Online market research panel members as controls in case-control studies to investigate gastrointestinal disease outbreaks: early experiences and lessons learnt from the UK.

Established methods of recruiting population controls for case-control studies to investigate gastrointestinal disease outbreaks can be time consuming, resulting in delays in identifying the source or vehicle of infection. After an initial evaluation of using online market research panel members as controls in a case-control study to investigate a Salmonella outbreak in 2013, this method was applied in four further studies in the UK between 2014 and 2016. We used data from all five studies and interviews with members of each outbreak control team and market research panel provider to review operational issues, evaluate risk of bias in this approach and consider methods to reduce confounding and bias. The investigators of each outbreak reported likely time and cost savings from using market research controls. There were systematic differences between case and control groups in some studies but no evidence that conclusions on the likely source or vehicle of infection were incorrect. Potential selection biases introduced by using this sampling frame and the low response rate are unclear. Methods that might reduce confounding and some bias should be balanced with concerns for overmatching. Further evaluation of this approach using comparisons with traditional methods and population-based exposure survey data is recommended.

Chemoprophylaxis and vaccination in preventing subsequent cases of meningococcal disease in household contacts of a case of meningococcal disease: a systematic review.

Household contacts of an index case of invasive meningococcal disease (IMD) are at increased risk of acquiring disease. In revising WHO guidance on IMD in sub-Saharan Africa, a systematic review was undertaken to assess the effect of chemoprophylaxis and of vaccination in preventing subsequent cases of IMD in household contacts following an index case. A literature search for systematic reviews identified a single suitable review on chemoprophylaxis in 2004 (three studies meta-analysed). A search for primary research papers published since 2004 on chemoprophylaxis and without a date limit on vaccination was therefore undertaken. There were 2381 studies identified of which two additional studies met the inclusion criteria. The summary risk ratio for chemoprophylaxis vs. no chemoprophylaxis (four studies) in the 30-day period after a case was 0·16 [95% confidence interval (CI) 0·04-0·64, P = 0·008]; the number needed to treat to prevent one subsequent case was 200 (95% CI 111-1000). A single quasi-randomized trial assessed the role of vaccination. The risk ratio for vaccination vs. no vaccination at 30 days was 0·11 (95% CI 0·01-2·07, P = 0·14). The results support the use of chemoprophylaxis to prevent subsequent cases of IMD in household contacts of a case. Conclusions about the use of vaccination could not be drawn.

Sex, drugs and smart phone applications: findings from semistructured interviews with men who have sex with men diagnosed with Shigella flexneri 3a in England and Wales.

OBJECTIVES: To inform control strategies undertaken as part of an outbreak of Shigella flexneri 3a among men who have sex with men (MSM). METHODS: All men aged ≥18 years diagnosed with S flexneri 3a between October 2012 and May 2013 were invited to participate. Semistructured in-depth quantitative interviews were conducted to explore lifestyle and sexual behaviour factors. RESULTS: Of 53 men diagnosed, 42 were interviewed of whom 34 were sexually active MSM. High numbers of sexual partners were reported (median=22) within the previous year; most were casual encounters met through social media networking sites (21/34). 63% (20/32) were HIV-positive and actively sought positive partners for condomless sex. 62% (21/34) of men had used chemsex drugs (mephedrone, crystal methamphetamine and γ-butyrolactone/γ-hydroxybutrate), which facilitate sexually disinhibiting behaviour during sexual encounters. 38% (8/21) reported injecting chemsex drugs. Where reported almost half (12/23) had attended or hosted sex parties. All reported oral-anal contact and fisting was common (16/34). Many had had gonorrhoea (23/34) and chlamydia (17/34). HIV-positive serostatus was associated with both insertive anal intercourse with a casual partner and receptive fisting (adjusted OR=15.0, p=0.01; adjusted OR=18.3, p=0.03) as was the use of web applications that promote and facilitate unprotected sex (adjusted OR=19.8, p=0.02). CONCLUSIONS: HIV-positive MSM infected with S flexneri 3a used social media to meet sexual partners for unprotected sex mainly at sex parties. The potential for the transmission of S flexneri, HIV and other infections is clear. MSM need to be aware of the effect that chemsex drugs have on their health.

Crab meat: a novel vehicle for E. coli O157 identified in an outbreak in South West England, August 2011.

In August 2011, we investigated an outbreak of Escherichia coli O157 in Plymouth, England, utilizing a case-control study and food traceback. Nine cases, eight laboratory-confirmed with E. coli O157 phage type 21/28 verocytotoxin 2 and one epidemiologically linked, had onsets from 30 July 2011 to 15 August 2011. We compared cases (n=8) with controls (n=28) of similar age and sex (median age 61 vs. 55 years, females 75% vs. 61%). Cases were 58 times more likely to have eaten crab (88% vs. 11%; odds ratio 58, 95% confidence interval 4-2700). Eight cases consumed crab sourced from the same supplier who was not registered with the local authority. This outbreak pointed to crab as a possible vehicle of E. coli O157 infection. We ensured the withdrawal of crab meat sourced from unregistered suppliers from food venues by 25 August 2011. We also emphasized the importance of only using registered suppliers to the food venues. Since then no further associated cases have been reported.

Ongoing outbreak of Shigella flexneri serotype 3a in men who have sex with men in England and Wales, data from 2009-2011.

Diagnoses of Shigella flexneri in the United Kingdom (UK) are usually travel-related. However, since 2009, there has been an overall increase in UK-acquired cases. The Health Protection Agency has been investigating a national outbreak of S. flexneri detected in 2011 and which is still ongoing. Cases occurred mostly in men who have sex with men and were of serotype 3a. The investigation aimed at obtaining epidemiological data to inform targeted outbreak management and control.

