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PubMed1995

Laboratory evaluation of a new repellent camouflage face paint.

A combined formulation of the U.S. Army's camouflage face paints and the new extended duration topical insect/arthropod repellent was tested on human volunteers to determine repellency and duration of protection (2-12 h) against Aedes aegypti and Anopheles stephensi. Under laboratory conditions (27 degrees C and 80% RH), the face paint/repellent formulation provided > or = 95% repellency or better for up to 6 h for Ae. aegypti and 8 h for An. stephensi. An analysis of variance showed no significant differences in the repellent efficacy of the 4 camouflage colors: white, green, loam, and sand.

Animals↗
PubMed1995

Permethrin as a tent treatment for protection against field populations of Aedes mosquitoes.

A tent treated with an oil-based 1% permethrin formulation (0.936 g AI/m2) was evaluated for protection against Aedes spp. Mosquito biting assessment was conducted in the field using 8 human subjects positioned inside and outside tents. Subjects inside tents received 66.8% fewer bites than subjects outside tents prior to treatment. Following treatment, subjects inside the treated tent had significant (P < or = 0.05) protection (84-94% bite reduction) for 42 days. Subjects outside the treated tent experienced 43-82% fewer biting mosquitoes than subjects outside the untreated tent. The treated tent remained lethal > or = 42 days to mosquitoes exposed to the tent fabric in field bioassays.

Aedes↗
PubMed1995

Knowledge of mosquitos in relation to public and domestic control activities in the cities of Dar es Salaam and Tanga.

A study of community awareness of mosquitos and related subjects in the residential areas of two Tanzanian cities (Dar es Salaam and Tanga) showed that residents were well aware of mosquitos. Almost all claimed to use some form of domestic mosquito control product for their personal protection, and many spend a significant portion of the household income on this. The problems of nuisance-biting and malaria transmission are usually not separated and are considered to be the result of poor environmental hygiene, for which both residents and local authorities are responsible. Although Culex mosquitos are not a primary target of the Urban Malaria Control Project (UMCP), the persistence of nuisance-biting has made residents sceptical and dissatisfied with insecticide spraying. The residents' priorities are evidently not the same as those of the health authorities, yet mutual cooperation is essential. In order to maintain community support, campaigns aimed at malaria vectors should consider the need for additional measures to control Culex mosquitos, such as those now being tried by the UMCP. Mosquito breeding sites are non-specifically associated with rubbish and standing water of all kinds, and so the actions that the community considers necessary for mosquito source reduction tend to be poorly targeted. Residents do not recognize that some sources produce malaria mosquitos while others produce nuisance mosquitos. The environmental anti-mosquito measures currently promoted by health education and other forms of propaganda are also poorly targeted. While some of them are directed at important Culex breeding sites, others are aimed at sites of little importance for mosquitos of any kind.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

Evaluation of the laboratory mouse model for screening topical mosquito repellents.

Eight commercial repellents were tested against Aedes aegypti 0 and 4 h after application in serial dilution to volunteers and laboratory mice. Results were analyzed by multiple regression of percentage of biting (probit scale) on dose (logarithmic scale) and time. Empirical correction terms for conversion of values obtained in tests on mice to values expected in tests on human volunteers were calculated from data obtained on 4 repellents and evaluated with data obtained on 4 others. Corrected values from tests on mice did not differ significantly from values obtained in tests on volunteers. Test materials used in the study were dimethyl phthalate, butopyronoxyl, butoxy polypropylene glycol, MGK Repellent 11, deet, ethyl hexanediol, Citronyl, and dibutyl phthalate.

Aedes↗
PubMed1994

Biology of malaria vectors in central Gujarat.

