Hookworm Diagnosis Research Articles

Establishment of a Simple and Rapid Nucleic Acid Detection Method for Hookworm Identification.

Traditional microscopic technology such as the Kato-Katz method is not suitable for hookworm diagnosis due to the rapid degeneration of fragile hookworm eggs or for species identification of hookworm infection. The aim of the present study was to establish and evaluate a novel nucleic acid detection method based on recombinase-aided isothermal amplification (RAA) for the detection of hookworm infections and species identification. Based on the specific target gene sequences of hookworms (5.8S rRNA for AD and ITS2 for NA, respectively), we designed and synthesized amplification primers and fluorescence probes referring to the principle of the fluorescence recombinase-aided amplification (RAA) technique. Each assay provided specific amplification of larval DNA from AD and NA by fluorescence RAA, and the detection limits in plasmids reached 102 copies and 10 copies, respectively. Genomic DNA of two hookworm species was successfully detected at a concentration of 0.1 pg/μL, revealing a high detection sensitivity. No positive amplification occurred for genomic DNA from crossed hookworm species and genomic DNA from Cryptosporidium, Giardia lamblia, Strongyloides stercoralis, Schistosoma japonicum, Ascaris lumbricoides, and Clonorchis sinensis, revealing a satisfactory specificity. Fecal sample detection results demonstrated a similar efficacy to the Kato-Katz method; however, it had a greater sensitivity than the larvae culture method. A simple and rapid nucleic acid method was successfully established based on RAA, which improved the detection efficacy and species identification for human hookworm infections.

Unexpected Bullae in a 12-year-old Boy

Unexpected Bullae in a 12-year-old Boy

Evaluation of Hookworm Diagnosis Techniques from Patients in Debre Elias and Sanja Districts of the Amhara Region, Ethiopia.

Background Inappropriate diagnosis could intimidate the prevention and control of hookworm infection. Thus, this study was aimed at evaluating the performance of hookworm diagnosis methods. Methods An institution-based cross-sectional study was conducted from patients in Debre Elias and Sanja districts of the Amhara region, Ethiopia, from November 2019 to January 2020. The study subjects were selected conveniently. After the data was entered into Statistical Package for the Social Sciences (SPSS), sensitivity, specificity, predictive values, test accuracy, and agreement of the different hookworm diagnosis methods, namely, test tube flotation technique (TFT), McMaster (MM), formol-ether concentration (FEC), Kato-Katz (KK), and direct wet mount microscopy (DWMM), were calculated by using SPSS software. The composite reference standard (CRS) was used as the gold standard method. The kappa (κ) test was used to measure the level of agreement between diagnosis tests. Result A total of 389 stool samples were collected from patients in the study. The overall prevalence of hookworm was 63.24%. The test tube flotation technique (TFT) was found to be the highest both in terms of sensitivity and diagnostic accuracy (100%). McMaster (MM) was the second most sensitive test (68.7%), followed by FEC (44.3%) and KK (38.2%). On the other hand, DWMM had the lowest sensitivity (37.4%), and its diagnostic accuracy was also the least (60%). Only TFT had a perfect agreement (agreement = 100%, kappa = 1) with the CRS. The sensitivity of DWMM, KK, and FEC showed a kind of linear function with the intensity of infection, but TFT and MM methods were not affected by the infection intensity. Conclusion Hookworm is still a public health problem in the study area. TFT is by far more sensitive than MM, FEC, KK, and DWMM techniques.

Comparison of direct wet mount, Kato–Katz and formol ether sedimentation technique for the diagnosis of hookworm infection in Debre Elias Woreda, Northwest Ethiopia

Hookworm infection is a neglected parasitic disease. Direct wet mount is the usual method for the diagnosis of hookworm in Ethiopia, but its sensitivity is unsatisfactory. A cross-sectional study was therefore conducted from January to February 2018 among 192 study participants in Debre Elias district. Stool samples were processed by three methods: the prevalence of hookworm was 77.6%, 68.2% and 49.0% by Kato-Katz, formol ether sedimentation technique and direct wet mount, respectively. Direct wet mount had relatively low sensitivity (61.4%) compared to formol ether sedimentation technique (85.6%) and Kato-Katz (97.4%). The latter two compared well with the gold standard method with kappa values of κ = 0.94, κ = 0.71 and κ = 0.39, respectively, and are therefore recommended over against the direct wet mount technique in detecting hookworm.

