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monoclonal antibody 11C5-B10. Five serapreviously showntoimmunoprecip- itate the230-and48/45-kDa antigens significantly inhibited 1IC5-B10 binding toan averageof24.2%of control. Theone serum whichprecipitated onlythe48/45-kDa antigen... more
monoclonal antibody 11C5-B10. Five serapreviously showntoimmunoprecip- itate the230-and48/45-kDa antigens significantly inhibited 1IC5-B10 binding toan averageof24.2%of control. Theone serum whichprecipitated onlythe48/45-kDa antigen didnotinhibit IIC5-B10 binding. For 26serawhich werenegative byimmunoprecipitation, mean binding intheassaywas 112.7%ofcontrol (pooled London nonimmune sera). Recognition ofboth230-kDa and48/45-kDa antigens was associated withatiter of 1:9orgreater (reciprocal geometric mean titer, 27.6) forinhibition tomore than2standard deviations from themean ofthenegative sera.Theresults showthatthe1IC5-B10 binding
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Vector incrimination studies were conducted from April 2003 to February 2005 at three riverine villages 1.5 km to 7.0 km apart, along the Matapi River, Amapa State, Brazil. A total of 113,117 mosquitoes were collected and placed in pools... more
Vector incrimination studies were conducted from April 2003 to February 2005 at three riverine villages 1.5 km to 7.0 km apart, along the Matapi River, Amapa State, Brazil. A total of 113,117 mosquitoes were collected and placed in pools of <or=7 mosquitoes (19,883 pools) and tested for species-specific circumsporozoite protein (CSP) of P. falciparum, P. vivax VK210, and P. vivax VK247 using the enzyme-linked immunoabsorbent assay (ELISA). A subset of 63,330 mosquitoes (12,191 pools) was tested for P. malariae. Anopheles darlingi and An. marajoara had the highest proportion of circumsporozoite protein positives for human malaria parasites compared with An. nuneztovari, An. triannulatus, and An. intermedius. Anopheles darlingi and An. marajoara had the highest entomological inoculation rates (EIR) and were considered to be the most important malaria vectors in the study. Anopheles nuneztovari was also an important vector. Differences in entomological inoculation rates were more de...
Research Interests: Malaria, Brazil, Plasmodium, Humans, Brazilian Amazon, and 5 moreAnopheles, Animals, Incidence, The American, and Insect Vectors
Interventions targeting adult mosquitoes are used to combat transmission of vector-borne diseases, including dengue. Without available vaccines, targeting the primary vector, Aedes aegypti, is essential to prevent transmission. Older... more
Interventions targeting adult mosquitoes are used to combat transmission of vector-borne diseases, including dengue. Without available vaccines, targeting the primary vector, Aedes aegypti, is essential to prevent transmission. Older mosquitoes (≥ 7 days) are of greatest epidemiological significance due to the 7-day extrinsic incubation period of the virus. Age-grading of female mosquitoes is necessary to identify post-intervention changes in mosquito population age structure. We developed models using near-infrared spectroscopy (NIRS) to age-grade adult female Ae. aegypti. To determine if diet affects the ability of NIRS models to predict age, two identical larval groups were fed either fish food or infant cereal. Adult females were separated and fed sugar water ± blood, resulting in four experimental groups. Females were killed 1, 4, 7, 10, 13, or 16 days postemergence. The head/thorax of each mosquito was scanned using a near-infrared spectrometer. Scans from each group were anal...
