The argument for integrating vector control with multiple drug administration campaigns to ensure elimination of lymphatic filariasis

BACKGROUND: There is a danger that mass drug administration campaigns may fail to maintain adequate treatment coverage to achieve lymphatic filariasis elimination. Hence, additional measures to suppress transmission might be needed to ensure the success of the Global Program for the Elimination of Lymphatic Filariasis. DISCUSSION: Vector control successfully eliminated lymphatic filariasis when implemented alone or with mass drug administration. Challenges to lymphatic filariasis elimination include uncertainty of the exact level and duration of microfilarial suppression required for elimination, the mobility of infected individuals, consistent non-participation of some infected individuals with mass drug administration, the possible development of anti-filarial drug resistance and treatment strategies in areas co-endemic with loasis. Integration of vector control with mass drug administration can address some of these challenges. The potential benefits of vector control would include: (1) the ability to suppress filariasis transmission without the need to identify all individual 'foci of infection'; (2) minimizing the risk of reestablishment of transmission from imported microfilaria positive individuals; and (3) decreasing the risk of dengue or malaria transmission where, respectively, Aedes or Anopheles are lymphatic filariasis vectors. SUMMARY: With adequate sustained treatment coverage, mass drug administration should meet the criteria for elimination of lymphatic filariasis. However, it may be difficult to sustain sufficiently high mass drug administration coverage to achieve lymphatic filariasis elimination in some areas, particularly, where Aedes species are the vectors. Since vector control was effective in controlling and even eliminating lymphatic filariasis transmission, integration of vector control with mass drug administration will ensure the sustainability of transmission suppression and thereby better ensure the success of national filariasis elimination programs. Although trials of some vector control interventions are needed, proven vector control strategies are ready for immediate integration with mass drug administration for many important vectors. Vector control is the only presently available additional lymphatic filariasis control measure with the potential for immediate implementation

Global prevalence and genotype distribution of hepatitis C virus infection in 2015 : A modelling study

Publisher Copyright: © 2017 Elsevier LtdBackground The 69th World Health Assembly approved the Global Health Sector Strategy to eliminate hepatitis C virus (HCV) infection by 2030, which can become a reality with the recent launch of direct acting antiviral therapies. Reliable disease burden estimates are required for national strategies. This analysis estimates the global prevalence of viraemic HCV at the end of 2015, an update of—and expansion on—the 2014 analysis, which reported 80 million (95% CI 64–103) viraemic infections in 2013. Methods We developed country-level disease burden models following a systematic review of HCV prevalence (number of studies, n=6754) and genotype (n=11 342) studies published after 2013. A Delphi process was used to gain country expert consensus and validate inputs. Published estimates alone were used for countries where expert panel meetings could not be scheduled. Global prevalence was estimated using regional averages for countries without data. Findings Models were built for 100 countries, 59 of which were approved by country experts, with the remaining 41 estimated using published data alone. The remaining countries had insufficient data to create a model. The global prevalence of viraemic HCV is estimated to be 1·0% (95% uncertainty interval 0·8–1·1) in 2015, corresponding to 71·1 million (62·5–79·4) viraemic infections. Genotypes 1 and 3 were the most common cause of infections (44% and 25%, respectively). Interpretation The global estimate of viraemic infections is lower than previous estimates, largely due to more recent (lower) prevalence estimates in Africa. Additionally, increased mortality due to liver-related causes and an ageing population may have contributed to a reduction in infections. Funding John C Martin Foundation.publishersversionPeer reviewe

Lymphatic filariasis in the Karonga district of northern Malawi: a prevalence survey.

