Epidemiology of Strongyloides stercoralis on Mekong islands in southern Laos

Vonghachack, Youthanavanh; Sayasone, Somphou; Bouakhasith, Dalouny; Taisayavong, Keoka; Akkavong, Kongsap; Odermatt, Peter

doi:10.1016/j.actatropica.2014.09.016

Cited by 34 publications

(40 citation statements)

References 26 publications

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“…It has been estimated that 50% of persons in resource-poor communities in the GMS have one or more STH [78], and strongyloidiasis afflicts between 40 to 60% of persons in rural Cambodia [79] and Laos [80]. Ivermectin was found to be very effective at treating strongyloidiasis and repeated MDAs would further benefit afflicted communities as re-infection rates in Cambodia can be quite high [81].…”

Section: Discussionmentioning

confidence: 99%

Ivermectin susceptibility and sporontocidal effect in Greater Mekong Subregion Anopheles

Kobylinski

Ubalee

Ponlawat

et al. 2017

Malar J

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BackgroundNovel vector control methods that can directly target outdoor malaria transmission are urgently needed in the Greater Mekong Subregion (GMS) to accelerate malaria elimination and artemisinin resistance containment efforts. Ivermectin mass drug administration (MDA) to humans has been shown to effectively kill wild Anopheles and suppress malaria transmission in West Africa. Preliminary laboratory investigations were performed to determine ivermectin susceptibility and sporontocidal effect in GMS Anopheles malaria vectors coupled with pharmacokinetic models of ivermectin at escalating doses.MethodsA population-based pharmacokinetic model of ivermectin was developed using pre-existing data from a clinical trial conducted in Thai volunteers at the 200 µg/kg dose. To assess ivermectin susceptibility, various concentrations of ivermectin compound were mixed in human blood meals and blood-fed to Anopheles dirus, Anopheles minimus, Anopheles sawadwongporni, and Anopheles campestris. Mosquito survival was monitored daily for 7 days and a non-linear mixed effects model with probit analyses was used to calculate concentrations of ivermectin that killed 50% (LC50) of mosquitoes for each species. Blood samples were collected from Plasmodium vivax positive patients and offered to mosquitoes with or without ivermectin at the ivermectin LC25 or LC5 for An. dirus and An. minimus.ResultsThe GMS Anopheles displayed a range of susceptibility to ivermectin with species listed from most to least susceptible being An. minimus (LC50 = 16.3 ng/ml) > An. campestris (LC50 = 26.4 ng/ml) = An. sawadwongporni (LC50 = 26.9 ng/ml) > An. dirus (LC50 = 55.6 ng/ml). Mosquito survivorship results, the pharmacokinetic model, and extensive safety data indicated that ivermectin 400 µg/kg is the ideal minimal dose for MDA in the GMS for malaria parasite transmission control. Ivermectin compound was sporontocidal to P. vivax in both An. dirus and An. minimus at the LC25 and LC5 concentrations.ConclusionsIvermectin is lethal to dominant GMS Anopheles malaria vectors and inhibits sporogony of P. vivax at safe human relevant concentrations. The data suggest that ivermectin MDA has potential in the GMS as a vector and transmission blocking control tool to aid malaria elimination efforts.Electronic supplementary materialThe online version of this article (doi:10.1186/s12936-017-1923-8) contains supplementary material, which is available to authorized users.

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Section: Discussionmentioning

confidence: 99%

Ivermectin susceptibility and sporontocidal effect in Greater Mekong Subregion Anopheles

Kobylinski

Ubalee

Ponlawat

et al. 2017

Malar J

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“…Female showed higher prevalence of Strongyloides infection than male (Mekonnen et al, 2014;Vonghachack et al, 2015). The elderly persons had higher prevalence than the young participants in Cambodia .…”

Section: Risk Factors Host Factorsmentioning

confidence: 90%

“…Harada Mori culture techniques provide the morphological identification of Strongyloides larvae which first introduced by (Harada and Mori, 1955) then it is widely used (Vonghachack et al, 2015;Banu et al, 2013;Steinmann et al, 2007). This culture method is more effecitve than direct saline smear and formal ether concentration techniques (Koga et al, 1990;Marchi and Cantos, 2003).…”