Biology of malaria vectors were studied in Kheda district of central Gujarat in order to understand the vector behaviour in the wake of ecological changes. Anopheles culicifacies and An. stephensi were mainly endophilic whereas An. fluviatilis exhibited marked exophily. All the three vectors were predominantly zoophilic. Peak biting activity period of An. culicifacies varied with season though biting continued in varying magnitudes throughout the night. An. stephensi and An. fluviatilis were arhythmic in their biting activity. Survival of all the three vectors was maximum during cold season owing to longer gonotrophic cycle which also yielded higher estimates for expected infective life. Instability of malaria in this area was probably due to low estimates of expected infective life for the three vectors. A wide range of breeding habitat preferences by An. culicifacies was observed whereas An. fluviatilis and An. stephensi showed restricted distribution.

Animals↗
PubMed1994

[Preliminary estimation of malaria transmission potential in areas where Anopheles sinensis is the only vector].

The data, vectorial capacity of Anopheles sinensis in the suburb of Jining city, Shandong Province in 1975, in 1980-1984, and the average gland infection rate of Anopheles sinensis infected with Plasmodium vivax artificially, were calculated by using Macdonald formula (1957). The basic reproduction rates were 4.44, 6.47 and 4.25 in the years 1975, 1980 and 1981, respectively. In 1982-1984, the rate was reduced to 0.69, 0.41 and 0.1, respectively. Since 1982, the incidence rate of malaria in the areas was reduced by 80% annually, indicating that the malaria transmission had been decreased obviously.

Animals↗
PubMed1995

[Medical problems of Israelis travelling to tropical countries].

Questionnaires were sent to 1500 Israelis who traveled overseas following evaluation and preparation in a travel advisory clinic. Of 517 who responded, 227 were males, and the mean age was 25 years. The most commonly encountered medical problems were insect bites (25%), diarrhea (67%), skin conditions (23%), high altitude problems (19%), tropical diseases (11%) and respiratory tract diseases (12%). Of the 476 who took antimalarial prophylaxis, there were possible side effects in 81 (17%). Insect repellents and water purification were used by 435 and 312 travelers, respectively, and condoms by 103. Young Israelis commonly tour for prolonged periods through Asia, Africa and Latin America, and often acquire a wide spectrum of medical diseases, both infectious and noninfectious. A program of professional consultation and immunization is important in the prevention of travel-related disease.

Adult↗
PubMed1995

Malaria vectors and transmission in an area deforested for a new international airport in southern Cameroon.

Nsimalen, a village in Southern Cameroon, has been deforested over a surface of 370 hectares for the construction of the new Yaounde international airport (Cameroon). Mosquitoes night catches on human bait were performed over a year in two hamlets of this village, one adjoining the airport and the other situated 3 kilometers off the deforested area. The aim of the survey was to observe malaria vectors and transmission around the airport and to record malaria epidemiological changes resulting from deforestation. The findings showed that the main malaria vector was Anopheles moucheti (95% of the vector population). Anopheles gambiae was also present but in very small quantities. The increased density of the latter near the airport combined with the low parity rates, indicated that deforestation favoured the breeding of this species. Malaria transmission was estimated at 106 and 68 infective bites per man per year in hamlets close to and far away from the airport zone respectively. An. gambiae accounted for 13% of the transmission in the hamlet adjoining the airport and 0% three kilometers off the airport.

Animals↗
PubMed1994

Observations on nocturnal activity and man biting habits of malaria vectors, Anopheles fluviatilis, An. annularis and An. culicifacies in the hill tracts of Koraput District, Orissa, India.

Biting and feeding behavior of malaria vectors were studied in nine villages (5 from Jeypore zone and 4 from Malkangiri zone) of Koraput District. Man biting catches comprised of 16 anopheline species including the incriminated vectors of this area: An. fluviatilis, An. annularis and An. culicifacies. An. fluviatilis was predominant and biting of this species recorded indoors throughout the year in both the zones. The period, during which the biting activity peaked, was different between the two zones and consequently the time of peak transmission was also different between the zones. The biting activity was at its peak between 21.00 and 03.00 hours in both the zones. However, in cold season the biting activity peaked in the first quarter of the night in Jeypore zone. The anthropophilic index (AI) of An. fluviatilis was 26.2% in Jeypore and 83.7% in Malkangiri and of An. culicifacies the AI was 0.4% in Jeypore and 7% in Malkangiri. Analysis of gonotrophic stages of night resting females indicated that in Jeypore zone, the majority of An. fluviatilis female left indoors for outdoor resting before the completion of gonotrophic cycle, but in Malkangiri, the females remained indoors till the end of the gonotrophic cycle. The presence of full-fed females in night resting catches in Jeypore village further suggested that the females do not leave the house immediately after taking blood meal but rest for some time.

