Studies on Polyparasitism: Helminth Infections in Scottish Sheep and Laboratory Rodents

A study of the nature and abundance of parasitic helminth communities of sheep in Scotland (Part 1), and complementary experimental investigations of concurrent helminth infections in rats (Part 2) are described in this dissertation. In Part 1, a brief discussion on the life histories of common parasites of sheep in temperate climates is presented followed by a review of publications on various aspects of helminth infections of Scottish sheep. The effects of gastrointestinal helminth infections on sheep productivity are also considered, and the rough cost of such infections to the meat industry in Scotland is estimated. The parasite fauna of Scottish sheep was investigated in an 18 month survey based at the Glasgow abattoir. Most sheep (N =511) were of Lowland origin, and parasite status was assessed by identifying and counting helminth eggs and protozoan oocysts in the faeces. The diversity and abundance of the helminth community of sheep in Scotland was found to have changed little over the last 70 years. Strongylid nematodes were found to be most common, and Trichuris ovis (Nematoda), Strongyloides papillosus (Nematoda) and Capillaria longipes (Nematoda) were also found to occur frequently. Eggs of Fasciola hepatica (Digenea) and of Moniezia expansa (Cestoda) were detected in slightly less than 10% of samples. Oocysts of the protozoon, Eimeria sp. were discovered in about a fifth of all samples. Host sex was not found to have any effect on prevalence or egg output of any of the parasite species investigated but, with the exception of sheep infected with F. hepatica, young sheep were found to harbour the majority of the infections. The prevalence of most parasite species, and the egg counts of strongylid nematodes and of T. ovis, were shown to conform to a distinct seasonal pattern, being high in July and October and low in January and April. Increased exposure to the infective stages of the various helminth species in late spring and summer may have been a consequence of the elevated helminth egg output of the peri-parturient ewe in spring. Additionally, climatic conditions for the development and transmission of the infective stages of these parasite species may be optimal in spring and summer. Associations between high egg counts of the strongylids, T. ovis and S. papillosus. and between the presence of strongylids and high T. ovis and S. papillosus egg counts, were detected by stepwise multiple regression analysis and by logistic regression analysis, respectively. Seasonal effects were, again, thought to be partly responsible for these observations since temperature and rainfall were found to explain a considerable proportion of the variation in helminth egg counts. Despite this, when season, source and age variables were removed, a positive, though weak, relationship between strongylid and T. ovis egg count intensities was discovered in sheep from certain batches. It is suggested that behavioural, physiological and immunological processes may also determine this particular relationship. In Part 2, a review of the literature on experimental investigations of concurrent parasitic infections in mammalian hosts concentrated specifically on antagonistic and synergistic interactions between parasite species and the consequences of effects on the host. In the experimental studies described, the relationship between Hymenolepis diminuta (Cestoda) and F. hepatica in rats was examined. The possibility of interactions between the helminth species was investigated. Both mature and immature F. hepatica infections in rats were found to confer no resistance to oral challenge with H. diminuta cysticercoids. In fact, H. diminuta survival was shown to be slightly enhanced by prior patent infection with F. hepatica, which may have resulted from some degree of immunosuppression associated with the concurrent F. hepatica infection, or from the increase in bile glucose symptomatic of patent F. hepatica infection in rats. The extensive intestinal mast cell response of F. hepatica-infected rats around day 35 p.i., may have been responsible for the slightly poorer growth of H. diminuta when administered at this time. Rats with mature H. diminuta infections offered no resistance to oral challenge with F. hepatica metacercariae. Density-dependent effects on F. hepatica growth and on H. diminuta fecundity were demonstrated. Intraspecific competition for a limiting resource, or increased stimulation of the immune system, both as a consequence of the increased worm burden, may explain these observations. (Abstract shortened by ProQuest.)

Recent epidemiology of sexually transmissible enteric infections in men who have sex with men.

PURPOSE OF REVIEW: Sexual transmission of enteric pathogens in men who have sex with men (MSM) has been described since the 1970s. Recently, an increasing number of enteric infection outbreaks have been reported in MSM. This article summarizes recent outbreaks and discusses the key issues for prevention and control. RECENT FINDINGS: Sexually transmissible enteric infections (STEIs) can spread rapidly and internationally within highly connected MSM populations and are often associated with antimicrobial resistance (AMR). The infections often cluster in high-risk groups of HIV-positive MSM who are more likely to engage in diverse sexual practices and chemsex, and to have multiple other sexually transmitted infections (STIs). SUMMARY: The roles of asymptomatic and/or persistent infection and other contextual factors in STEI transmission are not well described. STEI-associated AMR is increasing and has potential to spread rapidly in MSM, warranting further public health attention. A better understanding of the factors associated with sexual transmission will enable the development of more effective control measures. A holistic approach that promotes health and wellbeing as well as infection prevention and management is needed

Oropharyngeal Neisseria gonorrhoeae infections: should women be routinely tested?

