Gerard J. B. Sonder

Sexually transmitted infections: challenges ahead

WHO estimated that nearly 1 million people become infected every day with any of four curable sexually transmitted infections (STIs): chlamydia, gonorrhoea, syphilis, and trichomoniasis. Despite their high global incidence, STIs remain a neglected area of research. In this Commission, we have prioritised five areas that represent particular challenges in STI treatment and control. Chlamydia remains the most commonly diagnosed bacterial STI in high-income countries despite widespread testing recommendations, sensitive and specific non-invasive testing techniques, and cheap effective therapy. We discuss the challenges for chlamydia control and evidence to support a shift from the current focus on infection-based screening to improved management of diagnosed cases and of chlamydial morbidity, such as pelvic inflammatory disease. The emergence and spread of antimicrobial resistance in Neisseria gonorrhoeae is globally recognised. We review current and potential future control and treatment strategies, with a focus on novel antimicrobials. Bacterial vaginosis is the most common vaginal disorder in women, but current treatments are associated with frequent recurrence. Recurrence after treatment might relate to evidence that suggests sexual transmission is integral to the pathogenesis of bacterial vaginosis, which has substantial implications for the development of effective management approaches. STIs disproportionately affect low-income and middle-income countries. We review strategies for case management, focusing on point-of-care tests that hold considerable potential for improving STI control. Lastly, STIs in men who have sex with men have increased since the late 1990s. We discuss the contribution of new biomedical HIV prevention strategies and risk compensation. Overall, this Commission aims to enhance the understanding of some of the key challenges facing the field of STIs, and outlines new approaches to improve the clinical management of STIs and public health.

Mumps outbreak in a highly vaccinated student population, The Netherlands, 2004

In September 2004 a mumps outbreak occurred at an international hotel school in The Netherlands. We investigated this outbreak to identify risk factors for mumps. There were 105 mumps cases (overall mumps attack rate (AR) 12% (95% CI: 10-15%)). The AR for Dutch vaccinated and unvaccinated participants was 12% (95% CI: 10-15%) and 15% (95% CI: 3-42%), respectively. Independent risk factor was mumps contact. Explanations for the relatively high AR among vaccinated participants include primary vaccine failure, waning immunity and incomplete vaccine-induced immunity in the context of high mumps virus exposure in a school party and a crowded boarding school.

Trends in HIV postexposure prophylaxis prescription and compliance after sexual exposure in Amsterdam, 2000-2004

Objective: The objective of this study was to evaluate trends in HIV postexposure prophylaxis (PEP) requests after sexual exposure, compliance, and outcome of follow-up HIV tests. Study Design: The authors conducted a retrospective analysis of all HIV PEP requests after sexual exposure between January 1, 2000, and December 31, 2004, in Amsterdam. Results: In 5 years, there was a very modest increase in PEP requests, of which most (75%) came from men who have sex with men (MSM). Although 70% reported side effects, 85% completed their PEP course. Sexual assault victims less often completed their course (odds ratio [OR] = 0.1; 95% confidence interval [CI] = 0.05–0.4, P = 0.001). People who used HIV PEP more often complied with follow-up tests than people who did not use PEP (OR = 3.5; 95% CI = 1.6–7.9, P = 0.002). One HIV seroconversion was found caused by a later exposure than that for which PEP was given. Conclusions: Despite a widely available PEP program in Amsterdam, the number of PEP requests remained low. Most people completed their PEP course; compliance with follow-up HIV testing was high.

Symptoms of Infectious Diseases in Immunocompromised Travelers: A Prospective Study With Matched Controls

BACKGROUND Immunocompromised travelers to developing countries are thought to have symptomatic infectious diseases more often and longer than non-immunocompromised travelers. Evidence for this is lacking. This study evaluates whether immunocompromised short-term travelers are at increased risk of diseases. METHODS A prospective study was performed between October 2003 and May 2010 among adult travelers using immunosuppressive agents (ISA) and travelers with inflammatory bowel disease (IBD), with their non-immunocompromised travel companions serving as matched controls with comparable exposure to infection. Data on symptoms of infectious diseases were recorded by using a structured diary. RESULTS Among 75 ISA, the incidence of travel-related diarrhea was 0.76 per person-month, and the number of symptomatic days 1.32 per month. For their 75 controls, figures were 0.66 and 1.50, respectively (p > 0.05). Among 71 IBD, the incidence was 1.19, and the number of symptomatic days was 2.48. For their 71 controls, figures were 0.73 and 1.31, respectively (p > 0.05). These differences also existed before travel. ISA had significantly more and longer travel-related signs of skin infection and IBD suffered more and longer from vomiting. As for other symptoms, no significant travel-related differences were found. Only 21% of immunocompromised travelers suffering from diarrhea used their stand-by antibiotics. CONCLUSIONS ISA and IBD did not have symptomatic infectious diseases more often or longer than non-immunocompromised travelers, except for signs of travel-related skin infection among ISA. Routine prescription of stand-by antibiotics for these immunocompromised travelers to areas with good health facilities is probably not more useful than for healthy travelers.