Research Interests: Diet, Dengue Virus, Near Infrared Spectroscopy, Female, Animals, and 5 moreDengue, Time Factors, Larva, Aedes, and Insect Vectors
Malaria transmission by anopheline mosquitoes was studied in a traditional tank-irrigation-based rice-producing village in the malaria-endemic low country dry zone of northcentral Sri Lanka during the period August 1994-February 1997.... more
Malaria transmission by anopheline mosquitoes was studied in a traditional tank-irrigation-based rice-producing village in the malaria-endemic low country dry zone of northcentral Sri Lanka during the period August 1994-February 1997. Adult mosquitoes were collected from human and bovid bait catches, bovid-baited trap huts, indoor catches, and pit traps. Mosquito head-thoraces were tested for the presence of Plasmodium falciparum and P. vivax, and blood-engorged abdomens for the presence of human blood by ELISAs. House surveys were done at two-day intervals to record cases of blood film-confirmed malaria among the villagers. A total of 7,823 female anophelines representing 14 species were collected. Trends in anopheline abundance were significantly correlated with rainfall of the preceding month in An. annularis, An. barbirostris, An. subpictus, An. vagus, and An. varuna, but were not significant in An. culicifacies and An. peditaeniatus. Malaria parasite infections were seen in sev...
Research Interests: Nonparametric Statistics, Polymorphism, Sri Lanka, Disease Outbreaks, Humans, and 14 moreAnopheles, Female, Animals, Blood, Monoclonal Antibodies, Cattle, Plasmodium falciparum, Seasons, Protozoan Proteins, Indexation, Enzyme Linked Immunosorbent Assay, Plasmodium Vivax, The American, and Insect Vectors
Plasmodium berghei sporozoites delivered by mosquito bite were more infectious to outbred CD-1 mice than were sporozoites delivered by intravenous inoculation. The route of challenge also affected vaccine efficacy. In view of these... more
Plasmodium berghei sporozoites delivered by mosquito bite were more infectious to outbred CD-1 mice than were sporozoites delivered by intravenous inoculation. The route of challenge also affected vaccine efficacy. In view of these findings and the fact that mosquito bites are the natural mode of sporozoite delivery, infectious mosquito bites should be considered the challenge protocol of choice for sporozoite vaccine efficacy trials.
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We have isolated a small, heat stabile, hydrophilic molecule from the gut lumen of unfed, female Anopheles stephensi that is a potent inducer of gametogenesis in Plasmodium falciparum and P. gallinaceum at a hydrogen ion concentration, pH... more
We have isolated a small, heat stabile, hydrophilic molecule from the gut lumen of unfed, female Anopheles stephensi that is a potent inducer of gametogenesis in Plasmodium falciparum and P. gallinaceum at a hydrogen ion concentration, pH 7.4, that normally suppresses activation. This gamete activation factor (GAF) was purified using reverse phase high performance liquid chromatography and determined to have a major ion m/z of 206.1 by low resolution electrospray mass spectrometry. The molecule, which was also found in the heads of both female and male A. stephensi, absorbed light in the ultraviolet region at three maxima (lambda(max) = 213, 245 and 350 nm); the 245/350 nm absorbance ratio was 7.0. The structure of the molecule and its normal function in the mosquito are not yet known, but in a sample of diverse insect species, extracts from those that feed on blood were bioactive. We propose that GAF is the previously observed malaria exflagellation factor (MEF).
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We report on a prospective, prolective observational study, supplying information on how physicians and other health care professionals retrieve medical knowledge on-line within the Heidelberg University Hospital information system.... more
We report on a prospective, prolective observational study, supplying information on how physicians and other health care professionals retrieve medical knowledge on-line within the Heidelberg University Hospital information system. Within this hospital information system, on-line access to medical knowledge has been realised by installing a medical knowledge server in the range of about 24 GB and by providing access to it by health care professional workstations in wards, physicians' rooms, etc. During the study, we observed about 96 accesses per working day. The main group of health care professionals retrieving medical knowledge were physicians and medical students. Primary reasons for its utilisation were identified as support for the users' scientific work (50%), own clinical cases (19%), general medical problems (14%) and current clinical problems (13%). Health care professionals had accesses to medical knowledge bases such as MEDLINE (79%), drug bases ('Rote Liste...
