Enteric pathogenic protozoa in homosexual men from San Francisco

Enteric Infections in Men Who Have Sex With Men

BACKGROUND

Enteric pathogens are often associated with exposure to food, water, animals, and feces from infected individuals. However, in sexual networks of men who have sex with men (MSM), transmission of enteric pathogens may occur during direct or indirect oral-anal contact.

METHODS

We performed a scoping review of the literature for studies prior to July 2019 with key terms for gastrointestinal syndromes ("proctitis," "enteritis," "proctocolitis"), enteric pathogens or sexually transmitted infections (STIs), and outbreaks using multiple electronic databases.

RESULTS

We identified 5861 records through database searches, bibliography reviews, and keyword searches, of which 117 references were included in the pathogen-specific reviews.

CONCLUSIONS

The strength of observational data describing enteric pathogens in MSM and possible sexual transmission of enteric pathogens varies by pathogen; however, a robust body of literature describes the sexual transmission of Campylobacter, Giardia lamblia, and Shigella (particularly antimicrobial-resistant strains) in sexual networks of MSM. Providers are encouraged to consider enteritis or proctocolitis in MSM as possibly having been sexually transmitted and encourage targeted STI testing. Risk/harm reduction and prevention messages should also be incorporated, though there is an acknowledged paucity of evidence with regards to effective strategies. Further research is needed to understand the transmission and prevention of enteric pathogens in MSM.

Brazilian Protocol for Sexually Transmitted Infections, 2020: sexually transmitted enteric infections

The sexually transmitted enteric infections topic is one of the chapters of the Clinical Protocol and Therapeutic Guidelines for Comprehensive Care for People with Sexually Transmitted Infections, published by the Brazilian Ministry of Health in 2020. The document was developed based on scientific evidence and validated in discussions with specialists. This article presents epidemiological and clinical aspects of these infections and guidance for service managers on their programmatic and operational management. The aim is to assist health professionals with screening, diagnosis, and treatment of people with sexually transmitted enteric infections and their sexual partners, in addition to supporting strategies for their surveillance, prevention, and control. The incidence of anorectal sexually transmitted infections has increased over the last years, mainly due to the increase in the practice of unprotected receptive anal sexual intercourse.

[Brazilian Protocol for Sexually Transmitted Infections 2020: sexually transmitted enteric infections]

The topic of sexually transmitted enteric infections is one of the chapters of the Clinical Protocol and Therapeutic Guidelines for Comprehensive Care for People with Sexually Transmitted Infections, published by the Brazilian Ministry of Health in 2020. The document was developed based on scientific evidence and validated in discussions with specialists. This article presents epidemiological and clinical aspects related to these infections, as well as guidance for service managers on their programmatic and operational management. The aim is to assist health professionals with screening, diagnosis and treatment of people with sexually transmitted enteric infections and their sexual partners, in addition to supporting strategies for their surveillance, prevention and control.

Sexual Transmission of Intestinal Parasites and Other Enteric Pathogens among Men Who Have Sex with Men Presenting Gastrointestinal Symptoms in an STI Unit in Barcelona, Spain: A Cross-Sectional Study

Sexually transmitted infections (STIs) are a major problem worldwide. In addition, the spectrum of STIs is now expanding, including parasitic, bacterial, and viral infections. The study retrospectively describes the presence of enteric pathogens among 73 patients with gastrointestinal symptoms of enteritis and proctocolitis attending to an STI unit in Barcelona, Spain, between 2015 and 2016. Only patients investigated for intestinal parasitic infections were included in the study. Different diagnostic procedures were established for the detection of parasites, bacterial enteropathogens, and other STI agents. Entamoeba histolytica was the most prevalent pathogen in our cohort (20.5%), especially among individuals with proctocolitis. Contrarily, Giardia intestinalis was detected in 11.0% of patients, only associated with enteritis cases. Polymicrobial infections were common in our study (45.2%). Of note, 55.6% of shigellosis cases were coinfected with E. histolytica. The investigation highlights the importance of including parasites as differential gastrointestinal diagnosis, disregarding travel history, particularly among risk populations.

Outbreak of intestinal amoebiasis among men who have sex with men, Barcelona (Spain), October 2016 and January 2017

Entamoeba histolytica has been recently recognised as an emerging sexually transmissible pathogen in men who have sex with men (MSM), causing sporadic outbreaks in countries where it is not endemic. Here we report two closed clusters of invasive amoebiasis occurring in Barcelona, Spain, in October 2016 (four cases) and in January 2017 (four cases).

