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Strongyloides Hyperinfection Syndrome Combined with Cytomegalovirus Infection
case-report
Publication date (Electronic):
15 September 2016
Journal:
Case Reports in Transplantation
Publisher:
Hindawi Publishing Corporation
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Abstract
The mortality in Strongyloides hyperinfection syndrome (SHS) is alarmingly high. This is particularly common in bone marrow, renal, and other solid organ transplant (SOT) patients, where figures may reach up to 50–85%. Immunosuppressives, principally corticosteroids, are the primary triggering factor. In general, the clinical features of Strongyloides stercoralis hyperinfection are nonspecific; therefore, a high index of suspicion is required for early diagnosis and starting appropriate therapy. Although recurrent Gram-negative sepsis and meningitis have been previously reported, the combination of both cytomegalovirus (CMV) and strongyloidiasis had rarely been associated. We here describe a patient who survived SHS with recurrent Escherichia coli ( E. coli) urosepsis and CMV infection.
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Most cited references21
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Ivermectin versus albendazole or thiabendazole for Strongyloides stercoralis infection
Background Strongyloidiasis is a gut infection with Strongyloides stercoralis which is common world wide. Chronic infection usually causes a skin rash, vomiting, diarrhoea or constipation, and respiratory problems, and it can be fatal in people with immune deficiency. It may be treated with ivermectin or albendazole or thiabendazole. Objectives To assess the effects of ivermectin versus benzimidazoles (albendazole and thiabendazole) for treating chronic strongyloides infection. Search methods We searched the Cochrane Infectious Diseases Group Specialized Register (24 August 2015); the Cochrane Central Register of Controlled Trials (CENTRAL), published in the Cochrane Library; MEDLINE (January 1966 to August 2015); EMBASE (January 1980 to August 2015); LILACS (August 2015); and reference lists of articles. We also searched the metaRegister of Controlled Trials (mRCT) using 'strongyloid*' as a search term, reference lists, and conference abstracts. Selection criteria Randomized controlled trials of ivermectin versus albendazole or thiabendazole for treating chronic strongyloides infection. Data collection and analysis Two review authors independently extracted data and assessed risk of bias in the included trials. We used risk ratios (RRs) with 95% confidence intervals (CIs) and fixed- or random-effects models. We pooled adverse event data if the trials were sufficiently similar in their adverse event definitions. Main results We included seven trials, enrolling 1147 participants, conducted between 1994 and 2011 in different locations (Africa, Southeast Asia, America and Europe). In trials comparing ivermectin with albendazole, parasitological cure was higher with ivermectin (RR 1.79, 95% CI 1.55 to 2.08; 478 participants, four trials, moderate quality evidence). There were no statistically significant differences in adverse events (RR 0.80, 95% CI 0.59 to 1.09; 518 participants, four trials, low quality evidence). In trials comparing ivermectin with thiabendazole, there was little or no difference in parasitological cure (RR 1.07, 95% CI 0.96 to 1.20; 467 participants, three trials, low quality evidence). However, adverse events were less common with ivermectin (RR 0.31, 95% CI 0.20 to 0.50; 507 participants; three trials, moderate quality evidence). In trials comparing different dosages of ivermectin, taking a second dose of 200 μg/kg of ivermectin was not associated with higher cure in a small subgroup of participants (RR 1.02, 95% CI 0.94 to 1.11; 94 participants, two trials). Dizziness, nausea, and disorientation were commonly reported in all drug groups. There were no reports of serious adverse events or death. Authors' conclusions Ivermectin results in more people cured than albendazole, and is at least as well tolerated. In trials of ivermectin with thiabendazole, parasitological cure is similar but there are more adverse events with thiabendazole. Ivermectin versus benzimidazoles for treating Strongyloides stercoralis infection What is strongyloides infection and how might ivermectin work Strongyloides stercoralis is a parasite that lives in the gut of infected people. The infection is not serious for most people, but it can be fatal in people with immune deficiency. People become infected when they come in contact with soil or water contaminated with infectious worms. The chronic infection usually causes skin rash, vomiting, diarrhoea, and constipation, and respiratory problems, such as asthma-like illness. This disease may be treated with ivermectin or albendazole or thiabendazole. We wanted to know if ivermectin was better or worse than the other alternative therapies. What the research says We reviewed the evidence about the effect of ivermectin compared with albendazole and thiabendazole. After searching for relevant trials up to August 2015, we included seven randomized controlled trials, enrolling 1147 adults with chronic strongyloides infection, conducted between 1994 and 2011 in different locations (Africa, Southeast Asia, America, and Europe). Four trials assessed the effectiveness of ivermectin compared with albendazole and three trials assessed the effectiveness of ivermectin compared with thiabendazole. Comparison ivermectin versus albendazole Treatment with ivermectin probably cures more people than albendazole (moderate quality evidence), and may be equally or better tolerated (low quality evidence). The included trials did not report serious adverse events or death. Comparison ivermectin versus thiabendazole Treatment with ivermectin and thiabendazole may cure similar numbers of people with strongyloides infection (low quality evidence), but ivermectin is probably better tolerated (moderate quality evidence). The included trials did not report serious adverse events or death.
