Simple fecal flotation is a superior alternative to guadruple Kato Katz smear examination for the detection of hookworm eggs in human stool

Microscopy-based identification of eggs in stool offers simple, reliable and economical options for assessing the prevalence and intensity of hookworm infections, and for monitoring the success of helminth control programs. This study was conducted to evaluate and compare the diagnostic parameters of the Kato-Katz (KK) and simple sodium nitrate flotation technique (SNF) in terms of detection and quantification of hookworm eggs, with PCR as an additional reference test in stool, collected as part of a baseline cross-sectional study in Cambodia.; Fecal samples collected from 205 people in Dong village, Rovieng district, Preah Vihear province, Cambodia were subjected to KK, SNF and PCR for the detection (and in case of microscopy-based methods, quantification) of hookworm eggs in stool. The prevalence of hookworm detected using a combination of three techniques (gold standard) was 61.0%. PCR displayed a highest sensitivity for hookworm detection (92.0%) followed by SNF (44.0%) and quadruple KK smears (36.0%) compared to the gold standard. The overall eggs per gram feces from SNF tended to be higher than for quadruple KK and the SNF proved superior for detecting low egg burdens.; As a reference, PCR demonstrated the higher sensitivity compared to SNF and the quadruple KK method for detection of hookworm in human stool. For microscopic-based quantification, a single SNF proved superior to the quadruple KK for the detection of hookworm eggs in stool, in particular for low egg burdens. In addition, the SNF is cost-effective and easily accessible in resource poor countries

Ivermectin Treatment and Sanitation Effectively Reduce Strongyloides stercoralis Infection Risk in Rural Communities in Cambodia

BACKGROUND: Strongyloides stercoralis is the only soil-transmitted helminth with the ability to replicate within its host, leading to long-lasting and potentially fatal infections. It is ubiquitous and its worldwide prevalence has recently been estimated to be at least half that of hookworm. Information on the epidemiology of S. stercoralis remains scarce and modalities for its large-scale control are yet to be determined. METHODOLOGY/PRINCIPAL FINDINGS: A community-based two-year cohort study was conducted among the general population in a rural province in North Cambodia. At each survey, participants infected with S. stercoralis were treated with a single oral dose of ivermectin (200μg/kg BW). Diagnosis was performed using a combination of the Baermann method and Koga agar plate culture on two stool samples. The cohort included participants from eight villages who were either positive or negative for S. stercoralis at baseline. Mixed logistic regression models were employed to assess risk factors for S. stercoralis infection at baseline and re-infection at follow-up. A total of 3,096 participants were examined at baseline, revealing a S. stercoralis prevalence of 33.1%. Of these participants, 1,269 were followed-up over two years. Re-infection and infection rates among positive and negative participants at baseline were 14.4% and 9.6% at the first and 11.0% and 11.5% at the second follow-up, respectively. At follow-up, all age groups were at similar risk of acquiring an infection, while infection risk significantly decreased with increasing village sanitation coverage. CONCLUSIONS/SIGNIFICANCE: Chemotherapy-based control of S. stercoralis is feasible and highly beneficial, particularly in combination with improved sanitation. The impact of community-based ivermectin treatment on S. stercoralis was high, with over 85% of villagers remaining negative one year after treatment. The integration of S. stercoralis into existing STH control programs should be considered without further delay

The evaluation of control measures against Schistosoma mekongi in Cambodia by a mathematical model

We constructed a mathematical model for the transmission of Schistosoma mekongi in Cambodia. The simulation of the model will be instrumental in planning schistosomiasis control measures. The model includes two definitive hosts, humans and dogs, as animal reservoirs. Dogs are recognized to play an important role in schistosomiasis transmission in Cambodia. For the purpose of dealing with age-specific prevalence and intensity of infection, the human population was classified into eight age categories in the model. To describe the seasonal fluctuation of the intermediate host population of S. mekongi, the "Post-Spate Survival" hypothesis was adopted for the population dynamics of Neotricula aperta present in the Mekong River. We carried out simulations to evaluate the effect of universal treatment (UT) and targeted mass treatment (TT) with praziquantel on the reduction in prevalence of S. mekongi. The simulations indicated that biyearly UT for 8 years or yearly TT for 5 years after three courses of yearly UT could reduce the prevalence to below 5% when a UT or TT coverage of 85% of inhabitants was achieved. The simulation suggested that the suppression of S. mekongi in Cambodia would be possible by UT or TT with a high coverage rate.</p

