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M Coluzzi

Publications and source records attributed to M Coluzzi.

At least 73 records · Page 4Linked to original sources
PubMed1994

Ecological genetic studies in the chromosomal form Mopti of Anopheles gambiae s.str. in Mali, west Africa.

Among the sibling species of the Afrotropical Anopheles gambiae complex, the nominal taxon (An. gambiae s.str.) is the major malaria vector. Its bionomics suggest a man-dependent speciation process which involves, in West Africa, various incipient species chromosomally recognized by different combinations of 2R paracentric inversions. One of the most recent evolutionary steps of such a speciation process appears to be the chromosomal form Mopti, which is associated with dry season irrigation in arid zones, and is characterized by a remarkable ecological flexibility related to three 2R alternative arrangements, namely bc, u and +, whose expected karyotypes are found in Hardy-Weinberg equilibrium. The study of this chromosomal polymorphism in samples from a 16-locality transect in Mali shows wide variations and highly significant correlation with both temporal and spatial climatic differences. Mosquitoes homokaryotypic for 2Rbc are the actual dry season and arid areas breeders. The regular rise of 2Rbc frequency, up to fixation, during each dry season, corresponds to the South-North clinal increase of the same arrangement along the transect, from about 30% in the humid savanna to near fixation in the South-Saharan zone. This coherent ecological genetics case provides full support to the hypothesis of the adaptive nature of paracentric inversions. Moreover, the very peculiar system of combinations of contiguous 2R inversions, utilized by Mopti as well as by other chromosomal forms of An. gambiae, suggests a process of polygenic reorganization based on linkage disequilibria and involving the inversions as driving selection units.

Animals↗
PubMed1994

Amylin given by central and peripheral routes inhibits acid gastric secretion.

The effect of rat amylin on acid gastric secretion in the pylorus-ligated, unanesthetized rat system (Shay test) was examined. Amylin administered peripherally (2.5, 5, 10, 40, 100, or 160 micrograms/kg, SC) or intracerebroventricularly (1.5, 2.7, or 5 micrograms/rat, ICV) decreased acid gastric secretion in a dose-dependent manner. Central administration of amylin gave a stronger suppression of gastric secretion than peripheral injection. In addition, ICV-injected amylin inhibited insulin-stimulated acid gastric secretion and was effective in suppressing acid gastric secretion in rats depleted of somatostatin by pretreatment with cysteamine. This study suggests that amylin may participate in the central regulation of acid gastric secretion and indicates a possible biological function of amylin as a gastrointestinal peptide.

Amyloid↗
PubMed1994

Malaria and the Afrotropical ecosystems: impact of man-made environmental changes.

Subsaharan Africa is dramatically characterized by the most most powerful malaria vector system which accounts for more than 80% of the 120 million clinical cases estimated in the world in one year. Great difficulties are experienced in the control of the disease, while failures, more or less complete, were recorded in the control of the transmission. The historical perspectives emphasize the importance of malaria vector biology and the impact of man-made ecological changes which favour in many cases the increase of the transmission potential.

Africa South of the Sahara↗
PubMed1993

Effective population size and persistence of Anopheles arabiensis during the dry season in west Africa.

The way that the malaria vectors Anopheles arabiensis and An.gambiae survive the dry season in sub-saharan Sahel or northern Savanna areas of Africa remains enigmatic. We examined this problem by calculating the effective sizes (Ne) of An.arabiensis populations for several locations in West Africa. An indirect/genetic procedure was used, comparing gene frequencies at several time intervals. The amount of drift which occurred provides an estimate of Ne. Most estimates of Ne were approximately 2000 individuals, probably close to the yearly minimum. This supports the hypothesis that populations of An.arabiensis in this region are continuous throughout the year, with many individuals surviving through the dry season, perhaps in a physiologically altered state, rather than extinction or severe bottlenecks during the dry season, followed by recolonization by a few individual survivors or immigrants in the subsequent rainy season.

Africa, Western↗
PubMed1993

A new odour-baited trap to collect host-seeking mosquitoes.

