Quantification of Protozoa and Viruses from Small Water Volumes.

Large sample volumes are traditionally required for the analysis of waterborne pathogens. The need for large volumes greatly limits the number of samples that can be processed. The aims of this study were to compare extraction and detection procedures for quantifying protozoan parasites and viruses from small volumes of marine water. The intent was to evaluate a logistically simpler method of sample collection and processing that would facilitate direct pathogen measures as part of routine monitoring programs. Samples were collected simultaneously using a bilayer device with protozoa capture by size (top filter) and viruses capture by charge (bottom filter). Protozoan detection technologies utilized for recovery of Cryptosporidium spp. and Giardia spp. were qPCR and the more traditional immunomagnetic separation-IFA-microscopy, while virus (poliovirus) detection was based upon qPCR versus plaque assay. Filters were eluted using reagents consistent with the downstream detection technologies. Results showed higher mean recoveries using traditional detection methods over qPCR for Cryptosporidium (91% vs. 45%) and poliovirus (67% vs. 55%) whereas for Giardia the qPCR-based methods were characterized by higher mean recoveries (41% vs. 28%). Overall mean recoveries are considered high for all detection technologies. Results suggest that simultaneous filtration may be suitable for isolating different classes of pathogens from small marine water volumes. More research is needed to evaluate the suitability of this method for detecting pathogens at low ambient concentration levels.

Daily measures of microbes and human health at a non-point source marine beach.

Studies evaluating the relationship between microbes and human health at non-point source beaches are necessary for establishing criteria which would protect public health while minimizing economic burdens. The objective of this study was to evaluate water quality and daily cumulative health effects (gastrointestinal, skin, and respiratory illnesses) for bathers at a non-point source subtropical marine recreational beach in order to better understand the inter-relationships between these factors and hence improve monitoring and pollution prevention techniques. Daily composite samples were collected, during the Oceans and Human Health Beach Exposure Assessment and Characterization Health Epidemiologic Study conducted in Miami (Florida, USA) at a non-point source beach, and analyzed for several pathogens, microbial source tracking markers, indicator microbes, and environmental parameters. Analysis demonstrated that rainfall and tide were more influential, when compared to other environmental factors and source tracking markers, in determining the presence of both indicator microbes and pathogens. Antecedent rainfall and F+ coliphage detection in water should be further assessed to confirm their possible association with skin and gastrointestinal (GI) illness outcomes, respectively. The results of this research illustrate the potential complexity of beach systems characterized by non-point sources, and how more novel and comprehensive approaches are needed to assess beach water quality for the purpose of protecting bather health.

Presence of pathogens and indicator microbes at a non-point source subtropical recreational marine beach.

Swimming in ocean water, including ocean water at beaches not impacted by known point sources of pollution, is an increasing health concern. This study was an initial evaluation of the presence of indicator microbes and pathogens and the association among the indicator microbes, pathogens, and environmental conditions at a subtropical, recreational marine beach in south Florida impacted by non-point sources of pollution. Twelve water and eight sand samples were collected during four sampling events at high or low tide under elevated or reduced solar insolation conditions. The analyses performed included analyses of fecal indicator bacteria (FIB) (fecal coliforms, Escherichia coli, enterococci, and Clostridium perfringens), human-associated microbial source tracking (MST) markers (human polyomaviruses [HPyVs] and Enterococcus faecium esp gene), and pathogens (Vibrio vulnificus, Staphylococcus aureus, enterovirus, norovirus, hepatitis A virus, Cryptosporidium spp., and Giardia spp.). The enterococcus concentrations in water and sand determined by quantitative PCR were greater than the concentrations determined by membrane filtration measurement. The FIB concentrations in water were below the recreational water quality standards for three of the four sampling events, when pathogens and MST markers were also generally undetectable. The FIB levels exceeded regulatory guidelines during one event, and this was accompanied by detection of HPyVs and pathogens, including detection of the autochthonous bacterium V. vulnificus in sand and water, detection of the allochthonous protozoans Giardia spp. in water, and detection of Cryptosporidium spp. in sand samples. The elevated microbial levels were detected at high tide and under low-solar-insolation conditions. Additional sampling should be conducted to further explore the relationships between tidal and solar insolation conditions and between indicator microbes and pathogens in subtropical recreational marine waters impacted by non-point source pollution.