Dientamoeba fragilis, the Neglected Trichomonad of the Human Bowel

Dientamoeba fragilis is a protozoan parasite of the human bowel, commonly reported throughout the world in association with gastrointestinal symptoms. Despite its initial discovery over 100 years ago, arguably, we know less about this peculiar organism than any other pathogenic or potentially pathogenic protozoan that infects humans. The details of its life cycle and mode of transmission are not completely known, and its potential as a human pathogen is debated within the scientific community. Recently, several major advances have been made with respect to this organism's life cycle and molecular biology. While many questions remain unanswered, these and other recent advances have given rise to some intriguing new leads, which will pave the way for future research. This review encompasses a large body of knowledge generated on various aspects of D. fragilis over the last century, together with an update on the most recent developments. This includes an update on the latest diagnostic techniques and treatments, the clinical aspects of dientamoebiasis, the development of an animal model, the description of a D. fragilis cyst stage, and the sequencing of the first D. fragilis transcriptome.

Dientamoeba fragilis, One of the Neglected Intestinal Protozoa

Dientamoeba fragilis is a single-celled protozoan, closely related to the trichomonads. Reported worldwide as causing human gastrointestinal symptoms, D. fragilis is very common and is second only to Blastocystis spp. Dientamoebiasis equals or exceeds the incidence of giardiasis. This minireview includes diagnostic options, clinical relevance, therapy, an animal model, the confirmed cyst stage, and sequencing data. The development of a rodent model, fulfilling Koch's postulates, and the confirmation of a cyst stage have clarified transmission routes, including fecal-oral transmission. The prevalence of D. fragilis varies between 0% to over 82%; results depend on the geographic location, group studied, and diagnostic methods used.

Are enteric infections sexually transmitted in British Columbia?

BACKGROUND

Enteric infections may on occasion be sexually transmitted, particularly among people who engage in oral-anal sexual contact. Although outbreaks of enteric infections have been reported among men who have sex with men (MSM) in British Columbia (BC), the epidemiology of sexually transmitted enteric infections has never been assessed.

OBJECTIVE

To describe the epidemiology of enteric infections in BC to determine if sexual transmission may be occurring.

METHODS

A descriptive analysis was conducted of all reported cases of shigellosis, amebiasis and giardiasis in BC for the period 2003-2012.

RESULTS

For shigellosis and amebiasis, there was a high male-to-female ratio and a higher rate of infection in males aged 20-59 years as compared to all other age-sex groups. Additionally, for shigellosis, adult males were significantly more likely than females to acquire disease locally (RR 1.9; CI 1.7--.4).

CONCLUSION

Analysis suggests that sexual transmission of enteric infections, particularly shigellosis and amebiasis, may be occurring in MSM in BC. Further studies are indicated.

Sexual transmission of giardiasis: a neglected route of spread?

Sexually transmitted infections (STIs) are often discussed in the context of syphilis, gonorrhea, herpes, chlamydiasis and AIDS. However, since the past 30 years of the last century, epidemiology and natural history studies have led to improved understanding of giardiasis as a STI, as a result of oral-anal sexual contact. Studies suggest that Giardia is an increasingly recognized infection that may be underdiagnosed under the STI context. Health care providers should maintain a high index of suspicion for Giardia, obtain suitable diagnostic tests to identify and screen those at high risk for this infection, institute appropriate therapy, counsel patients regarding treatment compliance, follow-up, encourage partner notification and teach strategies for preventing the transmission of this disease, including the discussion of the risk of enteric infections after oral-anal sexual contact. We summarize some data concerning the research and clinical literature on Giardia infection as a STI and identify the specific recommendations for control of giardiasis as STI that available evidence indicates can reduce its transmission.

Seroprevalence of Entamoeba histolytica infection among Chinese men who have sex with men

Background

Men who have sex with men (MSM) were found to be one of the high-risk populations for Entamoeba histolytica (E. histolytica) infection. Accompanied by the prevalence of human immunodeficiency virus (HIV) among MSM, invasive amebiasis caused by E. histolytica has been paid attention to as an opportunistic parasitic infection. However, the status of E. histolytica infection among MSM has been barely studied in mainland China.

Methods

Seroprevalance of E. histolytica was determined using an enzyme-linked immunosorbent assay based on a cross-sectional study conducted in Beijing and Tianjin, China. Factors potentially associated with E. histolytica infection were identified by logistic regression analysis.

