Epidemiological features of intestinal infection with Entamoeba histolytica in Taiwan, 2002-2010

The Epidemiology of Entamoeba histolytica Infection and Its Associated Risk Factors among Domestic and Imported Patients in Taiwan during the 2011-2020 Period

Background and Objectives: Amebiasis remains an important public health problem worldwide, and immigration and increased international travel have affected incident disease cases. This study assesses the prevalence of Entamoeba histolytica in Taiwan between 2011 and 2020 by analyzing data from surveillance programs conducted by the Centers for Disease Control of Taiwan (TCDC) on laboratory-confirmed cases. Materials and Methods: The E. histolytica infection-related data reported to the National Infectious Diseases Statistics System at the TCDC from 1 January 2011 to 31 December 2020 were collected, including age, gender, place of residence, and the geographic season of exposure for each case. Results: In total, 3066 cases with E. histolytica infections were included in our analysis. Among them, 1735 (57%) cases were imported, and 1331 (43%) were locally acquired. The average annual incidence rate of E. histolytica infections in Taiwan between 2011 and 2020 was 10.6 and 16.1 per 1,000,000 patients. There were statistical differences in gender, age group, and place of residence (p < 0.001) by the source distribution of cases. Also, these differences were found every year (p < 0.05). There were statistical differences in gender and age group (p < 0.001) by place of residence (p < 0.001). The only difference between the distribution of cases and age group was in gender (p < 0.001). Eight patients with amebiasis died, and the fatality rate was 0.3% (8/3066), of whom 75% (6/8) were male, and 75% (6/8) were over 45 years old. This study demonstrates that multiple linear regression analysis shows positive associations between NO2 concentration and amebiasis cases (B value = 2.569, p = 0.019), O3 concentration and amebiasis cases (B value = 0.294, p = 0.008), and temperature and amebiasis cases (B value = 1.096, p = 0.046). Conclusions: This study is the first report of confirmed E. histolytica cases from TCDC surveillance data between 2011 and 2020. This study showed the importance of long periods, air pollutants, and geographically comprehensive analysis for estimating the effect of amebiasis transmission in Taiwan’s populations.

Symptomatic and Asymptomatic Protist Infections in Hospital Inpatients in Southwestern China

Cryptosporidium spp., Entamoeba histolytica, Giardia duodenalis, and Blastocystis sp. infections have been frequently reported as etiological agents for gastroenteritis, but also as common gut inhabitants in apparently healthy individuals. Between July 2016 and March 2017, stool samples (n = 507) were collected from randomly selected individuals (male/female ratio: 1.1, age range: 38–63 years) from two sentinel hospitals in Tengchong City Yunnan Province, China. Molecular (PCR and Sanger sequencing) methods were used to detect and genotype the investigated protist species. Carriage/infection rates were: Blastocystis sp. 9.5% (95% CI: 7.1–12.4%), G. duodenalis 2.2% (95% CI: 1.1–3.8%); and E. histolytica 2.0% (95% CI: 0.9–3.6%). Cryptosporidium spp. was not detected at all. Overall, 12.4% (95% CI: 9.7–15.6) of the participants harbored at least one enteric protist species. The most common coinfection was E. histolytica and Blastocystis sp. (1.0%; 95% CI: 0.3–2.2). Sequence analyses revealed that 90.9% (10/11) of the genotyped G. duodenalis isolates corresponded to the sub-assemblage AI. The remaining sequence (9.1%, 1/11) was identified as sub-assemblage BIV. Five different Blastocystis subtypes, including ST3 (43.7%, 21/48), ST1 (27.1%, 13/48), ST7 (18.8%, 9/48), ST4 (8.3%, 4/48), and ST2 (2.1%, 1/48) were identified. Statistical analyses confirmed that (i) the co-occurrence of protist infections was purely random, (ii) no associations were observed among the four protist species found, and (iii) neither their presence, individually or jointly, nor the patient’s age was predictors for developing clinical symptoms associated with these infections. Overall, these protist mono- or coinfections are asymptomatic and do not follow any pattern.