Oropharyngeal infection with Neisseria gonorrhoeae is important: it is harder to treat than anogenital infection and the oropharynx provides a niche for the development of antimicrobial resistance. Additionally, since oropharyngeal N gonorrhoeae infections are usually asymptomatic, they can easily remain undetected, providing a reservoir of infection that facilitates onward transmission. Emerging evidence suggests that in addition to oral sex, oropharyngeal infection might be transmitted through kissing

Places and people: the perceptions of men who have sex with men concerning STI testing: a qualitative study.

OBJECTIVES: To explore the experiences and views of men who have sex with men (MSM) on attending clinical sexual health services and their preferences regarding service characteristics in the context of the disproportionate burden of STIs experienced by this group. The wider study aim was to develop a risk assessment tool for use in sexual health clinics. METHODS: Qualitative study comprising eight focus group discussions with 61 MSM in four English cities. Topics included: experience of attending sexual health services, perceptions of norms of attendance among MSM, knowledge of, and attitudes towards, STIs and views on 'being researched.' Discussions were audio-recorded and transcribed and a thematic data analysis conducted. RESULTS: Attending sexual health services for STI testing was described as embarrassing by some and some clinic procedures were thought to compromise confidentiality. Young men seeking STI testing were particularly sensitive to feelings of awkwardness and self-consciousness. Black and ethnic minority men were concerned about being exposed in their communities. The personal qualities of staff were seen as key features of sexual health services. Participants wanted staff to be friendly, professional, discreet, knowledgeable and non-judgemental. CONCLUSIONS: A range of opinion on the type of STI service men preferred was expressed with some favouring generic sexual and reproductive health clinics and others favouring specialist community-based services. There was consensus on the qualities they would like to see in healthcare staff. The knowledge, conduct and demeanour of staff could exacerbate or ameliorate unease associated with attending for STI testing

The Acceptability and Feasibility of Implementing a Bio-Behavioral Enhanced Surveillance Tool for Sexually Transmitted Infections in England: Mixed-Methods Study.

BACKGROUND: Sexually transmitted infection (STI) surveillance is vital for tracking the scale and pattern of epidemics; however, it often lacks data on the underlying drivers of STIs. OBJECTIVE: This study aimed to assess the acceptability and feasibility of implementing a bio-behavioral enhanced surveillance tool, comprising a self-administered Web-based survey among sexual health clinic attendees, as well as linking this to their electronic health records (EHR) held in England's national STI surveillance system. METHODS: Staff from 19 purposively selected sexual health clinics across England and men who have sex with men and black Caribbeans, because of high STI burden among these groups, were interviewed to assess the acceptability of the proposed bio-behavioral enhanced surveillance tool. Subsequently, sexual health clinic staff invited all attendees to complete a Web-based survey on drivers of STI risk using a study tablet or participants' own digital device. They recorded the number of attendees invited and participants' clinic numbers, which were used to link survey data to the EHR. Participants' online consent was obtained, separately for survey participation and linkage. In postimplementation phase, sexual health clinic staff were reinterviewed to assess the feasibility of implementing the bio-behavioral enhanced surveillance tool. Acceptability and feasibility of implementing the bio-behavioral enhanced surveillance tool were assessed by analyzing these qualitative and quantitative data. RESULTS: Prior to implementation of the bio-behavioral enhanced surveillance tool, sexual health clinic staff and attendees emphasized the importance of free internet/Wi-Fi access, confidentiality, and anonymity for increasing the acceptability of the bio-behavioral enhanced surveillance tool among attendees. Implementation of the bio-behavioral enhanced surveillance tool across sexual health clinics varied considerably and was influenced by sexual health clinics' culture of prioritization of research and innovation and availability of resources for implementing the surveys. Of the 7367 attendees invited, 85.28% (6283) agreed to participate. Of these, 72.97% (4585/6283) consented to participate in the survey, and 70.62% (4437/6283) were eligible and completed it. Of these, 91.19% (4046/4437) consented to EHR linkage, which did not differ by age or gender but was higher among gay/bisexual men than heterosexual men (95.50%, 722/756 vs 88.31%, 1073/1215; P<.003) and lower among black Caribbeans than white participants (87.25%, 568/651 vs 93.89%, 2181/2323; P<.002). Linkage was achieved for 88.88% (3596/4046) of consenting participants. CONCLUSIONS: Implementing a bio-behavioral enhanced surveillance tool in sexual health clinics was feasible and acceptable to staff and groups at STI risk; however, ensuring participants' confidentiality and anonymity and availability of resources is vital. Bio-behavioral enhanced surveillance tools could enable timely collection of detailed behavioral data for effective commissioning of sexual health services

A qualitative study of attitudes towards, typologies, and drivers of concurrent partnerships among people of black Caribbean ethnicity in England and their implications for STI prevention.

