Indian journal of malariology最新文献

The synthetic pyrethroid, deltamethrin 2.5% wdp, was evaluated at a dosage of 25 mg/sq m in a group of villages of tribal area around Jagdalpur, District Bastar (Madhya Pradesh). Study was carried out in three consecutive years from 1986 to 1988 with a total of five rounds of deltamethrin spray covering a population of approximately 10,000. The suspension of deltamethrin wdp was white in colour, odourless, non-irritant and the deposits were faintly visible on the surface of wall. A total of 3848 kg of 2.5% deltamethrin wdp was consumed during the trial. Insecticide was found effective in keeping the adult vector density An. culicifacies to a very low level for a period of 14-16 wks. Both anopheline and culicine mosquitoes were affected by the spray. The trial confirmed its long residual effectiveness from 15 to 16 wks on both mud and cement plastered surfaces. Deltamethrin spray shortened the average life span of vector mosquitoes. Observations indicated that insecticide although has an excito-repellent effect on mosquitoes, thus forcing exodus from treated area but with poor survival. Partial impact of deltamethrin spray was observed on the larval population confirm this. Deltamethrin spray did not exhibit any fumigant effect on mosquitoes. Significant decline in SPR from 17.93 to 4.26% was observed in areas sprayed with deltamethrin as compared to the comparison area. Similarly, SfR showed 81% reduction in experimental area while the control area showed increase by 42 per cent. No ill-effect of spray was noticed on the inhabitants, spray personnels, animal population and other non-target organisms of the area. The acceptability of the deltamethrin spray was found to be very high.

In Calcutta, Plasmodium falciparum cases and death due to malaria show remarkably increasing trend since 1990. The incidence of P. falciparum malaria has increased more than eleven folds in 1996 in comparison to 1990, with 0, 0, 0, 3, 7, 52 and 17 deaths in 1990, 1991, 1992, 1993, 1994, 1995 and 1996 respectively. Situation is more serious than what it is projected in official records as annual blood examination rate (ABER) in Calcutta Municipal area is poor, varying from 1.5 to 3.9 in 1993 and 1996 respectively. This is further evident from the fact that in a study area in 19 months (January 1995 to July 1996) the slide positivity rate (SPR) was 47.94% on an average 28.72% suffer from P. falciparum infection (as low as 0.5% in June 1996 and as high as 71.5% in November 1996). For the first time resistance of P. falciparum to chloroquine has been noted at RII and RIII level. The response of the same parasite strain to sulfa-pyrimethamine combination drug is very much promising. Fresh infection is occurring in all the months of the year and the favourable period is from July to November 1995 that is corroborating with Container index and Breteau index related to the vector mosquito Anopheles. Susceptibility status of An. stephensi indicates that the mosquito species has acquired resistance to DDT, BHC, propoxure and malathion but is still susceptible to fenthion and deltamethrin.

Studies on ecological succession of anophelines and the malaria vectors were carried out in rice fields located in two ecologically different terrains, i.e. plains and forested hills in Jabalpur district during monsoon (July-October 1995). Nine and fifteen species of anophelines were found breeding in the rice fields of plain and forested hill villages respectively. Anopheles culicifacies and An. subpictus were dominant species in both the areas. The percentage emergence of adults of An. annularis, An. nigerrimus and An. pallidus was higher in plain villages while the percentage of An. theobaldi, An. fluviatilis and An. jeyporiensis was higher in forested hill villages. Among malaria vectors, three species were found breeding in rice fields of hilly terrain, i.e. An. culicifacies, An. fluviatilis and An. stephensi whereas in rice fields of plains An. culicifacies and An. fluviatilis were recorded.

The spatial distribution of malaria results from the interaction between vector, parasite, host, physical and human environments. This basic geographical approach provides an illustration of the geographical distribution of malaria in the world, particularly in the tropical regions. Due to the global climate change and population movements, it is predicted that malaria could have a greater impact on the non-immune or unprepared populations in the Northern Hemisphere in the coming decades. Presently, Sub-Saharan Africa (SSA) is the most adversely affected region in the world. Like any other SSA country, Ethiopia suffers from both epidemic (unstable) and endemic (stable) malaria in the high and lowland regions, respectively. Gambela is one of the areas with stable malaria in the humid tropical region of the country. This study is based on observations, unpublished data, interviews and discussions with settlers and officials in Gambela. It is found that a degree of diverse malaria prevalence is associated with altitudinal, temperature and rainfall variations. Owing to the settlement and land-use changes, unexpected rainfall patterns, temperature increase, unstable political system and poverty, malaria has gone beyond its geographical limits. As a result, the number of malaria affected people has increased in the last 12 years. It is suggested that proper physical and social planning, understanding the geography, entomology, epidemiology, behaviour and life-cycle of malaria parasite, cooperation between the policy-makers, malaria specialists, neighbouring countries and international communities are urgent, if malaria has to be controlled and eradicated.

Seasonal abundance of Anopheles dirus (s.l.) and malaria prevalence in an isolated forest fringed village was monitored at monthly intervals during August 1995 to July 1996. An. dirus was the only vector species detected during the study period. Its density pattern showed distinct seasonality with the peak occurring in the month of July and very low number during cool dry months. Positive correlation (r = 0.721) was found between the density of An. dirus and the amount of rainfall occurring two weeks prior to the collections. Overall sporozoite rate of 1.6% and parous rate of 64.7% were found in the study. Malaria transmission closely followed the density pattern of An. dirus and was seasonal with slide positivity rate and P. falciparum percentage of 47 and 83% respectively. Mean malaria prevalence was higher (p < 0.05) in females.