Leptospirosis among patients presenting with dengue-like illness in Puerto Rico.

Leptospirosis is difficult to distinguish from dengue fever without laboratory confirmation. Sporadic cases/clusters of leptospirosis occur in Puerto Rico, but surveillance is passive and laboratory confirmation is rare. We tested for leptospirosis using an IgM ELISA on sera testing negative for dengue virus IgM antibody and conducted a case-control study assessing risk factors for leptospirosis, comparing clinical/laboratory findings between leptospirosis (case-patients) and dengue patients (controls). Among 730 dengue-negative sera, 36 (5%) were positive for leptospirosis. We performed post mortem testing for leptospirosis on 12 available specimens from suspected dengue-related fatalities; 10 (83%) tested positive. Among these 10 fatal cases, pulmonary hemorrhage and renal failure were the most common causes of death. We enrolled 42 case-patients and 84 controls. Jaundice, elevated BUN, hyperbilirubinemia, anemia, and leukocytosis were associated with leptospirosis (p < .01 for all). Male sex, walking in puddles, rural habitation, and owning horses were independently associated with leptospirosis. Epidemiological, clinical, and laboratory criteria may help distinguish leptospirosis from dengue and identify patients who would benefit from early antibiotic treatment.

Early detection and response to meningococcal disease epidemics in sub-Saharan Africa: appraisal of the WHO strategy.

OBJECTIVE: To assess the sensitivity, specificity and predictive value positive of the WHO threshold strategy for detecting meningococcal disease epidemics in sub-Saharan Africa and to estimate the impact of the strategy on an epidemic at district level. METHODS: Data on meningitis cases at the district level were collected weekly from health ministries, WHO country and regional offices, and nongovernmental organizations in countries where there were epidemics of meningococcal disease in 1997. An epidemic was defined as a cumulative district attack rate of at least 100 cases per 100,000 population from January to May, the period of epidemic risk. The sensitivity, specificity and predictive value positive of the WHO threshold rate were calculated, and curves of sensitivity against (1 - specificity) were compared with alternatively defined threshold rates and epidemic sizes. The impact of the WHO strategy on a district epidemic was estimated by comparing the numbers of epidemic cases with cases estimated to have been prevented by vaccination. FINDINGS: An analysis was made of 48 198 cases reported in 174 districts in Benin, Burkina Faso, the Gambia, Ghana, Mali, Niger, and Togo. These cases were 80.3% of those reported from Africa to WHO during the 1997 epidemic period. District populations ranged from 10,298 to 573,908. The threshold rate was crossed during two consecutive weeks in 69 districts (39.7%) and there were epidemics in 66 districts (37.9%). Overall, the sensitivity of the threshold rate for predicting epidemics was 97%, the specificity was 95%, and the predictive value positive was 93%. Taken together, these values were equivalent or better than the sensitivity, specificity and predictive value positive of alternatively defined threshold rates and epidemics, and remained high regardless of district size. The estimated number of potential epidemic cases decreased by nearly 60% in the age group targeted for vaccination in one district where the guidelines were followed in a timely manner. CONCLUSION: The use of the WHO strategy was sensitive and specific for the early detection of meningococcal disease epidemics in countries of sub-Saharan Africa during 1997 and had a substantial impact on a district epidemic. Nevertheless, the burden of meningococcal disease in these countries remains formidable and additional control measures are needed.

Risk factors for acute symptomatic coccidioidomycosis among elderly persons in Arizona, 1996-1997.

Because of the increase in incidence of coccidioidomycosis among the elderly in Arizona between 1990 and 1996, a case-control study was conducted to look at risk factors for disease among these persons. Cases (n=89) were persons aged > or =60 years with laboratory-confirmed coccidioidomycosis; 2 control groups were selected, the first by use of random-digit dialing (geographic controls, n=91) and the second by use of lists of persons with negative serologic coccidioidomycosis tests (laboratory-negative controls, n=58). Elderly persons with coccidioidomycosis had spent significantly less time in Arizona than did persons in either control group and were more likely than geographic controls to have congestive heart failure or cancer, to have smoked, or to have taken corticosteroids. Elderly persons who recently have moved to Arizona or who have chronic illnesses and their physicians need to be aware of their higher risk for coccidioidomycosis in order to improve their chances of early diagnosis and treatment. These persons may benefit from vaccination, once an effective vaccine for coccidioidomycosis is developed.

An outbreak of acute bartonellosis (Oroya fever) in the Urubamba region of Peru, 1998.

During May 1998, we conducted a case-control study of 357 participants from 60 households during an outbreak of acute bartonellosis in the Urubamba Valley, Peru, a region not previously considered endemic for this disease. Blood and insect specimens were collected and environmental assessments were done. Case-patients (n = 22) were defined by fever, anemia, and intra-erythrocytic coccobacilli seen in thin smears. Most case-patients were children (median age = 6.5 years). Case-patients more frequently reported sand fly bites than individuals of neighboring households (odds ratio [OR] = 5.8, 95% confidence interval [CI] = 1.2-39.2), or members from randomly selected households > or = 5 km away (OR = 8.5, 95% CI = 1.7-57.9). Bartonella bacilliformis isolated from blood was confirmed by nucleotide sequencing (citrate synthase [g/tA], 338 basepairs). Using bacterial isolation (n = 141) as the standard, sensitivity, specificity, and positive predictive value of thin smears were 36%, 96%, and 44%, respectively. Patients with clinical syndromes compatible with bartonellosis should be treated with appropriate antibiotics regardless of thin-smear results.

Vasopressin levels and pediatric head trauma.

The syndrome of inappropriate secretion of antidiuretic hormone is associated with head trauma; however, there are no reports concerning vasopressin levels in pediatric patients with head trauma. Urine vasopressin in eight children (mean +/- SEM, age 7.5 +/- 1.6 years, range 1 to 15 years) was measured by radioimmunoassay during their hospitalization for head trauma. Urine vasopressin values for ten healthy children (mean age 5.4 +/- 1.3 years) and for eight children hospitalized for systemic antibiotic treatment of infections (age 5.9 +/- 1.8 years) also were obtained. Urine vasopressin, urine and serum sodium concentration and osmolality, urea nitrogen, creatinine, and fluid intake were measured within 24 hours of admission and daily for the following two days. For the first three days following head trauma, mean urine vasopressin levels in pediatric patients with head trauma were increased (P less than .05) compared with those of healthy children. Despite fluid restriction to 85% of maintenance level, 25% of patients with head trauma exhibited the clinical syndrome of inappropriate secretion of antidiuretic hormone (hyponatremia, increased urinary sodium, diminished serum osmolality, and urine osmolality greater than serum osmolality). Urine osmolality greater than 800 mosm/kg was associated with markedly increased urine vasopressin levels (200 to 1,650 pg/mL); children with this finding may be at particular risk for the syndrome of inappropriate secretion of anti-diuretic hormone without restrictive water intake.