A new odour-baited entry trap which releases an air stream containing chemical cues collected from a bait, has been used successfully to collect West African mosquito species, most of them important vectors of malaria, such as Anopheles gambiae s.l. and An. funestus. 85% of the yield consisted of live, unfed and partially fed specimens. The trap has some practical and theoretical advantages over similar sampling techniques.

Animals↗
PubMed1993

Advances in the study of Afrotropical malaria vectors.

The advances in the study of Afrotropical malaria vectors outlined in this report were obtained with the support of the EC-STD2 program by a network led by a research team of the Istituto di Parassitologia, University of Rome "La Sapienza" and including various collaborators based in different African countries. A list of authors and collaborating laboratories is given in the acknowledgements. The main results obtained are as follows. 1) Discovery of new chromosomally recognized taxa of the An. gambiae complex in Mali. One of them, the Mopti chromosomal form, is specifically adapted to breeding during the dry season and replaces other members of the complex in irrigated areas also in Burkina Faso and Northern Benin. 2) Evidence for increasing potential for P. falciparum transmission in the area of Cotonou (Benin) where highly anthropophilic An. gambiae (fresh water breeder) replaces the less effective vector An. melas (salt water breeder) when lagoon pile-dwelling traditional villages are converted into unplanned urban settlements. 3) Analysis of the vector system responsible for the P. falciparum epidemics on the Madagascar plateau showing the absence of An. gambiae, the secondary role of An. arabiensis (characterized by zoophilic and exophilic behaviour) and the primary role of An. funestus which is characterized by a peculiar focal distribution presumably depending on larval overwintering. 4) Evidence for a role for An. pharoensis (or at least of one of the taxa of this complex) in the transmission of P. falciparum malaria in the Senegal river delta. 5) Evidence for bionomical differences between An. gambiae and An. arabiensis and for intraspecific heterogeneities in both taxa associated with paracentric inversion polymorphisms.

Africa South of the Sahara↗
PubMed1992

Malaria vector analysis and control.

Antivector measures in malaria control should aim for a cost-effective reduction of the transmission potential ideally to below the critical level for sustained transmission. The available measures include those that decrease vector abundance, vector-human contact and vector survival rate or that increase the length of the sporogonic cycle. These have widely different impact on malaria transmission, as shown by epidemiological modelling. Direct modification of vector receptivity to Plasmodium is also hypothetically attainable by the use of transmission-blocking vaccines or by genetic manipulation and replacement of the vector population. Vector analysis constitutes the essential prerequisite for basic malaria epidemiology as well as for the development, planning and evaluation of antivector measures. The rationale, the problems and the perspectives of vector analysis are reviewed here by Mario Coluzzi, on the basis of his experience with Afrotropical and Mediterranean malaria vectors.

Journal Article↗
PubMed1992

Malaria transmission and vector biology on Sainte Marie Island, Madagascar.

A 17-mo longitudinal malaria survey (November 1988-March 1990) was carried out on Sainte Marie Island, an area on the east coast of Madagascar which is frequently visited by tourists. During 706 man-nights of capture, 46,401 mosquitoes belonging to 32 species were caught. Sporozoite rates were determined by ELISA and incriminated Anopheles gambiae Giles s.s., An. funestus Giles, and An. mascarensis De Meillon as vectors of malaria. An. gambiae, the main vector, was highly anthropophilic but largely exophilic. Transmission by this species occurred mainly from November to April; the overall circumsporozoite antigen positivity rate was 1.7%, with a maximum of 3.2% in March-April. The nightly peak of transmission occurred between midnight and 0400 hours. The annual inoculation rate was calculated to be 100 infective bites per human, of which 92 were of Plasmodium falciparum. An. funestus played a minor role in transmission. An. mascarensis, an anopheline endemic to Madagascar, was incriminated for the first time, as a malaria vector. The sporozoite rate in this species varied from 0.4 to 0.9% as shown by both ELISA and salivary gland dissections. Parasite indices in humans up to 20 yr of age fluctuated during the year from 64 to 80%. Bed nets are recommended for malaria protection for the local population and tourists.

Animals↗
PubMed1992

[Coastal urban malaria in Cotonou (Republic of Benin). Entomological study].

