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Biomedical subjects

P Reiter

Publications and source records attributed to P Reiter.

At least 37 records · Page 2Linked to original sources
PubMed1999

Field investigations of an outbreak of Ebola hemorrhagic fever, Kikwit, Democratic Republic of the Congo, 1995: arthropod studies.

During the final weeks of a 6-month epidemic of Ebola hemorrhagic fever in Kikwit, Democratic Republic of the Congo, an extensive collection of arthropods was made in an attempt to learn more of the natural history of the disease. A reconstruction of the activities of the likely primary case, a 42-year-old man who lived in the city, indicated that he probably acquired his infection in a partly forested area 15 km from his home. Collections were made throughout this area, along the route he followed from the city, and at various sites in the city itself. No Ebola virus was isolated, but a description of the collections and the ecotopes involved is given for comparison with future studies of other outbreaks.

Adult↗
PubMed1999

Absence of impact of aerial malathion treatment on Aedes aegypti during a dengue outbreak in Kingston, Jamaica.

During an outbreak of dengue fever in Jamaica from October to December 1995, a study was carried out to determine the impact of aerial ultra-low volume malathion treatment on adult Aedes aegypti. This was done by monitoring oviposition rates of the vector in three urban communities in Kingston and by exposing caged mosquitoes both directly and indirectly to the aerial malathion treatment. The insecticide was delivered at a rate of 219 mL/ha between 7:10 a.m. and 8:45 a.m. The results of the study clearly showed that the insecticide application was ineffective in interfering with Aedes aegypti oviposition, and adult mosquitoes held in cages inside dwellings were largely unaffected. Consequently, this type of intervention seemed to have little significant impact in arresting or abating dengue transmission.

Aedes↗
PubMed1998

Dengue and dengue haemorrhagic fever.

The incidence and geographical distribution of dengue have greatly increased in recent years. Dengue is an acute mosquito-transmitted viral disease characterised by fever, headache, muscle and joint pains, rash, nausea, and vomiting. Some infections result in dengue haemorrhagic fever (DHF), a syndrome that in its most severe form can threaten the patient's life, primarily through increased vascular permeability and shock. The case fatality rate in patients with dengue shock syndrome can be as high as 44%. For decades, two distinct hypotheses to explain the mechanism of DHF have been debated-secondary infection or viral virulence. However, a combination of both now seems to be the plausible explanation. The geographical expansion of DHF presents the need for well-documented clinical, epidemiological, and virological descriptions of the syndrome in the Americas. Biological and social research are essential to develop effective mosquito control, medications to reduce capillary leakage, and a safe tetravalent vaccine.

Dengue↗
PubMed1998

Exploratory space-time analysis of reported dengue cases during an outbreak in Florida, Puerto Rico, 1991-1992.

The spatial and temporal distributions of dengue cases reported during a 1991-1992 outbreak in Florida, Puerto Rico (population = 8,689), were studied by using a Geographic Information System. A total of 377 dengue cases were identified from a laboratory-based dengue surveillance system and georeferenced by their residential addresses on digital zoning and U.S. Geological Survey topographic maps. Weekly case maps were generated for the period between June and December 1991, when 94.2% of the dengue cases were reported. The temporal evolution of the epidemic was rapid, affecting a wide geographic area within seven weeks of the first reported cases of the season. Dengue cases were reported in 217 houses; of these 56 (25.8%) had between two and six reported cases. K-function analysis was used to characterize the spatial clustering patterns for all reported dengue cases (laboratory-positive and indeterminate) and laboratory-positive cases alone, while the Barton and David and Knox tests were used to characterize spatio-temporal attributes of dengue cases reported during the 1991-1992 outbreak. For both sets of data significant case clustering was identified within individual households over short periods of time (three days or less), but in general, the cases had spatial pattern characteristics much like the population pattern as a whole. The rapid temporal and spatial progress of the disease within the community suggests that control measures should be applied to the entire municipality, rather than to the areas immediately surrounding houses of reported cases. The potential for incorporating Geographic Information System technologies into a dengue surveillance system and the limitations of using surveillance data for spatial studies are discussed.

Adolescent↗
PubMed1998

Using disability-adjusted life years to assess the economic impact of dengue in Puerto Rico: 1984-1994.