Altitude↗
PubMed1994

[Transmission of malaria in villages far away or situated on the border of a mangrove in Senegal].

During 23 months period, entomological surveys were carried out in three villages of a mangrove area and two others far of the mangrove in the south part of Senegal. An. gambiae s.s was the main malaria vector and the sampling of its population was done by human baits catch. The An. gambiae density was important in the rainy season and the malaria transmission occurred from July to November; the inoculation rate rose from 0 to 123 infected bites per man. Marked yearly and local variations of the transmission intensity were observed. The transmission intensity was higher in the villages far of the mangrove than in those near. The variations of the transmission intensity were related to the larval breeding sites and to the longevity of the An. gambiae females.

Animals↗
PubMed1994

Public perception of mosquito annoyance measured by a survey and simultaneous mosquito sampling.

For randomly chosen residents of the Minneapolis-St. Paul, Minnesota, metropolitan area, survey responses, reported bites, and observed defensive behaviors (e.g., brushing, swatting) for a 5-min period in their yard were compared with simultaneous mosquito counts from a human-baited drop-net trap 6 m from the resident. When mosquitoes trapped, reported bites, or observed behaviors per 5 min were 3 or more, the majority of respondents described the mosquito levels as greater than "moderate" and anticipated reduced outdoor time and/or possible repellent use. At 25 or more mosquitoes trapped, 11 or more reported bites, or 16 or more observed behaviors per 5 min, response was "bad", with most people anticipating a major reduction in outdoor time (without repellent), "probably" or "definitely" planning to use repellent, and anticipating some outdoor time loss even if using repellent. Levels of less than 3 mosquitoes trapped per 5 min were related to moderate annoyance in 20-45% of the population. Individual response was highly variable, and the personal and environmental covariates measured did not account for more than half the variability.

Adult↗
PubMedDate not supplied

[Evaluation of a DEET-based repellent on 3 vectors of malaria in central Africa].

As part of the framework of studies on personal protection against disease-transmitting mosquitoes, a field evaluation was carried out in a forest area of Cameroon on human subjects to assess the efficacy of a common repellent: DEET (a 50% active ingredient formulation). One ml of DEET applied to the legs of resting persons gave an 85% reduction in Anopheles bites during the 5 hours following application. The repellent effect decreased gradually with time. The effect was more than 90% maximum after 3 hours, 50% by about the seventh hour and declined to 0% from the fifteenth hour onwards. No difference was found between the three Anopheles species: Anopheles gambiae ss, An. nili and An. funestus. The longevity and infectivity of Anopheles populations caught on humans with repellent and on untreated controls were similar. Thus the reduction of biting rate can be considered equivalent to the reduction in malaria transmission. The effect of sweating on the loss of the applied repellent was studied. Moderate sweating, corresponding to normal activity, did not reduce the efficacy of the repellent. More profuse sweating did not significantly reduce repellent efficacy. We conclude that the tested formulation of DEET has the same efficacy as commercial formulations already on the market. Protection did not last the whole night, which is the time required for protection against malarial infection. However, good protection levels lasted more than 5 hours.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Cutaneous↗
PubMed1994

Cytotaxonomy of the Simulium damnosum complex and description of new cytotypes in the Tukuyu focus, southwest Tanzania.

Larvae of Simulium damnosum complex collected from rivers draining Tukuyu onchocerciasis focus were chromosomally examined. Of the 970 larvae analysed, 910 were identified as Kiwira form, a newly described cytotype found in all S. damnosum larval habitats in the Tukuyu area, while 51 were classified as a new subpopulation, tentatively named as Kasyabone form. The F1 larval progeny obtained from wild caught human biting S. damnosum and reared in the laboratory were chromosomally examined. 509 F1 larvae from 70 females blood fed on human volunteers were identified as Kiwira form. As the main human-biting member of the complex in the Tukuyu area, and because some of the wild caught females had developing filarial larvae indistinguishable from those of Onchocerca volvulus, Kiwira form is thus incriminated as the local vector of onchocerciasis. These observations are discussed with respect to previous literature.