National outbreak of Salmonella Java phage type 3b variant 9 infection using parallel case-control and case-case study designs, United Kingdom, July to October 2010.

Between July and October 2010, a national outbreak comprising 136 cases of Salmonella Java phage type 3b variant 9 was identified by the Health Protection Agency. Most cases were female. Cases had a median age of 39.5 years and lived in London, the South East and East of England. Parallel case­control and case­case study designs were undertaken to test the generated hypotheses. The case­case study aimed to examine if the infection was associated with eating food items purchased from commercial catering settings, and the reference group comprised non-travel related cases of S. Enteritidis infected during the same time period as the cases. The case­control study was designed to examine if the infection was associated with specific food items purchased from commercial catering settings, and recruited case-nominated controls. However, in response to poor recruitment we adapted our methods to investigate food exposures in the same way. Results of epidemiological investigations are compatible with salad vegetables as the potential source, but no common suppliers of salad were identified and no organisms were isolated from environmental and food samples. Limitations in the case­control study highlight the potential value of using a combination of epidemiological methods to investigate outbreaks.

[The Leiden school]. / L'Ecole de Leiden.

Simultaneous horizontal and cyclovertical surgery gives better results than pure horizontal surgery; not only binocular vision reappears immediately and spontaneously but the accommodative component of the squint disappears as well. The question is to know why simultaneous surgery gives such good results. We think that the reduction of the vertical deviations associated with horizontal strabismus may give an explanation. In our experience, a vertical deviation is often present in accommodative strabismus and can disrupt fusion. The hemiretinal suppression which follows, puts the vergence system into open loop. The accommodative vergence caused by hypermetropia becomes manifest so that the correction needs to be reinforced frequently. In a young child this may impede the emmetropisation process. In addition, the spectacles being associated with strabismus, may be the source of psychological complexes. The fact that the squint is not cured and the deviation reappears without spectacles gives us the right to look for a more adequate remedy. The good results we obtained with simultaneous horizontal and cyclovertical surgery and especially the disappearance of the accommodative element encouraged us to operate accommodative strabismus.

[Photographic screening for amblyopia, strabismus and refraction errors]. / Dépistage photographique de l'amblyopie, du strabisme et des erreurs de réfraction.

The authors present a photographical method to screen infants on the presence of refractive errors and squint. The photoscreener indicates an absence of focusing in one or both eyes and/or a squint. This method can be used in mass-screening of siblings, the evaluation of glasses, the monitoring of the effects of occlusion and the postoperative follow-up of patients.

[Should accommodative strabismus be operated on?]. / Strabismes accommodatifs, peut-on les opérer?

Hypermetropia is probably not the real cause of accommodative squint. The arguments for this view are the absence of binocular vision in more than half and of the presence of a vertical deviation in about one third of cases of accommodative strabismus. Furthermore, after reduction of this vertical deviation by means of simultaneous surgery upon the horizontal and oblique muscles, binocular vision recovers spontaneously, the accommodative component of the squint disappears and visual acuity improves without glasses. Recent neurophysiologic research explains the beneficial effect of simultaneous surgery. According to these investigations there are two systems of accommodation and convergence; a quick phasic one, where accommodation is linked with convergence and a slow tonic one without interaction. The tonic system is responsible for the neutralization of the excess of convergence induced by hyperaccommodation. Tonic vergence depends on fixation disparity which is eliminated by a vertical deviation and restored by the surgical reduction of this vertical deviation. The fact of wearing positive correction produces and consolidates a hypo-accommodation, revealing a latent hypermetropia which could compromise emmetropisation. Furthermore, this correction being associated with squint, is a source of psychological complexes and the cost of an optical treatment is high, considering that spectacles need to be renewed frequently and many times during lifetime. On the other hand, simultaneous surgery removes an important obstacle to fusion and makes the patient independent of spectacles, not only regarding the squint, but also visual acuity.

[The treatment of Duane syndrome by a inversion of the right lateral muscle]. / Le traitement du syndrome de Duane par un renversement des droits verticaux.

The authors describe a new technique to deal with Duane's retraction syndrome. The vertical recti are rotated around their longitudinal axis with saving of the temporal ciliary arteries in order to prevent anterior segment ischemia. The results of 52 patients operated upon are discussed. The technique proved to be successful in the treatment of head posture, esotropia and limitation of abduction.

[Results of simultaneous horizontal and cyclovertical surgery in esotropia]. / Résultats de la chirurgie horizontale et cyclo-verticale simultanée dans les ésotropies.

The authors treat esotropia by simultaneous horizontal and cyclo-vertical surgery. Horizontal surgery consists of recession of both medial rectus muscles and cyclo-vertical surgery of desagittalization of the oblique muscles combined, if necessary, with a weakening of a vertical rectus muscles. Techniques and indications of this surgery are discussed and analysis made of the results of 785 cases treated with 960 operations. According to this analysis the surgical indications are adapted to this procedure.

[New view points on the pathogenesis and treatment of strabismus. 2nd part: Management of strabismus (author's transl)]. / Nouvelles conceptions sur la pathogénie et le traitement du strabisme. 2. partie: Traitement du strabisme. Introduction. Chirurgie primaire. Chirurgie secondaire.

A new method of surgical treatment of strabismus is presented. The desagittalisation of the oblique muscles is the main part of surgery; it is associated to surgery of the horizontal recti muscles and sometimes to surgery of the vertical recti muscles. The surgical procedures are described; the indications are set up for the primary surgery as well as for the secondary surgery which aims at the treatment of under and over corrections.