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M Zaim

Publications and source records attributed to M Zaim.

At least 19 recordsLinked to original sources

Exploiting the potential of vector control for disease prevention.

Although vector control has proven highly effective in preventing disease transmission, it is not being used to its full potential, thereby depriving disadvantaged populations of the benefits of well tried and tested methods. Following the discovery of synthetic residual insecticides in the 1940s, large-scale programmes succeeded in bringing many of the important vector-borne diseases under control. By the late 1960s, most vector-borne diseases--with the exception of malaria in Africa--were no longer considered to be of primary public health importance. The result was that control programmes lapsed, resources dwindled, and specialists in vector control disappeared from public health units. Within two decades, many important vector-borne diseases had re-emerged or spread to new areas. The time has come to restore vector control to its key role in the prevention of disease transmission, albeit with an increased emphasis on multiple measures, whether pesticide-based or involving environmental modification, and with a strengthened managerial and operational capacity. Integrated vector management provides a sound conceptual framework for deployment of cost-effective and sustainable methods of vector control. This approach allows for full consideration of the complex determinants of disease transmission, including local disease ecology, the role of human activity in increasing risks of disease transmission, and the socioeconomic conditions of affected communities.

Animals↗

Insecticide-treated plastic tarpaulins for control of malaria vectors in refugee camps.

Spraying of canvas tents with residual pyrethroid insecticide is an established method of malaria vector control in tented refugee camps. In recent years, plastic sheeting (polythene tarpaulins) has replaced canvas as the utilitarian shelter material for displaced populations in complex emergencies. Advances in technology enable polythene sheeting to be impregnated with pyrethroid during manufacture. The efficacy of such material against mosquitoes when erected as shelters under typical refugee camp conditions is unknown. Tests were undertaken with free-flying mosquitoes on entomological study platforms in an Afghan refugee camp to compare the insecticidal efficacy of plastic tarpaulin sprayed with deltamethrin on its inner surface (target dose 30 mg/m2), tarpaulin impregnated with deltamethrin (initially > or = 30 mg/m2) during manufacture, and a tent made from the factory impregnated tarpaulin material. Preliminary tests done in the laboratory with Anopheles stephensi Liston (Diptera: Culicidae) showed that 1-min exposure to factory-impregnated tarpaulins would give 100% mortality even after outdoor weathering in a temperate climate for 12 weeks. Outdoor platform tests with the erected materials (baited with human subjects) produced mosquito mortality rates between 86-100% for sprayed or factory-impregnated tarpaulins and tents (average approximately 40 anophelines and approximately 200 culicines/per platform/night), whereas control mortality (with untreated tarpaulin) was no more than 5%. Fewer than 20% of mosquitoes blood-fed on human subjects under either insecticide-treated or non-treated shelters. The tarpaulin shelter was a poor barrier to host-seeking mosquitoes and treatment with insecticide did not reduce the proportion blood-feeding. Even so, the deployment of insecticide-impregnated tarpaulins in refugee camps, if used by the majority of refugees, has the potential to control malaria by killing high proportions of mosquitoes and so reducing the average life expectancy of vectors (greatly reducing vectorial capacity), rather than by directly protecting refugees from mosquito bites. Mass coverage with deltamethrin-sprayed or impregnated tarpaulins or tents has strong potential for preventing malaria in displaced populations affected by conflict.

Afghanistan↗

Safety of pyrethroid-treated mosquito nets.

The use of insecticide treated nets (ITNs) for personal protection against malaria vector Anopheles mosquitoes (Diptera: Culicidae) has become popular during the past decade. With the precautions outlined in this paper, field use of pyrethroids--at concentrations recommended for treatment of mosquito nets--poses little or no hazard to people treating the nets or to users of the treated nets. With frequent exposure to low concentrations of pyrethroids, the risk of toxicity of any kind is remote. Pyrethroids entering the systemic circulation are rapidly metabolized to much less toxic metabolites. Toxicologically, pyrethroids have a useful characteristic--the production of skin paraesthesia--which gives an early indication of exposure. This reversible symptom of exposure is due to transient stimulation of peripheral sensory nerves and not a toxic effect. In the retail market, for home use, the provision of proper packaging and labelling, with clear instructions on safe and effective use of the product are most important. Because many domestic users of pyrethroid 'home treatment kits' for ITNs may not be fully literate, it is essential that 'instructions for use' should be portrayed via pictograms with supporting text in appropriate local language(s).

Animals↗

Cyfluthrin (EW 050)-impregnated bednets in a malaria control program in Ghassreghand (Baluchistan, Iran).

