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PubMed2003

Experimental transmission of Leishmania tropica to hamsters and mice by the bite of Phlebotomus sergenti.

Phlebotomus sergenti is a natural vector of Leishmania tropica. However, the ability of P. sergenti to transmit L. tropica by bite has not been proven experimentally yet. We have transmitted L. tropica to golden hamsters and BALB/c mice by the bite of P. sergenti. Sand flies and Leishmania both originated from an anthroponotic cutaneous leishmaniasis focus in Urfa, Turkey. P. sergenti females from a laboratory colony were infected by feeding on lesions of needle-inoculated hamsters or mice. Gravid females were allowed to refeed on uninfected hosts 9-15 d after the infective feeding. At the second feeding, some infected females took a full blood meal, while others only a partial one; some females failed to feed at all. The ability of infected females to take a blood meal did not correlate with the parasite transmissibility. In four BALB/c mice, lesions developed after 1-6 months. In two albino hamsters (Mesocricetus auratus), lesions developed 1 month after the infective feeding, and Leishmania could be reisolated from these sites. Another hamster did not develop a lesion; however, the feeding site and the adjacent ear were PCR positive 1 year after infective feeding. Our results show that dissemination to other parts of host body occurs in L. tropica after sand fly bite. Experimental transmission of the parasite confirms that P. sergenti is a natural vector of L. tropica.

Animals↗
PubMed1986

Seasonal activity and abundance of the arbovirus vector Culex annulirostris skuse near Echuca, Victoria, in the Murray Valley of Southeastern Australia 1979-1985.

Abundance of Culex annulirostris in a state forest near Echuca, northern Victoria, was sampled with a dry ice-baited EVS trap from 1979 to 1985, generally on a fortnightly basis. The species regularly became active from October, the population reached peak abundance in mid summer and then declined to become undetectable from late May. Abundance varied between years, related to availability of larval habitats. The results confirm a pattern of seasonal activity in the Murray Valley that is relevant to arbovirus epidemiology and to vector control.

Animals↗
PubMed1990

Effect of Plasmodium falciparum on the survival of naturally infected afrotropical Anopheles (Diptera: Culicidae).

The effect of the malarial parasite, Plasmodium falciparum Welch, on the daily survival rates and longevity of Anopheles gambiae Giles sensu lato and Anopheles funestus Giles was determined for wild-caught, naturally infected females from western Kenya. Mosquitoes were collected inside houses and held in cages until death, after which they were assayed for P. falciparum circumsporozoite protein by an enzyme-linked immunosorbent assay (ELISA). Survival rates of field populations determined by parity rates were significantly higher than survival rates estimated by regression for Anopheles dying in cages. Overall, An. gambiae s.l. had a significantly higher daily mortality rate (means = 17.5%) than An. funestrus (means = 13.2%). P. falciparum ELISA infection rates, which were higher for An. gambiae s.l. (means = 19.8%; n = 1,221) than for An. funestus (means = 11.9%; n = 1,128), did not increase as a function of time for caged Anopheles. For An. gambiae s.l., there was a significant negative correlation between holding time and P. falciparum ELISA absorbance, suggesting that detectable circumsporozoite protein and perhaps the number of sporozoites may decrease with time in the vector. In western Kenya, an area where Anopheles populations often have extremely high malaria infection rates. Plasmodium infections did not reduce vector survivorship.

Animals↗
PubMed1990

Use of an electrostatic sprayer for control of anopheline mosquitoes.

The Electrodyn sprayer was compared with a compression sprayer (Hudson X-pert) for residual application of cypermethrin, a pyrethroid insecticide, to control the malaria vectors Anopheles arabiensis Patton and An. funestus Giles in experimental huts at Magugu in Tanzania. The time taken for hut spraying, 2-2.5 min per hut, was similar for both types of sprayer. Two or three huts were treated internally with cypermethrin at 40 or 80 mg a.i./m2 using Electrodyn formulation for comparison with 80 mg a.i./m2 using wettable powder formulation. Each of the twelve huts (including five untreated controls) was fitted with window exit traps and either louvre or verandah traps for mosquito sampling. The Electrodyn sprayer was fitted with a pair of elbowed deflectrodes to direct the positively charged spray droplets onto walls and ceiling. All treatments gave 94-100% mortality-rates of indoor-resting anophelines throughout the evaluation period of 11 weeks post-spray. Reductions of An.arabiensis and An.funestus females by 10-42% and 62-91%, respectively, in rooms and by 72% and 51% in exit traps indicated that cypermethrin deterred mosquitoes from entering the huts. Overall mortality-rates of mosquitoes were 66% of both species in huts treated with 40 mg/m2 Electrodyn, 43% An.funestus and 71% An.arabiensis due to 80 mg/m2 Electrodyn formulation and 49% An.funestus and 64% An.arabiensis due to 80 mg/m2 WP formulation (no significant differences). It is concluded that the Electrodyn sprayer with deflectrodes is a convenient and effective means of residual house-spraying with pyrethroid insecticide for malaria vector control.

Aerosols↗
PubMed2000

Could malaria return to Britain?

With predicted global warming, the mosquito fauna of Britain is certain to change. How will this effect our native Anopheles mosquitoes and the development of malarial parasites within them? Will exotic species become established, and act as more effective vectors of malaria?

Animals↗
PubMed1975

[Bread beetle (Stegobium paniceum L.) as Salmonella vector in fodder and fodder mixture (author's transl)].

