The dengue and dengue hemorrhagic fever epidemic in Puerto Rico, 1994-1995.

From June 1, 1994 to May 31, 1995 a total of 24,700 cases of dengue (7.01/1,000 population) were reported to the laboratory-based surveillance system in Puerto Rico (1991-1994, annual average: 2.55/1,000). Dengue virus 2 predominated. The earliest indicator of epidemic activity was the virus isolation rate in May 1994 (14.0% versus 5.7% average). The male-to-female ratio among cases was 1:1.1; 65.4% were younger than 30 years (the 10 to 19 year age group had the highest incidence, 11.8/1,000). At least 5,687 cases (23.0%) showed a hemorrhagic manifestation; 4,662 (18.9%) were hospitalized, and 40 died (0.2%; 10 laboratory-positive). Two cases documented by laboratory were transmitted by unusual routes--intrapartum and through a bone marrow transplant. Among 2,004 hospitalized cases reported by infection control nurses, 139 (6.9%) fulfilled the criteria for dengue hemorrhagic fever (DHF) and another 13 cases (0.6%) had dengue shock syndrome. This epidemic produced the largest number of hospitalizations, DHF cases, and deaths from any dengue epidemic in Puerto Rico. Severity did not change throughout the year. Surveillance capabilities were maintained by temporary, simplified reporting methods, none of which could be recommended as the single method of choice for surveillance; each must be used (on site, or as a service available from a reference laboratory) at the right time in the epidemic cycle. The utility of comparisons of current and previous data underscores the value of long-term surveillance. Our analysis was unable to document whether significantly increased transmission occurred more often in cities where the water supply was rationed or where the local landfill was closed.     

Epidemic dengue fever in Puerto Rico, 1977: a cost analysis

During the period July-December 1977, a widespread epidemic of dengue fever occurred in Puerto Rico. The cost of the epidemic was calculated, using upper and lower limit incidence figures, in terms of direct costs (medical care and epidemic control measures) and indirect costs (lost production of ill workers and parents of ill children). Direct costs were estimated to range between $2.4 and $4.7 million. Indirect costs were calculated by using current (1977) employment and wage data and population extrapolations from the 1970 census, and entailed a loss to the Puerto Rico economy of from $3.7 to $10.9 million. The total cost of this epidemic, therefore, was estimated to be in a range of $6.0 to $15.6 million, of which epidemic control measures comprised 7.8--20.2%.     

Assessment of dengue risk in relief workers in Puerto Rico after Hurricane Georges, 1998

Health risk assessment is important in the safe deployment of workers to tropical areas. We monitored dengue incidence in 204 of 222 North American relief workers visiting Puerto Rico after Hurricane Georges and during a dengue epidemic in 1998. We recorded information regarding participants' living conditions and any illness they experienced from arrival to 2 weeks after their departure. Virus isolation, polymerase chain reaction, and serological tests for anti-dengue immunoglobulin (Ig) M and IgG antibodies were used to diagnose dengue infection by means of departure and follow-up serum specimens. Among respondents, 82% (164 of 199) reported mosquito bites, 97% (156 of 161) reported having insect repellent available, and 41% (79 of 195) reported using repellent every day. Twelve participants reported a mild denguelike illness. No participants had laboratory evidence of dengue infection after 1.8 person-years of assessable exposure to areas with dengue transmission (upper 95% confidence limit of 1.67 cases per person-year). The risk of acquiring dengue among relief workers in this study appears low, possibly as a result of protective factors. Travelers to dengue-endemic areas should continue to be advised to protect themselves against mosquito bites.     

Community-based dengue prevention programs in Puerto Rico: impact on knowledge,behavior, and residential mosquito infestation

Dengue is a major health burden in Puerto Rico. Televised public service announcements and posters, elementary and pre-school educational programs, and an exhibit at the Children's Museum in Old San Juan were evaluated separately using knowledge and practices surveys administered to children and their parents, surveys of house lots for larval container habitats, focus groups, and interviews with program organizers and participants. Exposure to the programs was associated with increased dengue-related knowledge, increased proportion of tires protected from rain, decreased proportion of water storage containers positive for mosquito larvae, and increased indoor use of aerosol insecticides. Exposure to the elementary school program was associated with slightly lower indices of residential mosquito infestation. The programs have resulted in high levels of awareness, some behavior change, and limited change in larval indices. Greater emphasis on the skills necessary for community members to keep containers free of mosquito larvae would increase program effectiveness.     

The epidemiology of tuberculosis in patients with AIDS in Puerto Rico: morbidity and survival, 1981-1998.

