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PubMed2006

[Breeding places and biting activity of Anopheles species in the municipality of Cimitarra, Santander, Colombia].

INTRODUCTION: Forty five percent of malaria cases in the department of Santander, Colombia originate in the municipality of Cimitarra. This locality has reported cases from the rural and urban areas. The population between 15 and 45 years of age is the most affected. Additionally, Cimitarra has registered malaria cases in children under 1 year of age. OBJECTIVE: To determine the biology and behavioral aspects of Anopheles mosquitoes from Cimitarra to more effectively orient control strategies. MATERIALS AND METHODS: During October to December/2002 and March/2003, anopheline collections were undertaken. Isofamilies were obtained from 620 wild females. RESULTS: The following species were found in order of abundance: Anopheles (Nyssorhynchus) triannulatus (Neiva y Pinto 1922), Anopheles (Nyssorhynchus) nuneztovari Gabaldón 1940, Anopheles (Nyssorhynchus) rangeli Gabaldón, Cova-García y López 1940, Anopheles (Anopheles) pseudopunctipennis Theobald 1901, Anopheles (Anopheles) mattogrosensis Lutz y Neiva 1911 and Anopheles (Anopheles) neomaculipalpus Curry 1933. The highest biting rate (0.5) was recorded for An. nuneztovari and An. triannulatus indoors between 20-21 hours. Forty two breeding places were sampled, 81% were fish ponds, 9.5% puddles and 2.3% cement tanks. Eighty seven percent of fish ponds were located near dwellings, being positive for anopheline larvae. CONCLUSION: This study has shown that in Cimitarra cryptic and sister species of Anopheles genus occur in sympatry, Nyssorhynchus subgenera.

Adolescent↗
PubMed2006

[The risk of yellow fever in travellers].

Yellow fever is a tropical virus disease characterised by high fever, jaundice, heart and kidney failure, and haemorrhagic diathesis. The causative Flavivirus is endemic in parts of tropical Africa and South America and is transmitted among humans and primates by mosquitoes. The chance that an unvaccinated traveller to West Africa will die of yellow fever is estimated at 1:650 to 1:5000 visitors per month of stay, depending on whether an epidemic occurs. Vaccination with the attenuated yellow fever Asibi 17D virus results in limited virus replication in the body and long-term protection due to the formation of neutralising antibodies. Vaccination is contraindicated in immunocompromised persons. Serious disseminated disease and encephalitis due to infection with the vaccine virus strain are seen more often in the elderly. One should therefore refrain from vaccination in persons over 60 years of age when the risk of infection is negligible. In recent years, the number of yellow fever epidemics has risen substantially, particularly in West Africa and the Amazon region. Reintroduction of yellow fever vaccination in childhood vaccination programmes is necessary in endemic areas to turn the tide of increasing outbreaks of yellow fever.

Animals↗
PubMedDate not supplied

[Pilot study to evaluate the efficiency of insecticide-treated mosquito net fences for the protection of horses against nuisance insects in northern Brandenburg].

A fence of black mosquito netting of 100 cm height, pre-treated with 80 mg/m2 of deltamethrin and UV-protected, was used to shelter horses from nuisance and biting insects on pasture in northern Brandenburg. The netting material was attached to the surrounding poles of the existing fences at a height of 15 cm above ground. Three trial groups were selected grazing in spatially separated areas with comparable densities of insect populations. One paddock was completely fenced apart from a wall of 170 cm height and 70 m length. The second pasture had only partial protection with 126 m (13.4%) of fence out of a total perimeter of 942 m. The third pasture served as control. Trap catches outside the fully or partially protected pasture were by at least 60% lower than those recorded for the control pasture. Digital pictures from five different anatomical regions indicated fewer flies on horses kept at the completely or partially protected areas as compared to the control area. The average attack rate in the protected areas amounted to 4.4 and 7.6 flies per horse at the completely or partially protected areas, respectively, as opposed to horses on the control pasture with 172.1 flies. In comparison to the control pasture the horses grazing on the protected areas showed fewer defensive movements, grazing in an undisturbed manner.

Animals↗
PubMedDate not supplied

[Vector capacities of Similium damsnosum s.l and risk for Onchocerca volvulus transmission in Inga (Democratic Republic of Congo)].

This article analyzes the results of a one-year entomological survey conducted near the Yalala rapids in the Inga region, Democratic Republic of Congo, prior to the implementation of Community-Directed Treatment with Ivermectin (CDTI). A vector control program had been undertaken from October 1969 to December 1980, 20 kilometers upstream from the study site. The results of the present study show that during 122 collection days, 5,824 females were captured, of which 3,899 were dissected; 2,001 (51.3%) were parous while 44 (2.2%) were infected while 4 (0.2%) were infective. The crude Annual Transmission Potential (ATP) was 65 infective larvae per man and per year at the river as against 12 in Yalala village located two kilometers from the rapids. The average biting rate was 5 flies/man/day during the dry season and 90 during the rainy season. The vector capacity of similium shows that the risk of transmission of Onchocerca volvulus to the human population was not only reduced in time (2-3 months), but was also negligible all year round.