Section: Cultural Techniquesmentioning

confidence: 99%

Overview of Strongyloidiasis: A Neglected Tropical Disease

Hossain¹,

Bhuiyan²

2016

J. Adv. Parasitol.

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| Strongyloidiasis infection caused by Strongyloides stercoralis is still an elusive disease in spite of recent advances with experiments on animal models. As it is endemic in developing countries such as Asia, Africa, Southeast Asia, Bangladesh, Central and South America but still poses a threat to the developed world owing to its peculiar trait of autoinfection, hyper-infection syndrome involving pulmonary and gastrointestinal system and disseminated infection with involvement of other organs like liver, brain and lungs. It can occur asymptomatically which confuses the clinicians during diagnosis as it has no gold standard diagnostic techniques although luciferase immune-precipitation system shows increased sensitivity and specificity to detect S. stercoralis specific antibody titter in serum and PCR method to detect DNA in fecal samples. Ivermectin and albendazole are recommended anthelmintic for strongyloides infection. This review will be focused on current published research on improved diagnostic techniques for strongyloidiasis detection and immune mechanism thought to be responsible for hyper-infection along with epidemiology, pathogenesis, clinical manifestations, diagnosis, treatment, prevention and control. S. stercoralis is still a global health concerned topic that is undermined in many countries. Novel diagnostic methods are expected to improve epidemiological studies, treatment, control and prevention of strongyloidiasis. Further studies are needed to open the mechanism of severe clinical manifestations of human strongyloidiasis.

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“…Finally, the odds of S. stercoralis infection were lower among participants living in villages located in croplands, i.e. association between age and S. stercoralis infection was found in Lao PDR, South Cambodia, or Zanzibar [10,44,47]. Age-specific infection risk is of particular importance to target 401 control programs and should be further documented.…”

Section: Risk Factors For S Stercoralis Infection 306mentioning

confidence: 92%

Strongyloides stercoralis: spatial distribution of a highly prevalent and ubiquitous soil-transmitted helminth in Cambodia

Forrer

Khieu

Vounatsou

et al. 2018

Preprint

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14Background 15 Strongyloides stercoralis is a neglected soil-transmitted helminth that occurs worldwide and 16 can cause long-lasting and potentially fatal infections due to its ability to replicate within its 17 host. S. stercoralis causes gastrointestinal and dermatological morbidity. The objective of this 18 study was to assess the S. stercoralis infection risk, and using geostatistical models, to predict 19 its geographical distribution in Cambodia. 20 Methodology / Principal Findings 21A nation-wide community-based parasitological survey was conducted among the population 22 aged 6 years and above. S. stercoralis was diagnosed using a serological diagnostic test 23 detecting antigens in urine. Data on demography, hygiene and knowledge about helminth 24 infection were collected. S. stercoralis prevalence among 7,246 participants with complete 25 data record was 30.5% and ranged across provinces between 10.9% and 48.2%. The parasite 26 was ubiquitous in Cambodia, with prevalence rates below 20% only in five south-eastern 27 provinces. Infection risk increased with age both in men and women although girls aged less 28 than 13 years and women aged 50 years and above had lower odds of infection than their male 29 counterparts. Open defecation was associated with higher odds of infection while declaring 30 having some knowledge about health problems caused by worms was protective. Infection 31 risk was positively associated with night maximum temperature, minimum rainfall, and 32 distance to water, and negatively associated with land occupied by rice fields. 33 Conclusions / Significance 34 S. stercoralis infection is ubiquitous and rampant in Cambodia. The parasite needs to be 35 addressed by control programs delivering ivermectin. However the high cost of this drug in 36 Cambodia currently precludes control implementation. Donations, subsidization or the 3 37 production of affordable generic production are needed so S. stercoralis, which infests almost 38 a third of the Cambodian population, can be addressed by an adequate control program. 39 40 41 Authors Summary 42The threadworm, Strongyloides stercoralis, is a most neglected worm infection transmitted 43 through infective larvae on the soil. Threadworms occur worldwide and particularly in 44 tropical climates. It may cause long-lasting and potentially fatal infections due to its ability to 45 replicate within its host. This study aimed to assess the risk of threadworm infection in at the 46 national level in Cambodia. 47We conducted a nation-wide community-based parasitological survey among the population 48 aged 6 years and above. The threadworm was diagnosed using a serological diagnostic test 49 detecting antigens in urine. Data on demography, hygiene and knowledge about helminth 50 infection were collected. The threadworm infection risk was calculated by using geostatistical 51 models to predict its geographical distribution in Cambodia. About one third (30.5%) of the 52 enrolled study participants (n=7,246) were infected with threadworms. The lowest ...

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Epidemiology of Strongyloides stercoralis on Mekong islands in southern Laos

Abstract: Strongyloides stercoralis is a neglected helminth infection potentially leading to a systemic

Cited by 34 publications

References 26 publications

Ivermectin susceptibility and sporontocidal effect in Greater Mekong Subregion Anopheles

Ivermectin susceptibility and sporontocidal effect in Greater Mekong Subregion Anopheles

Overview of Strongyloidiasis: A Neglected Tropical Disease

Strongyloides stercoralis: spatial distribution of a highly prevalent and ubiquitous soil-transmitted helminth in Cambodia

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