In Malawi, two main foci of lymphatic filariasis (LF) are known to exist: one in the south, in the Shire valley, and the other in the north, along the Songwe River, on the border with Tanzania. There have been no formal surveys in the Songwe area since the 1960s but an opportunity arose in 2000-2001 to map LF in this area, in the context of a leprosy survey that formed part of the follow-up of a large leprosy and tuberculosis vaccine trial. Overall 687 immunochromatographic (ICT) tests were carried out. Wuchereria bancrofti antigenaemia was found in > 25% of adults in each of the 12 villages sampled (four in the Songwe area and eight in the rest of the Karonga district), with village prevalences varying from 28%-58%. Of the 685 adult male residents of the Songwe area who were each given full-body clinical examinations, 80 (11.7%) were identified as cases of hydrocele. Lymphoedema was found in seven (1.0%) of these adult males and in 29 (3.7%) of the 769 adult female residents of the Songwe area who were also examined. Microfilariae were detected in 33 (30.8%) of the 107 thick smears of night-blood samples that were made from individuals with positive ICT cards. The W. bancrofti infection focus in Karonga district is therefore wider than was previously known. This has important implications for the implementation and eventual impact of LF-control activities in this area

Flies and Helicobacter pylori infection.

Houseflies have been proposed to be a reservoir and vector for Helicobacter pylori. We assessed the effect of insecticide spraying in villages in The Gambia on H. pylori infection in young children. Effective control of flies did not prevent infection with H. pylori

Distance to water source and altitude in relation to active trachoma in Rombo district, Tanzania.

OBJECTIVES: To investigate the relationship between distance to water source, altitude and active trachoma in children in Rombo district, Tanzania. METHODS: In each of Rombo's 64 villages, 10 balozis (groups of 8-40 households) were selected at random and all resident children aged 1-9 years were examined for clinical signs of active trachoma. The households of these children and village water sources were mapped using differentially corrected global positioning system data to determine each household's altitude and distance to the nearest water supply. RESULTS: We examined 12 415 children and diagnosed 1171 cases of active trachoma (weighted prevalence=9.1%, 95% CI: 8.0, 10.2%). Active trachoma prevalence ranged from 0% to 33.7% across villages. Increasing distance to the nearest water source was significantly associated with rising trachoma prevalence (age-adjusted odds ratio for infection (OR) for highest quartile compared to lowest=3.56, 95% CI 2.47, 5.14, P for trend <0.0001). Altitude was significantly inversely associated with trachoma prevalence (age-adjusted OR for highest quartile compared to lowest=0.55, 95% CI 0.41, 0.75, P for trend <0.0001). These associations remained significant after adjustment in multivariate analysis. CONCLUSIONS: Trachoma is endemic in Rombo district, although the prevalence varies considerably between villages. Spatial mapping is a useful method for analysing risk factors for active trachoma

The household distribution of trachoma in a Tanzanian village: an application of GIS to the study of trachoma.

The distribution of active trachoma in Kahe Mpya, Tanzania, an endemic village of approximately 1000 people, was mapped spatially and analysed for associated risk factors and evidence of clustering. An association between distance to water source and active disease was demonstrated, although this was reduced after accounting for the lack of independence between cases in the same household. Significant clustering of active trachoma within households was demonstrated, adding support to the hypothesized importance of intra-familial transmission. The spatial distribution of trachoma was analysed using the spatial scan statistic, and evidence of clustering of active trachoma cases detected. Understanding the distribution of the disease has implications for understanding the dynamics of transmission and therefore appropriate control activities. The demonstrated spatial clustering suggests inter-familial as well as intra-familial transmission of infection may be common in this setting. The association between active trachoma and geographical information system (GIS) measured distance to water may be relevant for planning control measures

An index of community ocular Chlamydia trachomatis load for control of trachoma.

Quantitative PCR (Q-PCR) technology has recently been applied to the measurement of ocular loads of Chlamydia trachomatis. We present an index called the community ocular C. trachomatis load (COCTL) which is similar to the community microfilarial load (CMFL) of onchocerciasis. Our index has the advantage of being scale-independent so that, for example, percentage changes are the same whether calculated per eye swab or per Q-PCR capillary. The COCTL for a population or subgroup is formed by adding the arbitrary concentration of 1 organism per ml to each individual Q-PCR quantification, calculating the geometric mean, and finally subtracting 1 per ml again. The use of the COCTL is illustrated in a study of trachoma in northern Tanzania. The COCTL is higher in people with clinical trachoma than those without (5.8 organisms per swab vs. 0.1), and in children aged six months to ten years than in the overall population (1.1 vs. 0.4). The COCTL index is potentially useful for sentinel sites, operational research and calibration of clinical measures of trachoma