Animals↗
PubMed2006

Bionomics studies of Mansonia mosquitoes inhabiting the peat swamp forest.

The present study was conducted in the years 2000-2002 to determine the bionomics of Mansonia mosquitoes, vectors of nocturnally subperiodic Brugia malayi, inhabiting the peat swamp forest, "Phru Toh Daeng", Narathiwat Province, Thailand. Fifty-four species of mosquitoes belonging to 12 genera were added, for the first time, to the list of animal fauna in the peat swamp forest. Mansonia mosquitoes were the most abundant (60-70%) by all collection methods and occurred throughout the year with a high biting density (10.5-57.8 bites per person-hour). Ma. bonneae was most prevalent (47.5%) and fed on a variety of animal hosts, including domestic cats, cows, monkeys, and man with a maximum biting density of 24.3 bites per person-hour in October. The infective bites were found for the first time in Ma. annulata collected at Ban Toh Daeng (13 00-14 00 hours) and also Ma. bonneae at forest shade (16 00-17 00 hours) and in a village (20 00-21 00 hours) with rates of 0.6, 1.1 and 1.0%, respectively. The biting activities of these two species occurred in both the day and night time, with two lower peaks at 10 00 hours (18.5 bites per person-hour) and 13 00-15 00 (8.5-10.0 bites per person-hour) hours, but the highest peak was 19 00-21 00 hours (31.5-33.0 bites per person-hour) The biting activity patterns corresponded with the periodicity found in man and domestic cats and may play an important role in either transmission or maintenance of the filarial parasites in the peat swamp forest. The relative role of Ma. bonneae and Ma. uniformis in different environmental settings (primary swamp forest and open swamp) on the transmission of nocturnally subperiodic B. malayi merits further study.

Animals↗
PubMedDate not supplied

[Experimental antitriatomic program in Santiago].

The rural migration to urban centers occurred since the 40s in many Latin American countries, including Santiago the capital city of Chile, originated a growing belt of premises built with light poor material (the rests of previous rural habitations, mud, pieces of timber, plastic and cardboard for walls, and cane stalks and artificial clinkstones for roofs) giving raise to many types of slums. This situation facilitated the passive transport of the different instars, including eggs, of triatomine bugs. Due to the fact that in the 1959-1960 warm seasons, the Santiago province health institutions had received an increasing reported number of triatomine bugs (Triatoma infestans) in dwellings from different periurban, even urban and rural sections of the province, the central local health authorities with the advise of the University of Chile, Department of Parasitology decided to carry out an experimental program against these vectors of Chagas' disease. The program consisted basically in an spray and thorough application of liquid forms (emulsion, suspension, solution) of 1% lindane (average > or = 500 mg per 1 m2), depending on the material of the constructions, to all the surfaces of walls, ceilings, attics and peridomiciliary structures of all the infested dwellings in a sector and those located less than 100 m around. In order to reach triatomine bugs not affected, for different reasons, in the first spraying, a second application, identical to the first was performed to the total number of premises between 30 and 120 days later. Periodical evaluations were made, and positive dwellings found and neighboring ones were sprayed again. During insecticide applications adequate protection measures for spraying workers, inhabitants, domestic animals, household goods and food were adopted. All the steps of the program were accompanied by health education activities directed to individuals, families, school teachers and community institutions, tending to motivate the people to an active participation, as in the report of the presence or reappearing of triatomines in premises as in cooperating in the sprayings and improving the material conditions of their properties. Thus, in the period 1960-1972 the following goals were achieved: 1) Spraying twice with 1% lindane 32,708 dwellings located in 199 quarters from 26 periurban and rural sections. 2) Protection to 191,090 people against T. infestans bites and the eventual acquired chagasic infection. 3) Percentages of triatomines infested dwellings decreased from to 18.7 to 3.0 according to residents and from 3.0 to 0.3 according insects collection. At present, a significant proportion of the sprayed dwellings has been demolished and replaced by new constructions.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1991

Permethrin and dimethyl phthalate as tent fabric treatments against Aedes aegypti.