Levels of serum eosinophil cationic protein are associated with hookworm infection and intensity in endemic communities in Ghana.

BackgroundThe eosinophil cationic protein (ECP) is a cytotoxic protein mainly secreted by eosinophils granulocytes and plays a role in host defense against parasitic infections. Infection with Necator americanus (hookworm) is traditionally diagnosed by the Kato-Katz method which is inherently tedious, subjective and known to underestimate infection intensity. This study aimed to assess levels of serum ECP in relation to hookworm infection intensity.MethodsStool samples from 984 (aged 4 to 80 years) participants in a cross-sectional study conducted in the Kintampo North Municipality of Ghana were examined using the Kato-Katz and formol-ether concentration methods. Serum ECP levels were measured by ECP assay kit and compared between 40 individuals infected with hookworm only, 63 with hookworm- Plasmodium falciparum co-infection, 59 with P. falciparum infection and 36 with no infection.ResultsHookworm infection prevalence was 18.1% (178/984). ECP levels were significantly higher in individuals infected with hookworm only (β = 2.96, 95%CI = 2.69, 3.23, p<0.001) or co-infected with P. falciparum (β = 3.15, 95%CI = 2.91, 3.39, p<0.001) compared to the negative control. Levels of ECP were similar between those with only P. falciparum infection and the uninfected control (p>0.05). Increased hookworm intensity was associated with a significant increase in ECP level (β = 4.45, 95%CI = 2.25, 9.11, rs = 0.193, n = 103, p<0.01). ECP threshold of 84.98ng/ml was associated with a positive predictive value (PPV) of 98% (95% CI = 92, 100), and negative predictive value (NPV) of 76% (95% CI = 62, 87) in classifying hookworm infection status with an AUROC of 96.3%.ConclusionSerum ECP level may be a good biomarker of hookworm infection and intensity and warrant further investigations to help improve current hookworm diagnosis.

Estimating sensitivity of the Kato-Katz technique for the diagnosis of Schistosoma mansoni and hookworm in relation to infection intensity.

The Kato-Katz technique is the most widely used diagnostic method in epidemiologic surveys and drug efficacy trials pertaining to intestinal schistosomiasis and soil-transmitted helminthiasis. However, the sensitivity of the technique is low, particularly for the detection of light-intensity helminth infections. Examination of multiple stool samples reduces the diagnostic error; yet, most studies rely on a single Kato-Katz thick smear, thus underestimating infection prevalence. We present a model which estimates the sensitivity of the Kato-Katz technique in Schistosoma mansoni and hookworm, as a function of infection intensity for repeated stool sampling and provide estimates of the age-dependent ‘true’ prevalence. We find that the sensitivity for S. mansoni diagnosis is dominated by missed light infections, which have a low probability to be diagnosed correctly even through repeated sampling. The overall sensitivity strongly depends on the mean infection intensity. In particular at an intensity of 100 eggs per gram of stool (EPG), we estimate a sensitivity of 50% and 80% for one and two samples, respectively. At an infection intensity of 300 EPG, we estimate a sensitivity of 62% for one sample and 90% for two samples. The sensitivity for hookworm diagnosis is dominated by day-to-day variation with typical values for one, two, three, and four samples equal to 50%, 75%, 85%, and 95%, respectively, while it is only weakly dependent on the mean infection intensity in the population. We recommend taking at least two samples and estimate the ‘true’ prevalence of S. mansoni considering the dependence of the sensitivity on the mean infection intensity and the ‘true’ hookworm prevalence by taking into account the sensitivity given in the current study.

How long can stool samples be fixed for an accurate diagnosis of soil-transmitted helminth infection using Mini-FLOTAC?

