Indian journal of malariology最新文献

The antimalarial activity of chloramphenicol, a broad-spectrum antibiotic was studied in three Indian Plasmodium falciparum isolates having high or low sensitivity to chloroquine. The antimalarial activity was evaluated in 72 hours culture in the presence of various doses of chloramphenicol alone or in combination with a fixed dose of chloroquine added at a concentration that is well tolerated by parasites in vitro. Significant growth inhibition with chloramphenicol was observed at concentrations above 10 micrograms/ml in three isolates. However, an increase in the antimalarial activity of the compound at low concentrations in the range of 0.25-2.5 micrograms/ml has also been observed in the presence of chloroquine. Parasite growth was significantly inhibited in chloroquine resistant parasites. Use of chloramphenicol with chloroquine may be useful as a combination therapy to improve efficacy of the antimalarials and to retard the development of resistance to the individual components of the combination.

About 110 patients were enrolled to study the atypical presentations and the chloroquine sensitivity pattern of Plasmodium vivax malaria. The diagnosis was made from Giemsa stained peripheral blood smear. The co-infection of falciparum malaria was excluded both by smear and ParaSight F-test. After a thorough clinical work up, biochemical investigations were done. The fever clearance and parasite clearance time were determined in all cases. Absence of malarial paroxysm (22.8 per cent), migrainous headache (4.5 per cent), myalgia (6.3 per cent), episodic urticarial rash (1.8 per cent), relative bradycardia (13.6 per cent) and postural hypotension (2.7 per cent) were the atypical manifestations encountered. Besides this, severe forms like jaundice (7.2 per cent), cerebral involvement (0.9 per cent), severe anaemia (7.2 per cent), thrombocytopenia (3.6 per cent) and pancytopenia (0.9 per cent) had been detected. All, except the patient with cerebral involvement were treated with chloroquine patients responded well to the treatment except two (1.8 per cent) patients who had chloroquine resistance. This study showed that vivax malaria can present with atypical and protean manifestations. The changing clinical profile along with development of chloroquine resistance may be considered as a warning signal.

Studies were carried out to evaluate the repellent action of neem oil against Culex quinquefasciatus. Application of 2 and 5 per cent neem oil @ 5 ml/person/night gave 50 and 40.9 per cent protection in indoor collections and 17.4 and 5.6 per cent in outdoor collections as compared with that of untreated control respectively. The protection time ranged from 0100 to 0300 hrs and 0100 to 0600 hrs in indoor and outdoor collections respectively. Results of repellent action of Autan, a synthetic mosquito repellent studied concurrently showed a relatively higher protection rate from the bites of Cx. quinquefasciatus.

Haptoglobin (Hp) polymorphism analysed among P. vivax and P. falciparum patients and malaria negative subjects from areas with different epidemiological situations had shown high incidence of ahaptoglobinemia (HpO) among malaria patients. A definite association of HpO with P. vivax as well as P. falciparum malaria in Indian subjects had been observed. However, low sensitivity and reliability of HpO index indicates that it can not be a good indicator for determination of malaria endemicity. About 75 per cent of HpO subjects with P. vivax infection when treated with chloroquine showed typable Hp polymorphs by 8-9 days of post-treatment.

A total of 31 species of mosquitoes belonging to 10 genera, i.e. Anopheles, Aedes, Armigeres, Culex, Harpagomyia, Hodgesia, Mansonia, Orthopodomyia, Toxorhynchites and Uranotaenia were collected from Car Nicobar Island. Four Anopheles species, An. barbumbrosus, An. insulaeflorum, An. kochi and An. roperi were recorded for the first time from this Island. An. sundaicus was the most predominant species encountered. The results of the study on anophelines with emphasis on species-specific breeding preference in various aquatic habitats have been recorded.

There are a number of microbial agents including fungus, protozoa, virus and bacteria which act as mosquitocidal agents. However, among these agents, Bacillus thuringiensis var israelensis and B. sphaericus are the most potent mosquitocidal agents. Bacillus thuringiensis var israelensis and B. sphaericus are gram-positive sporulating bacteria which produce protoxin crystals during sporulation and are highly toxic to susceptible mosquito larvae when they ingest them. These bacterial agents are environmentally safe due to their host specificity, require in very low dosage, easy to prepare commercially in large-scale and are less costly. Field trials with various formulations of B. sphaericus and B. thuringiensis var israelensis have demonstrated their safety and potential for controlling mosquitoes. Moreover, cloning and expression of the toxin genes of these organisms in other environment friendly bacteria have also made them important for further investigation. Recent advances with novel types of recombinant micro-organisms with new cloning strategies and cloning the toxin genes under strong promoter for over expression together with in vitro gene manipulation and site directed mutagenesis of the active sites for increased toxicity have the potential to provide more effective control of mosquitoes by exploiting these two bacteria. But the toxins of B. sphaericus and B. thuringiensis var israelensis in particular, do not persist long in nature and require frequent application which is a limiting factor for these organisms to be most successful and potent biolarvicide. Nevertheless, they are by far the best choice for controlling mosquitoes. In this review article different mosquitocidal agents with particular emphasis on B. thuringiensis var israelensis and B. sphaericus have been described.

In this study, effects of timed sequential exposure to various concentrations of chloroquine and its two metabolites (SA100387/050 B, SA 100487/053 B), quinine, hydroquinine and quinidine were monitored by morphological analyses, using synchronous cultures of Plasmodium falciparum. The trophozoites and schizonts were sensitive to chloroquine and its metabolites. However, quinine and two of its derivatives were lethal without particularly being stage-specific.