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Strongyloidiasis in transplant patients.
A Limaye, Alison Roxby, Geoffrey Gottlieb (2009)
Strongyloides stercoralis is an intestinal nematode that can persist in the human host for decades after the initial infection and can progress to fulminant hyperinfection syndrome in immunocompromised hosts. We describe a patient who died of Strongyloides hyperinfection syndrome 2 months after orthotopic heart transplantation and discuss approaches to prevention, diagnosis, and treatment. Current practice guidelines recommend screening for and treatment of Strongyloides infection before transplantation, but physicians in the United States often miss opportunities to identify patients with chronic strongyloidiasis. Screening tests have limitations, and clinical suspicion remains an important component of the evaluation before transplantation. After immunocompromised patients develop hyperinfection syndrome, diagnosis is often delayed and mortality is high, so emphasis must be placed on screening and treatment before transplantation. We review current strategies for prevention, diagnosis, and treatment of chronic intestinal strongyloidiasis in patients who will undergo transplantation and discuss the clinical features and management of Strongyloides hyperinfection syndrome in transplant recipients.
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Occurrence of Strongyloides stercoralis in Yunnan Province, China, and Comparison of Diagnostic Methods
Peter Steinmann, Xiao-Nong Zhou, Zun-Wei Du … (2007)
Introduction Soil-transmitted helminthiases are caused by infections with intestinal nematodes, of which Ascaris lumbricoides, Trichuris trichiura and the hookworms (Ancylostoma duodenale and Necator americanus) are the most widespread species [1–3]. Collectively, these soil-transmitted helminths affect over 1 billion people and cause a huge public-health burden; yet, soil-transmitted helminthiases are so-called neglected tropical diseases [4]. Strongyloides stercoralis is another and even more neglected soil-transmitted helminth, although an estimated 30–100 million people are infected worldwide [2]. An infection with S. stercoralis occurs transcutaneously and can be perpetuated over long periods by autoinfection [5,6]. Clinical signs of S. stercoralis-infected immunocompetent people can be inconspicuous or even absent, but hyperinfection involving the gastrointestinal and pulmonary system is possible. Potentially fatal disseminated infections are seen in immunocompromised individuals, for example, as a result of immunosuppressive drugs or following human T-cell lymphotropic virus type 1 (HTLV-1) infection [6–8]. S. stercoralis is endemic in tropical and temperate zones but accurate information on the geographic distribution and the global burden of strongyloidiasis is lacking. An important underlying reason is that one of the most widely used diagnostic approaches in helminth epidemiology, i.e., the Kato-Katz method [9], fails to detect S. stercoralis. Moreover, microscopic examination of direct fecal smears, often used in endemic settings, has a low sensitivity [10,11]. More sensitive diagnostic approaches for detection of S. stercoralis larvae include the Koga agar plate method [12] and the Baermann technique [13]. Their sensitivity can be further increased by examining multiple stool samples [14]. In East Asia and Thailand in particular, the epidemiology of S. stercoralis has been studied in some detail. In different investigations carried out among schoolchildren and adults in northern and central Thailand, prevalences ranging between 2.3% and 28.9% were found [15–19]. S. stercoralis has also been investigated in other Asian countries, including Japan [20], but there is a paucity of epidemiologic data and comparison of different diagnostic methods from China. This can be illustrated by consulting the PubMed database (http://www.pubmed.gov) where the following search strategy “strongyloides OR strongyloidiasis AND China” resulted in only 6 hits; 3 case reports, 1 study on animal strongyloidiasis, 1 global review, and 1 old publication that looked at single and multiple species parasitic infections among 15,952 Chinese using direct-smear examinations [21] (accessed on 29 June 2007). Here, we report findings from a cross-sectional parasitologic and questionnaire survey carried out in a random population sample in a rural setting of southern Yunnan province, China. We investigated the occurrence of S. stercoralis by screening multiple stool samples from the same individuals and comparatively assessed the performance of different diagnostic methods. Materials and Methods Study Area and Population The study was carried out in Nongyang village, located