Last data update: May 06, 2024. (Total: 46732 publications since 2009)
Records 1-5 (of 5 Records) |
Query Trace: McClintock S[original query] |
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First evidence of spatial clustering of lymphatic filariasis in an Aedes polynesiensis endemic area
Joseph H , Moloney J , Maiava F , McClintock S , Lammie P , Melrose W . Acta Trop 2011 120 Suppl 1 S39-47 Successful elimination of lymphatic filariasis (LF) requires accurate identification of residual foci of transmission and stringent surveillance strategies to combat potential resurgence. This is challenging in areas where the day-biting Aedes polynesiensis is endemic, such as Samoa, since in previous studies no geographical clustering of infection has been demonstrated. Another challenge for this low prevalence phase is the choice of diagnostic assay as testing for circulating filarial antigen (CFA) or microfilariae (Mf) alone may not have adequate sensitivity. This could be solved by using the commercially available filariasis Cellabs enzyme linked immunosorbent assay (CELISA) to measure antibody. In the current study five Samoan villages were chosen based on previous epidemiological assessments to represent a range of infection prevalences. CFA, Mf, and antibody levels in children ≤10 years had been recorded and results linked to household of residence and/or primary school of attendance. To ascertain the location of exposure, two scenarios based on potential foci of transmission around communities and schools were explored. Both scenarios revealed significant spatial clusters of households with infected individuals and a relationship to antibody positive children when they were included in the spatial analysis. Fasitoo-Tai had the highest LF prevalence and largest geographical spatial clusters for both scenarios. In Falefa, spatial clusters were detected only for the primary school scenario. In Tafua, which spanned an area of 19.5km(2), no spatial clusters were detected. Lastly, in Siufaga, the village with the lowest LF prevalence, significant clustering of infected individuals was observed and, for the primary school scenario, this was geographically related to exposure. These promising findings are the first published evidence of spatial clustering of LF in a day-biting Ae. polynesiensis endemic area. |
Comparison of insecticide-treated nets and indoor residual spraying to control the vector of visceral leishmaniasis in Mymensingh District, Bangladesh
Chowdhury R , Dotson E , Blackstock AJ , McClintock S , Maheswary NP , Faria S , Islam S , Akter T , Kroeger A , Akhter S , Bern C . Am J Trop Med Hyg 2011 84 (5) 662-667 Integrated vector management is a pillar of the South Asian visceral leishmaniasis (VL) elimination program, but the best approach remains a matter of debate. Sand fly seasonality was determined in 40 houses sampled monthly. The impact of interventions on Phlebotomus argentipes density was tested from 2006-2007 in a cluster-randomized trial with four arms: indoor residual spraying (IRS), insecticide-treated nets (ITNs), environmental management (EVM), and no intervention. Phlebotomus argentipes density peaked in March with the highest proportion of gravid females in May. The EVM (mud plastering of wall and floor cracks) showed no impact. The IRS and ITNs were associated with a 70-80% decrease in male and female P. argentipes density up to 5 months post intervention. Vector density rebounded by 11 months post-IRS, whereas ITN-treated households continued to show significantly lower density compared with households without intervention. Our data suggest that both IRS and ITNs may help to improve VL control in Bangladesh. |
Anti-folate drug resistance in Africa: meta-analysis of reported dihydrofolate reductase (dhfr) and dihydropteroate synthase (dhps) mutant genotype frequencies in African Plasmodium falciparum parasite populations
Sridaran S , McClintock SK , Syphard LM , Herman KM , Barnwell JW , Udhayakumar V . Malar J 2010 9 (1) 247 BACKGROUND: Mutations in the dihydrofolate reductase (dhfr) and dihydropteroate synthase (dhps) genes of Plasmodium falciparum are associated with resistance to anti-folate drugs, most notably sulphadoxine-pyrimethamine (SP). Molecular studies document the prevalence of these mutations in parasite populations across the African continent. However, there is no systematic review examining the collective epidemiological significance of these studies. This meta-analysis attempts to: 1) summarize genotype frequency data that are critical for molecular surveillance of anti-folate resistance and 2) identify the specific challenges facing the development of future molecular databases. METHODS: This review consists of 220 studies published prior to 2009 that report the frequency of select dhfr and dhps mutations in 31 African countries. Maps were created to summarize the location and prevalence of the highly resistant dhfr triple mutant (N51I, C59R, S108N) genotype and dhps double mutant (A437G and K540E) genotype in Africa. A hierarchical mixed effects logistic regression was used to examine the