Tests were conducted to determine the persistence of compounds applied to tents to protect against mosquitoes. Interiors of 2 camping tents were treated by the manufacturer--one with the repellent dimethyl phthalate (DMP) and one with the insecticide permethrin. A third tent was untreated. Tents were set up outdoors and exposed to weathering for one year. Weekly tests were conducted by releasing Aedes aegypti into the tents, then recording knockdown (KD) and biting behavior during a 3-h period. Weather data were collected 24 h/day during the study. Year-long mean KD of mosquitoes exposed in the tent to permethrin was 58.6%, to DMP 2.7% and the control 0.9%. Mean biting was 11.9, 43.8 and 58%, respectively. Under constant exposure to weathering, the permethrin-treated tent gave best results with average protection from bites greater than 96% for 9 months (DMP was less than 31%). Although preliminary, the data suggest permethrin would be effective as a tent treatment to reduce annoyance of mosquitoes.

Aedes↗
PubMed1991

Potential for dengue in South Africa: mosquito ecology with particular reference to Aedes aegypti.

Observations on prevalence, geographical distribution, utilization of artificial larval habitats and anthropophilism were made on diurnal mosquitoes at selected localities along the coast of Natal and inland in the Transvaal to identify potential vectors of dengue in South Africa. Larval collections made in artificial containers on the ground, the exposure of bamboo pots as ovitraps in trees and collection of mosquitoes biting man showed the following species as the most likely candidates for vectors: Aedes aegypti, Ae. demeilloni, Ae. simpsoni, Ae. strelitziae, Ae. furcifer, Ae. cordellieri and Eretmapodites quinquevittatus. The bamboo pots showed that Ae. aegypti and Ae. simpsoni were the most widespread species, occurring at 11 of 12 localities. Aedes aegypti was the most prevalent species with mean pot index of 60.3 +/- 9.8% (SE) and abundance index of 0.43 +/- 0.15 (SE). Aedes aegypti was frequently present as larvae in artificial containers at indices of 11-83% (mean 56.8 +/- 5.6%, SE) and was the most anthropophilic species with average biting rates of 10-29 per man-hour at 7 localities. Although Ae. aegypti was abundant in the pots at Ndumu (northern Natal) and at Skukuza (eastern Transvaal), the local populations were poorly anthropophilic at these localities. At some localities, populations of Ae. demeilloni, Ae. simpsoni and Ae. strelitziae had average biting rates of 5.4-9.6 per man-hour. Aedes furcifer was collected for the first time at Durban, extending its distribution southward to latitude 29 degrees 53' S.

Aedes↗
PubMed1991

Gel diffusion analysis of Anopheles bloodmeals from 12 malarious study villages of Orissa State, India.

In Orissa State, India, the double gel diffusion technique was used to analyze 97,405 bloodmeals of all fed anophelines that were caught during standardized monthly surveys in 12 malarious study villages, from 1982 through 1988. Anopheles culicifacies contributed the highest number of smears from the 19 Anopheles species recovered. It was observed that a pronounced predilection to take mixed bloodmeals attenuates the vector potential of the species concerned. Consequently, prevalences based only upon "pure" (unmixed) primate bloodmeals provide the most accurate way to assess the intensity of feeding contact that actually occurs between a given species and man. By this method, the ranking order is Anopheles fluviatilis, An. culicifacies and An. annularis (N); a sequence which concurs with current knowledge on the vector status of malaria mosquitoes in Orissa.

Animals↗
PubMed1991

Efficacy assessment of Quwenling, a mosquito repellent from China.

Quwenling, an insect repellent product of China derived from extracts of the lemon eucalyptus plant (Eucalyptus maculata citriodon), was evaluated. Laboratory tests compared Quwenling with deet against Anopheles albimanus, An. quadrimaculatus, Aedes aegypti, Ae. albopictus and field tests with Ae. taeniorhynchus. Cloth treated with Quwenling at greater than 2x the dosage of deet was effective against 2 of 4 species tested (Ae. albopictus 29 days, An. quadrimaculatus 28 days). On the skin of volunteers at 2x the dosage of deet, the duration of protection for Quwenling was significantly less than deet with Ae. aegypti and Ae. taeniorhynchus, and was not significantly different with Ae. albopictus. Both repellents were ineffective against the anopheline species. As a topically applied mosquito repellent, Quwenling has a shorter duration of effectiveness than deet.

Aedes↗
PubMed1991

Malaria transmission potential by Anopheles mosquitoes of Dajabon, Dominican Republic.

A field and laboratory study was conducted to determine some of the parameters relevant to malaria transmission by Anopheles mosquitoes in Dajabon Province, Dominican Republic. Although all 4 species occurring in the area, i.e., An. albimanus, An. crucians, An. grabhamii and An. vestitipennis, were included in the investigations, most of the work focused on the first and last named species because of their abundance. Gonotrophic cycles were determined to be 2.6 and 3.2 days for An. albimanus and An. vestitipennis, respectively. Mean parity rates for the 2 species were 37.3 and 20.7%, respectively, in outdoor samples. The human blood index, as determined by ELISA, was 0.08 for An. albimanus and 0.12 for An. vestitipennis. Only An. albimanus was confirmed positive for Plasmodium falciparum circumsporozoite protein, using ELISA. The vectorial capacity of An. albimanus was determined to be 0.019 and that of An. vestitipennis 0.005.