Results

A total of 602 MSM were included in the study and the laboratory data on serostatus of E. histolytica were available for 599 of them (99.5%). 246 (41.1%) and 51 (8.5%) of the study participants were E. histolytica seropositive and HIV seropositive, respectively. Univariate analyses suggested preferred anal sex behaviors were associated with E. histolytica seropositivity. In multivariate logistic regression analysis, “only has receptive anal sex” (OR: 2.03; 95% CI: 1.22 3.37), “majority receptive anal sex” (OR: 1.83; 95% CI: 1.13, 2.95), and “sadomasochistic behavior (SM)” (OR: 2.30; 95% CI: 1.04, 5.13) were found to be significantly associated with E. histolytica infection.

Conclusions

High seroprevalence of E. histolytica infection was observed among MSM from Beijing and Tianjin, China. Receptive anal sex behavior and SM were identified as potential predictors. Therefore, E. histolytica and HIV co-infection needs to be concerned among MSM due to their sharing the common risk behaviors.

Entamoeba histolytica (E. histolytica) is a very common human gastrointestinal parasitic disease which affects 50 million people worldwide. Men who have sex with men (MSM) have already been found to be one of the high-risk populations with E. histolytica infection. Previous studies have reported an increased risk for E. histolytica infection and invasive amebiasis in HIV seropositive MSM. This pilot study aimed to investigate the serology of E. histolytica among MSM from mainland China. High prevalence of E. histolytica infection (41.1%, 246/599) was observed among the study population, receptive anal sex behavior and sadomasochistic behavior were found to be associated with the E. histolytica serostatus. Although HIV infection was not found to be associated with E. histolytica infection in this pilot study, studies from other countries had reported increased risks for E. histolytica infection and invasive amebiasis among HIV-positive MSM. Our findings suggest E. histolytica infection control needs to be concerned with respect to the increasing HIV prevalence among Chinese MSM population.

Entamoeba histolytica infection in men who have sex with men

Entamoeba histolytica infection (amoebiasis) is the second leading cause of death from parasitic diseases. Epidemiological studies from developed countries have reported an increasing prevalence of amoebiasis and of invasive infections, such as amoebic colitis, among men who have sex with men (MSM) who engage in oral-anal sex. Although most infections with E histolytica are asymptomatic, clinical manifestations of invasive amoebiasis mainly include amoebic colitis and amoebic liver abscess, which are associated with substantial morbidity and medical cost. Laboratory diagnosis of amoebiasis should be based on detection of E histolytica by use of tests with high sensitivity and specificity, such as specific amoebic-antigen or PCR-based assays. Microscopy used in routine clinical laboratories is not sensitive or specific enough for detection of E histolytica. Metronidazole or tinidazole remains the mainstay of treatment for invasive amoebiasis, followed by treatment with luminal agents to prevent relapse and transmission of E histolytica to sexual partners or close contacts.

Advances in sexually transmitted infections of the gastrointestinal tract

The gastrointestinal mucosa is a target of many sexually transmitted infections, and major advances have increased our understanding of the consequences of such infections within the gastrointestinal system. HIV-1 is associated with a marked loss of mucosal CD4(+) T cells that express CC-chemokine receptor 5. This process seems to be more rapid and more severe in mucosa-associated lymphoid tissue than in the peripheral blood. Mechanistic insights into the underlying cause of acute and chronic gastrointestinal damage with HIV infection-microbial translocation, defects in intestinal epithelial barrier function and activation of a systemic immune response-have also been achieved. Increased understanding of the pathogenesis of mucosal HIV-1 infection may identify therapeutic targets to restore immunological function and the integrity of the intestinal mucosal epithelial barrier. The increasing prevalence of lymphogranuloma venereum in Europe, mostly in HIV-positive men who have sex with men, suggests a change in the epidemiology of what was previously considered to be a 'tropical' disease. The increasing incidence of acute HCV infection transmitted via sexual contact has also been fueled by high-risk sexual behaviors among men who have sex with men, many of whom are also HIV-positive. The first part of this Review discusses the pathogenesis and gastrointestinal complications of HIV infection, and the second part summarizes advances in our understanding of other sexually transmitted infections of the gastrointestinal system.

Sexual transmission of intestinal parasites in men who have sex with men

Direct oral-anal sexual contact is a common practice among men who have sex with men (MSM) and is implicated in the transmission of various enteric pathogens including intestinal parasites. The present study reviewed data on the sexual transmission of intestinal parasites among MSM, and highlighted advances in the diagnosis of such infections. The emergence and spread of intestinal parasites is of public health concern particularly in the homosexual community. Intestinal parasitic infection should be considered in the differential diagnosis of gastrointestinal disease in this population. Combination of traditional diagnostic procedures with implementation of testing based on novel molecular methods in the accurate identification of intestinal parasites is important so that early intervention and control of infection is facilitated.