in Menghai county, Xishuangbanna prefecture, Yunnan province, China (21.81° N latitude and 100.35° E longitude). The village was selected because (i) the hookworm prevalence in this area is known to be high (used as a proxy for the likely occurrence of S. stercoralis, as both species have the same way of transmission), and (ii) it is readily accessible by project car to assure a rapid transfer of stool samples to the nearby laboratory. Details of the study village and the population sample have been presented elsewhere [22]. In brief, the village is inhabited by members of the Bulang ethnic group, and is situated 20 km southwest of the town of Menghai in a hilly area at an elevation of 1350 m above sea level. The economy of the village is governed by the surrounding tea and sugar cane plantations, other sources of income than farming are not available. Pigs and poultry are the most common domestic animals, others include dogs and buffaloes. Whilst all houses have untreated tap water originating from a nearby river, there are no household-based sanitation facilities. A single community latrine serves the entire population, but it is not consistently used. Consent, Field and Laboratory Procedures The village authorities were informed about the study, and a copy of the village family registry, containing basic demographic information, was obtained. According to the village family registry, there were some 150 households. Families with odd registration numbers (n = 78) were contacted in batches of 20–30 families per week, and all members were invited to participate in the survey. The aim and procedures of the study were explained, and an informed consent sheet was signed by the head of the household or a designated literate substitute. Pre-tested individual and household questionnaires were administered to obtain demographic (age, sex, education attainment), behavioral (wearing shoes, food consumption, personal hygiene, health care seeking) and occupational data, as well as information about the living conditions (household asset ownership, house type, sanitation infrastructure, domestic animals). Next, pre-labeled plastic containers for stool sample collection were handed out to all participants and their ability to recognize their names was checked. Each morning, filled containers were collected and replaced by empty ones for stool collection on the following day. This procedure was repeated with the goal to obtain 3 stool samples from each individual. The stool samples were stored at ambient temperature and transferred to the laboratory within 2 hours post-collection. They were processed by the Kato-Katz technique [9], the Baermann method [13] and the Koga agar plate procedure [12]. In addition, one sub-sample per study participant was stored in sodium acetate-acetic acid-formaline (SAF) solution, forwarded to a reference laboratory in Switzerland, and processed there by an ether-concentration method for the examination of helminth eggs and intestinal protozoa [23]. All tests were performed according to standard operating procedures and carried out or initiated within 12 hours after sample collection. Specifically, a single Kato-Katz thick smear was prepared from each stool sample and examined within 1 hour of preparation. Helminth eggs were counted separately to obtain parasite-specific infection intensity estimates. For the Baermann test, an apricot-sized stool sample was placed on a gauze-lined mesh in a glass funnel equipped with a rubber tube and a clamp, covered with deionised water and illuminated from below with a bulb. After 2 hours, the lowest 50 ml of the liquid were drained, centrifuged and the sediment examined under a microscope for S. stercoralis larvae (L1-stage). The Koga agar plates were freshly prepared once per week and kept at 4°C in humid conditions pending utilization. A hazelnut-sized stool sample was placed in the middle of the plate and the covered plates were incubated in a humid chamber for 2 days at 28°C. All plates were rinsed with 12 ml SAF solution, the eluent centrifuged and the sediment examined under a microscope. Recovered larvae were differentiated to distinguish S. stercoralis L3 larvae from hookworm larvae. Samples were considered positive if larval or adult S. stercoralis were observed. Statistical Analyses Questionnaire data were entered in EpiData version 3.0 (EpiData Association; Odense, Denmark) and statistical analyses were carried out in STATA version 9.2 (StataCorp.; College Station, USA). Prevalence estimates for S. stercoralis according to the Koga agar plate and the Baermann methods were calculated by means of a mathematical model presented and used elsewhere [24,25]. Based on the relative frequency of single and repeated positive test