In a study carried out in the Ghassreghand Division (Baluchistan, Iran) from March through November 1995, efficacy of cyfluthrin-impregnated bednets was compared to that of untreated nets, in relation to malaria control. Ten villages with a total population of 4,572 and 3 villages with a total population of 1,935 were used as treatment and control, respectively. The collection, impregnation (target dosage of 40 mg active ingredient [AI]/m2), and redistribution of the nets (9% nylon, 52% light cotton, 30% medium cotton, and 9% heavy cotton), carried out in mid-April, were done by local health workers, supervised by the senior research staff. Anopheles culicifacies was considered to be the main vector of malaria in the named area. This species is mainly zoophilic, endophilic, and exophagic. The initial uptake of the insecticide was lower than the target dosage, with high variation (nylon, 12.5 +/- 5.4 mg AI/m2; light cotton, 33.3 +/- 26.1 mg AI/m2; medium cotton, 25.9 +/- 20 mg AI/m2; heavy cotton, 17.6 +/- 12.5 mg AI/m2). The use of impregnated mosquito nets (used primarily outside) had no significant effect on the incidence of malaria. No difference was detected in the parasite density of patients with positive slides. No significant effect was observed in the parous rate, human blood index, and sporozoite rate of anopheline vectors. Only the indoor resting densities of An. culicifacies and other malaria vectors were drastically reduced after the introduction of the cyfluthrin-impregnated nets into the treatment villages. The residual activity of cyfluthrin was lower than expected. The mortality of anophelines brought in contact with the treated nets for 3 min in bioassays dropped to less than 55% in 3 months. The loss of chemical activity was greatest for the light cotton nets, followed by the medium cotton nets. Cyfluthrin-treated nets were mildly irritating to host-seeking female anophelines in the laboratory. The protective rate of impregnation (all fabric kinds included) in preventing female mosquitoes from biting through the impregnated nets was initially 5-6 times that of the nonimpregnated nets. The study did not detect any significant difference between the use of untreated versus impregnated bednets in the Ghassreghand area. In planning future medium-scale trials, comparison of new compounds and formulations to the more widely used pyrethroids such as permethrin and deltamethrin is highly recommended.

Animals↗

Knowledge and practice of residents about malaria in southeast Iran (1994).

A survey was undertaken between November 1994 and January 1995 to assess the knowledge and practice with respect to malaria of 1946 randomly selected households in endemic urban and rural areas of Hormozgan, Kerman and Sistan and Baluchistan Provinces, southeast Iran. Knowledge of inhabitants was relatively poor in the study area despite activities to control the disease there for more than 35 years. Mean scores of the knowledge of the residents of the villages having access to primary health care (PHC) services was significantly lower than that under the services of the mobile teams which may reflect the insignificant attention which has been devoted to health education by PHC workers with respect to malaria and malaria control. An educational campaign directed at increasing the knowledge should result in greater acceptance of residents of personal protection methods and vector control and drug treatment programmes.

Data Collection↗

Anopheles culicifacies in Baluchistan, Iran.

Anopheles culicifacies (probably species A) is the main vector of malaria in Baluchistan, southeastern Iran. Adult mosquitoes were collected during 1990-92 by five methods of sampling: knock-down pyrethrum space-spray indoors, human and animal bait (18.00-05.00 hours), pit shelters and CDC light traps, yielding 62%, 3%, 6%, 4% and 25% of specimens, respectively. Whereas spray-catches comprised c. 70% gravid and semi-gravid females, light trap catches were mostly (c. 60%) unfed females, while females from pit shelters comprised all abdominal stages more equally (13-36%). An.culicifacies populations peaked in April-May and rose again during August-November. Densities of indoor-resting mosquitoes were consistently greater in an unsprayed village than in villages subjected to residual house-spraying with propoxur, malathion or pirimiphos-methyl. Monthly malaria incidence generally followed fluctuations of An.culicifacies density, usually with a peak in May-June.

Animals↗

Survival rates of Anopheles culicifacies s.l. and Anopheles pulcherrimus in sprayed and unsprayed villages in Ghassreghand district, Baluchistan, Iran, 1991.

Survival rates, expectation of life, and expectation of infective life of Anopheles culicifacies and Anopheles pulcherrimus were estimated in sprayed and unsprayed villages in the highly malarious Ghassreghand District, Iran, during the 2 peak malaria transmission seasons in 1991. The daily survival rate of An. culicifacies was estimated as 0.84 and 0.78 during May and 0.89 and nil during September-October in the unsprayed and sprayed villages, respectively. For An. pulcherrimus the daily survival rate was estimated as 0.80 and 0.78 in May and 0.83 and 0.78 in September-October in the unsprayed and sprayed villages, respectively. The impact of indoor residual spraying during the first peak of transmission on An. culicifacies and An. pulcherrimus (expressed as the product of the degree of reduction of the expectation of infective life and the degree of reduction of expectation of life) was calculated as 3.5 and 1.5 times, respectively, that in the absence of control. The impact of indoor residual spraying on An. culicifacies during the second peak of transmission was almost complete, whereas that for An. pulcherrimus was 3.4 times than that in the absence of control.