Entamoeba histolytica/Entamoeba dispar infections in human immunodeficiency virus-infected patients in the United States

We describe the incidence of and laboratory and clinical characteristics associated with Entamoeba histolytica/Entamoeba dispar infection diagnosed in human immunodeficiency virus (HIV)-infected persons enrolled in the Adult and Adolescent Spectrum of HIV Disease Project. From 1 January 1990 to 1 January 1998 (82, 518 person-years of follow-up), 111 patients (98% men) were diagnosed with E. histolytica/E. dispar infection. Among HIV-infected patients in the United States, the incidence of diagnosed E. histolytica disease is low (13.5 cases per 10,000 person-years [95% confidence interval, 7.7-22.2], with diagnosis most common in those patients exposed to HIV through male-male sex.

Factors associated with the detection of Entamoeba histolytica in homosexual men

In a study of bowel parasites in 128 Australian homosexual men attending a sexually transmitted diseases (STD) clinic, Entamoeba histolytica was detected in 37%, Giardia intestinalis in 3% and at least one protozoan in 81% of the group. There was no evidence of pathogenicity of E. histolytica, nor was there any association between the detection of E. histolytica and sexual practices, gastrointestinal symptoms, proctitis, human immunodeficiency virus antibody result or T-cell subset values. However it was noted that those subjects with an elevated IgM greater than 4 g/l were more likely to harbour E. histolytica trophozoites than those with a level below 4 g/l (OR 6.54, 95% CI 1.3-32.8). Travel to South-East Asia, India, China, Africa, South America or the Pacific islands in the previous 3 years emerged also as an independent factor (OR 2.70, 95% CI 1.12-6.53) associated with detection of E. histolytica.

Coincidence of deficient delayed hypersensitivity and intestinal protozoa in homosexual men

Stool samples of 134 subjectively and apparently healthy male homosexual volunteers were studied, and in 86 men (64.2%) 190 parasite infestations, up to 6 per host, were identified. The most frequent species were Endolimax nana (40), Entamoeba coli (38), Entamoeba histolytica (34), Entamoeba hartmanni (32), and Iodamoeba bütschlii (22); Cryptosporidium was not found. All 11 isolates of Entamoeba histolytica analysed belonged to a noninvasive zymodeme: 10 were of zymodeme I and I of zymodeme III. In 172 healthy control adults 6 parasite infestations were found. In the homosexual men, a negative tuberculin test was more frequent in the presence than in the absence of parasites. Entamoeba histolytica (p = 0.005) Entamoeba coli (p = 0.013) and Iodamoeba bütschlii (p = 0.004) were associated with the anergy.

Prevalence of enteric parasites in homosexual patients attending an outpatient clinic

A total of 372 pooled stool specimens from 274 homosexual men with diarrhea were submitted for parasitologic examination over a 2.5-year period. Each two-vial pooled specimen set contained portions of stool from 3 consecutive days in Formalin and polyvinyl alcohol. Of the 274 patients, 133 (48.5%) harbored one or more intestinal protozoa, with 161 (43.3%) of the 372 specimens submitted being positive for one or more organisms. The parasites identified included Entamoeba histolytica (71 patients), Giardia lamblia (22 patients), Endolimax nana (106 patients), Entamoeba coli (39 patients), Entamoeba hartmanni (25 patients), Dientamoeba fragilis (3 patients), Iodamoeba bütschlii (2 patients), and Chilomastix mesnili (2 patients). Cryptosporidium sp. (2 patients) and Isospora belli (1 patient) were also detected. Results of this study support the experience of other workers regarding high rates of infection with intestinal parasites in the homosexual population and also indicate that symptomatic individuals belonging to this acquired immunodeficiency syndrome risk group be screened for both common and uncommon intestinal pathogens.

Parasitic infections in asymptomatic homosexual men: cost-effective screening

The purpose of this study was to develop a cost-effective strategy for screening for enteric protozoan infections in homosexual men without gastrointestinal symptoms suggesting infection. One hundred and one homosexual men in Portland, Oregon, each submitted at least one unpurged stool sample; 91% submitted three samples each. Of these, 27% had Entamoeba histolytica, 61% had nonpathogenic protozoa with or without E. histolytica, 36% had a nonpathogen alone, and 3% had Giardia lamblia. Protozoan infection was highly associated with the practice of anilingus (p less than 0.005). Infection with E. histolytica correlated significantly with the presence of nonpathogenic protozoa (p less than 0.005). The following screening strategy was judged to be the most cost-effective: examine one sample first; if E. histolytica is found or if the sample is negative, no further investigation is required; if a nonpathogen is found, one additional sample should be obtained. This strategy had a sensitivity for E. histolytica of 85% and a cost of $136 per case detected.