. Neither the existence of concomitant viral infection nor the duration of illness or hospitalization before starting treatment influenced the interval between initiation of treatment and onset of clinical improvement. While these observations do not prove, they are at least compatible with the hypotheses that C trachomatis plays a central etiologic role in this illness and that termination of chlamydial infection is beneficial clinically. Pending the availibility of data from controlled studies, we believe that either of the treatment programs outlined warrant consideration in the clinical management of patients with chlamydial pneumonia of infancy.