Genetic diversity of Plasmodium vivax Pvcsp and Pvmsp1 in Guyana, South America.

Approximately 55% of malaria infections in the Guyana Amazon region are attributed to Plasmodium falciparum while the other 45% are attributed to non-falciparum, mostly Plasmodium vivax. However, little is known about the P. vivax strain types circulating in the region. Using PCR for Plasmodium detection and two genetic markers specific to P. vivax to detect the polymorphic circumsporozoite protein (CSP) and the conserved 19-kDa region of the merozoite surface protein-1 (MSP-1), we investigated the overall Plasmodium strain distribution and population diversity within P. vivax in isolates collected from the blood of infected individuals in the interior Amazon region of Guyana, South America. Out of a total of 250 samples positive for Plasmodium, P. vivax was detected in 30% (76/250) and P. falciparum was detected in 76% (189/250). Mixed infections containing both P. falciparum and P. vivax constituted 6% (15/250) of the total positive samples. Further analysis of P. vivax strains showed that 92% (56/61) of the P. vivax samples hybridized with a probe specific to type VK210, 39% (24/61) hybridized with a probe specific for type VK247, and 25% (15/61) hybridized with a probe specific for the P. vivax-like CS genotype. DNA sequencing of the 19-kDa C-terminal domain in block 13 of MSP-1 amplified from 61 samples from patients infected with P. vivax demonstrated that this region is highly conserved, and all samples were identical at the nucleotide level to the Belem and Salvador-1 types. No synonymous or nonsynonymous mutations were observed in this region of the gene, indicating that current vaccine-development efforts based on the MSP-1(19) fragment would be applicable in Guyana.

Multicenter study to evaluate the OptiMAL test for rapid diagnosis of malaria in U.S. hospitals.

More than 1,000 cases of malaria are diagnosed each year in the United States. Reported numbers, however, may be artificially low because many clinicians fail to consider the diagnosis on presentation, U.S. hospital laboratory technologists have very limited experience in detecting and identifying malaria parasites, and reporting of malaria to state health departments is sporadic in many states. In this study, a rapid malaria diagnostic test, the OptiMAL test (DiaMed; under license from Flow Inc., Portland, Oreg.) was evaluated in six U.S. hospitals and compared with results of microscopy. The OptiMAL test is a 15-min rapid immunochromatographic test that both identifies and differentiates Plasmodium falciparum from non-P. falciparum malaria parasites on the basis of the detection of parasite lactate dehydrogenase in a drop of patient blood. A total of 216 specimens from patients suspected of having malaria were tested. Results indicated that 43 samples (20%) were positive for malaria parasites by microscopy (32 P. falciparum, 11 non-P. falciparum) while 42 (19%) were positive by OptiMAL (31 P. falciparum, 11 non-P. falciparum). The sensitivity of the OptiMAL test was 98%; its specificity was 100%, with positive and negative predictive values of 100 and 99%, respectively. Participating hospital physicians and laboratory directors independently reported that the OptiMAL rapid malaria test was accurate, easy to use, and well accepted by those working in their diagnostic laboratories. The overall conclusion was that integration of the OptiMAL rapid malaria test into the U.S. health care infrastructure would provide an important and easy-to-use tool for the timely diagnosis of malaria.

Cryptosporidium muris, a rodent pathogen, recovered from a human in Perú.

Cryptosporidium muris, predominantly a rodent species of Cryptosporidium, is not normally considered a human pathogen. Recently, isolated human infections have been reported from Indonesia, Thailand, France, and Kenya. We report the first case of C. muris in a human in the Western Hemisphere. This species may be an emerging zoonotic pathogen capable of infecting humans.

HIV prevalence in a gold mining camp in the Amazon region, Guyana.

The prevalence of HIV infection among men in a gold mining camp in the Amazon region of Guyana was 6.5%. This high percentage of HIV infection provides a reservoir for the virus in this region, warranting immediate public health intervention to curb its spread. As malaria is endemic in the Amazon Basin (>30,000 cases/year), the impact of coinfection may be substantial.

Influence of soil on fecal indicator organisms in a tidally influenced subtropical environment.