A Case-Control Study of Timely Control and Investigation of an Entamoeba Histolytica Outbreak by Primary Health Care in Idahluy-e Bozorg Village, Iran

Background and aims: Experience transfer and the knowledge utilization of rapid and timely outbreak control can be the key path-finding to health systems (HSs). The aim of this study was to investigate an Entamoeba histolytica diarrhea outbreak through timely control. Methods: A case-control study and an environmental survey were conducted to identify the source of infection and the outbreak etiological agent. Sixty-two confirmed cases in Idahluye Bozorg village, Iran, and 62 group-matched controls (in terms of age and sex) were selected from the healthy neighbors of the same village during the same period. Then, multiple logistic regression was applied to calculate the adjusted odds ratio for diarrhea risk. Results: Totally, 250 cases were identified by a continuous common source epidemic from January 19th to 31st, 2018. Out of the total 36 stool samples, E. histolytica was detected as the common organism. In addition, the final analysis indicated that network drinking water (NDW) increased the odds of diarrhea (16.56, 95% CI=4.14-64.87), whereas well water and boiling water had protective effects and decreased the odds of diarrhea by 81% and 66%, respectively. Conclusion: Overall, the source of infection was detected due to the contamination of underground NDW by pipe sewage erosion. Therefore, additional monitoring of water systems is necessary, especially during the summer and regarding full readiness for outbreak control.

The state of art of neutrophil extracellular traps in protozoan and helminthic infections

Neutrophil extracellular traps (NETs) are DNA fibers associated with histones, enzymes from neutrophil granules and anti-microbial peptides. NETs are released in a process denominated NETosis, which involves sequential steps that culminate with the DNA extrusion. NETosis has been described as a new mechanism of innate immunity related to defense against different pathogens. The initial studies of NETs were carried out with bacteria and fungi, but currently a large variety of microorganisms capable of inducing NETs have been described including protozoan and helminth parasites. Nevertheless, we have little knowledge about how NETosis process is carried out in response to the parasites, and about its implication in the resolution of this kind of disease. In the best case, the NETs entrap and kill parasites in vitro, but in others, immobilize the parasites without affecting their viability. Moreover, insufficient studies on the NETs in animal models of infections that would help to define their role, and the association of NETs with chronic inflammatory pathologies such as those occurring in several parasitic infections have left open the possibility of NETs contributing to pathology instead of protection. In this review, we focus on the reported mechanisms that lead to NET release by protozoan and helminth parasites and the evidence that support the role of NETosis in the resolution or pathogenesis of parasitic diseases.

Multiple simultaneous infections in a patient with well-controlled HIV: when Occam's razor fails

Multiple concurrent infectious processes have previously been reported in the context of advanced HIV with significant immunosuppression. Here we report a case of multiple infections in a 56-year-old man with well-controlled HIV diagnosed 5 years earlier. Soon after returning to Australia following 12 years living in Thailand, he became unwell with fevers, night sweats, arthralgia and myalgia. There were no localising symptoms and examination was unremarkable. Investigations revealed positive syphilis (Treponema pallidum) serology with an RPR of 16, a positive urine culture (Klebsiella pneumoniae), a pulmonary nodule, a liver abscess and colitis (Entamoeba histolytica). Recovery was only complete when all the individual infections were treated.

A decade of intestinal protozoan epidemiology among settled immigrants in Qatar

Background

The World Health Organization estimates that about 3.5 billion people worldwide are affected by intestinal parasitic infections. Reports have already emphasized the role of immigrants in outbreaks of parasitic diseases in industrialized countries. With the mass influx of immigrants to Qatar, patent intestinal parasitic infections have been observed. Herein, the prevalence of intestinal protozoan infections was analysed in 29,286 records of subjects referred for stool examination at the Hamad Medical Corporation over the course of a decade (2005 to 2014, inclusive).

Results

Overall prevalence of combined protozoan infections was 5.93 % but there were significant temporal trends, age and sex effects and those arising from the region of origin of the subjects. The most common protozoan was Blastocystis hominis (overall prevalence 3.45 %). Giardia duodenalis, Chilomastix mesnili, Entamoeba coli, Entamoeba hartmanni, Endolimax nana, Iodamoeba butschlii, Entamoeba histolytica/dispar, Cryptosporidium sp. and a single case of Isospora were also detected. The prevalence of combined protozoan infections, G. duodenalis and the non-pathogenic amoebae all declined significantly across the decade. That of B. hominis varied between years but showed no directional trend across years and there was no evidence that prevalence of E. histolyitica/dispar changed significantly. Protozoan infections were observed among all regional groups, but prevalence was higher among subjects from the Arabian Peninsula, Africa and Asia compared to those from the Eastern Mediterranean and Qatar. Prevalence was higher among male subjects in all cases, but age-prevalence profiles differed between the taxa.