Research Interests: Information Systems, Publishing, Decision Making, Health Care, Knowledge Based System, and 18 moreGermany, Hospital Information System, Prospective studies, Medical Students, Humans, Computer Systems, Physicians, Decision Support, Medline, Online Systems, Knowledge base, Computer User Interface Design, Information Storage and Retrieval, Hospital Information Systems, Evaluation Studies, Observational Study, Medical Information System (MIS), and Health Personnel(Germany, Hospital Information System, Prospective studies, Medical Students, Humans, Computer Systems, Physicians, Decision Support, Medline, Online Systems, Knowledge base, Computer User Interface Design, Information Storage and Retrieval, Hospital Information Systems, Evaluation Studies, Observational Study, Medical Information System (MIS), and Health Personnel)
(Germany, Hospital Information System, Prospective studies, Medical Students, Humans, Computer Systems, Physicians, Decision Support, Medline, Online Systems, Knowledge base, Computer User Interface Design, Information Storage and Retrieval, Hospital Information Systems, Evaluation Studies, Observational Study, Medical Information System (MIS), and Health Personnel)
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Restrained Anopheles stephensi mosquitoes infected with Plasmodium falciparum were made to produce time-dependent series of saliva droplets in mineral oil. The relative volume of each droplet and the number of sporozoites each contained... more
Restrained Anopheles stephensi mosquitoes infected with Plasmodium falciparum were made to produce time-dependent series of saliva droplets in mineral oil. The relative volume of each droplet and the number of sporozoites each contained were determined microscopically; gland sporozoites were estimated with an enzyme-linked immunosorbent assay. Median gland infection was 8170 and median number of sporozoites ejected was 15 (range, 0-978). Inoculum size was positively correlated to the number of sporozoites in the salivary glands. Most mosquitoes ejected sporozoites only at the beginning of salivation; this suggests that only those parasites in the common and secondary salivary ducts at the time of feeding can be ejected. The small size of inocula may explain some aspects of malaria transmission, including the often observed discrepancy between inoculation and incidence rates.
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We present evidence that a parasite with characteristics of Plasmodium vivax is being transmitted among Duffy blood group-negative inhabitants of Kenya. Thirty-two of 4,901 Anopheles gambiae and An. funestus (0.65%) collected in Nyanza... more
We present evidence that a parasite with characteristics of Plasmodium vivax is being transmitted among Duffy blood group-negative inhabitants of Kenya. Thirty-two of 4,901 Anopheles gambiae and An. funestus (0.65%) collected in Nyanza Province were ELISA positive for the P. vivax circumsporozoite protein VK 247. All positives were found late in the rainy season, when An. funestus predominated, and disproportionately many were found at a single village. A P. vivax specific sequence of the SSU rRNA gene was amplified from three of six ELISA-positive mosquitoes. Erythrocytes from 31 children, including 9 microscopically diagnosed as infected with P. vivax, were negative by flow cytometry for the Fy3 or Fy6 epitopes, which indicate Duffy blood group expression. A DNA fragment specific for the C terminus of the gene for P. vivax merozoite surface protein 1 (MSP-1) was amplified from the blood of four of these children and subsequently sequenced from two.
Research Interests: Flow Cytometry, Kenya, Seasonality, Humans, Child, and 14 moreAnopheles, Animals, Blood groups, Anopheles gambiae, Protozoan Proteins, Amino Acid Sequence, Erythrocytes, SSU rRNA, Enzyme Linked Immunosorbent Assay, Plasmodium Vivax, The American, Insect Vectors, DNA fragmentation, and Merozoite surface protein 1
Recent outbreaks of locally acquired mosquito-transmitted malaria in the United States demonstrate the continued risk for reintroduction of the disease. Since 1957, when CDC's Malaria Branch started conducting malaria surveillance, 63... more
Recent outbreaks of locally acquired mosquito-transmitted malaria in the United States demonstrate the continued risk for reintroduction of the disease. Since 1957, when CDC's Malaria Branch started conducting malaria surveillance, 63 outbreaks have occurred, constituting 156 cases (annual range: 1-32) that were a result of locally acquired mosquitoborne transmission. This report describes the steps that should be taken to 1) investigate a case that might have been acquired locally, 2) prevent a small focus of malaria cases from becoming a source of sustained transmission, and 3) inform clinicians regarding the process of an investigation so they can effectively address concerns and questions from patients. Although these locally acquired mosquito-transmitted outbreaks frequently involve only a limited number of infected persons, they frequently raise concerns in the community and require substantial public health resources. For example, as a result of the most recent local outb...