Animals↗
PubMedDate not supplied

[The effect of ivermectin on the transmission of Onchocerca volvulus in southern Mexico].

We assessed the transmission potential and the mean infected and infective biting density of S. ochraceum in an onchocerciasis endemic community in the southern Mexican state of Chiapas. In addition, the impact of first treatment of ivermectin during the peak of natural infection of host-seeking S. ochraceum populations was also evaluated. Monthly entomological sampling was carried out during the year before treatment to assess the seasonal biting behavior of parous host-seeking S. ochraceum females, and either infected (with whatever stage of O. volvulus) or infective females (with only third larval stage of O. volvulus). The mean of infective biting density was unimodal with the peak in February. Higher densities of infective females were detected from January to March. Annual infective biting density estimated was 95.2 and the annual transmission potential of 152.3. After treatment with ivermectin, entomological collections were carried out during the December-April period. In these months, the first ivermectin mass treatment produced a reduction of natural infection rates of 55 per cent in the mean infected females density (p < 0.001) and of 30 per cent in the transmission potential. However, significative differences were found in parity rates of biting females during the evaluation periods. Decrease of infection rates in vector populations was caused by immediate effect of ivermectin over the skin microfilariae. Microfilariae community load available for transmission declined significantly from 14 Dmg/mg to 5.9 Dmf/mg. These means were statistically different (p < 0.001) and were reduced by 58 per cent from the baseline value.

Animals↗
PubMed1993

[Malaria prevention without drugs].

One can prevent malaria without antimalaria drug by avoiding insect bites through physical and chemical means. Because of the growing problems with the drugs used for malaria prophylaxis such as resistance and side effects, prevention without drugs is becoming increasingly important again. Repellents are substances applied to the skin which effectively prevent mosquitoes from biting. The most efficient and best documented repellents are diethyl-m-toluamide (DEET) and dimethylphthalate (DMP). Insecticides have a direct toxic effect on the nervous system of the arthropods. Nowadays, mainly synthetic pyrethroids are used because they produce less ecological problems. Such pyrethroids are supplied in form of sprays, vaporizing mats, mosquito coils or in combination with physical means such as bed nets. Although completely ineffective against mosquitoes, systemic vitamin B1, acoustic devices and so-called electrocuting light traps are still sold and used. Travellers must be made aware that they will not get malaria if they can avoid being bitten by mosquitoes.

Animals↗
PubMed1993

Anthropophilic mosquitoes and malaria transmission at Edea, Cameroon.

An entomological study was carried out during 1990 in the town of Edea in the south of Cameroon to study anthropophilic mosquitoes with special reference to malaria transmission. Man-biting mosquitoes were caught regularly during one night each month in two different districts: Bilalang which is a well planned suburb with 160 houses on a hill-top, provided with a piped water supply; and Pongo which is a densely urbanised suburb in a valley. From 188 man-nights 1030 mosquitoes were collected, comprising 700 Culex quinquefasciatus (68%), 262 Anopheles gambiae (25%) and others species (7%) belonging to the genus Anopheles, Mansonia, Culex and Aedes. The estimated annual biting rates of mosquitoes were 811 bites per man in Bilalang and 2,866 in Pongo. The estimated yearly malaria inoculation rates were 3.8 and 30.2 infective bites per man in Bilalang and Pongo, respectively. In different parts of Pongo district much variation existed; extreme values of the estimated yearly inoculation rate were zero and 86.3 in two houses 200 m apart, located on the top of a hill and in the bottom of a valley, respectively. This study is one of the first conducted on malaria transmission in a moderate sized African town; it shows that the mosquito populations are typically urban and differ greatly from rural ones.

Aedes↗