The potential regrowth of fecal indicator bacteria released into coastal environments in recreational water bodies has been of concern, especially in tropical and subtropical areas where the number of these bacteria can be artificially elevated beyond that from fecal impacts alone. The task of determining the factors that influence indicator bacterial regrowth was addressed though a series of field sampling and laboratory experiments using in situ densities of Escherichia coli, enterococci, and Clostridium perfringens in river water, sediment, and soil. Field sampling efforts included the collection of surface sediments along the cross section of a riverbank, a 20-cm-deep soil core, and additional surface soils from remote locations. In addition to field sampling, two types of laboratory experiments were conducted. The first experiment investigated the survival of bacteria already present in river water with the addition of sterile and unsterile sediment. The second experiment was designed to simulate the wetting and drying effects due to tidal cycles. The results from the sampling study found elevated numbers of E. coli and C. perfringens in surficial sediments along the riverbank near the edge of the water. C. perfringens was found in high numbers in the subsurface samples obtained from the soil core. Results from laboratory experiments revealed a significant amount of regrowth for enterococci and E. coli with the simulation of tides and addition of sterile sediment. Regrowth was not observed for C. perfringens. This study demonstrates the need to further evaluate the characteristics of indicator microbes within tropical and subtropical water systems where natural vegetation, soil embankments, and long-term sediment accumulation are present. In such areas, the use of traditional indicator microbes to regulate recreational uses of a water body may not be appropriate.

Intestinal parasites among young children in the interior of Guyana

Intestinal parasites contribute greately to morbidity in developing countries. While there have been several studies of the problem in the Caribbean, including the implementation of control programmes, this has not been done for Guyana. The aim of this study was to determine the prevalence of intestinal parasites among young children in a town located in the interior of Guyana. Eighty-five children under the age of 12 years were studied prospectively for intestinal parasites in Mahdia, Guyana. Stool samples were transported in formalin to the Department of microbiology, the University of the West Indies, Jamaica, for analysis using the formalin-ether concentration and Ziehl-Neelsen techniques. Data on age and gender of the children were recorded on field sheets. At least one intestinal parasite was detacted in 43.5 percent (37/85) of the children studied and multiple parasitic infections were recorded in 21.2 percent (18/85). The most common intestinal helminth parasite was hookworm (28.2 percent; 24/85), followed by Ascaris lumbricoides (18.8 percent; 16/85) and then Trichuris trichuria (14.1 percent; 12/85). Among the protozoan infections Giardia lamblia was detected in 10.5 percent (9/85) of the study population while Entamoeba histolytica appeared rarely. All stool samples were negative for Cryptosporidium and other intestinal Coccidia. There was no predilection for gender with any of the parasites. The pattern of distribution of worms in this area of Guyana was unlike that seen in other studies. Hookworm infection was the most common among the children and a large proportion had multiple infections. The study established the occurrence and prevalence of a number of intestinal parasites in the population of Guyana. This sets the stage for the design and implementation of more detailed epidemiological studies. (AU)

Seroepidemiology of Helicobacter pylori infection in a Jamaican community

We researched epidemiologic associations between environmental and demographic factors and prevalence of Heliobacter pylori infection in a suburban Jamaican community. Using a clustered sampling technique, 22 domestic yards enclosing 60 separate households were randomly selected from a local community. All household members (n=346) were invited to participate following informed consent; the overall compliance rate ws 58.9 percent. A detect IgG antibodies raised against H. pylori. Environmental and demographic information was obtained by questionnaire. The seroprevalence of H. pylori was 69.9 percent (n=202). Analysis of the independent variables revealed three major components: Component 1 described, collectively, good personal hygiene and sanitation, indoor water supply and absence of straying animals in the peridomestic area; Component 2 included older age, good personal hygiene and large yard size; Component 3 the presence of domestic animals (cats and dogs) and again, large yard size. These three complexes explained 42.2 percent of the variability in the data set. Logistic regression showed that Components 2 and 3 were independently associated with H. pylori seropositivity, indicating that a combination of demographic, environmental and zoonotic factors is involved in the spread of H. pylori infections at the tropical community level. (AU)

Dengue in Guyana

Evaluates patients in a clinic in Georgetown, Guyana for dengue fever and dengue hemorhagic fever. Evidence of 50 cases of dengue infection; Guyana reporting less than five cases per eyar for most of the 1990s; Suggestion for surveillance measures for dengue virus infections in Guyana and surrounding countries.(AU)