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We used sentinel animal enclosures to measure the rate of infestation by the Chagas disease vector, Triatoma infestans, in an urban community of Arequipa, Peru, and to evaluate the effect of deltamethrin-impregnated netting on that rate.... more
We used sentinel animal enclosures to measure the rate of infestation by the Chagas disease vector, Triatoma infestans, in an urban community of Arequipa, Peru, and to evaluate the effect of deltamethrin-impregnated netting on that rate. Impregnated netting decreased the rate of infestation of sentinel enclosures (rate ratio, 0.23; 95% confidence interval, 0.13-0.38; P < 0.001), controlling for the density of surrounding vector populations and the distance of these to the sentinel enclosures. Most migrant insects were early-stage nymphs, which are less likely to carry the parasitic agent of Chagas disease, Trypanosoma cruzi. Spread of the vector in the city therefore likely precedes spread of the parasite. Netting was particularly effective against adult insects and late-stage nymphs; taking into account population structure, netting decreased the reproductive value of migrant populations from 443.6 to 40.5. Impregnated netting can slow the spread of T. infestans and is a potenti...
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In a region of northeastern Amazonia, we find a species previously of minor importance, Anopheles marajoara, to be the principal malaria vector. In a total of five collections during 1996-97 in three replicated sites near the city of... more
In a region of northeastern Amazonia, we find a species previously of minor importance, Anopheles marajoara, to be the principal malaria vector. In a total of five collections during 1996-97 in three replicated sites near the city of Macapa´, Amapastate, this species occurs in much greater abundance compared with the presumed vector Anopheles darlingi. Also, a significantly higher proportion of
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Research Interests: Algorithms, Medical Microbiology, Ecological Niche Modeling, Emerging Infectious Diseases, Dogs, and 11 moreComputer Simulation, Animals, Chagas disease, Clinical Sciences, Texas, Ecosystem, Trypanosoma Cruzi, Public health systems and services research, Triatoma, Chagas Cardiomyopathy, and Insect Vectors
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After three dogs died from acute Chagas cardiomyopathy at one location, an investigation was conducted of the home, garage, and grounds of the owner. A serologic study was con- ducted on stray dogs, and an ecologic niche model was devel-... more
After three dogs died from acute Chagas cardiomyopathy at one location, an investigation was conducted of the home, garage, and grounds of the owner. A serologic study was con- ducted on stray dogs, and an ecologic niche model was devel- oped to predict areas where the vector Triatoma gerstaeckeri might be expected.
Research Interests: Algorithms, Medical Microbiology, Ecological Niche Modeling, Emerging Infectious Diseases, Dogs, and 11 moreComputer Simulation, Animals, Chagas disease, Clinical Sciences, Texas, Ecosystem, Trypanosoma Cruzi, Public health systems and services research, Triatoma, Chagas Cardiomyopathy, and Insect Vectors
Phenotypic heterogeneity in the repetitive portion of a human malaria circumsporozoite (CS) protein, a major target of candidate vaccines, has been found. Over 14% of clinical cases of uncomplicated Plasmodium vivax malaria at two sites... more
Phenotypic heterogeneity in the repetitive portion of a human malaria circumsporozoite (CS) protein, a major target of candidate vaccines, has been found. Over 14% of clinical cases of uncomplicated Plasmodium vivax malaria at two sites in western Thailand produced sporozoites immunologically distinct from previously characterized examples of the species. Monoclonal antibodies to the CS protein of other P. vivax isolates
