Ecological surveillance for West Nile in Catalonia (Spain), learning from a five-year period of follow-up

To enhance early detection of West Nile virus (WNV) transmission, an integrated ecological surveillance system was implemented in Catalonia (north-eastern Spain) from 2007 to 2011. This system incorporated passive and active equine surveillance, periodical testing of chicken sentinels in wetland areas, serosurveillance wild birds and testing of adult mosquitoes. Samples from 298 equines, 100 sentinel chickens, 1086 wild birds and 39 599 mosquitoes were analysed. During these 5 years, no acute WNV infection was detected in humans or domestic animal populations in Catalonia. WNV was not detected in mosquitoes either. Nevertheless, several seroconversions in resident and migrant wild birds indicate that local WNV or other closely related flaviviruses transmission was occurring among bird populations. These data indicate that bird and mosquito surveillance can detect otherwise silent transmission of flaviviruses and give some insights regarding possible avian hosts and vectors in a European setting.

An outbreak of primary pneumonic tularemia on Martha's Vineyard

BACKGROUND

In the summer of 2000, an outbreak of primary pneumonic tularemia occurred on Martha's Vineyard, Massachusetts. The only previously reported outbreak of pneumonic tularemia in the United States also occurred on the island in 1978.

METHODS

We conducted a case-control study of adults with pneumonic tularemia and investigated the environment to identify risk factors for primary pneumonic tularemia. Patients with confirmed cases were residents of or visitors to Martha's Vineyard who had symptoms suggestive of primary pneumonic tularemia, were ill between May 15 and October 31, 2000, and had a positive laboratory test for tularemia. Controls were adults who had spent at least 15 days on Martha's Vineyard between May 15 and September 28, 2000.

RESULTS

We identified 15 patients with tularemia; 11 of these cases were primary pneumonic tularemia. Francisella tularensis type A was isolated from blood and lung tissue of the one man who died. Patients were more likely than controls to have used a lawn mower or brush cutter in the two weeks before the illness or before an interview, for controls (odds ratio, 9.2; 95 percent confidence interval, 1.6 to 68.0) and during the summer (odds ratio, undefined; 95 percent confidence interval, 1.8 to infinity). Lawn mowing and brush cutting remained significant risk factors after adjustment for other potentially confounding variables. Only one patient reported being exposed to a rabbit while cutting brush. Of 40 trapped animals, 1 striped skunk (Mephitis mephitis) and 1 Norway rat (Rattus norvegicus) were seropositive for antibodies against F. tularensis.

CONCLUSIONS

Study of this outbreak of primary pneumonic tularemia implicates lawn mowing and brush cutting as risk factors for this infection.

Epidemic West Nile encephalitis, New York, 1999: results of a household-based seroepidemiological survey

BACKGROUND

In the summer of 1999, West Nile virus was recognised in the western hemisphere for the first time when it caused an epidemic of encephalitis and meningitis in the metropolitan area of New York City, NY, USA. Intensive hospital-based surveillance identified 59 cases, including seven deaths in the region. We did a household-based seroepidemiological survey to assess more clearly the public-health impact of the epidemic, its range of illness, and risk factors associated with infection.

METHODS

We used cluster sampling to select a representative sample of households in an area of about 7.3 km(2) at the outbreak epicentre. All individuals aged 5 years or older were eligible for interviews and phlebotomy. Serum samples were tested for IgM and IgG antibodies specific for West Nile virus.

FINDINGS

677 individuals from 459 households participated. 19 were seropositive (weighted seroprevalence 2.6% [95% CI 1.2-4.1). Six (32%) of the seropositive individuals reported a recent febrile illness compared with 70 of 648 (11%) seronegative participants (difference 21% [0-47]). A febrile syndrome with fatigue, headache, myalgia, and arthralgia was highly associated with seropositivity (prevalence ratio 7.4 [1.5-36.6]). By extrapolation from the 59 diagnosed meningoencephalitis cases, we conservatively estimated that the New York outbreak consisted of 8200 (range 3500-13000) West Nile viral infections, including about 1700 febrile infections.

INTERPRETATION

During the 1999 West Nile virus outbreak, thousands of symptomless and symptomatic West Nile viral infections probably occurred, with fewer than 1% resulting in severe neurological disease.