results among the multiple stool samples submitted by the participants, the model extrapolates a ‘true’ prevalence and calculates additional test characteristics for a given method. Anthelminthic Treatment and Ethical Considerations At completion of the study, free treatment with compound mebendazole (i.e., mebendazole 100 mg/tablet plus levamisole hydrochloride 25 mg/tablet; 2 tablets per day for 3 consecutive days) was offered to all inhabitants of the village by staff of the local parasite control station. The institutional review boards of the National Institute for Parasitic Diseases (Shanghai, China) and the Swiss Tropical Institute (Basel, Switzerland) approved the study. As mentioned before, written informed consent was sought from household heads or appropriate literate substitutes. Results Population Sample and Study Cohort In total, 283 individuals from 71 families participated in the survey (average family size: 4.0 people; range: 1–8). At least 1 stool sample of sufficient quantity to perform the various diagnostic tests was available from 234 individuals (82.7%). Two or 3 samples were submitted by 180 individuals (63.6%) and subsequent analyses were performed on this cohort. There were 98 females (54.4%) and the age of the participants ranged from 4 to 84 years. Among those aged 15 years and above, 92.0% were farmers, the others were students. The illiteracy rate in the same age group was 67.2%. The majority of those aged 14 years and below attended school (58.5%), whereas the remaining individuals were either pre-school children (26.8%) or had never attended school. Occurrence of S. stercoralis Fourteen different parasite species were identified, 7 helminths and 7 intestinal protozoa. Very high prevalences of A. lumbricoides (93.3%), T. trichiura (88.9%) and hookworms (87.8%) were found. Here, we focus on the S. stercoralis results. Stool examination utilizing the Koga agar plate and the Baermann technique resulted in the identification of 19 and 21 S. stercoralis infections, respectively. As summarized in Table 1, all S. stercoralis infections detected by the Koga agar plate method were also diagnosed by the Baermann technique, whereas 2 infections were identified by the latter method only. Thus, the observed infection prevalence of S. stercoralis, according to Baermann was 11.7%. The Kato-Katz method and the ether-concentration technique on SAF-conserved stool specimens failed to identify even a single infection with S. stercoralis. 10.1371/journal.pntd.0000075.t001 Table 1 Comparison of results obtained by the Koga agar plate and the Baermann methods for the diagnosis of S. stercoralis among 180 individuals with at least 2 stool samples examined in Nongyang village, Yunnan province, China. Baermann test Total Positive Negative Koga agar plate test positive 19 0 19 Koga agar plate test negative 2 159 161 Total 21a 159 180 a The sensitivity of the Koga agar plate method was 90.5% and that of the Baermann method was 100% if the combined results from both tests are considered as diagnostic ‘gold’ standard. Table 2 shows that the prevalence of S. stercoralis was significantly higher among males than females (18.3% versus 6.1%, χ2 = 6.42, degrees of freedom (df) = 1, p = 0.011) and increased with age, albeit not significantly (χ2 = 8.70, df = 4, p = 0.069). No infections were found among participants <15 years, whereas the highest prevalence was recorded in those aged 15–24 years (19.6%). S. stercoralis infections were not found among students of any age. No additional risk factors for a S. stercoralis infection could be identified. Neither protective measures against infection, such as wearing shoes (odds ratio (OR) = 0.64, p = 0.516), nor hygiene behavior, e.g., hand washing before eating (OR = 1.03, p = 0.963) or after defecation (OR = 1.23, p = 0.671), willingness to see a doctor in case of illness (OR = 2.91, p = 0.310) or presence of domestic animals (e.g., dogs; OR = 1.88, p = 0.267) were associated with infection status. 10.1371/journal.pntd.0000075.t002 Table 2 Number and percentage of study participants infected with S. stercoralis as determined by the combined Koga agar plate and Baermann techniques, stratified by sex, age group and occupation among 180 individuals from Nongyang village in Yunnan province, China. Characteristics No. of individuals examined No. of individuals positive for S. stercoralis Percent positive χ2 p value All individuals 180 21 11.7 Sex Female 98 6 6.1 Male 82 15 18.3 6.42 0.011 Age group (years) ≤9 17 0 0 10–14 20 0 0 15–24 46 9 19.6 25–39 53 5 9.4 ≥40 44 7 17.5 8.70 0.069 Occupationa Pre-school, student 40 0 0 Farmer 138 19 13.8 6.17 0.013 a Only those individuals with known occupation were included (n = 178). Performance of Different Diagnostic