In 1965 Salmonella eimsbuettel was isolated from two samples of fodder mixture for poultry and one sample of fodder mixture for pigs. In these samples of fodder mixtures there were also numerous specimen of bread beetles (Stegobium paniceum L.). The bread beetles remained in these fodder mixtures during more than 9 years (till June 1974), and by them S. eimsbuettel was proved in one sample of fodder mixture for chickens as well. From the other sample of fodder mixture for chickens Salmonella was isolated during 6 years and from the sample of fodder mixture for pigs S. eimsbuettel was isolated during seven and half years. In 1969 into 12 sterile samples of fodder 5-10 adult bread beetles were inserted. These bread beetles had been taken from fodder mixtures contaminated by S. eimsbuettel and bread beetles. The bread beetles multiplied in these fodder mixtures and from a year thereafter the fodders were searched for Salmonella every 6 months. In 4 samples of fodder (out of 12) S. eimsbuettel was proved till June 1974. The same Salmonella was isolated from well-washed and mashed bread beetles. Therefore the bread beetles (Stegobium paniceum L.) should be included into Salmonella vectors.

Animal Feed↗
PubMed1990

[Medical entomology in Taiwan].

Following the establishment of the Environmental Protection Administration in 1987 and the occurrence of the dengue epidemic in 1988, resurgent interest and need have been created to promote and support medical entomology in Taiwan. Steps should be taken to strengthen the training of workers in medical entomology, to establish a society for vector ecology and control, to issue periodicals in English, and to coordinate with foreign institution. Items for applied research on vector and best control are suggested.

Animals↗
PubMed1980

Plasmodium falciparum and Plasmodium vivax infections in Saudi Arabia, with a note on the distribution of anopheline vectors.

Variations in the intensity of Plasmodium infections were observed in the surveyed regions of Saudi Arabia. The highest incidence had been recorded from the Southern region and the lowest form the Northern and Eastern regions. The Western region, however, showed a regular and uniform occurrence of infection throughout the year. Five anopheline vectors were identified in the country.

Animals↗
PubMed2000

Purification and characterization of human alpha-galactosidase A expressed in insect cells using a baculovirus vector.

Fabry disease is an X-linked inborn error of glycolipid metabolism caused by deficiency of the lysosomal enzyme alpha-galactosidase A. The enzyme is responsible for the hydrolysis of terminal alpha-galactoside linkages in various glycolipids. To perform more extensive biochemical characterization and to develop new approaches for enzyme therapy, a method of producing and purifying recombinant alpha-galactosidase A suitable for scale-up manufacture for use in humans is needed. Previously, a catalytically active recombinant human alpha-galactosidase A was expressed using a baculovirus vector and purified using conventional chromatography. However, the level of expression was too low to permit economical production and the chromatographic techniques used for enzyme purification were not suitable for enzyme to be used in humans. Therefore, the cDNA of the enzyme was cloned to an improved baculovirus vector and the enzyme was expressed in a 15-liter bioreactor using optimized growth conditions. Infection of insect cells by the baculovirus resulted in a significant fivefold increase in the level of secreted recombinant alpha-galactosidase A activity that is compatible with economic manufacturing. The recombinant alpha-galactosidase A was purified to homogeneity using ion exchange (Poros 20-CM, Poros 20-HQ) and hydrophobic chromatography (Toso-ether, Toso-butyl) using the BioCAD HPLC workstation. These chromatographic steps are readily scalable to larger volumes and are appropriate for the purification of the recombinant human alpha-galactosidase A to be used in clinical trials of enzyme replacement therapy for Fabry disease patients.

Amino Acid Sequence↗
PubMed2006

A heme-degradation pathway in a blood-sucking insect.

Hematophagous insects are vectors of diseases that affect hundreds of millions of people worldwide. A common physiological event in the life of these insects is the hydrolysis of host hemoglobin in the digestive tract, leading to a massive release of heme, a known prooxidant molecule. Diverse organisms, from bacteria to plants, express the enzyme heme oxygenase, which catalyzes the oxidative degradation of heme to biliverdin (BV) IX, CO, and iron. Here, we show that the kissing bug Rhodnius prolixus, a vector of Chagas' disease, has a unique heme-degradation pathway wherein heme is first modified by addition of two cysteinylglycine residues before cleavage of the porphyrin ring, followed by trimming of the dipeptides. Furthermore, in contrast to most known heme oxygenases, which generate BV IXalpha, in this insect, the end product of heme detoxification is a dicysteinyl-BV IXgamma. Based on these results, we propose a heme metabolizing pathway that includes the identified intermediates produced during modification and cleavage of the heme porphyrin ring.

Animals↗
PubMed1999

Temperature and relative humidity affect the selection of shelters by Triatoma infestans, vector of Chagas disease.

The preference of Triatoma infestans for shelters at different temperatures or relative humidities (RH) was tested in laboratory assays. The insects preferred refuges at a temperature of 34 degrees C rather than 26 degrees C, and chose to stay in refuges with an RH of 20% rather than 80%. Temperature and RH records made inside and outside experimental chicken-houses under natural climatic conditions showed that such habitats tend to maintain an inner climate favourable to T. infestans. Typical refuges in adobe walls showed strongly damped fluctuations in minimum and maximum temperatures, and delayed changes in these parameters when compared with an external reference. Similarly, the jarilla (Larrea sp.), a plant used for constructing roofing, damps fluctuations in minimum and maximum RH and delays these RH fluctuations when compared to an external reference. We discuss possible effects of environmental factors on the distribution of insects in human dwellings, and analyse the environmental characteristics of normally available refuges in materials used for house building in endemic zones.

Animals↗