Surveillance for Lyme disease--United States, 1992-1998

PROBLEM/CONDITION

Lyme disease is caused by infection with the spirochete Borrelia burgdorferi and is the most commonly reported vector-borne disease in the United States. Borrelia burgdorferi is transmitted to humans by infected Ixodes scapularis and I. pacificus ticks. Lyme disease is typically evidenced in its early stage by a characteristic rash (erythema migrans), accompanied by nonspecific symptoms (e.g., fever, malaise, fatigue, headache, myalgia, and arthralgia). Lyme disease can usually be treated successfully with standard antibiotic regimens.

REPORTING PERIOD

1992-1998.

DESCRIPTION OF SYSTEM

Lyme disease surveillance data are reported to CDC through the National Electronic Telecommunication System for Surveillance, a computerized public health database for nationally notifiable diseases. During 1992-1998, data regarding reported cases of Lyme disease included county and state of residence, age, sex, and date of onset. Descriptive analyses were performed, and cumulative incidence by state, county, age group, and sex were calculated.

RESULTS

During 1992-1998, a total of 88,967 cases of Lyme disease was reported to CDC by 49 states and the District of Columbia, with the number of cases increasing from 9,896 in 1992 to 16,802 in 1998. A total of 92% of cases was reported from eight northeastern and mid-Atlantic states and two north-central states. Children aged 5-9 years and adults aged 45-54 years had the highest mean annual incidence.

INTERPRETATION

Lyme disease is a highly focal disease, with the majority of reported cases occurring in the northeastern and north-central United States. The number of reported cases of Lyme disease increased during 1992-1998. Geographic and seasonal patterns of disease correlate with the distribution and feeding habits of the vector ticks, I. scapularis and I. pacificus.

PUBLIC HEALTH ACTION

The results presented in this report will help clinicians evaluate the prior probability of Lyme disease and provide the framework for targeting human Lyme disease vaccine use and other prevention and treatment interventions.

Assessing the prevention effectiveness of local Lyme disease control

The effectiveness of any public health intervention is determined by its theoretical efficacy and by the level of engagement of the target population. A computer simulation model and basic epidemiologic concepts were used to estimate the effectiveness of interventions for preventing Lyme disease in a hypothetical community. The process for estimating numbers of Lyme disease cases prevented by each intervention is described. This assessment compares the effectiveness of alternative community-based prevention strategies, illuminates the limitations and distributive effects of interventions, and helps clarify available prevention options for community residents.

Health status of pediatric refugees in Portland, ME

BACKGROUND

An understanding of the health conditions affecting pediatric refugees is essential to providing responsible health care for them when they arrive in the United States.

OBJECTIVE

To assess the health status of pediatric refugees in an area of increased refugee resettlement.

DESIGN

Retrospective medical records review.

SETTING

Ambulatory clinic at Maine Medical Center in Portland, a community and referral hospital.

PATIENTS

One hundred thirty-two refugees and immigrants aged 2 months through 18 years who had initial health care evaluations during 1994 and 1995.

RESULTS

Sixty-six patients arrived from Africa, 22 from the former Yugoslavia, and the remainder from the former Soviet Union, Middle Asia, Southeast Asia, and Latin America. The mean age of the patients was 10 years; 56 (42.4%) were female. The overall health status of most of the children was good, with most having appropriate weight and height for age. Dental caries and dermatologic conditions were the most prevalent findings on physical examination. Two patients had evidence of traumatic injuries. The results of tuberculin (Mantoux) tests were positive (> or =10 mm) in 45 (35.2%) of 128 children for whom results were noted, hepatitis B surface antigen was detected in 5 (4.0%) of 124 children, and hepatitis B surface antibody was detected in 26 (21.1%) of 123 children. Five (16.7%) of 30 children younger than 6 years had elevated blood lead levels; anemia was detected in 25 (19.7%) of 127 children with hematocrit results available. Stool specimens were obtained from 87 patients, of whom 38 (43.7%) had pathogenic parasites in at least 1 specimen.

CONCLUSIONS

Pediatric refugees arrive in the United States with a variety of conditions that may be unfamiliar to practitioners trained in this country. The results of this study support the screening of refugees from Africa and other regions for tuberculosis, stool parasites, and hepatitis B.