Methods Indicators of the diagnostic performance of the Koga agar plate and the Baermann methods, in relation to different sampling efforts, are presented in Table 3. The examination of 3 stool samples, rather than a single one, resulted in a significant increase in the number of infections detected by either method. The observed S. stercoralis prevalence increased from 7.3% to 11.7% when using the Koga agar plate method (an increase of 62%), and from 7.0% to 14.0% in the case of the Baermann method (an increase of 100%). Whilst using Koga agar plates, larvae were detected with equal frequencies in only 1, 2 or all 3 stool samples from infected individuals, the Baermann method often failed to detect larvae in multiple samples from the same person. Using the results of the Koga agar plate method and a mathematical model developed by Marti and Koella [24], we estimated a ‘true’ S. stercoralis prevalence of 12.3%. The corresponding value for the Baermann technique was 16.3%. The probability of correctly identifying infected individuals by analyzing single stool samples was estimated at 0.63 and 0.48 for the Koga agar plate and the Baermann technique, respectively. 10.1371/journal.pntd.0000075.t003 Table 3 Identification of S. stercoralis larvae by the Koga agar plate and the Baermann methods in 3 different stool samples obtained from inhabitants of Nongyang village in Yunnan province, China, and ‘true’ prevalence and test characteristics according to a model developed by Marti and Koella (1993) [24]. Sampling effort Koga agar plate method Baermann method Number % Number % 3 stool samples analyzed 179 100 129 100 Cumulative result after analysis of 1st stool sample 13 7.3 9 7.0 2nd stool sample 20 11.2 14 10.9 3rd stool sample 21 11.7 18 14.0 Larvae recovered from 1 stool sample 7 3.9 9 7.0 2 stool samples 7 3.9 6 4.7 3 stool samples 7 3.9 3 2.3 1, 2 or 3 stool samples 21 11.7 18 14.0 Estimated prevalence (SD) 12.3 (±5.1) 16.3 (±7.6) Sensitivity of method (3 samples) 95.1 85.6 Sensitivity of individual test (SD) 63.4 (±13.8) 47.5 (±17.1) SD: standard deviation. Table 4 shows the effect of the sampling effort for multiple stool sample collection on the observed prevalence and the influence of the available stool quantity on the completeness of the diagnostic results. Three Koga agar plate tests could be performed for 70.5% of the 254 participants who submitted at least 1 sufficiently-large stool sample. The higher requirements of the Baermann method regarding the available stool quantity are reflected in the lower number of tests. Only 236 participants had at least one Baermann result, whereas 129 (54.7%) submitted 3 large enough stool samples. One S. stercoralis infection was identified by the Koga agar plate method among those participants who submitted stool samples of insufficient quantity to concurrently perform the Baermann test. Combined, the Koga agar plate and the Baermann technique identified 30 S. stercoralis infections among 254 individuals who submitted at least 1 stool sample of sufficient quantity to perform at least the Koga agar plate test, resulting in an observed prevalence of 11.8%. 10.1371/journal.pntd.0000075.t004 Table 4 Effect of sampling efforts for stool collection and evaluation with the Koga agar plate and Baermann technique on the observed prevalence, total number of identified infections and the completeness of datasets. Number of stool samples from participants Koga agar plate method Baermann method S. stercoralis from 1–3 stool samples; Koga agar plate and/or Baermann method Number of participants 1st sample positive 1st and/or 2nd sample positive 1st and/or 2nd and/or 3rd sample positive Number of participants 1st sample positive 1st and/or 2nd sample positive 1st and/or 2nd and/or 3rd sample positive Koga Baermann Koga & Baermann No. % No. % No. % No. % No. % No. % No. % No. % No. % ≥1 254 19 7.5 n.a. n.a. 236 19 8.1 n.a. n.a. 27c 10.6 29 12.3 30 11.8 ≥2 215 13a 6.0 20 9.3 n.a. 180 11a 6.1 17 9.4 n.a. 3 179 13a 7.3 20b 11.2 21 11.7 129 9a 7.0 14b 10.9 18 14.0 a Results from 1st sample only. b Results from 1st and 2nd sample only. c 26 cases jointly diagnosed by the Koga agar plate and the Baermann methods, 1 additional case for which no Baermann test could be performed. n.a.: not applicable. Discussion There is a paucity of parasitologic and epidemiologic investigations pertaining to S. stercoralis in China, and to our knowledge the performance of different diagnostic approaches has never been assessed in this setting. We carried out an in-depth study in a random population sample from a small village in Yunnan province in the south-western part of China. The collection of multiple stool samples and their screening by the Koga agar plate and the Baermann