Evaluation of the MRL diagnostics dengue fever virus IgM capture ELISA and the PanBio Rapid Immunochromatographic Test for diagnosis of dengue fever in Jamaica

We evaluated two new commercial dengue diagnostic tests, the MRL Diagnostics Dengue Fever Virus IgM Capture ELISA and the PanBio Rapid Immunochromatographic Test, on serum samples collected during a dengue epidemic in Jamaica. The MRL ELISA method correctly identified 96 percent (78 of 80) of the samples as dengue positive, while the PanBio test identified 100 percent (80 of 80). Both tests were 100 percent (20 samples of 20) specific.(Au)

Intestinal parasites in human immunodeficiency virus infected patients

Treatment of concurrent opportunistic and non-opportunistic infections is a priority in improving quality of life in HIV infected patients in developing countries. The objective of the study was to determine the prevalence of opportunistic intestinal parasites in persons with and without HIV infection in Honduras. It was based on study of 52 HIV-positive and 48 HIV-negative persons at the Social Security Hospital in San Pedro Sula. Data sheets recording age, sex, stool parasitology, HIV serology and clinical state of HIV infection were completed for each study participant. Cryptosporidium parvum and Strongyloides stercoralis, which are intracellular or live in the mucosa, were found exclusively in persons infected with HIV. In contrast, the prevalence of the extracellular parasites Giardia lamblia, Ascaris lumbricoides and Trichuris trichiura was significantly higher in persons who were HIV-negative. It appears that infection with HIV may selectively deter the establishment of some intestinal parasites. This may be due to HIV induced enteropathy which does not favor the establishment of extracellular parasites. However, intracellular and mucosal dwelling organisms may benefit from pathological changes and reduced local immune responses which are induced by the virus which, in turn, lead to higher prevalence among HIV-infected individuals. We further postulate that the switch from a Th-1 to a predominantly Th-2 response as HIV infection progresses to AIDS may lead to an environment which is unsuitable for parasite survival (AU)

Epidemiology of giardiasis and cryptosporidiosis in Jamaica

We report the findings of a cross-sectional epidemiologic of Giardia lamblia and Cryptosporidum infections in Jamaica. Three hundred twenty eight stool samples from patients less than one to 81 years of age were examined using formalin-ether concentration for G. lamblia, Zeihl-Neelsen staining for Cryptosporidum, and the Prospect rapid enzyme immunoassay (EIA; Alexon, Sunnyvale, CA) for parasite diagnosis. The Prospect Giardia rapid assay detected 17 cases of G. lamblia infections compared with six by formalin-ether concentration. However, the Prospect Cryptosporidum EIA did not increase the rate of detection of Cryptosporidum when compared with Zeihl-Neelsen staining. Cryptosporidum infections were most frequently diagnosed in children less than five years old and prevalence decreased with age. In contrast, the prevalence of giardiasis increased as children became older. There were no associations between the infections and stool consistency, clinical manifestations, or sex of the individuals. The contribution of the parasites to childhood morbidity will depend on accurate laboratory diagnosis (Au)

Increased prevalence of Plasmodium falciparum malaria in Honduras, Central America

We report on our investigation of a malaria outbreak in Honduras, Central America, in January 1997. We tested 202 patients with fever and chills using thin and thick blood film microscopy. Sixteen patients lived in the city and the rest lived in the rural areas. A total of 95 samples (47 percent) were positive for malaria parasites. Seventy-nine percent (63/80) of the rural patients were infected with Plasmodium vivax and 21 percent (17/80) were infected with P. falciparum. In the urban area, all 15 infected patients had P. vivax malaria and none showed evidence of P. falciparum. Since previous reports inidicate that falciparum malaria accounts for only 2 percent of the overall malaria infections in Honduras, the results reported here suggest that there is a dramatic increase in flaciparum malaria in the area of Honduras investigated in this study (AU)

Increased prevalence of Plasmodium falciparum malaria in Honduras, Central America

We report on our investigation of a malaria outbreak in Honduras, Central America, in January 1997. We tested 202 patients with fever and chills using thin and thick blood film microscopy. Sixteen patients lived in the city and the rest lived in rural areas. A total of 95 samples (47%) were positive for malaria parasites. Seventy-nine percent (63/80) of the rural patients were infected with Plasmodium vivax and 21% (17/80) were infected with P. falciparum. In the urban area, all 15 infected patients had P. vivax malaria and none showed evidence of P. falciparum. Since previous reports indicate that falciparum malaria accounts for only 2% of the overall malaria infections in Honduras, the results reported here suggest that there is a dramatic increase in falciparum malaria in the area of Honduras investigated in this study.