A one year entomological was carried out the survey in the coastal town of Cotonou to study the urban transmission of malaria. Three representative areas of Cotonou were chosen. The method adopted concerned night catches on human bait and dissection of A. gambiae s.l. The density of the vector (A. gambiae s.l.) fluctuated with the level of urbanization of the areas the annual aggressivity rates reached 1179 in the town center, 3666 in an the outskirts and 3363 in intermediate areas. Mean sporozoitic index was 1.7% and corresponding annual inoculation rate 46. In center of the town, transmission is seasonal and short, with a very high level. Sporozoitic index is 12% and the corresponding inoculation rate is 1.02. Outside of the town, transmission is seasonal and long: lasting 8 months. Transmission is imperceptible in the middle of the dry season and at the beginning of the long rain season. Malaria transmission into urban areas is generally low but in coastal like zones Cotonou, the intensity may be higher.

Animals↗
PubMed1991

Low-resolution genome map of the malaria mosquito Anopheles gambiae.

We have microdissected divisions of the Anopheles gambiae polytene chromosomes, digested the DNAs with a restriction enzyme, and PCR-amplified the DNA fragments to generate a set of pooled probes, each corresponding to approximately 2% of the mosquito genome. These divisional probes were shown to have high complexity. Except for those derived from near the centromeres, they hybridize specifically with their chromosomal sites of origin. Thus, they can be used to map cloned DNAs by a dot blot procedure, which is much more convenient than in situ hybridization to polytene chromosomes. We discuss additional potential uses of these probes, such as easier isolation of molecular markers and genes, including those that cross-hybridize with clones available from other insects. It is expected that the probes will substantially accelerate molecular genetic analysis of this most important malaria vector.

Animals↗
PubMed1991

Identification of Dirofilaria in man by multilocus electrophoretic analysis.

Biochemical keys based on the electrophoretic patterns of nine enzymatic loci diagnostic between Dirofilaria repens and D. immitis were used to examine an immature female of Dirofilaria removed from a 32-year-old woman resident in Caserta, Italy. The worm, tentatively assigned on a morphological basis to D. conjunctivae-D. repens, showed at all the loci examined the same electrophoretic pattern as an Italian dog strain of D. repens. This genetic evidence is in substantial agreement with the hypothesis, already supported by morphological and epidemiological data, that D. conjunctivae (Addario, 1885) Desportes, 1939-1940 and D. repens Railliet and Henry, 1911 should be considered as synonyms. According to the law of priority D. conjunctivae should be the valid name for the species; however, it is proposed to preserve the name repens, well-established for the dog subcutaneous filaria. Multilocus electrophoretic analysis appears to be a valuable tool for the identification of aetiological agents of human zoonotic filariae, particularly in areas where more than one species of the subgenus Nochtiella are present.

Adult↗
PubMed1991

[Longitudinal study on malaria transmission and biology of vectors in the island of Sainte Marie, on the east coast of Madagascar, from 1988 to 1990].

A 17-month longitudinal malaria survey was carried out in Sainte Marie Island, on the East Coast of Madagascar, from November 1988 to March 1990. During 706 man-nights of captures, 46401 mosquitoes belonging to 32 species were caught. Sporozoïte rates were calculated by Elisa. The malaria vectors were Anopheles gambiae sensu stricto, An. funestus and An. mascarensis. An. gambiae was the main vector. It was highly anthropophilic and partially exophilic. Transmission by this species mainly occurred from November to April, monthly sporozoïte antigene positivity rate varied from 0 to 3.85. The annual inoculation rate was about 100 infecting bites per man, in which 92 by Plasmodium falciparum. An. funestus intervened weakly in transmission. An. mascarensis, a malagasy endemic region anopheline is a newly discovered vector. The observed sporozoïte rate varied from 0.4 to 0.9 between September and March 1990. Parasite indexes in human fluctuated during the year from 64 to 80%. Because of the high level of transmission, recommendations for inhabitants and tourists are proposed.

Adolescent↗
PubMed1991

[Further data on the spread to Genoa of Aedes albopictus].