Hepatitis A outbreak among men who have sex with men (MSM) predominantly linked with the EuroPride, the Netherlands, July 2016 to February 2017

Between July 2016 and February 2017, 48 male cases of hepatitis A were notified in the Netherlands. Of these, 17 identified as men who have sex with men (MSM). Ten of the 13 cases for whom sequencing information was available, were infected with a strain linked with the EuroPride that took place in Amsterdam in 2016. This strain is identical to a strain that has been causing a large outbreak among MSM in Taiwan.

Fecal-orally transmitted diseases among travelers are decreasing due to better hygienic standards at travel destination.

OBJECTIVE To evaluate whether changes in attack rates of fecal-orally transmitted diseases among travelers are related to changes in pretravel vaccination practices or better hygienic standards at travel destination. METHODS National surveillance data on all laboratory-confirmed cases of travel-related hepatitis A, shigellosis, and typhoid fever diagnosed in the Netherlands from 1995 to 2006 were matched with the number of Dutch travelers to developing countries to calculate region-specific annual attack rates. Trends in attack rates of non-vaccine-preventable shigellosis were compared with those of vaccine-preventable hepatitis A and typhoid fever. Trends were also compared with three markers for hygienic standards of the local population at travel destinations, drawn from the United Nations Development Programme database: the human development index, the sanitation index, and the water source index. RESULTS Attack rates among Dutch travelers to developing regions declined for hepatitis A, shigellosis, and typhoid fever. Region-specific trends in attack rates of shigellosis resembled trends of hepatitis A and typhoid fever. Declining attack rates of the three fecal-orally transmitted diseases correlated with improvements in socioeconomic, sanitary, and water supply conditions of the local population at travel destination. CONCLUSIONS These findings suggest that improved hygienic standards at travel destination strongly contributed to the overall decline in attack rates of fecal-orally transmitted diseases among visiting travelers.

Declining incidence of imported malaria in the Netherlands, 2000-2007

BackgroundTo describe the epidemiology and trends of imported malaria in the Netherlands from 2000 through 2007.MethodsBased on national surveillance data regarding all reported infections of imported malaria, diagnosed 2000 through 2007, incidence and trends of imported malaria in the Netherlands were estimated. Travellers statistics were used to estimate incidence, and data on malaria chemoprophylaxis prescriptions were used to estimate the number of unprotected travellers.ResultsImportation of malaria to the Netherlands is declining even as more travellers visit malaria-endemic countries. On average, 82% were acquired in sub-Saharan Africa, and 75% were caused by Plasmodium falciparum. The overall incidence in imported falciparum malaria fell from 21.5 to 6.6/10,000 of unprotected travellers. The percentage of unprotected travellers rose from 47% to 52% of all travellers. The incidence of imported falciparum infections is greatest from Middle and West Africa, and decreased from 121.3 to 36.5/10,000 travellers. The import of malaria from this region by immigrants visiting friends and relatives (VFR) decreased from 138 infections in 2000, to 69 infections in 2007.ConclusionThe annual number of imported malaria shows a continuing declining trend, even with an increasing number of travellers visiting malaria endemic countries. VFR import less malaria than previously, and contribute largely to the declining incidence seen. The decline is not readily explained by increased use of chemoprophylaxis and may reflect a reduced risk of infection due to decreasing local malaria transmission as observed in some malaria endemic areas. Nevertheless, the increasing number of unprotected travellers remains worrisome.

Risk of Hepatitis B for Travelers: Is Vaccination for All Travelers Really Necessary?