techniques revealed a prevalence of S. stercoralis of 11.7%. It is conceivable that the observed prevalence still underestimates the ‘true’ prevalence, which is justified on the following grounds. First, in the absence of a diagnostic ‘gold’ standard, it is not possible to determine how often larvae failed to emigrate from the stool sample, or actually resided on the surface of the agar plate, but were not recovered. With regard to the Baermann technique, it is possible that some larvae had not yet reached the water, or settled to the ground of the funnel when the water was drained after 2 hours of exposure to light. Second, a recent study carried out in rural Malawi showed that a delay of 3 hours or more between evacuation of stool specimens by humans and processing/examining of stool samples in the laboratory resulted in a considerably decreased sensitivity of hookworm diagnosis [26]. Hence, there is concern that delays in stool processing might also negatively influence the sensitivity of diagnosing other helminth infections, including S. stercoralis. Future studies should investigate the effect of time from stool evacuation to laboratory examination with an emphasis on S. stercoralis. Third, a mathematical model [24] predicted a considerably higher prevalence of S. stercoralis when compared to the results of 3 stool specimens subjected to either the Koga agar plate or the Baermann technique. The application of other diagnostic methods, such as the charcoal coproculture method, which includes a culture step before harvesting the larvae by the Baermann method, and serology, might detect additional infections. Yet, based on our previous experience, we are confident that the approach taken in the current study (multiple stool samples and different diagnostic methods) detected S. stercoralis infections with a high sensitivity. Nonetheless, serological methods suitable to also identify very light infections should be used in future studies to further investigate the conspicuous absence of infections among children. On the other hand, the collection of stool samples over several days under limited supervision by our research team bears the risk of mixing up collection containers at the household level. This would result in the attribution of samples from one infected person to different household members who might not be infected, thus inflating the prevalence. We are confident that this issue did not distort our data, as we provided detailed explanations to all study participants about the importance of stool collection using the designated containers, and checked the ability of at least one household member to recognize each name on the pre-lab containers. Moreover, the age and sex distribution of S. stercoralis infections matched the previously presented epidemiologic patterns from neighboring countries. The 21 infections diagnosed by the Baermann approach originated from 18 families, suggesting that mis-attribution was certainly not a major issue. We also assume that the participation of only 63.6% of the eligible villagers did not affect the representativeness of the sample since the age and sex distribution of these 180 individuals was similar to the remaining 103 people who failed to provide at least 2 stool samples of sufficient quantity. Concerning the recovery of larvae from the agar plates, an attempt was made to first visually inspect the plate for larval tracks and characteristic signs of fungal and bacterial growth, but the high prevalence of hookworm larvae necessitated the recovery of the actual larvae for microscopic examination. In some cases signs of larval activity were noted, but no larvae could be recovered. Contrarily, it was shown that larvae can be present even if no signs of their activity can be detected on the surface of the agar plate [12]. We are not aware of previous community-based studies focusing on S. stercoralis in Yunnan province. The overall prevalence of S. stercoralis (11.7%) is similar to reports from northern Thailand [17]. Interestingly, southern Yunnan shares some eco-epidemiologic characteristics with northern Thailand, such as the climate, land use patterns and ethnic background. Moreover, in both settings, the prevalence of infection was significantly higher in males than in females [15,17], and increased with age, with the peak prevalence observed in adolescents and young adults [18]. Similar sex and age patterns were also reported from Laos [27]. However, in Laos and Thailand, infections were also found among children, whereas in the current study, infections were confined to individuals aged 15 years and above. These findings might point to age- and gender-specific occupational risk factors, e.g., different behavioral patterns related to