This study presents the disability-adjusted life years (DALYs), a non-monetary economic measure of impact, lost to dengue in Puerto Rico for the period 1984-1994. Data on the number of reported cases, cases with hemorrhagic manifestations, hospitalizations, and deaths were obtained from a surveillance system maintained at the Dengue Branch, Division of Vector-Borne Infectious Diseases, Centers for Disease Control and Prevention (San Juan, PR). The reported cases were divided into two age groups (0-15 years old and >15 years old), and then multiplied by predetermined factors (10 for 0-15 years; 27 for >15 years) to allow for age-related under-reporting of cases. Severity of dengue was modeled by classifying cases into three groups: dengue fever, dengue with severe manifestations, and hospitalized cases. Each group was assigned a different number of days lost because of dengue-related disability. Dengue caused an average of 658 DALYs per year per million population (SE = 114, range = 145-1,519). A multivariate sensitivity analysis, which simultaneously altered the values of six input variables, produced a mean of 580 DALYs/year/million population, with a maximum average of 1,021 DALYs/year/million population, and a maximum, single-year estimate for 1994 of 2,153 DALYs/million population. The most important input was the number of days lost to classic dengue. The DALYs/year/million population lost to dengue in Puerto Rico are much greater than previous estimates concerning the impact of dengue hemorrhagic fever alone. The loss to dengue is similar to the losses per million population in the Latin American and Caribbean region attributed to any of the following diseases or disease clusters; the childhood cluster (polio, measles, pertussis, diphtheria, tetanus), meningitis, hepatitis, or malaria. The loss is also of the same order of magnitude as any one of the following: tuberculosis, sexually transmitted diseases (excluding human immunodeficiency virus), tropical cluster (e.g., Chagas' disease, leishmaniasis), or intestinal helminths. The results objectively suggest that when governments and international funding agencies allocate resources for research and control, dengue should be given a priority equal to many other infectious diseases that are generally considered more important.

Adolescent↗
PubMed1998

First recorded outbreak of yellow fever in Kenya, 1992-1993. I. Epidemiologic investigations.

Outbreaks of yellow fever (YF) have never been recorded in Kenya. However, in September 1992, cases of hemorrhagic fever (HF) were reported in the Kerio Valley to the Kenya Ministry of Health. Early in 1993, the disease was confirmed as YF and a mass vaccination campaign was initiated. Cases of suspected YF were identified through medical record review and hospital-based disease surveillance by using a clinical case definition. Case-patients were confirmed serologically and virologically. We documented 55 persons with HF from three districts of the Rift Valley Province in the period of September 10, 1992 through March 11, 1993 (attack rate = 27.4/100,000 population). Twenty-six (47%) of the 55 persons had serologic evidence of recent YF infection, and three of these persons were also confirmed by YF virus isolation. No serum was available from the other 29 HF cases. In addition, YF virus was isolated from a person from the epidemic area who had a nonspecific febrile illness but did not meet the case definition. Five patients with confirmed cases of YF died, a case-fatality rate of 19%. Women with confirmed cases of YF were 10.9 times more likely to die than men (P = 0.010, by Fisher's exact test). Of the 26 patients with serologic or virologic evidence of YF, and for whom definite age was known, 21 (81%) were between 10 and 39 years of age, and 19 (73%) were males. All patients with confirmed YF infection lived in rural areas. There was only one instance of multiple cases within a single family, and this was associated with bush-clearing activity. This was the first documented outbreak of YF in Kenya, a classic example of a sylvatic transmission cycle. Surveillance in rural and urban areas outside the vaccination area should be intensified.

Adolescent↗
PubMed1998

First recorded outbreak of yellow fever in Kenya, 1992-1993. II. Entomologic investigations.