BackgroundKato-Katz is a widely used method for the diagnosis of soil-transmitted helminth infection. Fecal samples cannot be preserved, and hence, should be processed on the day of collection and examined under a microscope within 60 min of slide preparation. Mini-FLOTAC is a technique that allows examining fixed fecal samples. We assessed the performance of Mini-FLOTAC using formalin-fixed stool samples compared to Kato-Katz and determined the dynamics of prevalence and intensity estimates of soil-transmitted helminth infection over a 31-day time period.MethodologyThe study was carried out in late 2013 on Pemba Island, Tanzania. Forty-one children were enrolled and stool samples were subjected on the day of collection to a single Kato-Katz thick smear and Mini-FLOTAC examination; 12 aliquots of stool were fixed in 5% formalin and subsequently examined by Mini-FLOTAC up to 31 days after collection.Principal FindingsThe combined results from Kato-Katz and Mini-FLOTAC revealed that 100% of children were positive for Trichuris trichiura, 85% for Ascaris lumbricoides, and 54% for hookworm. Kato-Katz and Mini-FLOTAC techniques found similar prevalence estimates for A. lumbricoides (85% versus 76%), T. trichiura (98% versus 100%), and hookworm (42% versus 51%). The mean eggs per gram of stool (EPG) according to Kato-Katz and Mini-FLOTAC was 12,075 and 11,679 for A. lumbricoides, 1,074 and 1,592 for T. trichiura, and 255 and 220 for hookworm, respectively. The mean EPG from day 1 to 31 of fixation was stable for A. lumbricoides and T. trichiura, but gradually declined for hookworm, starting at day 15.Conclusions/SignificanceThe findings of our study suggest that for a qualitative diagnosis of soil-transmitted helminth infection, stool samples can be fixed in 5% formalin for at least 30 days. However, for an accurate quantitative diagnosis of hookworm, we suggest a limit of 15 days of preservation. Our results have direct implication for integrating soil-transmitted helminthiasis into transmission assessment surveys for lymphatic filariasis.

Diagnostic Accuracy of Kato–Katz, FLOTAC, Baermann, and PCR Methods for the Detection of Light-Intensity Hookworm and Strongyloides stercoralis Infections in Tanzania

Sensitive diagnostic tools are crucial for an accurate assessment of helminth infections in low-endemicity areas. We examined stool samples from Tanzanian individuals and compared the diagnostic accuracy of a real-time polymerase chain reaction (PCR) with the FLOTAC technique and the Kato–Katz method for hookworm and the Baermann method for Strongyloides stercoralis detection. Only FLOTAC had a higher sensitivity than the Kato–Katz method for hookworm diagnosis; the sensitivities of PCR and the Kato–Katz method were equal. PCR had a very low sensitivity for S. stercoralis detection. The cycle threshold values of the PCR were negatively correlated with the logarithm of hookworm egg and S. stercoralis larvae counts. The median larvae count was significantly lower in PCR false negatives than true positives. All methods failed to detect very low-intensity infections. New diagnostic approaches are needed for monitoring of progressing helminth control programs, confirmation of elimination, or surveillance of disease recrudescence.

Mini-FLOTAC and Kato-Katz: helminth eggs watching on the shore of lake Victoria

BackgroundOne of the challenges for monitoring helminth control programmes based on preventive chemotherapy is the lack of a copro-parasitological gold–standard method that combines good sensitivity with quantitative performance, low cost, and easy-to-learn technique.The aim of our study was to evaluate and compare, the WHO recommended quantitative diagnostic technique (Kato-Katz) and the Mini-FLOTAC.MethodsMini-FLOTAC is an innovative method based on floatation of helminths eggs with two different solutions (FS2 and FS7) using a close system (Fill-FLOTAC) with 5% fixative. Kato-Katz was performed following WHO recommendation. The study was carried out in a rural part of Tanzania, close to Lake Victoria, where the laboratory facilities are fairly scarce, and the basic technique used in the local laboratory (direct smear) was taken as reference standard.Results201 children were screened for intestinal helminths and 91% of them were found to be positive. The agreement among the three techniques was calculated with k Cohen coefficient and was fairly good (k = 0.4), although the Mini-FLOTAC results were more sensitive for hookworm (98%) with FS2, and for S.mansoni (90%) with FS7 followed by Kato-Katz (91% and 60% respectively) and direct smear (30% and 10% respectively). A good agreement was found between Mini-FLOTAC and Kato-Katz (k = 0.81) with FS7 (k = 0.76) for hookworm diagnosis and a fairly good one for S.mansoni diagnosis (k = 0.5). For both infections we had a poor agreement between the two quantitative techniques and the direct smear (k<0.3). Kato-Katz diagnosed a higher number of eggs (calculated by arithmetic mean) both for hookworm (455 vs 424 EPG) and for S.mansoni (71 vs 58 EPG) compared with the Mini-FLOTAC, but the differences were not significant (p = 0.4).ConclusionsMini-FLOTAC is a promising technique, comparable and as sensitive as the Kato-Katz, which is the recommended method in intestinal helminthology for monitoring helminth control programmes. A comparative advantage of the Mini-FLOTAC is that it comprises of a closed system with preserved samples that both protects the operators and allows subsequent examination of the samples. Further studies are needed to validate the mini-FLOTAC with other quantitative techniques (McMaster) and in different settings where other soil-transmitted helminths are also endemic.