agricultural activities. The absence of infections among children suggests that the main transmission sites are outside the core village, despite the precarious sanitary conditions with 86.5% of the participants reporting not using the single community latrine available in the entire village. Possibly as a result of the rather uniform educational, occupational and behavioral population characteristics, we were unable to identify additional risk factors for infection. It is commonly assumed that even if multiple stool samples are available, no single diagnostic technique can detect all S. stercoralis infections. Different methods are therefore employed for the parasitological diagnosis of this helminth but they are often poorly standardized and their performance has rarely been assessed comparatively. In one of the few available studies that compared the diagnostic performance between the Koga agar plate and the Baermann method, the former technique was superior to the Baermann technique [28]. In the present study, however, the Baermann technique identified ‘all’ infections, whereas the Koga agar plate method failed to do so in 3 cases when considering all individuals who provided at least 1 stool sample of sufficient quantity (Table 4). Even taking into account the somewhat lower sensitivity of the Koga agar plate method, this technique still has advantages in field-based epidemiologic surveys. First, it allows the analysis of small stool samples, thereby reducing the number of participants who have to be excluded from the analysis due to insufficient amounts of stool, as was the case in the current study (note the total numbers of Koga agar plate and Baermann technique test results in Table 4). Second, the Koga agar plate technique also detects hookworm infections, thus allowing for concurrent diagnosis of both parasites [29]. Previous studies have shown that formaline-ether concentration methods were able to detect S. stercoralis infections, but compared to the Baermann and Koga agar plate methods, their sensitivity was considerably lower [10,16],[30]. The low sensitivity of direct fecal smears and the Kato-Katz method for diagnosis of S. stercoralis is also well known [11]. Over the past decades, profound demographic, ecologic and socio-economic changes have occurred across China [31,32], and the health system underwent significant reforms [33]. These changes also resulted in an increased availability and use of sophisticated medical techniques, including immunomodulatory drugs and organ transplantation. Consequently, it must be assumed that the immunocompromised population is expanding. Previous research has indicated that this population group is at high risk of severe disease when concurrently infected with S. stercoralis. Nevertheless, the obvious importance of S. stercoralis for public-health has yet to prompt new research into the epidemiology and control of this neglected helminth infection in China and elsewhere. In this connection, the importance of differential diagnosis of soil-transmitted helminth infections must be emphasized, particularly in view of the large-scale administration of albendazole and/or mebendazole that usually show good efficacy against A. lumbricoides and hookworms (only moderate efficacy against T. trichiura), but commonly fail to clear S. stercoralis [1]. We have launched additional studies with the objective of enhancing our understanding of the epidemiologic situation of S. stercoralis in adjacent parts of Yunnan province with different environmental, socio-economic and ethnic characteristics, and will also investigate current and future treatment options. Finally, we encourage other groups who focus their research on helminths, not to neglect S. stercoralis any longer.
Author and article information
Journal
Journal ID (nlm-ta): Case Rep Transplant
Journal ID (iso-abbrev): Case Rep Transplant
Journal ID (publisher-id): CRIT
Title:
Case Reports in Transplantation
Publisher:
Hindawi Publishing Corporation
ISSN
(Print):
2090-6943
ISSN
(Electronic):
2090-6951
Publication date
(Print):
2016
Publication date
(Electronic):
15
September
2016
Volume: 2016
Electronic Location Identifier: 1786265
Affiliations
Author notes
Author information
Fatehi Elnour Elzein
http://orcid.org/0000-0002-0465-3004
Article
DOI: 10.1155/2016/1786265
PMC ID: 5040796
PubMed ID: 27703835
SO-VID: ba3899b3-ccd8-44d7-a2db-5f1d888c5d4e
Copyright © Copyright © 2016 Fatehi Elnour Elzein et al.
License:
This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
History
Date
received
: 11
June
2016
Date
revision received
: 14
August
2016
Date
accepted
: 28
August
2016
Categories
Subject:
Case Report
ScienceOpen disciplines: Transplantation
Data availability:
ScienceOpen disciplines: Transplantation