Animals↗
PubMed1991

Controlled release repellent formulations on human volunteers under three climatic regimens.

Two controlled-release repellent formulations containing 33% (3M) and 42% (Biotek) deet and an Army repellent containing 75% deet were evaluated in 3 different climatic regimens (tropical forested, tropical open and basic hot environments). The 3 repellents provided similar protection for different time periods after application under all 3 climates against Aedes aegypti, Ae. taeniorhynchus and Anopheles stephensi whereas there was no difference in protection period against An. albimanus.

Aedes↗
PubMed1991

Biting periodicity index of Culex quinquefasciatus & its relationship with microfilaria periodicity in Pondicherry.

The biting periodicity index of the bancroftian filariasis vector, C. quinquefasciatus, was calculated on the basis of a large longitudinal data base and compared with the periodicity index of microfilariae of Wuchereria bancrofti. The biting periodicity index of the vector population was 29.78 and found to be close to the periodicity index of the microfilariae. The peak biting activity of the vector and peak appearance of microfilariae in the peripheral blood occurred at about 01.00 h, which accounts for the optimum infection of the vector population. The early night biting density of the vector population showed a highly significant (P less than 0.0005) linear relationship with all night biting density.

Animals↗
PubMed1991

A temporary focus of savanna species of the Simulium damnosum complex in the forest zone of Liberia.

Savanna species of the Simulium damnosum complex, the major vectors of the blinding savanna type of onchocerciasis, were considered to be rare in Liberia, until the dry season of 1988. In 1988 they became a serious nuisance, biting people at the Bong iron ore mine within the rain forest zone. S. damnosum s.str. and S. sirbanum were found breeding, in association with S. adersi a non man-biting savanna species, in a stream emerging from the mine's tailings pond. The local forest species were extremely rare in this stream. The water of the stream was characterized by an increased hardness and higher temperatures in comparison with those of natural watercourses in the area. The mass occurrence of flies was probably related to expansions of the tailings ponds, when rich nutrition was provided for the blackfly larvae by the decaying forests submerged by the rising water levels. The phenomenon did not recur in 1989 when only a few savanna flies were caught, and none were seen in the dry season of 1990. Although it is not known why the artificial environment of the tailings ponds was so attractive for the savanna species the events clearly demonstrated that savanna flies seasonally invading the area, possibly aided by the northeasterly harmattan winds, can become established in the rain forest zone if suitable conditions are met. No infections with Onchocerca volvulus were found in more than 1000 flies caught by vector collectors but, after experimental infection with the local forest strain, a few parasites developed to the infective stage. As yet there is no evidence that the occurrence of savanna flies in the rain forest zone of Liberia was of epidemiological significance.

Animals↗
PubMed1991

A new realistic index of experimental transmission efficiency for Bancroftian filariasis.

An index for experimental transmission of filariasis infection was first introduced by Kartman and subsequently modified by Wharton who defined it as 'the number of infective larvae per mosquito when the microfilaria count is 1.0 mm-3 of human blood'. Since mosquitoes may not imbibe the expected number of microfilariae from the donor's blood during feeding because of various interference phenomena and/or mechanisms, this paper presents the index mosquito meal (Index MM), based on the actual number of viable microfilariae that are observed in the mosquito gut immediately after feeding. The Index MM is defined as 'the number of infective larvae per mosquito when the microfilaria count is 1.0 mm-3 of mosquito blood meal'. The Index MM proved to be a more valid indicator of transmission potential than the Wharton Index when applied to the data of two controlled field studies where groups of laboratory-reared Culex pipiens molestus, the primary vector of filariasis in Egypt, were fed on volunteers having different microfilaraemic densities.

Animals↗
PubMed1991

Deet and permethrin as protectants against malaria-infected and uninfected Anopheles stephensi mosquitoes.

Deet and permethrin were evaluated as protectants against Plasmodium falciparum-infected, P. berghei-infected and uninfected Anopheles stephensi mosquitoes. Deet 50% effective dose (ED50) values were 3.2 micrograms/cm2 for P. falciparum-infected and 1.9 micrograms/cm2 for uninfected mosquitoes; permethrin values were 0.5 micrograms/cm2 and 0.6 micrograms/cm2, respectively. Deet ED50 values were 2.3 micrograms/cm2 for P. berghei-infected and 1.3 micrograms/cm2 for uninfected mosquitoes; the permethrin values were both 0.5 micrograms/cm2. There were no significant differences in the protective efficacy of deet or permethrin between malaria-infected and uninfected An. stephensi mosquitoes.

Animals↗