Comparison of Kato-Katz, ethyl-acetate sedimentation, and Midi Parasep® in the diagnosis of hookworm, Ascaris and Trichuris infections in the context of an evaluation of rural sanitation in India

The Kato-Katz, conventional ethyl-acetate sedimentation, and Midi Parasep® methods for diagnosing infection with soil-transmitted helminths were compared. The Kato-Katz technique gave the best overall diagnostic performance with the highest results in all measures (prevalence, faecal egg count, sensitivity) followed by the conventional ethyl-acetate and then the Midi Parasep® technique. The Kato-Katz technique showed a significantly higher faecal egg count and sensitivity for both hookworm and Trichuris as compared to the Midi Parasep® technique. The conventional ethyl-acetate technique produced smaller pellets and showed lower pellet mobility as compared to the Midi Parasep®.

Efficacy of parasitological methods for the diagnosis of Strongyloides stercoralis and hookworm in faecal specimens

To compare the efficacy of stool examination for the detection of Strongyloides stercoralis and hookworm, a total of 634 stool samples from the routine laboratory service of the Pharmacia Faculty, Federal University of Bahia, Brazil, were examined by agar plate culture (APC), Baermann-Moraes and spontaneous sedimentation. The sensitivity of agar plate culture, calculated by combining results of all 3 methods, was 95% for S. stercoralis and 77.6% for hookwoorm. Moreover, APC had superior accuracy than Baermann-Moraes and spontaneous sedimentation for S. stercoralis and hookworm diagnosis, respectively. The S. stercoralis and hookworm positive samples from the laboratory routine, obtained after the previous analysis, along with those initially selected, were used to evaluate the concordance between microscopic examination and both the type of furrows left by larvae and the time for culture positivity using the APC method. Of 115 stool samples positive for S. stercoralis and 92 positive for hookworm, 110 (95.7%) and 89 (96.7%), respectively, had concordant results for furrows and morphological characteristics. The cumulative percentage of positivity increased to 94% by the third day of observation; at this time, only 19.6% of hookworm-positive samples had positive culture plates. Analyses of 74 S. stercoralis-positive stool samples stored at 4°C for 24, 48 and 72h showed the presence of larvae in 48.6%, 28.4% and 23% of samples, respectively when re-examined by the APC. As a definitive diagnosis of strongyloidiasis depends on the microscopic demonstration of parasites, increasing the sensitivity of the detection requires the use of different parasitological methods, including APC.

FLOTAC: a new sensitive technique for the diagnosis of hookworm infections in humans