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A simple method for rapid identification of large numbers of Anopheles mosquitoes was developed based on polymerase chain reaction (PCR) amplification of the rDNA intergenic spacer and internal transcribed spacer 2. By means of previously... more
A simple method for rapid identification of large numbers of Anopheles mosquitoes was developed based on polymerase chain reaction (PCR) amplification of the rDNA intergenic spacer and internal transcribed spacer 2. By means of previously described primers for the Anopheles gambiae and An. quadrimaculatus species complexes, rDNA was amplified simultaneously from 96 whole mosquitoes or parts. No homogenization or individual
Research Interests: Genetics, Microbiology, Parasitology, Immunology, Polymorphism, and 41 moreMedical Microbiology, Malaria, Leishmania, Adolescent, Plasmodium, Genetic Diversity, Biological Sciences, Phylogeny, Enzymes, Humans, Anopheles, Female, Animals, Nucleic acid hybridization, Male, Polymerase Chain Reaction, Cluster Analysis, New World, Songbirds, Dendritic cell, Species identification, Life Cycle, Anopheles gambiae, Enzyme, Clinical Sciences, European, Urinalysis, Middle Aged, Urinary Tract, Electrophoresis, Genotype, Adult, Sibling Species, Veterinary Sciences, Protozoan Proteins, Propionibacterium Acnes, Base Sequence, Sensitivity and Specificity, DNA probes, The American, and False Negative(Medical Microbiology, Malaria, Leishmania, Adolescent, Plasmodium, Genetic Diversity, Biological Sciences, Phylogeny, Enzymes, Humans, Anopheles, Female, Animals, Nucleic acid hybridization, Male, Polymerase Chain Reaction, Cluster Analysis, New World, Songbirds, Dendritic cell, Species identification, Life Cycle, Anopheles gambiae, Enzyme, Clinical Sciences, European, Urinalysis, Middle Aged, Urinary Tract, Electrophoresis, Genotype, Adult, Sibling Species, Veterinary Sciences, Protozoan Proteins, Propionibacterium Acnes, Base Sequence, Sensitivity and Specificity, DNA probes, The American, and False Negative)
(Medical Microbiology, Malaria, Leishmania, Adolescent, Plasmodium, Genetic Diversity, Biological Sciences, Phylogeny, Enzymes, Humans, Anopheles, Female, Animals, Nucleic acid hybridization, Male, Polymerase Chain Reaction, Cluster Analysis, New World, Songbirds, Dendritic cell, Species identification, Life Cycle, Anopheles gambiae, Enzyme, Clinical Sciences, European, Urinalysis, Middle Aged, Urinary Tract, Electrophoresis, Genotype, Adult, Sibling Species, Veterinary Sciences, Protozoan Proteins, Propionibacterium Acnes, Base Sequence, Sensitivity and Specificity, DNA probes, The American, and False Negative)
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Research Interests: Evolutionary Biology, Zoology, Phylogenetics, Taxonomy, Morphology, and 17 moreSystematic Entomology, Cladistics, Phylogeny, Mitochondrial DNA, Maximum Likelihood, Classification, Morphological Characters, New Guinea, Systematic, Statistical Test, Genetic Analysis, Amino Acid Sequence, Keys, Cladism, Data Partitioning, Nucleotides, and DNA sequence
Proteosomes are hydrophobic, membranous, multimolecular preparations of meningococcal outer membrane proteins that are also B cell mitogens. These characteristics suggested that proteosomes may serve as carrier proteins and adjuvants to... more
Proteosomes are hydrophobic, membranous, multimolecular preparations of meningococcal outer membrane proteins that are also B cell mitogens. These characteristics suggested that proteosomes may serve as carrier proteins and adjuvants to enhance peptide immunogenicity. Although high titers of malaria circumsporozoite (CS) antibodies protect against malaria, vaccines thus far tested in humans have been insufficiently immunogenic to be clinically useful. Here it is shown that synthetic CS peptides hydrophobically complexed to proteosomes by way of lauroyl-cysteine become highly immunogenic in mice without other adjuvants. The high titers of antibodies produced and the safety of proteosomes in humans suggest that this novel system is widely applicable for the development of peptide vaccines to protect against many diseases.
