Non-Communicable Disease and Healthcare System Developments
Research Highlights: Three Clinically Significant Publications
Editorial note: No EMA CHMP or PRAC meeting output was available as a source document for Week 21. The non-communicable disease section this week draws on three high-impact peer-reviewed publications with immediate relevance to clinical and public health practice.
Type 1 Diabetes Screening in Children: Bavarian Population Study
A large population-based screening study published in JAMA (Winkler et al., 2026) reports the frequency and progression of presymptomatic type 1 diabetes among children in Bavaria, Germany, enrolled between February 2015 and July 2025. Islet autoantibody testing was performed in 220,476 children aged 1.75 to 10.99 years through 716 primary care paediatricians; 590 were identified with early-stage (stage 1 or 2) type 1 diabetes at first screening, yielding an adjusted population prevalence of 0.3% (95% CI 0.28–0.32%). Stage 1 (normoglycaemia with two or more autoantibodies) accounted for 0.23% and stage 2 (dysglycaemia) for 0.06%. Repeat screening in 11,726 children after a median of 3.3 years identified 29 additional cases. Over a median follow-up of 5.7 years, 212 children with an early-stage diagnosis at first screening progressed to clinical (stage 3) diabetes, yielding a five-year progression rate of 36.2% (95% CI 31.2–40.8%) and an annualised rate of 9.6%. Critically, progression rates did not differ significantly between children with and without a first-degree family history of type 1 diabetes (p = 0.54), a finding with direct implications for screening programme design: restricting screening to genetically or familiarly selected populations would exclude the majority of children who would benefit from early identification. With teplizumab now available as a disease-modifying therapy proven to delay progression from stage 2 to stage 3 diabetes, these data provide a quantitative basis for population-level screening as a public health intervention—a model that several EU member states are beginning to evaluate for national implementation.
Azithromycin for Preschool Wheezing: A Futility Trial
A multicentre randomised controlled trial published in The New England Journal of Medicine (Denninghoff et al., 2026) evaluated azithromycin versus placebo in 840 children aged 18 to 59 months presenting to emergency departments with moderate-to-severe acute wheezing. The trial was stopped early for futility following a planned interim analysis by the data and safety monitoring board. Among 521 participants who tested positive for pathogenic bacteria (Streptococcus pneumoniae, Moraxella catarrhalis, or Haemophilus influenzae), symptom scores over five days did not differ between azithromycin and placebo (median ADYC score 9.59 versus 9.72; p = 0.70), nor did they differ in the bacterium-negative cohort (9.30 versus 9.10; p = 0.69). Secondary outcomes—including emergency department length of stay, hospitalisation duration, and return visits within 72 hours—were also comparable between arms. Although azithromycin achieved bacterial clearance in 58.7% of the positive-cohort treated group (versus 11.4% with placebo), clearance did not translate into clinical benefit. These findings have immediate implications for paediatric antibiotic stewardship: a substantial proportion of preschool children with wheezing currently receive macrolide antibiotics in clinical practice across EU health systems, a practice unsupported by this evidence and associated with accelerated macrolide resistance and disruption of the developing gut microbiome. The trial strengthens existing guidance against routine antibiotic prescribing for acute viral-triggered wheezing episodes in young children.
Calcium and Vitamin D Supplementation: No Meaningful Fracture or Fall Prevention
A systematic review and meta-analysis published in the BMJ (Massé et al., 2026) synthesised evidence from 69 randomised controlled trials involving 153,902 adults to assess the effect of calcium, vitamin D, or their combination on fracture and fall outcomes. Participants were predominantly community-dwelling (87%) and not at high fracture risk (73%). For the primary outcome of any fracture, high or moderate certainty evidence found little to no effect: calcium monotherapy (RR 0.91; 95% CI 0.81–1.01; moderate certainty), vitamin D monotherapy (RR 1.00; 95% CI 0.95–1.06; high certainty), and combined supplementation (RR 0.91; 95% CI 0.84–0.99; high certainty). Findings were similarly null or non-meaningful for hip fracture, non-vertebral fracture, vertebral fracture, and fall outcomes. Results were robust across extensive subgroup analyses. This meta-analysis, representing the most comprehensive synthesis to date, consolidates a growing evidence base against routine supplementation as a population-level fracture prevention strategy in community-dwelling adults without demonstrated deficiency. The public health significance lies in the widespread prescription of these supplements in older adult populations across EU health systems, often without a clinical indication, and the resource implications of continuing such practice without evidence of benefit.
Infectious Diseases: Global Perspective
Contact and Direct Transmission
Ebola Disease Caused by Bundibugyo Virus — Democratic Republic of the Congo and Uganda, 2026
The most significant global infectious disease event of Week 21 is an Ebola disease outbreak caused by Bundibugyo virus in the Democratic Republic of the Congo (DRC) and Uganda, declared a Public Health Emergency of International Concern (PHEIC) by WHO on 17 May 2026—the first PHEIC declared in 2026 and the most consequential high-consequence pathogen event since the 2022–2024 mpox PHEIC. On 18 May 2026, Africa CDC additionally declared the event a Public Health Emergency of Continental Security.
