Prevalence of Strongyloides stercoralis infection and associated clinical symptoms among schoolchildren living in different altitudes of Amhara National Regional State, northwest Ethiopia

Abstract

Background Strongyloides stercoralis is a parasite that causes strongyloidiasis in humans. It is prevalent in the tropics and sub-tropics where poor sanitation is a common problem. The true prevalence of S. stercoralis in Ethiopia is underestimated due to the lack of a “Gold” standard diagnostic method. Moreover, its prevalence across altitudinal gradient in Amhara Region has not been studied. Methods A cross-sectional study was conducted among 844 schoolchildren in Amhara Region from April to December 2019. A stool sample was collected from each study participant and processed using formol ether concentration technique (FECT), spontaneous tube sedimentation technique (STST), Baermann concentration technique (BCT), agar plate culture (APC) and real-time polymerase chain reaction (RT-PCR). Data were entered using EpiData and analyzed by SPSS version 23 statistical software. Prevalence of S. stercoralis infection was determined using a single diagnostic technique and combination of techniques. Association of clinical variables with S. stercoralis infection was assessed by logistic regression and independent variables with p<0.05 were considered statistically significant. Results Prevalence of soil-transmitted helminths (STHs) and S. mansoni infections was 38.0% and 20.4%, respectively. Among STHs, the prevalence of hookworm infection was 32.8%. Prevalence of S. stercoralis infection was 39.0%, 28.8%, 10.9%, 10.3%, 4.0% and 2.0% by the respective, combinations of the five methods, RT-PCR, APC, BCT, STST and FECT. The highest prevalence rates, 48.2%, 45.0% and 41.1% of S. stercoralis were recorded in the age group of 12–14 years, males and rural dwellers, respectively. Prevalence rates of S. stercoralis infection in highland, semi-highland and lowland areas were 40.4%, 41.8% and 25.9%, respectively. Having abdominal pain (AOR = 2.48; 95% CI:1.65–3.72), cough (AOR = 1.63;95%CI:1.09–2.42), urticaria (AOR = 2.49;95%CI:1.50–4.01) and being malnourished (AOR = 1.44;95%:1.10–2.01) were significantly associated with strongyloidiasis. Conclusion Prevalence of S. stercoralis infection was high and varied across different altitudes in Amhara Region. Some clinical syndromes were found to be significantly associated with S. stercoralis infection. Therefore, proper diagnosis and preventive strategies against S. stercoralis infection are highly recommended to be devised and implemented in Amhara Region.

Intestinal Parasitic Infections Among Pediatric Patients in a Metropolitan City of Bangladesh With Emphasis on Cryptosporidiosis

“…One container contained a 10% formalin preserved fecal sample for direct wet mount preparation, and the other retained an unpreserved fecal sample. This was followed by the concentration procedure which consisted of the following step: i) By using a stick, an estimated 1gm of feces was emulisified in about 4 ml of 10% formol water contained in a tube, ii) A further 3-4 ml of 10% v/v formol water was added, the tube was capped, and mixed well by shaking, iii) The emulsified feces were sieved collecting the sieved suspension in a beaker, iv) the solution was transferred to a centrifuge tube and 3-4 ml of ethyl acetate was added, v) The tube was then vortexed for 15 minutes, vi) It was centrifuged immediately at low speed 1000 rpm for one minute, vii) A pipette was used to remove the entire column of fluid below the fecal debris and ether and this was transferred to another centrifuge tube, viii) Formol water was added to make the volume up to 10 to 15 ml and centrifuged at 3000 rpm for 5-10 minutes, ix) The supernatant was removed and the bottom of the tube was tapped to resuspend and mix the sediment [90][91][92] was followed with this unpreserved sample before the staining procedure. The sediment was now ready to make a smear on the slide for microscopic examination.…”

The transmission dynamics of Strongyloides stercoralis and the impact of mass drug administration

“…For 3). In all these studies, it should be noted that they do not use the most sensitive of the current diagnostic tools (RT-PCR) that was employed in the Ethiopian study of Jember et al [4], and as such will underestimate true prevalence. To illustrate this point table 1 records estimates of prevalence by diagnostic used in the Ethiopian study of Jember et al [4].…”

“…In all these studies, it should be noted that they do not use the most sensitive of the current diagnostic tools (RT-PCR) that was employed in the Ethiopian study of Jember et al [4], and as such will underestimate true prevalence. To illustrate this point table 1 records estimates of prevalence by diagnostic used in the Ethiopian study of Jember et al [4]. The large variation by method is very striking and suggests that most estimates in past studies in the published literature using other than the PCR method greatly underestimate prevalence.…”

“…These are a formol ether concentration technique (FECT), a spontaneous tube sedimentation technique, the Baermann concentration technique, an agar plate culture method, and a real-time polymerase chain reaction (RT-PCR). Recent studies in the Amhara region of northwest Ethiopia employing all these approaches on stool samples, for example, have revealed a high prevalence of infection in some regions of the country where other soil transmitted helminths (STHs) are also common, such as Ascaris lumbricoides , Trichuris trichuria and hookworm [4]. With what is assumed to be the most sensitive diagnostic, RT-PCR, the prevalence of infection approached 40% in a large sample of school-aged children.…”

Respiratory morbidity in Schistosoma mansoni infection: a rapid review of literature

“…Seven records were excluded, of which three did not provide relevant data, [11][12][13] respiratory symptoms were attributed to other causes in two records 14,15 and respiratory symptoms specific for S. mansoni were not enumerated in the other two records. 16,17 Study characteristics A total of 2243 patients with S. mansoni were reported from 24 case reports (24 patients), 11 cross-sectional studies (1121 patients), 7 case series (45 patients), 2 cohort studies (53 patients) and 2 randomized controlled trials (1000 patients). Of all the studies, 26 (56.5%) were published more than 10 years ago (before 2013).…”