Comparative economic analysis of strategies for Japanese encephalitis vaccination of U.S. travelers

BackgroundJapanese encephalitis (JE) virus is the leading vaccine-preventable cause of encephalitis in Asia. For most travelers, JE risk is very low but varies based on several factors, including travel duration, location, and activities. To aid public health officials, health care providers, and travelers evaluate the worth of administering/ receiving pre-travel JE vaccinations, we estimated the numbers-needed-to-treat to prevent a case and the cost-effectiveness ratios of JE vaccination for U.S. travelers in different risk categories.MethodsWe used a decision tree model to estimate cost per case averted from a societal and traveler perspective for hypothetical cohorts of vaccinated and unvaccinated travelers. Risk Category I included travelers planning to spend ≥1 month in JE-endemic areas, Risk Category II were shorter-term (<1 month) travelers spending ≥20% of their time doing outdoor activities in rural areas, and Risk Category III were all remaining travelers. We performed sensitivity analyses including examining changes in cost-effectiveness with 10- and 100-fold increases in incidence and medical treatment costs.ResultsThe numbers-needed-to-treat to prevent a case and cost per case averted were approximately 0.7 million and $0.6 billion for Risk Category I, 1.6 million and $1.2 billion for Risk Category II, and 9.8 million and $7.6 billion for Risk Category III. Increases of 10-fold and 100-fold in disease incidence proportionately decreased cost-effectiveness ratios. Similar levels of increases in medical treatment costs resulted in negligible changes in cost-effectiveness ratios.ConclusionNumbers-needed-to-treat and cost-effectiveness ratios associated with preventing JE cases in U.S. travelers by vaccination varied greatly by risk category and disease incidence. While cost effectiveness ratios are not the sole rationale for decision-making regarding JE vaccination, the results presented here can aid in making such decisions under very different risk and cost scenarios.     

The prospect of malaria elimination in the Arabian Peninsula: A population genetic approach

BackgroundIn the Arabian Peninsula malaria control is progressing steadily, backed by adequate logistic and political support. As a result, transmission has been interrupted throughout the region, with exception of limited sites in Yemen and Saudi Arabia. Here we examined Plasmodium falciparum parasites in these sites to assess if the above success has limited diversity and gene flow.MethodsWe examined 108 P. falciparum isolates in three sites in Yemen (Taiz, Dhamar and Hodeidah) and 91 isolates from Saudi Arabia (Jazan). Nine microsatellites were analyzed for allelic diversity, multi-locus haplotype and inter-population differentiation.ResultsDiversity at each locus (unbiased heterozygosity [H]) was relatively lower in Yemen; (Hodeidah, H = 0.615, Taiz, H = 0.66, Dhamar, H = 0.481), compared to Saudi Arabia (Jazan, H = 0.76). Microsatellites were distributed widely and private alleles, detected in a single population, were rare.Pairwise comparisons revealed that parasites population in Dhamar was relatively distanced (F_ST = 0.19). However, Taiz (Yemen) (F_ST = 0.065) and Hodeidah (F_ST = 0.107) populations were closer to that in Jazan (Saudi Arabia). Nonetheless, parasites in the four sites can be considered as one population.ConclusionAlthough malaria risk in Saudi Arabia has been cut considerably, the extent of diversity and parasite genetic structure are indicative of a large population size. Elimination strategy should target demographic factors that favor parasite dispersal and flow of imported malaria.     

细粒棘球蚴病传播动力学模型的建立及应用

应用疾病动力学模型可定量描述疾病发展变化的过程和传播规律, 预测疾病发生的状态, 评估各种控制措施的效果, 为防治决策提供依据。本文介绍了近年来细粒棘球蚴病传播动力学数学模型的发展情况, 并就其应用进行讨论。     

气候变暖对血吸虫病传播的影响及相关研究技术的应用

钉螺是日本血吸虫的中间宿主, 钉螺的分布与血吸虫病的分布一致。温度是钉螺孳生的重要环境因素之一, 研究气候变暖对钉螺的孳生和血吸虫病传播的影响具有重要意义。本文就气候变暖对钉螺的生长繁殖和血吸虫病传播的影响, 以及相关研究技术作一综述。     

2007年全国疟疾形势

本文根据2007年伞国有疟疾发病的23省(市、区)专业单位卜报的年度疟疾防治工作总结和有关疫情报表(年报系统)汇总整理,除特别注明外,所有疫情数据均来自年报系统.     

卫氏并殖吸虫感染循环抗原检测方法的建立与应用

用CAg-dot-ELISA法和CAb-ELISA法分别对并殖吸虫病临床诊断患者、并殖吸虫病流行区人群、卫氏并殖吸虫早期感染者及其他寄生虫感染者进行循环抗原和抗体检测。用CAg-dot-ELISA检测70份卫氏并殖吸虫病临床诊断患者血清，阳性29份，敏感性为41.5%（29/70），与华支睾吸虫病和日本血吸虫病患者血清分别有25%（5/20）和20%（4/20）的交叉反应，与其他寄生虫感染者血清和健康人血清（60份）均为阴性，特异性为93.6%。CAb-ELISA检测70例卫氏并殖吸虫病临床诊断患者血清阳性67份，敏感性为95.7%（67/70），与华支睾吸虫病和日本血吸虫病患者血清分别有25%（5/20）和20%（4/20）的交叉反应，对其他寄生虫感染者血清和健康人血清的特异性为92.1%。CAg-dot-ELISA和CAb-ELISA分别检测并殖吸虫病流行区人群220份血清，阳性率分别为0和3.2%（7/220）。CAg-dot-ELISA法对辅助诊断并殖吸虫早期感染有一定价值。     

PCR检测婴儿利什曼原虫无症状感染的研究

目的 建立适合检测我国婴儿利什曼原虫无症状感染的PCR方法。 方法 选择6种常用于诊断内脏利什曼病的PCR引物（RV1-RV2、K13A-K13B、MC1-MC2、174-798、Pia3-Pia4和DBY-Ajs31），以培养的甘肃人株利什曼原虫前鞭毛体种植人抗凝全血抽提的DNA为模板，确定了这6种PCR引物检测我国婴儿利什曼原虫的最适条件，并比较其检测的敏感性和特异性。选用两种敏感性和特异度均佳的引物对采自利什曼病疫区100份无利什曼病症状居民的静脉血进行检测。 结果 6种PCR引物检测的特异性均达到100%，而检测的敏感性各异，检测到的原虫数目从0.1~1000条原虫/ml，其中引物RV1-RV2（0.1个原虫/ml血）和K13A-K13B（1个原虫/ml血）敏感性较高。这两对引物对100份无症状居民血的阳性检出率分别为33%（33/100）和30%（30/100）。 结论 引物RV1-RV2和K13A-K13B适于检测我国婴儿利什曼原虫无症状感染。在我国甘肃动物源性利什曼病疫区，人群利什曼原虫无症状感染率颇高。