Further data are presented on the presence of Aedes albopictus in the town of Genoa (Italy) where this oriental mosquito was first reported in September 1990. Scattered foci of Ae albopictus were documented during the 1991 summer months in spite of a rather long and rigid '90-'91 winter season with temperatures frequently below 0 degree C. The newly imported mosquito shows the capacity to become a permanent pest in Italy where it could also increase the probability of transmission of pathogens such as arboviruses and filariae.

Aedes↗
PubMed1991

Plasmodium falciparum malaria transmission indices in a highland village of the Ikopa River Valley near Antananarivo, Madagascar.

Data are reported from a malaria survey carried out in June 1991 in the small village of Ankadimbazinba, near Miantso, about 45 km North-West of Antananarivo (Madagascar). The objective was to evaluate the level of transmission of P. falciparum by entomological, parasitological and serological indices. All indices were found consistent with the description of a focus of hyperendemic transmission dependent on the presence of An. funestus at high density, corresponding to more than 50 females per house collected by hand catch. The positivity rate for the circumsporozoite protein (CS) of P. falciparum in blood-fed or gravid An. funestus was 2.0% (11/562) in the house resting sample. The parasite rate in the village population was 47.9% reaching 68.4% in the 0-14 age group and the gametocyte rate in the total sample was 25.0%. The seroprevalence of P. falciparum antisporozoite antibodies was 40.0% in children under 15 years old, 84.2% in the 15-29 age group and 90.9% in the over 29 age group.

Adult↗
PubMed1990

Anopheles pharoensis and transmission of Plasmodium falciparum in the Senegal River delta, West Africa.

1. Anopheles pharoensis Theobald was found to be the prevalent man-biting anopheline mosquito in the central area of the Senegal River delta. 2. Blood-fed females of An. pharoensis were obtained during September-December 1987 from mosquito bednets in the village of Souhloul, near the Boundoum dam, 70 km NE of St Louis. 3. Dried mosquito specimens were identified morphologically and each thorax processed using monoclonal antibody against the circumsporozoite protein of Plasmodium falciparum. 4. Five An. pharoensis out of 912 examined were sporozoite positive, while ninety-eight An. gambiae Giles sensu lato were all negative. This finding strongly supports the local importance of An. pharoensis as a malaria vector. 5. Successful use of pyrethroid-impregnated bednets against malaria transmission in this situation has helped to achieve more than 90% reduction of malaria prevalence.

Africa, Western↗
PubMed1990

Malaria transmission and vector biology in Manarintsoa, high plateaux of Madagascar.

To evaluate the factors which determine the transmission level of falciparum malaria, entomological and parasitological surveys were conducted from October 1988 to February 1990 in Manarintsoa in the central highland plateaux of Madagascar. Mosquitoes were collected for 928 man-nights in pit shelters and indoor resting sites. Malaria vectors were Anopheles arabiensis and An. funestus, with no evidence of the presence of An. gambiae sensu stricto. Vectors were mainly exophilic and zoophilic. The index of stability was less than 1.5. The sporozoite rate was 0.11 for An. gambiae sensu lato and 0.47 for An. funestus. The transmission level was low, with an inoculation rate of 0.91 infective bites/person/year and an infection risk of 0.62. Malaria transmission occurs 7 months of the year in this area, from November to May. Human parasite rates fluctuated from 29% in October to 53% in May.

Animals↗
PubMed1990

[Malaria vectors and their role in transmission, in Manarintsoa in the Highland Plateaux of Madagascar from 1988 to 1990].

To evaluate the factors determining malaria transmission level, entomological and parasitological surveys were conducted from October 1988 to February 1990 in MANARINTSOA, in the central highland plateaux of MADAGASCAR. Mosquitoes were collected during 928 man-nights of captures, in pit shelters and in indoors resting sites. The malaria vectors were An. arabiensis and An. funestus, with no evidence of the presence of An. gambiae s.s. The vectors were mainly exophilic and zoophilic. The index of stability was below 1.5. The sporozoite rate was 0.11 for An. gambiae s.l. and 0.47 for An. funestus. The transmission level was low: the inoculation rate was 0.91 infected bite per man and per year and the infection risk 0.62. Transmission occurs 7 months per year, from November to May. In the human population parasite rates fluctuated from 29% in October to 53% in May.

Altitude↗