Animals↗

Role of Anopheles culicifacies s.l. and An. pulcherrimus in malaria transmission in Ghassreghand (Baluchistan), Iran.

A 2-site immunoradiometric assay (IRMA) was performed on the head and thorax of Anopheles culicifacies s.l. and An. pulcherrimus females, the 2 most common anopheline species in the District of Ghassreghand (Baluchistan, Iran), collected during the 2 peak malaria transmission seasons (May and September-October 1991). Positive IRMA results revealed the 2 species as potential vectors of malaria in this highly endemic district. This finding serves as the first report on natural infection of An. pulcherrimus in Iran and is the second on natural infection of An. culicifacies since the previous report of 1959.

Animals↗

Efficacy of a flowable concentrate formulation of Bacillus thuringiensis (H-14) against larval mosquitoes in southern Iran.

A flowable concentrate formulation of Bacillus thuringiensis (H-14) [Bactimos FC (1000 ITU/mg)] was evaluated for the control of mosquito larvae in simulated ponds and natural breeding sites in Kazeroun (Fars Province), southern Iran. A comparison was made with Abate emulsifiable concentrate. Bactimos FC caused 93-96% anopheline and 97% culicine larval mortality 24 h posttreatment in simulated ponds and natural breeding sites, when used at the rate of 0.2 cc/m2. Abate (0.015 cc/m2) resulted in significantly higher anopheline (98.1%) and culicine (100%) mortality at 24 h posttreatment. There was a relatively sharp decline in larval mortality 48 h posttreatment when Bactimos FC was applied. Five-day applications were suggested to prevent pupal production.

Analysis of Variance↗

Ecology of Anopheles pulcherrimus in Baluchistan, Iran.

Studies were conducted on the ecology of Anopheles pulcherrimus over a period of 20 months in the village of Zeineddini, Sistan and Baluchistan Province, southeastern Iran. The species was active throughout the year with 2 peaks of activity, April-May and August-September. Light traps captured the highest number of An. pulcherrimus females (65%) as compared to cattle bait collections (19.3%), pyrethrum space spray catches (14.2%), pit shelter (1%) and human bait collections (0.6%). However, 95% of the females captured in light traps were unfed or freshly fed females as opposed to about only 44% of those collected in pyrethrum space spray catches and pit shelter collections. The species was mainly exophilic as shown by the gravid/fed ratio of 0.4 obtained in outlet window traps.

Animals↗

A review of malaria in Iran, 1975-90.

Since 1958, when the malaria eradication program officially started in Iran, great strides has been made in controlling the disease in most of the country. However, because of certain technical, operational and administrative problems, malaria is still highly prevalent in southeastern Iran, affecting 6% of the population. The situation of malaria in Iran from 1975 through 1990 is discussed in detail, with particular emphasis given to the epidemiological characteristics and vector transmission factors in each region of the country.

Animals↗

Occurrence of Anopheles culicifacies species A in Iran.

Polytene chromosome preparations of the ovarian nurse cells of Anopheles culicifacies females collected in 6 different parts of Baluchistan, Iran, during September-October 1987 and May-June 1988 revealed the existence of species A in this country. The chromosome arms are homosequential with those of species A of India. This report confirms the distribution of species A in Iran.

Animals↗

Field application of Romanomermis culicivorax (Mermithidae: Nematoda) to control anopheline larvae in southern Iran.

The efficacy of the parasitic nematode Romanomermis culcivorax in controlling anopheline larvae, including malaria vectors, was studied in Fars and Baluchistan provinces. Twenty sites were treated once with the preparastic stage of R. culicivorax in 1984 with 3,000, 5,000 or 10,000 preparasites per m2 surface area, depending on larval density. The average parasitism of anopheline larvae ranged from 56 to 69% based on 24 hr posttreatment dissections. No correlation was found between the level of parasitism and the density of mosquito larvae present in a site. About 61% parasitism was obtained when different rates of preparasites were released in 14 larval breeding sites in 1985. No apparent difference was observed in the rate of parasitism in 10 sites receiving one treatment compared with four sites receiving two treatments, with a seven day interval between each treatment. Romanomermis culcivorax was established in the release sites but caused only minor reductions in anopheline larval populations. The nematode would be of limited use in antimalaria campaigns in southern Iran.

Animals↗

Malaria control in Iran--present and future.

The malaria eradication campaign in Iran, which started in 1958, has not been able to achieve its final goals. The technical, administrative, socio-economic and financial obstacles involved in this unfinished task are mentioned and the present status of malaria in the country is discussed. It is urged that eradication policy, presently used, be substituted by malaria control program, as defined by The World Health Organization. This would serve as a prerequisite for eventual eradication of malaria, from the country, in the future. Within such agreement, the improvement of basic health services and search for better technical means of controlling the transmission of the infection are emphasized as vital to achieve this goal. Intensive training of experienced staff, in Iran, for stimulation and promotion of relevant research and training activities in malaria control is highly recommended.

Animals↗