influence of various factors on reported mutant genotype frequency. These factors include: year and location of study, age and clinical status of sampled population, and reporting conventions for mixed genotype data. RESULTS: A database consisting of dhfr and dhps mutant genotype frequencies from all African studies that met selection criteria was created for this analysis. The map illustrates particularly high prevalence of both the dhfr triple and dhps double mutant genotypes along the Kenya-Tanzania border and Malawi. The regression model shows a statistically significant increase in the prevalence of both the dhfr triple and dhps double mutant genotypes in Africa. CONCLUSION: Increasing prevalence of the dhfr triple mutant and dhps double mutant genotypes in Africa are consistent with the loss of efficacy of SP for treatment of clinical malaria in most parts of this continent. Continued assessment of the effectiveness of SP for the treatment of clinical malaria and intermittent preventive treatment in pregnancy is needed. The creation of a centralized resistance data network, such as the one proposed by the WorldWide Antimalarial Resistance Network (WWARN), will become a valuable resource for planning timely actions to combat drug resistant malaria. |
A community-based study of factors associated with continuing transmission of lymphatic filariasis in Leogane, Haiti
Boyd A , Won KY , McClintock SK , Donovan CV , Laney SJ , Williams SA , Pilotte N , Streit TG , Beau de Rochars MV , Lammie PJ . PLoS Negl Trop Dis 2010 4 (3) e640 Seven rounds of mass drug administration (MDA) have been administered in Leogane, Haiti, an area hyperendemic for lymphatic filariasis (LF). Sentinel site surveys showed that the prevalence of microfilaremia was reduced to <1% from levels as high as 15.5%, suggesting that transmission had been reduced. A separate 30-cluster survey of 2- to 4-year-old children was conducted to determine if MDA interrupted transmission. Antigen and antifilarial antibody prevalence were 14.3% and 19.7%, respectively. Follow-up surveys were done in 6 villages, including those selected for the cluster survey, to assess risk factors related to continued LF transmission and to pinpoint hotspots of transmission. One hundred houses were mapped in each village using GPS-enabled PDAs, and then 30 houses and 10 alternates were chosen for testing. All individuals in selected houses were asked to participate in a short survey about participation in MDA, history of residence in Leogane and general knowledge of LF. Survey teams returned to the houses at night to collect blood for antigen testing, microfilaremia and Bm14 antibody testing and collected mosquitoes from these communities in parallel. Antigen prevalence was highly variable among the 6 villages, with the highest being 38.2% (Dampus) and the lowest being 2.9% (Corail Lemaire); overall antigen prevalence was 18.5%. Initial cluster surveys of 2- to 4-year-old children were not related to community antigen prevalence. Nearest neighbor analysis found evidence of clustering of infection suggesting that LF infection was focal in distribution. Antigen prevalence among individuals who were systematically noncompliant with the MDAs, i.e. they had never participated, was significantly higher than among compliant individuals (p<0.05). A logistic regression model found that of the factors examined for association with infection, only noncompliance was significantly associated with infection. Thus, continuing transmission of LF seems to be linked to rates of systematic noncompliance. |
Comparison of national malaria surveillance system with the national notifiable diseases surveillance system in the United States
Hwang J , McClintock S , Kachur SP , Slutsker L , Arguin P . J Public Health Manag Pract 2009 15 (4) 345-51 BACKGROUND: The Centers for Disease Control and Prevention (CDC) is in the process of integrating the existing dual mechanisms for reporting cases of malaria diagnosed in the United States into a single electronic reporting mechanism. Before adoption of this new system, an evaluation of the existing systems for state-level reporting of malaria data to the CDC was conducted. METHODS: CDC guidelines for evaluating surveillance systems were used to assess the attributes of the National Malaria Surveillance System (NMSS), the current National Notifiable Diseases Surveillance System (NNDSS), and the projected fully integrated NNDSS. We analyzed data collected from NMSS and NNDSS from 2001 to 2005 using the Chandra-Sekar-Deming method to estimate completeness of reporting. RESULTS: The projected fully integrated system was assessed likely to perform better than either of the existing systems on all attributes except stability. The overall completeness of reporting was estimated to be 80.3 percent for NNDSS and 74.7 percent for NMSS. CONCLUSIONS: Both existing systems have reasonably high ascertainment of cases. A fully integrated system with malaria-specific data fields would improve upon existing systems if it proved to be stable. |
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