Control of Schistosoma mekongi in Cambodia: results of eight years of control activities in the two endemic provinces

In Cambodia, schistosomiasis is transmitted in the provinces of Kratie and Stung Treng where approximately 80 000 individuals are estimated to be at risk of infection. The baseline prevalence of infection was estimated to be between 73% and 88%, and cases of severe morbidity (hepatosplenomegaly, puberty retardation) and mortality were very common. In 1994, the Ministry of Health of Cambodia started schistosomiasis control applying universal chemotherapy with praziquantel (40 mg/kg). The coverage of the programme was between 62% and 86% for 8 years. This simple control measure resulted in the control of the disease: no cases were reported in 2004 and only three cases were reported in 2005. In addition, there are no longer reports of cases of severe morbidity due to schistosomiasis. Since the beginning of the control programme, a single dose of mebendazole (500 mg) has been combined with praziquantel during the mass chemotherapy; as a result the prevalence of Ascaris lumbricoides and hookworms dropped from 74.5% to 10% and from 86% to 40% respectively. The experience in Cambodia demonstrates that, with political commitment, control of parasitic diseases is achievable even in a situation of minimal resources. The programme represents a successful model for other developing countrie

Echinostoma revolutum Infection in Children, Pursat Province, Cambodia

To determine the prevalence of helminthic infections in Pursat Province, Cambodia, we tested fecal specimens from 471 children, 10–14 years of age, in June 2007. The prevalence of infection with echinostome flukes ranged from 7.5% to 22.4% in 4 schools surveyed. Adult worms were identified as Echinostoma revolutum

Different but overlapping populations of Strongyloides stercoralis in dogs and humans-Dogs as a possible source for zoonotic strongyloidiasis

Strongyloidiasis is a much-neglected soil born helminthiasis caused by the nematode Strongyloides stercoralis. Human derived S. stercoralis can be maintained in dogs in the laboratory and this parasite has been reported to also occur in dogs in the wild. Some authors have considered strongyloidiasis a zoonotic disease while others have argued that the two hosts carry host specialized populations of S. stercoralis and that dogs play a minor role, if any, as a reservoir for zoonotic S. stercoralis infections of humans. We isolated S. stercoralis from humans and their dogs in rural villages in northern Cambodia, a region with a high incidence of strongyloidiasis, and compared the worms derived from these two host species using nuclear and mitochondrial DNA sequence polymorphisms. We found that in dogs there exist two populations of S. stercoralis, which are clearly separated from each other genetically based on the nuclear 18S rDNA, the mitochondrial cox1 locus and whole genome sequence. One population, to which the majority of the worms belong, appears to be restricted to dogs. The other population is indistinguishable from the population of S. stercoralis isolated from humans. Consistent with earlier studies, we found multiple sequence variants of the hypervariable region I of the 18 S rDNA in S. stercoralis from humans. However, comparison of mitochondrial sequences and whole genome analysis suggest that these different 18S variants do not represent multiple genetically isolated subpopulations among the worms isolated from humans. We also investigated the mode of reproduction of the free-living generations of laboratory and wild isolates of S. stercoralis. Contrary to earlier literature on S. stercoralis but similar to other species of Strongyloides, we found clear evidence of sexual reproduction. Overall, our results show that dogs carry two populations, possibly different species of Strongyloides. One population appears to be dog specific but the other one is shared with humans. This argues for the strong potential of dogs as reservoirs for zoonotic transmission of S. stercoralis to humans and suggests that in order to reduce the exposure of humans to infective S. stercoralis larvae, dogs should be treated for the infection along with their owners

Molecular Surveillance for Multidrug-Resistant Plasmodium falciparum, Cambodia

We conducted surveillance for multidrug-resistant Plasmodium falciparum in Cambodia during 2004–2006 by assessing molecular changes in pfmdr1. The high prevalence of isolates with multiple pfmdr1 copies found in western Cambodia near the Thai border, where artesunate–mefloquine therapy failures occur, contrasts with isolates from eastern Cambodia, where this combination therapy remains highly effective