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As part of a study of potential vaccines against malaria, the protective efficacy of sporozoite subunit vaccines was determined by using the Plasmodium berghei murine malaria model. Mice were immunized with recombinant DNA-produced or... more
As part of a study of potential vaccines against malaria, the protective efficacy of sporozoite subunit vaccines was determined by using the Plasmodium berghei murine malaria model. Mice were immunized with recombinant DNA-produced or synthetic peptide-carrier subunit vaccines derived from the repetitive epitopes of the Plasmodium berghei circumsporozoite gene, or with radiation-attenuated sporozoites. Immunization with subunit vaccines elicited humoral responses that were equivalent to or greater than those elicited by irradiated sporozoites, yet the protection against sporozoite challenge induced by either of the subunit vaccines was far less than that achieved by immunization with attenuated sporozoites. Passive and adoptive transfer studies demonstrated that subunit vaccines elicited predominantly antibody-mediated protection that was easily overcome whereas irradiated sporozoites induced potent cell-mediated immunity that protected against high challenge doses of sporozoites. These studies indicate that new strategies designed to induce cellular immunity will be required for efficacious sporozoite vaccines.
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The gene for the circumsporozoite (CS) protein of Plasmodium falciparum has been cloned and its nucleotide sequence determined. The gene encodes a protein of 412 amino acids as deduced from the nucleotide sequence. The protein contains 41... more
The gene for the circumsporozoite (CS) protein of Plasmodium falciparum has been cloned and its nucleotide sequence determined. The gene encodes a protein of 412 amino acids as deduced from the nucleotide sequence. The protein contains 41 tandem repeats of a tetrapeptide, 37 of which are Asn-Ala-Asn-Pro and four of which are Asn-Val-Asp-Pro. Monoclonal antibodies against the CS protein of Plasmodium falciparum were inhibited from binding to the protein by synthetic peptides of the repeat sequence. The CS protein of Plasmodium falciparum and the CS protein of a simian malaria parasite, Plasmodium knowlesi, have two regions of homology, one of which is present on either side of the repeat. One region contains 12 of 13 identical amino acids. Within the nucleotide sequence of this region, 25 of 27 nucleotides are conserved. The conservation of these regions in parasites widely separated in evolution suggests that they may have a function such as binding to liver cells and may represent an invariant target for immunity.
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The circumsporozoite (CS) protein of the human malaria parasite Plasmodium falciparum may be the most promising target for the development of a malaria vaccine. In this study, proteins composed of 16, 32, or 48 tandem copies of a... more
The circumsporozoite (CS) protein of the human malaria parasite Plasmodium falciparum may be the most promising target for the development of a malaria vaccine. In this study, proteins composed of 16, 32, or 48 tandem copies of a tetrapeptide repeating sequence found in the CS protein were efficiently expressed in the bacterium Escherichia coli. When injected into mice, these recombinant products resulted in the production of high titers of antibodies that reacted with the authentic CS protein on live sporozoites and blocked sporozoite invasion of human hepatoma cells in vitro. These CS protein derivatives are therefore candidates for a human malaria vaccine.
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A candidate Plasmodium falciparum sporozoite vaccine, R32tet32, which includes 32 tetrapeptide repeats derived from the circumsporozoite protein of P. falciparum, has been developed on the basis of the hypothesis that antibodies to the... more
A candidate Plasmodium falciparum sporozoite vaccine, R32tet32, which includes 32 tetrapeptide repeats derived from the circumsporozoite protein of P. falciparum, has been developed on the basis of the hypothesis that antibodies to the repeat region of this protein will protect against sporozoite infection. The results of two in vitro assays, the circumsporozoite precipitation reaction and the inhibition of sporozoite invasion into hepatoma cells, are thought to indicate protective immunity. We therefore tested serum samples from persons living in a hyperendemic malarious area of Indonesia for antibodies against R32tet32 and for their ability to produce circumsporozoite precipitation and to inhibit sporozoite invasion of hepatoma cells. The prevalence and mean titer of antibody against R32tet32 increased with the age of the subjects, whereas the prevalence of P. falciparum infection in the community decreased. Only serum samples with IgG or IgM R32tet32 antibody titers greater than or equal to 1/800 had precipitation activity and invasion-inhibiting activity of more than 75 percent. When the serum samples were fractionated by affinity chromatography, only the fractions containing purified human antibody to R32tet32 were found to contain this activity. These data support the hypotheses that antibodies to the circumsporozoite protein are important in reducing the prevalence of malaria with increasing age among persons in areas in which malaria is endemic and that vaccine-elicited antibody to the circumsporozoite repeat region will protect against infection with P. falciparum sporozoites.