Notificamos los resultados de un estudio de un brote de malaria que se produjo en Honduras, Centroamérica, en enero de 1997. Sometimos a examen microscópico frotis delgados y frotis gruesos de la sangre de 202 pacientes con fiebre y escalofríos. Dieciséis pacientes eran habitantes de la zona urbana y el resto de la zona rural. Un total de 95 especímenes (47%) fueron positivos a parásitos de la malaria. Setenta y ocho por ciento (62/80) de los pacientes del área rural estaban infestados con Plasmodium vivax y 22% (17/80) con P. falciparum. En la zona urbana, todos los 15 pacientes que estaban infestados tenían P. vivax y en ninguno se detectó P. falciparum. Ya que según informes previos la malaria de tipo falciparum representa solamente 2% de todos los casos de malaria en Honduras, nuestros resultados sugieren que hay un gran incremento del número de casos de malaria falciparum en la zona de Honduras en que se llevó a cabo esta investigación.

A pilot project to improve surveillance for dengue fever in three Caribbean islands - abstract

Simultaneous or sequential circulatin of dengue serotypes 1, 2 and 4 has been detected in several Caribbean countries. This may increase the chances of persons experiencing secondary infections with heterotypic dengue serotypes. Consequently there may be an increased risk of dengue haemorrhagic fever/dengue shock syndrome. Furthermore, Caribbean populations may not have been exposed to dengue serotype 3 in over 20 years and a large proportion of the population may not have immunity to this virus. Dengue type 3 has been recently isolated during epidemics in Central America and its introduction poses a further threat to the Caribbean. Sentinel surveillance was undertaken in a pilot study during August to December 1995 to improve the monitoring of Dengue serotypes on the islands of Jamaica, Trinidad and Dominica. Virological investigations were performed on a total of 92 patients who presented at designated community and hospital health care facilities on the 3 islands. Dengue virus types 1 and 2 were isolated from Jamaican patients. No dengue isolates were obtained from Dominica or Trinidad, although IgM capture ELISA test results suggested current or recent exposure to dengue virus in one Dominican patient. Improved surveillance for dengue could lead to detection of the emergence of new dengue serotypes, or detection of increased virus activity. Using surveillance data to target efforts to control the Aedes aegypti mosquito vector in areas where infection cases reside could reduce the impact of dengue disease in the Caribbean. (AU)

Peripheral T cell lymphomas in Jamaica: relationship to HTLV-1 serostatus (abstract)

The clinico-pathologic features of 111 patients with non-Hodgkin's Lymphoma (NHL) exhibiting morphologic and immunophenotypic features of peripheral T-cell lymphoma (PTL) were analysed with respect to HTLV-I serostatus. 73 (65.8 percent) were HTLV-I seropositive (HTLV-I+) and 38 (34.2 percent) were HTLV-I seronegative (HTLV-I-). HTLV+ cases had a lower mean age (42.2 yrs) than HTLV- cases (50 yrs) and a male to female ratio of 1:1 while HTLV- cases showed a male preponderance (M:F 2:1). No significant differences in morphology were noted using the Japan Study Group classification. Both groups shared clinical features consistent with Adult T-cell leukemia/lymphoma but hypercalcemia was more likely to occur in the HTLV+ group [Hypercalcemia:- HTLV+ 50.7 percent, HTLV- 15.8 percent; Leukemia:- HTLV+ 39.7 percent, HTLV- 34.2 percent; Skin infiltration:- HTLV+ 38.3 percent, HTLV- 42.1 percent]. It would appear that some cases of HTLV- PTL could be included in the group classified as ATL given the occurrence of sentinel clinical features associated with ATL. Perhaps these will prove to be HTLV-I proviral DNA positive. Further studies to define this group are indicated. (AU)