Chronic disease mortality in Maine: assessing the targets for prevention

From 1982 through 1991, nine chronic diseases accounted for over 55 percent of deaths in Maine. Using the lowest age-specific death rates as theoretically achievable rates, there were over 8,000 excess deaths. Over 25,000 deaths could be attributed to preventable causes over the 10-year period. Cigarette smoking was the single largest contributor to chronic disease mortality, accounting for 17,688 deaths, followed by physical inactivity, high blood pressure, and diet. This assessment provides a measure of the size of the chronic disease prevention target in Maine and is a first step in assessing the potential impact of prevention programs.

Development of a screening tool for prediction of children at risk for lead exposure in a midwestern clinical setting

OBJECTIVE

Universal screening for childhood lead poisoning is becoming quite common, with many states having legislation requiring screening. We set out to determine whether a questionnaire could be used to identify children at risk for exposure to lead to determine whether selective screening of those at risk was possible.

METHODS

Parents of 370 children 12 to 36 months of age having well-child examinations completed a questionnaire and their children were screened by a fingerstick capillary blood lead test at two clinics.

RESULTS

Of patients from clinic A, 5.4% had lead levels > or = 10 micrograms/dL compared with 16.8% of those from clinic B (P < .001). This difference between clinics could not be explained by the demographic characteristics of the patients or by differences in their potential exposures to lead. We evaluated the five questions suggested by Centers for Disease Control and Prevention for anticipatory guidance for their ability to identify children with elevated blood lead levels. In clinic A, this instrument had a sensitivity of 76.9% and a negative predictive value of 96.5%. In clinic B, it had a sensitivity of 63.6% and a negative predictive value of 81.4%. Based on an assessment of significant items from a large questionnaire, we determined five questions that were the best predictors of risk. On the basis of this risk assessment, 100% of the children from clinic A with elevated lead levels and 90.9% of the children from clinic B with elevated lead levels were classified as being at "high risk." Had this risk assessment been used as an initial screen in this sample, 40% of the patients from clinic A and 37% of the patients from clinic B would not have been screened with a blood lead test, because they were classified as being at "low risk."

CONCLUSIONS

Results of this study suggest that there is great variability in the prevalence of elevated lead levels and potential risks between clinics within a fairly homogeneous community; however, selective screening with a community-specific questionnaire may be feasible if the prevalence is low and the risks to the population are known.

Long-term trends in blood lead levels among children in Chicago: relationship to air lead levels

OBJECTIVES

To evaluate trends in blood lead levels among children in Chicago from 1968 through 1988, and to determine the impact of the changes in the Centers for Disease Control and Prevention (CDC) blood lead level of concern.

METHODS

We reviewed a systematic sample of blood lead screening records of the Chicago Department of Health Laboratory for high-risk children aged 6 months to 5 years. Median blood lead levels for each quarter of the years 1974 through 1988 were determined and regressed against mean air lead levels recorded at air-monitoring stations in Chicago during the same period.

RESULTS

Median blood lead levels declined from 30 micrograms/dL in 1968 to 12 micrograms/dL in 1988, and were strongly associated with declining average air lead levels (r = .8, P < .001) from 1974 through 1988. A regression model using log-transformed data predicted a decline of 0.56 microgram/dL in the median blood lead level with each 0.1 microgram/m3 decline in the mean air lead level when the air lead level was near 1.0 microgram/m3; the predicted slope was steeper at lower air lead levels. Despite the nearly 20-fold reduction in air lead levels, the median blood lead level of 12 micrograms/dL in 1988 indicates substantial continuing lead exposure. The CDC blood lead level of concern was lowered twice from 1968 to 1988, but due to the decline in blood lead levels, fewer than 30% of the children were above the level of concern throughout most of the study.

CONCLUSION

Although substantial lead exposure persists in Chicago, reductions in airborne lead emissions seem to have contributed to a long-term decline in the median blood lead level of high-risk Chicago children.