SETTING: Puerto Rico. OBJECTIVE: To describe the characteristics and survival experience of AIDS patients with tuberculosis (TB) from 1981 through 1998. DESIGN: A population based study using the AIDS Surveillance System, including survival analysis. RESULTS: During the period studied, 1000 AIDS cases were reported with TB, representing 4.3% of total cases. Of these, males accounted for 82.1%, and 84% were diagnosed with pulmonary TB. Approximately 71% of the cases were reported as having died. AIDS cases who were intravenous drug users (IDU) accounted for 63.7% of the cases. The median survival of AIDS/TB cases was 21.4 months, and did not differ by sex or TB site (P > 0.05). IDUs with TB had a longer survival than IDUs with other AIDS-defining conditions; however, AIDS/TB cases with a CD4 count < 200/mm3 had a poorer survival (23.4 months) than those with a count of > or = 200/mm3 (47.9 months). CONCLUSIONS: The overall prevalence of TB in AIDS patients in Puerto Rico is low compared with other countries. As in other studies, the variable that explained poorer survival among AIDS/TB cases was the CD4+ lymphocyte count. Further prospective studies regarding survival in the Hispanic population are needed to confirm these findings.     

Seroepidemiology of schistosomiasis in Puerto Rico: evidence for vanishing endemicity.

The current study summarizes our findings of anti-schistosome egg antibody by the circumoval precipitin test for two different populations in Puerto Rico. One group, exclusively males more than 40 years of age and from all municipalities on the island, was from the Veterans Administration Hospital for the period 1988-1997. The second group resided southeast of San Juan, around the municipality of Caguas and adjacent municipalities east of Caguas, was of both sexes and mostly until 1997 of undetermined ages for the period 1993-1997. Results reveal a yearly decrease in testing requests from the Veterans Administration Hospital from 148 in 1988 and 1989 with 16% positive to three in 1996 through 1998 with none positive. This decrease in testing requests was because of a decrease of suspicion of schistosomiasis in this group. The other patient population from the Caguas region showed a gradual but continuous decrease in seropositive individuals from 21% in 1993 to 12% in 1996, with precipitous decrease to 5% in 1997 and only 1% in 1998. Moreover, there were four patients from which at least two serum samples were obtained one or two years apart and tested. In each instance the more recently obtained sample had lower antibody reactions than the first as reflected in lower percentages of positive egg reactors. The fact that they were treated with praziquantel after the first testing also suggests that the infected population was being eliminated through chemotherapy. These combined results suggest the elimination of infections with Schistosoma mansoni in the traditionally high prevalence regions east of San Juan in the absence of any proactive control efforts in Puerto Rico. Because of the rapid urbanizing of Puerto Rico, the one identifiable control effort is economic development and well being.     

Dengue outbreaks in Guánica-Ensenada and Villalba, Puerto Rico, 1972-1973.

Epidemics of dengue fever occurring in Puerto Rico in 1963 to 1964 and 1969 were caused by dengue-3 and dengue-2 (DN-2) viruses, respectively, but endemic dengue transmission has never been documented on the Island. Since the 1969 epidemic, a surveillance system has detected DN-2 activity on the Island during each of the years 1970 through 1973, which suggests endemic persistence of the virus. This report describes the investigation of localized outbreaks of DN-2 in Guanica-Ensenada (1972) and Villalba (1973), and presents epidemiological, serological, and virological data from the outbreaks. Analysis of geographic distribution of dengue activity in Puerto Rico in recent years indicates that the DN-2 transmission in 1970 to 1973 may represent a long tail-off of the 1969 epidemic rather than the emergence of a truly endemic situation.     

Schistosomiasis control in Puerto Rico: twenty-five years of operational experience.

A program to control schistosomiasis in Puerto Rico was initiated in 1953, using limited chemotherapy and snail control by environmental, biological and chemical means. At the same time, extensive programs of water supply, health education, and free latrine distribution were underway throughout the island. The impact of the program was evaluated initially by examinations of fecal samples from first-grade children until 1966, and subsequently by island-wide surveys using adult worm antigen for skin test on fifth-graders in 1963, 1969, and 1976. There was a decrease in the proportion of children reacting positively to the skin test from 24% in 1963 to 5% in 1976. The decrease in the proportion of positive skin test reactions was one and a half times as great in the area under snail control as in the rest of the endemic area, and most of the decrease outside the snail control program was due to improved water supply. Calibration tests indicated a decrease in prevalence among the entire population, if determined by multiple fecal exams, from 15% in 1963 to less than 4% in 1976. Thus the estimated number of persons passing eggs in Puerto Rico was about 100,000 in 1976, in a population of 3 million. The cost of snail control was minimized by emphasizing environmental and biological methods, showing that the disease can be controlled on a large scale with simple techniques. Eradication of the parasite from Puerto Rico is quite likely in the next few years with the advent of the new drug, oxamniquine, and would be a cheaper strategy than continued snail control.     