The first recorded outbreak of yellow fever in Kenya occurred from mid-1992 through March 1993 in the south Kerio Valley, Rift Valley Province. We conducted entomologic studies in February-March 1993 to identify the likely vectors and determine the potential for transmission in the surrounding rural and urban areas. Mosquitoes were collected by landing capture and processed for virus isolation. Container surveys were conducted around human habitation. Transmission was mainly in woodland of varying density, at altitudes of 1,300-1,800 m. The abundance of Aedes africanus in this biotope, and two isolations of virus from pools of this species, suggest that it was the principal vector in the main period of the outbreak. A third isolate was made from a pool of Ae. keniensis, a little-known species that was collected in the same biotope. Other known yellow fever vectors that were collected in the arid parts of the valley may have been involved at an earlier stage of the epidemic. Vervet monkeys and baboons were present in the outbreak area. Peridomestic mosquito species were absent but abundant at urban sites outside the outbreak area. The entomologic and epidemiologic evidence indicate that this was a sylvatic outbreak in which human cases were directly linked to the epizootic and were independent of other human cases. The region of the Kerio Valley is probably subject to recurrent wandering epizootics of yellow fever, although previous episodes of scattered human infection have gone unrecorded. The risk that the disease could emerge as an urban problem in Kenya should not be ignored.

Adolescent↗
PubMed1998

Aedes albopictus and the world trade in used tires, 1988-1995: the shape of things to come?

In the decade since used tires were identified as the mode of introduction of Aedes albopictus to the United States, similar infestations have been reported from 10 other countries in the Americas and 2 in Europe. Millions of used tires are still being traded throughout the world and although a few governments have implemented inspection procedures to prevent further introductions, these are unlikely to be effective. Further introductions of mosquitoes of potential public health significance are inevitable.

Aedes↗
PubMed1998

Introduction and establishment of Aedes (Stegomyia) albopictus skuse (Diptera: Culicidae) in Albania.

In August-October 1979, infestations of the mosquito Aedes albopictus were discovered at a number of widely separated sites in Albania. Used tires were the principal larval habitat. The species was probably introduced from China in the mid-1970s. The initial infestation was probably at a rubber factory adjacent to the port of Durrës (Durazzo), from where the mosquito was shipped in tires to recapping plants in other parts of the country. This is the first recorded infestation of Ae. albopictus outside Oriental and Australasian regions.

Aedes↗
PubMed1996

Population genetics with RAPD-PCR markers: the breeding structure of Aedes aegypti in Puerto Rico.

RAPD-PCR polymorphisms at 57 presumptive loci were used to examine the breeding structure of the mosquito Aedes aegypti in Puerto Rico. Mosquitoes were sampled from 16 locations in six cities and samples were located in a nested spatial design to examine local patterns of gene flow. Allele frequencies were estimated assuming (1) that genomic regions amplified by RAPD-PCR segregate as dominant alleles, (2) that genotypes at RAPD loci are in Hardy-Weinberg proportions, (3) identity in state (iis) among dominant amplified alleles and (4) iis among null alleles. The average genic heterozygosity was 0.354, more than twice the level detected in earlier allozyme surveys. Nested analysis of variance indicated extensive genetic differentiation among locations within cities. Effective migration rates (Nm) among cities were estimated from FST assuming an island model of migration. Estimates of Nm ranged from 9.7 to 12.2 indicating a high dispersal rate. The large number of polymorphisms revealed by RAPD-PCR allowed the distribution of FST and linkage disequilibrium to be examined among loci and demonstrated that small samples inflate FST and linkage disequilibrium. No linkage disequilibrium maintained through epistasis was detected among alleles at the 57 loci.

Aedes↗
PubMed1996

[Oviposition and dispersion of Aedes aegypti in an urban environment].

It is generally accepted that female Aedes aegypti do not fly more than 50-100 m in their entire lifetime, yet the rapidity with which this species colonizes new areas, and the explosive nature of dengue and yellow fever epidemics appear to contradict this. Using molecular methods, we have confirmed that the Ae. aegypti females lay small numbers of eggs at many sites. The distribution of available sites implies that the female may fly a considerable distance to deposit her whole egg batch. We developed a method of monitor dispersal during oviposition by labelling the eggs of the mosquito with rubidium, a relatively rare, non-radioactive element. Eggs laid by females fed in the laboratory on blood containing rubidium were collected in the field with ovitraps and assayed by atomic emission spectroscopy. Our study revealed rapid dispersal over our entire study area, more than 800 m in diameter. We conclude that dispersal may be driven by the availability of oviposition sites. Marked eggs were collected for up to 7 days after feeding, suggesting that the gonotrophic cycle in the field is longer than generally assumed. This implies that calculations of longevity based on ovarian dissection and estimates of the duration of the gonotrophic cycle may need to be revised. Novel studies on sugar feeding and blood feeding are also mentioned.

Aedes↗
PubMed1996

[Dengue in the Americas].