OBJECTIVES Behavioral studies in travelers suggest that 33% to 76% of all travelers to hepatitis B virus (HBV)-endemic countries are at risk for HBV infection. We study the incidence and risk factors for HBV infection in travelers. METHODS Retrospective analysis of the characteristics and risk factors of all reported acute HBV patients in Amsterdam, the Netherlands, from January 1, 1992, until December 31, 2003. RESULTS The estimated incidence in travelers from Amsterdam to HBV-endemic countries is 4.5/100,000 travelers. Two thirds of these patients were immigrants who lived in Amsterdam and who had visited their friends and relatives in their country of origin. In 12 years, only three Dutch short-term tourists contracted HBV while traveling, all by heterosexual contacts. CONCLUSIONS Dutch tourists who travel to HBV-endemic countries run a very low risk of contracting HBV. Vaccination of short-term Dutch tourists is not necessary. Immigrants run a higher risk irrespective of travel or duration of travel. This group should be advised vaccination.

High HIV incidence among MSM prescribed postexposure prophylaxis, 2000-2009: indications for ongoing sexual risk behaviour

Objective:To determine (trends in) HIV incidence among MSM\ who have recently had postexposure prophylaxis (PEP) prescribed in Amsterdam, compared with MSM participating in the Amsterdam Cohort Studies (ACS). Design and methods:We used data from MSM who were prescribed PEP in Amsterdam between 2000 and 2009, who were HIV-negative at the time of PEP prescription and had follow-up HIV testing 3 and/or 6 months after PEP prescription (n = 395). For comparison, cohort data from MSM participating in the ACS in the same period were used (n = 782). Poisson log-linear regression analyses were performed to model trends in HIV incidence and identify differences in HIV incidence between both cohorts at different time points. Results:Between 2000 and 2009, among MSM who were prescribed PEP, an overall HIV incidence of 6.4 [95% confidence interval (CI) 3.4–11.2] per 100 person-years was found, compared with an HIV incidence of 1.6 (95% CI 1.3–2.1) per 100 person-years among MSM participating in the ACS (P < 0.01). In both cohorts, an increasing trend in HIV incidence over time was observed [incidence rate ratio (IRRpercalendaryear) 1.3 (95% CI 0.9–1.7) and 1.1 (95% CI 1.0–1.2) among MSM prescribed PEP and MSM of the ACS, respectively]. The difference in HIV incidence between both cohorts was most evident in more recent years [IRRPEPversusACS in 2009 4.8 (95% CI 2.0–11.5)]. Conclusion:Particularly in more recent years, MSM recently prescribed PEP had a higher HIV incidence compared with MSM participating in the ACS, indicating ongoing sexual risk behaviour.

What do Dutch MSM think of preexposure prophylaxis to prevent HIV-infection? A cross-sectional study.

Objectives:Although preexposure prophylaxis (PrEP) is not registered in Europe, including the Netherlands, its approval and implementation are expected in the near future. We aimed to gain insight into PrEP awareness and the intention to use PrEP among MSM. Design:Cross-sectional study among 448 HIV-negative participants of the Amsterdam Cohort Study who completed a questionnaire concerning behavior and PrEP between 2012 and 2013. Methods:Characteristics, PrEP awareness, and intention to use PrEP were described and multinomial logistic regression was used to identify determinants of a medium and high intention to use PrEP. Results:PrEP awareness was 54%, but only 13% reported a high intention to use PrEP. High-risk MSM were more likely to have a medium [adjusted odds ratio (aOR): 1.78 (95% confidence interval [CI] 1.07–2.97)] or high [aOR: 3.92 (95% CI 1.68–9.15)] intention to use PrEP than low-risk MSM, as were MSM with higher perceptions of self-efficacy to use PrEP [high intention: aOR: 6.15 (95% CI 2.50–15.09)] and higher perceptions of relief due to PrEP [medium intention: aOR: 2.67 (95% CI 1.32–5.40); high intention: aOR: 14.87 (95% CI 5.98–37.01)] than MSM with lower perceptions. MSM with higher perceptions of shame about using PrEP [medium intention: aOR: 0.35 (95% CI 0.19–0.62); high intention: aOR: 0.22 (95% CI 0.07–0.71)] or with more worries about side-effects were less likely to have a high [aOR: 0.18 (95% CI 0.06–0.54)] or medium [aOR: 0.29 (95% CI 0.12–0.72)] intention to use PrEP. Conclusion:The overall intention to use PrEP was relatively low, but higher among high-risk MSM. If PrEP implementation among high-risk MSM in the Netherlands becomes reality, PrEP awareness should be increased and psychosocial determinants that will influence uptake should be addressed.