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The number of malaria sporozoites in the salivary glands was determined microscopically for 1137 wild, naturally infected Anopheles from western Kenya. Infective Anopheles gambiae Giles sensu lato (n = 874) contained a geometric mean (GM)... more
The number of malaria sporozoites in the salivary glands was determined microscopically for 1137 wild, naturally infected Anopheles from western Kenya. Infective Anopheles gambiae Giles sensu lato (n = 874) contained a geometric mean (GM) of 962 sporozoites and An.funestus Giles (n = 263) contained 812. No significant differences were detected in geometric mean numbers of sporozoites between species, collection techniques or sites. Of the infective An.gambiae, 1.7% (15/874) contained more than 41,830 sporozoites, the maximum observed for An.funestus. Microscopic techniques were found to be more sensitive than enzyme-linked immunosorbent assays (ELISA) for detecting low-grade sporozoite infections in salivary glands. Salivary gland sporozoites from 83.6% of the 1137 gland infections were identified by ELISA as either Plasmodium falciparum Welch (n = 910), P.ovale Stephens (n = 7), P.malariae Grassi &amp; Feletti (n = 3) or mixed (n = 30). The 187 gland infections which could not be identified by ELISA contained significantly fewer sporozoites (GM = 242) than those which could be identified (GM = 1200).
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In villages of northern Guadalcanal in the Solomon Islands, where the predominant malaria vector is An.farauti No. 1 and An.puctulatus is also involved, malaria transmission rates were compared for three zones: (1) non-intervention: 438... more
In villages of northern Guadalcanal in the Solomon Islands, where the predominant malaria vector is An.farauti No. 1 and An.puctulatus is also involved, malaria transmission rates were compared for three zones: (1) non-intervention: 438 people in seventeen villages; (2) residual DDT house-spraying two cycles per year: 644 people in thirty villages; (3) bednets impregnated with permethrin 0.5 g/m2 twice per year, used by 580 people in sixteen villages. Regular DDT spraying in zones 1 and 3 had been withdrawn 18 months previously. Malariological blood smear surveys of children aged 1-9 years in August 1986 to January 1987 showed a mean baseline malaria parasite rate of 38% (32/84). By February 1988, 18 months after introduction of impregnated bednets, the Plasmodium falciparum infection rate in children was lowest in the zone using impregnated bednets (21% of 29), intermediate in the untreated zone (29% of 34) and highest in the DDT zone (46% of 53), but these differences were not statistically significant. P. vivax infection rates were 9-14%. Using ELISA tests for malaria circumsporozoite antigen in the vectors, overall positivity rates were 0.7% of 49,902 An.farauti and 2.54% of 118 An.punctulatus, comprising 228 P.falciparum and 124 P.vivax infections. In the study zones, vector positivity rates were 0.93% of 31,615 An.farauti in the untreated zone; 0.32% of 16,883 An.farauti in the DDT zone; 0.07% of 1404 An.farauti and 2.54% of 118 An.puctulatus in the impregnated bednet zone. here was no significant correlation between malaria parasite rates in the vectors and the children.(ABSTRACT TRUNCATED AT 250 WORDS)
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Bloodmeals of exophilic anopheline mosquitoes collected resting on vegetation in a malaria endemic area in western Venezuela were identified by ELISA. Using a TMB peroxidase substrate in the ELISA, human bloodmeals were readily identified... more
Bloodmeals of exophilic anopheline mosquitoes collected resting on vegetation in a malaria endemic area in western Venezuela were identified by ELISA. Using a TMB peroxidase substrate in the ELISA, human bloodmeals were readily identified up to 40 h after ingestion in all laboratory-fed mosquitoes tested. Assay sensitivity declined to 75% identifiable 44 h post-feeding. The Human Blood Index and the Feeding Index of each species differed between the three villages studied. An.triannulatus was generally more anthropophilic than An.nuneztovari and An.oswaldoi. These contrasting results emphasize the difficulties of interpreting host choice data.