Conclusion

These results offer optimism that prevalence will continue to decline in the years ahead.

Epidemiology of Domestically Acquired Amebiasis in Japan, 2000-2013

Notifications of amebiasis have been increasing in Japan. Using national surveillance data during 2000-2013, reported cases of amebiasis were analyzed. A case of amebiasis was defined as laboratory-confirmed Entamoeba histolytica infection, regardless of presence of symptoms. We described temporal trends and analyzed correlates of asymptomatic versus symptomatic cases based on odds ratios (ORs) and 95% confidence intervals (CIs) using logistic regression. Of 9,946 cases reported during 2000-2013, 7,403 were domestic cases. During this period, the proportion of domestic cases increased from 63% to 85%. Among male cases, majority were middle aged, and from 2008, the number of cases attributed to heterosexual contact surpassed that of homosexual contact. During 2010-2013, increase in notifications was associated with asymptomatic cases, colonoscopy diagnosis, and males with unknown or heterosexual route of infection. Among males, colonoscopy (OR = 31.5; 95% CI = 14.0-71.0) and cases with unknown route of infection, relative to homosexual contact (OR = 2.2; 95% CI = 1.3-3.9), were associated with asymptomatic infections in multivariate analysis. Although the recent rise may have been due to enhanced detection by colonoscopy or reporting, the large number of asymptomatic cases, with reportedly unknown or heterosexual route of infection, has led to a better understanding of amebiasis in Japan and highlights the potential public health concern.

Urban transportation energy and carbon dioxide emission reduction strategies

Sustainability is an urban development priority. Thus, energy and carbon dioxide emission reduction is becoming more significant in the sustainability of urban transportation systems. However, urban transportation systems are complex and involve social, economic, and environmental aspects. We present solutions for a sustainable urban transportation system by establishing a simplified system dynamics model with a timeframe of 30 years (from 1995 to 2025) to simulate the effects of urban transportation management policies and to explore their potential in reducing vehicular fuel consumption and mitigating CO₂ emissions. Kaohsiung City was selected as a case study because it is the second largest metropolis in Taiwan and is an important industrial center. Three policies are examined in the study including fuel tax, motorcycle parking management, and free bus service. Simulation results indicate that both the fuel tax and motorcycle parking management policies are suggested as potentially the most effective methods for restraining the growth of the number of private vehicles, the amount of fuel consumption, and CO₂ emissions. We also conducted a synthetic policy consisting of all policies which outperforms the three individual policies. The conclusions of this study can assist urban transport planners in designing appropriate urban transport management strategies and can assist transport operation agencies in creating operational strategies to reduce their energy consumption and CO₂ emissions. The proposed approach should be generalized in other cities to develop an appropriate model to understand the various effects of policies on energy and CO₂ emissions.

The first case of huge amebic intra-abdominal tumor with asymptomatic amebic colitis

We report a rare case of huge amebic intra-abdominal tumor with asymptomatic amebic colitis. This appears to represent the first report of amebic intra-abdominal tumor. A 31-year-old woman presented to a local doctor with only a sensation of abdominal fullness. Abdominal computed tomography (CT) showed a huge intra-abdominal tumor in the left abdominal cavity, and she was referred to our hospital. Colonofiberscopy for detailed examination showed multiple slight, discrete ulcers in the cecum. Ameboid trophozoites were identified from biopsy specimens, and asymptomatic amebic colitis was diagnosed. Oral metronidazole (MTZ) was administered at 1500 mg/day for 10 days. CT 14 days after starting MTZ showed no change in the intra-abdominal tumor, and resection of the tumor was therefore performed. Pathological examination revealed Entamoeba histolytica with engulfed erythrocytes complicated by hemorrhagic cyst. If an intra-abdominal tumor is present and colitis is observed, amebic intra-abdominal tumor should be considered among the differential diagnoses.