Dengue and dengue hemorrhagic fever

Hundreds of thousands of dengue cases are reported worldwide each year. Given the difficulty in obtaining full reporting, the actual number of human infections is probably much higher than the number reported. Dengue is usually a nonspecific febrile illness that resolves with supportive therapy but the clinical spectrum ranges from asymptomatic infection through severe hemorrhage and sudden fatal shock. The pathophysiology of the severe forms of dengue may be related to sequential infection with different serotypes, variations in virus virulence, interaction of the virus with environmental and host factors or a combination of these factors. Control of dengue at the present time is dependent on control of the principal vector mosquito, A. aegypti. Efforts to achieve such control are now focusing on community education and action towards eliminating this mosquito's breeding sites near human dwellings. Vaccine development continues, but at present the only way to avoid dengue in an area where it is endemic or epidemic is to use repellents and mosquito barriers. The movement of people to and from tropical areas makes dengue an important differential diagnosis in any patient with an acute illness and history of recent travel to tropical areas. Because of continued infestation of the southeastern United States with A. aegypti, indigenous transmission in the continental United States remains a public health concern.

Large community outbreak of cryptosporidiosis due to contamination of a filtered public water supply

Between January 12 and February 7, 1987, an outbreak of gastroenteritis affected an estimated 13,000 people in a county of 64,900 residents in western Georgia. Cryptosporidium oocysts were identified in the stools of 58 of 147 patients with gastroenteritis (39 percent) tested during the outbreak. Studies for bacterial, viral, and other parasitic pathogens failed to implicate any other agent. In a random telephone survey, 299 of 489 household members exposed to the public water supply (61 percent) reported gastrointestinal illness, as compared with 64 of 322 (20 percent) who were not exposed (relative risk, 3.1; 95 percent confidence interval, 2.4 to 3.9). The prevalence of IgG to cryptosporidium was significantly higher among exposed respondents to the survey who had become ill than among nonresident controls. Cryptosporidium oocysts were identified in samples of treated public water with use of a monoclonal-antibody test. Although the sand-filtered and chlorinated water system met all regulatory-agency quality standards, sub-optimal flocculation and filtration probably allowed the parasite to pass into the drinking-water supply. Low-level cryptosporidium infection in cattle in the watershed and a sewage overflow were considered as possible contributors to the contamination of the surface-water supply. We conclude that current standards for the treatment of public water supplies may not prevent the contamination of drinking water by cryptosporidium, with consequent outbreaks of cryptosporidiosis.

Respiratory syncytial virus outbreak on American Samoa. Evaluation of risk factors

Acute respiratory illness is one of the leading causes of childhood mortality in developing nations. We investigated an increase in hospitalizations of children less than 2 years old for severe lower respiratory tract illness (LRI) from October 1986 through December 1986 on the island of American Samoa. Hospitalization rates were highest in children less than 6 months of age (60 of 1000 compared with 22 of 1000 for those 6 to 11 months of age, and seven of 1000 for those 12 to 24 months of age). The outbreak was more severe than in previous years, with ten (19%) of 54 patients admitted to the intensive care unit (ICU) compared with three (7%) of 42 and one (3%) of 40 during the same months of 1985 and 1984. Two patients died. Most patients had clinical bronchiolitis; of 34 patients tested, serologic or nasal aspirate evidence of recent respiratory syncytial virus (RSV) infection was found in 18 (53%). A study of patients younger than 1 year of age demonstrated that patients hospitalized with LRI were more likely to have a household member who smoked cigarettes (18/20, 90%) than outpatient controls without recent respiratory illness (8/15, 53%). Maternal sera obtained between December 1985 and October 1986 showed no protective effect of either detectable IgG or neutralizing antibody to two major groups of RSV. Our study documents the involvement of RSV in an outbreak of severe LRI among infants in a tropical area and further suggests that exposure to cigarette smoke is a risk factor for LRI infants.

Unexplained febrile illnesses after exposure to ticks. Infection with an Ehrlichia?

The Ehrlichia are tick-borne rickettsial organisms that cause disease in animals throughout the world but that have been previously recognized as human pathogens only in Asia. We have identified six patients with serological evidence of recent infection with an Ehrlichia: a fourfold or greater rise or fall in titer to Ehrlichia canis. All of the patients reported recent tick bites. Rigors, myalgia, headache, nausea, and anorexia were each reported by five patients. Fever was present in all patients and was accompanied by relative bradycardia and leukopenia in five patients, thrombocytopenia and abnormal liver function test results in four, and anemia in three. Five of the six patients were treated with tetracycline hydrochloride, and all recovered. Infection with Ehrlichia should be considered in patients with unexplained febrile illnesses after tick exposure.