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Biomedical subjects

Christopher Curtis

Publications and source records attributed to Christopher Curtis.

7 recordsLinked to original sources
PubMed2005

Mosquito behavior and vector control.

Effective indoor residual spraying against malaria vectors depends on whether mosquitoes rest indoors (i.e., endophilic behavior). This varies among species and is affected by insecticidal irritancy. Exophilic behavior has evolved in certain populations exposed to prolonged spraying programs. Optimum effectiveness of insecticide-treated nets presumably depends on vectors biting at hours when most people are in bed. Time of biting varies among different malaria vector species, but so far there is inconclusive evidence for these evolving so as to avoid bednets. Use of an untreated net diverts extra biting to someone in the same room who is without a net. Understanding choice of oviposition sites and dispersal behavior is important for the design of successful larval control programs including those using predatory mosquito larvae. Prospects for genetic control by sterile males or genes rendering mosquitoes harmless to humans will depend on competitive mating behavior. These methods are hampered by the immigration of monogamous, already-mated females.

Animals↗
PubMed2004

Infectious reservoir of Plasmodium infection in Mae Hong Son Province, north-west Thailand.

BACKGROUND: It was unknown whether the main reservoir of Plasmodium falciparum and Plasmodium vivax, which infects mosquitoes in Thailand, was (a) in people feeling sufficiently ill with malaria to come to a clinic or (b) in people who had remained in their home villages with some fever symptoms or with none. METHODS: Mass surveys were carried out in Thai villages to identify people with Plasmodium infections and with fever. Malaria patients were also located at a clinic which served these villages. Adults from both sources whose blood slides registered positive for Plasmodium spp. were requested to allow laboratory-bred Anopheles minimus to feed on them. Seven to nine days after the blood feeds the mosquitoes were dissected and checked for presence of oocysts. RESULTS AND DISCUSSION: There were higher rates of Plasmodium infection among people in the villages with fever than without fever and much higher rates of infection among clinic patients than among people who had remained in the villages. People with malarial infections identified via the clinic and the village surveys could infect mosquitoes, especially, but not only, if their blood slides showed visible gametocytes. Because only a very small minority of the village populations were visiting the clinic on any one day, assessment indicated that the main reservoir of infection was not primarily among clinic patients but among those in the villages, especially those feeling feverish. CONCLUSIONS: Efficient use of an anti-gametocyte drug to suppress the parasite reservoir in a population requires that it be given, not just to clinic patients, but to infected people located by mass surveys of the villages, especially those feeling feverish.

Adolescent↗
PubMed2004

Measuring the efficacy of insecticide treated bednets: the use of DNA fingerprinting to increase the accuracy of personal protection estimates in Tanzania.

Summary Insecticide-treated nets have proved successful in the prevention of malaria as a result of both the personal protection with which they provide the sleeper and also the 'mass effect' on the local mosquito population when they are used on a community-wide basis. Personal protection estimates are normally based on comparisons of the numbers of bloodfed mosquitoes found in rooms with and without nets, however it seemed possible that a number of those mosquitoes may not have fed on the occupants of the rooms in which they were found but had entered after feeding elsewhere. To address this possible source of error, we used an 8-locus microsatellite system to identify the source of bloodmeals of Anopheles gambiaes.l. and A. funestus mosquitoes collected in rooms and window traps in Tanzanian villages with and without nets treated with alphacypermethrin. DNA fingerprints were produced from blood samples taken from people who had slept in these rooms and were matched to fingerprints obtained from the mosquito bloodmeals. We were able to type successfully over 90% of the bloodmeals collected and found that proportions of bloodfed mosquitoes that had fed on occupants of the rooms in which they were found were high and only slightly greater in villages without treated nets than those with them (95% and 88%, respectively). When these percentages were used to adjust estimates of personal protection, it was found that the error due to mosquitoes not feeding in the rooms in which they were collected is negligible.

Adult↗
PubMed2003

Scaling-up coverage with insecticide-treated nets against malaria in Africa: who should pay?

Insecticide-treated nets (ITNs) have been shown to reduce the burden of malaria in African villages by providing personal protection and, if coverage of a community is comprehensive, by reducing the infective mosquito population. We do not accept the view that scaling-up this method should be by making villagers pay for nets and insecticide, with subsidies limited so as not to discourage the private sector. We consider that ITNs should be viewed as a public good, like vaccines, and should be provided via the public sector with generous assistance from donors. Our experience is that teams distributing free ITNs, replacing them after about 4 years when they are torn and retreating them annually, have high productivity and provide more comprehensive and equitable coverage than has been reported for marketing systems. Very few of the free nets are misused or sold. The estimated cost would be an annual expenditure of about US$295 million to provide for all of rural tropical Africa where most of the world's malaria exists. This expenditure is affordable by the world community as a whole, but not by its poorest members. Recently, funding of this order of magnitude has been committed by donor agencies for malaria control.

Africa↗
PubMed2001

Reducing psychiatric hospital use of the rural poor through intensive transitional acute care.

A controlled study of the impact of brief, transitional acute care in reducing psychiatric treatment costs for people in rural areas is presented. Treatment emphasized home-based counseling and support, 24-hour rapid response, rural outreach, and intensive support management. The objective was to avert hospitalizations when possible, expedite discharge, and reduce likelihood of readmission, while maintaining comparable or superior clinical outcome. One-hundred eighty-two participants were randomly assigned to the experimental group or a routine care control group. Clinical and utilization data tracked at initial contact, 2 weeks, 6 months, and 12 months suggest substantially lower hospital utilization for the experimental group. Clinical outcomes were comparable between groups.

Counseling↗