Hookworms infect more than 10% of the world's population, but current diagnostic tools have drawbacks. Our objective was to compare the diagnostic performance of three methods (Kato-Katz, ether concentration and FLOTAC techniques) for hookworm diagnosis. Stool samples were obtained from 102 schoolchildren in Côte d'Ivoire. First, a duplicate 41.7mg Kato-Katz thick smear was prepared. Next, a small portion of stool (mean weight 1.8g) was preserved in sodium acetate-acetic acid-formalin and forwarded to a European laboratory. These samples were split in three parts, one processed by an ether concentration technique and two by the FLOTAC technique. All samples were examined by experienced technicians for hookworm eggs using light microscopy. The observed hookworm prevalences as assessed by the FLOTAC, Kato-Katz and ether concentration techniques were 65.7%, 51.0% and 28.4%, respectively. Considering the combined results as the diagnostic 'gold' standard, the FLOTAC technique had a sensitivity of 88.2% compared with 68.4% for the Kato-Katz and 38.2% for the ether concentration techniques. The Kato-Katz method resulted in a significantly higher mean number of eggs per gram of stool (155.8 EPG) compared with the FLOTAC (37.7 EPG) and ether concentration (5.7 EPG) methods. The FLOTAC method shows promise as an important new tool for individual hookworm diagnosis and for rigorous monitoring of helminth control programmes. [Clinical Trial No. ISRCTN21782274].

Public health policy paradoxes: science and politics in the Rockefeller Foundation’s hookworm campaign in Mexico in the 1920s

The origins of US international health endeavors are intertwined with the Progressive Era’s faith in science as arbiter of humankind’s secular problems. No agency better exemplifies the period’s confidence in science than the Rockefeller Foundation’s International Health Board (IHB), which set out to export the new public health theory and practice around the world. An examination of the IHB’s hookworm program in Mexico in the 1920s demonstrates that, notwithstanding the Rockefeller Foundation’s (RF) self-conscious commitment to scientific neutrality, its programs continuously engaged political criteria, exhibiting the competition, coexistence, and inseparability of the worlds of science, politics, and international health policy. Analysis of the program’s quotidian decisions and larger strategies further reveals the protean quality of RF science–politics, which enabled responses to parochial and broadly-conceived needs at multiple levels. In the focus on hookworm, the selection of campaign sites, hookworm diagnosis methods, treatment procedures, definition of cure, and the assignment of responsibility for prevention, scientific and political considerations were inextricably bound. The science–politics paradox was molded by the hookworm program’s constituencies in Mexico, including political leaders, health bureaucrats, physicians, business interests, public health workers, peasants, and Rockefeller officers. The multiple, often contradictory, roles of the RF’s hookworm campaign are characteristic of the policy paradoxes that emerge when science is summoned to drive policy. In Mexico the campaign served as a policy cauldron through which new knowledge could be demonstrated applicable to social and political problems on many levels. The repeated pledge of scientific neutrality belied the hookworm program’s inherent aim of persuading government officials, the medical community, business interests, and the populace of the value of investing in public health as a means to improve social conditions, further a medical model of health and sickness, increase economic productivity, and promote good relations between the US and Mexico.

Quantitative Hookworm Diagnosis by Direct Smear

Quantitative Hookworm Diagnosis by Direct Smear

A COMPARISON OF THE EFFICIENCY OF THE STOLL EGG-COUNTING TECHNIQUE WITH THE SIMPLE SMEAR METHOD IN THE DIAGNOSIS OF HOOKWORM*

Journal Article A COMPARISON OF THE EFFICIENCY OF THE STOLL EGG-COUNTING TECHNIQUE WITH THE SIMPLE SMEAR METHOD IN THE DIAGNOSIS OF HOOKWORM Get access A. E. KELLER A. E. KELLER Search for other works by this author on: Oxford Academic PubMed Google Scholar American Journal of Epidemiology, Volume 20, Issue 2, September 1934, Pages 307–316, https://doi.org/10.1093/oxfordjournals.aje.a118073 Published: 01 September 1934 Article history Received: 03 May 1934 Published: 01 September 1934

THE PLACE OF THE SMEAR IN HOOKWORM DIAGNOSIS*

Journal Article THE PLACE OF THE SMEAR IN HOOKWORM DIAGNOSIS Get access W.C. HAUSHEER, M.D., W.C. HAUSHEER, M.D. Search for other works by this author on: Oxford Academic PubMed Google Scholar C.A. HERRICK C.A. HERRICK Sc.D. Search for other works by this author on: Oxford Academic PubMed Google Scholar American Journal of Epidemiology, Volume 6, Issue supp2, July 1926, Pages 136–148, https://doi.org/10.1093/oxfordjournals.aje.a120055 Published: 01 July 1926 Article history Received: 07 April 1926 Published: 01 July 1926