The high prevalence of anemia in Cambodian children and women cannot be satisfactorily explained by nutritional deficiencies or hemoglobin disorders

Background: Anemia is highly prevalent in Cambodian women and children, but data on causes of anemia are scarce. We performed a national micronutrient survey in children and women that was linked to the Cambodian Demographic Health Survey 2014 (CDHS-2014) to assess the prevalence of micronutrient deficiency, hemoglobin disorders and intestinal parasite infection. Methods: One-sixth of households from the CDHS-2014 were selected for a follow-up visit for the micronutrient survey. Households were visited from two weeks to two months after the CDHS-2014 visit. Data on micronutrient status were available for 1512 subjects (792 children and 720 women). Results: Anemia was found in 43% of the women and 53% of the children. Hemoglobin disorders affected &gt;50% of the population, with Hemoglobin-E the most prevalent disorder. Deficiencies of iron (ferritin &lt; 15 g/L), vitamin A (retinol-binding-protein (RBP) &lt; 0.70 mol/L) or vitamin B12 (&lt;150 pmol/L) were not prevalent in the women (&lt;5% for all), whereas 17.8% of the women had low concentrations of folic acid (&lt;10 nmol/L). In the children, the prevalence of iron, vitamin A, vitamin B12 or folic acid deficiency was &lt;10%. Zinc deficiency, hookworm infection and hemoglobinopathy were significantly associated with anemia in children, whereas in the women none of the factors was significantly associated with anemia. Iron deficiency anemia (IDA) was more prevalent in children &lt;2 years, but in older children and women, the prevalence of IDA was &lt;5%. The most prevalent, preventable causes of anemia were hookworm infection and zinc and folic acid deficiency. Over 40% of the anemia was not caused by nutritional factors. Conclusion: The very high prevalence of anemia in Cambodian women and children cannot be explained solely by micronutrient deficiencies and hemoglobin disorders. Micronutrient interventions to improve anemia prevalence are likely to have limited impact in the Cambodian setting. The focus of current interventions to reduce the high prevalence of anemia in children and women should be broadened to include zinc and folic acid as well as effective anti-hookworm measures

Large-Scale Preventive Chemotherapy for the Control of Helminth Infection in Western Pacific Countries: Six Years Later

In 2001, Urbani and Palmer published a review of the epidemiological situation of helminthiases in the countries of the Western Pacific Region of the World Health Organization indicating the control needs in the region. Six years after this inspiring article, large-scale preventive chemotherapy for the control of helminthiasis has scaled up dramatically in the region. This paper analyzes the most recent published and unpublished country information on large-scale preventive chemotherapy and summarizes the progress made since 2000. Almost 39 million treatments were provided in 2006 in the region for the control of helminthiasis: nearly 14 million for the control of lymphatic filariasis, more than 22 million for the control of soil-transmitted helminthiasis, and over 2 million for the control of schistosomiasis. In general, control of these helminthiases is progressing well in the Mekong countries and Pacific Islands. In China, despite harboring the majority of the helminth infections of the region, the control activities have not reached the level of coverage of countries with much more limited financial resources. The control of food-borne trematodes is still limited, but pilot activities have been initiated in China, Lao People's Democratic Republic, and Vietnam

Molecular Identification of Taenia Tapeworms by Cox1 Gene in Koh Kong, Cambodia

We collected fecal samples from 21 individuals infected with Taenia tapeworms in Koh Kong Province, Cambodia, and performed nucleotide sequencing of the cox1 gene and multiplex PCR on the eggs for DNA differential diagnosis of human Taenia tapeworms. Genomic DNA was extracted from the eggs of a minimum number of 10 isolated from fecal samples. Using oligonucleotide primers Ta7126F, Ts7313F, Tso7466F, and Rev7915, the multiplex PCR assay proved useful for differentially diagnosing Taenia solium, Taenia saginata, and Taenia asiatica based on 706, 629, and 474 bp bands, respectively. All of the Taenia specimens from Kho Kong, Cambodia, were identified as either T. saginata (n=19) or T. solium (n=2) by cox1 sequencing and multiplex PCR