BACKGROUND: Partner concurrency, (having sexual partnerships overlapping in time), especially when condoms are not used, can facilitate sexually transmitted infections (STI) transmission. In Britain, STI diagnoses rates and the reporting of concurrency are higher among black Caribbeans than other ethnic groups. We explored attitudes towards, drivers, characteristics, and contexts of concurrent partnerships, and their implications for STI risk among black Caribbeans in England. METHODS: Purposive sampling, by sex and age-groups, was used to recruit participants (overall n = 59) from five sexual health clinics and community settings in London and Birmingham, England. Audio-recorded four focus group discussions (n = 28 participants), and in-depth interviews (n = 31) were conducted (June 2014-December 2015). Transcribed data were thematically analysed using Framework Analysis. RESULTS: 'Main plus' and 'non-main' concurrency were identified in this population. Main plus concurrency involves an individual having a main partner with whom s/he has a "relationship" with, and the individual and/or their partner secretly or explicitly have other non-main partners. In contrast, non-main concurrency entails having multiple, non-committed partners overlapping in time, where concurrency is usually taken as a given, making disclosure to partners irrelevant. While main partnerships were usually long-term, non-main partnerships ranged in duration from a single event through to encounters lasting several months/years. Condomless sex was common with ex/long-term/married/cohabiting partners; whereas condoms were typically used with non-main partners. However, condom use declined with partnership duration and familiarity with partners. Awareness of partners' concurrency facilitated condom use, STI-testing, and partner notification. While unresolved feelings, or sharing children with ex-partners, usually facilitated main plus concurrency; non-main concurrency was common among young, and single people. Gender norms, notions of masculinity, and sexual desires influenced concurrency. Black Caribbean popular music, social media, peer pressure, and relationship norms among black Caribbeans were also perceived to encourage concurrency, especially among men and young people. CONCLUSIONS: Concurrency among black Caribbeans is shaped by a complex interaction between emotional/psychological, interpersonal, sociocultural, and structural factors. Concurrency type, its duration, and awareness influence sexual health choices, and thus STI risk in this population. Collecting these data during clinic consultations could facilitate offering partner notification methods tailored to concurrency type. Gender- and age-specific, culturally-sensitive interventions addressing STI risks associated with concurrency are needed

Neisseria gonorrhoeae molecular typing for understanding sexual networks and antimicrobial resistance transmission: A systematic review.

OBJECTIVES: Neisseria gonorrhoeae (NG) is a significant global public health concern due to rising diagnoses rates and antimicrobial resistance. Molecular combined with epidemiological data have been used to understand the distribution and spread of NG, as well as relationships between cases in sexual networks, but the public health value gained from these studies is unclear. We conducted a systematic review to examine how molecular epidemiological studies have informed understanding of sexual networks and NG transmission, and subsequent public health interventions. METHODS: Five research databases were systematically searched up to 31st March 2017 for studies that used sequence-based DNA typing methods, including whole genome sequencing, and linked molecular data to patient-level epidemiological data. Data were extracted and summarised to identify common themes. RESULTS: Of the 49 studies included, 82% used NG Multi-antigen Sequence Typing. Gender and sexual orientation were commonly used to characterise sexual networks that were inferred using molecular clusters; clusters predominantly of one patient group often contained a small number of isolates from other patient groups. Suggested public health applications included using these data to target interventions at specific populations, confirm outbreaks, and inform partner management, but these were mainly untested. CONCLUSIONS: Combining molecular and epidemiological data has provided insight into sexual mixing patterns, and dissemination of NG, but few studies have applied these findings to design or evaluate public health interventions. Future studies should focus on the application of molecular epidemiology in public health practice to provide evidence for how to prevent and control NG

Gonorrhoea: tackling the global epidemic in the era of rising antimicrobial resistance.

This Special Issue of Sexual Health aims to collate the latest evidence base focussed on understanding the current epidemic and transmission of gonorrhoea, choice of treatment, molecular epidemiology application, concerns about antimicrobial resistance and alternative prevention and control for gonorrhoea