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Nine monoclonal antibodies (MAbs) developed against Plasmodium vivax (Grassi &amp; Feletti) salivary gland sporozoites were evaluated for use in an enzyme-linked immunosorbent assay (ELISA), using sporozoites developed in Anopheles... more
Nine monoclonal antibodies (MAbs) developed against Plasmodium vivax (Grassi &amp; Feletti) salivary gland sporozoites were evaluated for use in an enzyme-linked immunosorbent assay (ELISA), using sporozoites developed in Anopheles dirus Peyton &amp; Harrison An. gambiae Giles and An.maculatus Theobald. Four of the antibodies were unsuitable due to the low sensitivity of the resulting assays or the requirement for high concentrations of capture antibody. An additional two MAbs were rejected because they resulted in assays with high background absorbance, attributed to self-binding. Of the three remaining MAbs, the use of Navy vivax sporozoite (NVS) 3 resulted in an ELISA with the highest sensitivity and the lowest concentration requirement for capture antibody. Assay sensitivity varied with sporozoite strain indicating possible quantitative epitope heterogeneity. None of the MAbs cross-reacted with the heterologous sporozoites tested by immunofluorescence antibody assay (IFA). The IFA activity was not an indicator of ELISA sensitivity. The use of MAb NVS 3 in a standardized ELISA method resulted in an assay 10 times more sensitive than reported previously for P. vivax sporozoites, with a detection limit of fewer than 100 sporozoites per mosquito.
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The malaria transmission potential of wild, infective Anopheles from western Kenya was evaluated by determining the number of sporozoites transmitted in vitro by salivation when their mouthparts were inserted into capillary tubes... more
The malaria transmission potential of wild, infective Anopheles from western Kenya was evaluated by determining the number of sporozoites transmitted in vitro by salivation when their mouthparts were inserted into capillary tubes containing either sucrose or blood. With sucrose, 86.6% of 102 infective Anopheles transmitted a geometric mean (GM) of 3.84 sporozoites (range 1-34). With blood, 23.1% of 104 infective Anopheles, tested on the day of collection, transmitted a GM of 2.30 sporozoites (range 1-117). For Anopheles held 5 days postcapture before testing with blood, 53.6% of 56 transmitted a GM of 6.04 sporozoites (range 1-420). Transmitting Anopheles contained significantly more salivary gland sporozoites than non-transmitters. No significant differences were detected between Anopheles gambiae Giles sensu lato and Anopheles funestus Giles in sporozoite transmission by individuals with sporozoites in their salivary glands. Sporozoites were detected microscopically in the salivary duct from heads in 80.3% of 117 infective Anopheles (GM = 11.2, range 1-71). Sporozoite detection in mosquito heads by ELISA was 25% less efficient than microscopic detection. Over 98% of the infective Anopheles transmitted less than twenty-five Over 98% of the infective Anopheles transmitted less than twenty-five sporozoites. Transmitted sporozoites represented only about 3% of the total sporozoites in the salivary glands suggesting that sporozoite transmission may be restricted to sporozoites in the salivary duct at the time of feeding. Results are discussed in relation to anti-sporozoite vaccine development.
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Three morphologically different pupal phenotypes (green, striped, brown) were selected from a parent strain of Anopheles albimanus Wiedemann collected from the Suchiate region in the state of Chiapas, Mexico. Significant differences in... more
Three morphologically different pupal phenotypes (green, striped, brown) were selected from a parent strain of Anopheles albimanus Wiedemann collected from the Suchiate region in the state of Chiapas, Mexico. Significant differences in susceptibility to coindigenous Plasmodium vivax Grassi &amp; Feletti were observed when striped was compared with the parent colony as well as with brown and with green phenotypes. Differences in susceptibility were not significant between the other phenotypes and the parent colony.