Dengue fever is endemic from Argentina to Mexico, where serotypes 1, 2 and 4 are in wide circulation. After an absence of almost 20 years, serotype 3 arrived in Central America in late 1994. Over the past decade dengue has become a major public health problem in many of these countries, with an increase in the prevalence of dengue haemorrhagic fever and in the number of fatal cases. The situation is not new; there is evidence of a least eight pandemics from the early 19th century until the initiation of the Aedes aegypti eradication campaign in 1947. The resurgence of serious disease was predicted in the early 1980's, and has followed a pattern of increasing severity observed 20 years earlier in Asia.

Aedes↗
PubMed1995

Short report: dispersal of Aedes aegypti in an urban area after blood feeding as demonstrated by rubidium-marked eggs.

Strategies for the control of Aedes aegypti during urban outbreaks of dengue or yellow fever assume that this species has a maximum flight range of 50-100 meters. Because Ae. aegypti distributes its eggs among several oviposition sites, we postulated that dispersal is driven by the search for oviposition sites, so an ovipositing female may have to fly much further than 50-100 meters to lay all of her eggs. We developed a method for marking Ae. aegypti eggs with a rare alkali metal (rubidium) and showed that in an urban area, oviposition activity in a single gonotrophic cycle lasts several days and covers an area at least 840 meters in diameter (55.4 hectares). We suggest that current practice for the control of dengue and yellow fever transmission by focal treatments with insecticides 50-100 meters around presumed or confirmed cases is unlikely to be effective. Moreover, source reduction (the elimination of breeding sites) may enhance dissemination of virus-infected mosquitoes by reducing the number of available oviposition sites.

Aedes↗
PubMed1995

Risk factors for dengue infection during an outbreak in Yanes, Puerto Rico in 1991.

In November 1991, during a five-month dengue outbreak, we performed epidemiologic and serologic surveys linked to an earlier entomologic study in a community of 425 houses in Yanes (Florida), Puerto Rico. We obtained a household response rate of 95% (98 of 103) and blood samples from 84% (345 of 410) of the participants. Dengue incidence, as volunteered by the respondents, was 5% (21 of 410), but serologic diagnosis (immunoglobulin M and IgG-enzyme-linked immunosorbent assays [ELISA]) indicated a recent infection rate of 18% (59 of 331). The presence of anti-dengue antibodies was detected in 277 (84%) of 331 persons tested. In our final sample of 65 households and 112 persons, we analyzed (by univariate and multivariate logistic regression methods) the association of 12 entomologic, environmental, and behavioral variables with the proportion of household members with laboratory-confirmed recent dengue. The number of female Aedes aegypti per person was the only significant (P = 0.02) household risk factor. The results of our study underscore the importance of intradomiciliary mosquito populations in dengue transmission, and may serve as a guide for mosquito control efforts.

Adolescent↗
PubMed1995

Detoxifying esterases in Culex pipiens quinquefasciatus from the Caribbean countries.

Several over-produced esterases confer resistance to organophosphorus insecticides in the Culex pipiens complex. We describe their distribution in islands and countries of the Caribbean region based on new collections and previous studies, and discuss the need to: 1) undertake DNA studies to correctly identify the esterase B alleles that are amplified in different regions, and 2) investigate the variability among gene copies within each amplification system in order to fully understand their origin and their evolution through time.

Animals↗
PubMed1994

Use of randomly amplified polymorphic DNA amplified by polymerase chain reaction markers to estimate the number of Aedes aegypti families at oviposition sites in San Juan, Puerto Rico.

We report the application of a molecular genetic technique to estimate the number of full-sibling families of Aedes aegypti contained in oviposition traps. Randomly amplified polymorphic DNA amplified by the polymerase chain reaction markers were used to estimate the numbers and sizes of families in traps at field locations in San Juan, Puerto Rico. Forty-nine presumptive loci were amplified with five primers in a total of 813 individuals from 26 sites. The average family size was 10.95, but the size distribution was skewed with an excess of small families containing 1-2 individuals. The number of families increased with the number of eggs in traps; however, the average family size decreased as the number of eggs increased. This suggests that females oviposited only a few eggs in traps that were recently placed in the field and lacked mosquito eggs or fewer eggs were oviposited as traps became crowded.

Aedes↗