Hospital based clinical surveillance for dengue haemorrhagic fever in Bandung, Indonesia 1994-1995

In Indonesia, by law dengue haemorrhagic fever (DHF) cases must be reported within 24 h to the district health authority. The objective of this study was to evaluate the adequacy, accuracy and reporting delay of this reporting system. In four major hospitals of the city of Bandung, medical records of hospitalised DHF cases admitted between April 1994 and March 1995 were reviewed. This list of DHF cases was compared with the list of reported cases to the Bandung Municipality Health Office. During the study period, 569 DHF cases and 81 dengue shock syndrome (DSS) cases were diagnosed. Only 199 (31%) of the 650 hospitalised cases with suspected DHF/DSS were reported to the Bandung Municipality Health Office. The percentage of fatal cases was significantly lower among all hospitalised cases 11/650 (1.7%) than among reported cases 5/199 (2.5%). In only 443 of the 583 hospitalised cases (76%) in which a dengue serological test was performed, was this test positive. Of the 199 reported DHF/DSS cases 151 (76%) had a positive haemagglutination inhibition test. This study shows that the surveillance system for DHF/DSS in Bandung should be strengthened. DHF/DSS cases should be reported on the basis of a diagnosis made during hospitalisation preferably after a serological confirmation is obtained.     

Crohn's disease incidence in Cardiff from 1930: an update for 1991-1995

OBJECTIVE: To report the incidence of Crohn's disease in the city of Cardiff between 1991 and 1995, in relation to the data of the preceding 65 years. METHODS: The incidence of Crohn's disease was studied by collecting information from clinical records, the department of pathology database and a questionnaire sent to local family practitioners. RESULTS: Eighty-four new patients with Crohn's disease, and resident in Cardiff, were diagnosed between 1991 and 1995. The mean incidence for this quinquennium was 56 cases per 10(6) population per year (95% confidence interval, 44-68). There was a female predominance, particularly in young adults, with an overall male to female ratio of 0.47. Colorectal disease was the most common site of disease at the time of diagnosis. CONCLUSIONS: In relation to the findings of our previous studies, the data suggest that the overall incidence of Crohn's disease is now stable, but that the proportion with colorectal disease continues to increase and there is a marked female preponderance in Crohn's disease presenting in young people.     

Spatiotemporal analysis of epizootic raccoon rabies propagation in Connecticut, 1991-1995

The quantitative analysis of pathogen transmission within its specific spatial context should improve our ability to predict and control the epizootic spread of that disease. We compared two methods for calibrating the effect of local, spatially distributed environmental heterogeneities on disease spread. Using the time-of-first-appearance of raccoon rabies across the 169 townships in Connecticut, we estimated local spatial variation in township-to-township transmission rate using Trend Surface Analysis (TSA) and then compared these estimates with those based on an earlier probabilistic simulation using the same data. Both the probabilistic simulation and the TSA reveal significant reduction in transmission when local spatial domains are separated by rivers. The probabilistic simulation suggested that township-to-township transmission was reduced sevenfold for townships separated by a river. The global effect of this sevenfold reduction is to increase the time-to-first-appearance in the eastern townships of Connecticut by approximately 29.7% (spread was from west to east). TSA revealed a similar effect of rivers with an overall reduction in rate of local propagation due to rivers of approximately 22%. The 7.7% difference in these two estimates reveals slightly different aspects of the spatial dynamics of this epizootic. Together, these two methods can be used to construct an overall picture of the combined effects of local spatial variation in township-to-township transmission on patterns of local rate of propagation at scales larger than the immediate nearest neighboring townships.     

Epidemiological and clinical observations on patients with dengue in Puerto Rico: results from the first year of enhanced surveillance--June 2005-May 2006

From June 2005 to May 2006, a clinic-based enhanced surveillance system for dengue was implemented in a Puerto Rican municipality to provide a population-based measure of disease incidence and clinical outcomes. We obtained demographic and clinical information from suspected cases and performed serologic and virologic testing. We used World Health Organization (WHO) criteria to classify cases and applied a simplified case definition for severe dengue illness. There were 7.7 laboratory-positive cases of dengue per 1,000 population. The highest incidence, 13.4 per 1,000, was among 10 to 19 year olds. Of the 156 laboratory-positive cases, three patients (1.9%) met WHO criteria for dengue hemorrhagic fever, and 30 patients (19.2%) had at least one severe clinical manifestation of dengue infection. Our data suggest that in a community with endemic dengue, enhanced surveillance is useful for detecting symptomatic infections. Furthermore, the simplified case definition for severe dengue may be useful in clinic-based surveillance.