As of 21 May 2026, over 650 suspected cases—including 160 deaths among suspected cases—have been reported, with 64 confirmed cases in DRC and two in Uganda. Confirmed cases are concentrated in two DRC provinces: Ituri Province (60 confirmed cases, 4 deaths), primarily in the Mongbwalu and Rwampara health zones, and North Kivu Province (4 confirmed cases, 2 deaths), with cases reported in the provincial capitals of Bunia and Goma. Media have additionally reported a confirmed case in South Kivu Province in a person who had traveled from Tsopo Province, raising the spectre of further geographic expansion. The two Ugandan confirmed cases had documented travel links to DRC, and the first Ugandan patient subsequently died. An American healthcare worker in the affected area tested positive and was transferred to Germany along with six high-risk contacts; one additional contact was transferred to Czechia.
The index case was identified as a nurse who died in a healthcare facility in Bunia (Ituri Province capital), presenting with fever, bleeding, vomiting, and weakness—the classic haemorrhagic presentation of Ebola virus disease. Clusters of community deaths and deaths among healthcare workers in DRC have been reported, consistent with patterns documented in prior Ebola outbreaks where nosocomial amplification plays a critical early role. Over 1,000 contacts were under follow-up in Ituri and over 100 in Uganda as of mid-week reporting.
Bundibugyo virus (species Orthoebolavirus bundibugyoense) is a critically important pathogen dimension of this outbreak. Bundibugyo virus was first identified in 2007 during an outbreak in Bundibugyo district, Uganda (151 cases, 37 deaths; CFR ~24%), and last caused an outbreak in DRC in 2012 (52 cases, 17 deaths; CFR ~33%). The current outbreak’s preliminary genomic analysis shows that circulating sequences are distinct from both 2007 and 2012 outbreaks, suggesting evolutionary divergence rather than re-emergence of a stored strain. Crucially, unlike the species Orthoebolavirus zairense (Zaire ebolavirus), no licensed vaccines or specific antiviral treatments exist for Bundibugyo virus. The rVSV-ZEBOV vaccine (Ervebo) and the Zabdeno/Mvabea prime-boost regimen offer no demonstrated cross-protection against Bundibugyo virus, leaving classical outbreak containment measures—case isolation, contact tracing, infection prevention and control, safe burials, and community engagement—as the only available tools. The absence of medical countermeasures substantially increases the challenge of outbreak control and the risk of sustained amplification in settings characterised by healthcare system fragility and active humanitarian crises.
The epidemiological context is further complicated by ongoing insecurity and humanitarian challenges in Ituri and North Kivu, provinces with documented histories of armed conflict, population displacement, and limited healthcare infrastructure. WHO has explicitly assessed that neighbouring countries sharing land borders with DRC are at high risk for further spread given population mobility and trade and travel networks. ECDC has published a Threat Assessment Brief (21 May 2026) and deployed an ECDC expert to Africa CDC headquarters in Addis Ababa on 19 May via the EU Health Task Force, in collaboration with DG ECHO, DG INTPA, and GOARN. The ECDC assessment characterises the likelihood of infection for people from the EU/EEA living in or travelling to affected areas as low, and the likelihood of infection for EU/EEA residents as very low, noting that the very low probability of importation and limited human-to-human transmission capacity in European settings constrain secondary spread. ECDC explicitly advises against screening of incoming travellers from DRC and Uganda, citing evidence from the 2013–2016 West Africa EVD outbreak that exit screening is more effective than arrival screening for outbreak containment. The situation remains highly dynamic, and ECDC will revise the risk assessment as the outbreak evolves.
Respiratory and Droplet Transmission
Hantavirus Disease Outbreak (MV Hondius Cruise Ship) — South Atlantic, 2026: Update
The Andes hantavirus cluster associated with the Dutch-flagged cruise ship MV Hondius, first reported in Week 19, has reached a stable phase. As of 22 May 2026, the cumulative total remains 11 cases (9 confirmed, 2 probable) with 3 deaths—a case fatality ratio of 27%, consistent with the documented range for Andes virus hantavirus cardiopulmonary syndrome. No new cases or deaths have been reported since the previous update. Following disembarkation of 122 passengers and crew in Tenerife, Canary Islands on 10–11 May 2026 via coordinated EU repatriation flights (Netherlands, Spain, France, Ireland, Greece, and several non-EU countries), the vessel arrived in Rotterdam on 18 May with 27 remaining individuals on board (25 crew and 2 medical professionals). All asymptomatic individuals disembarked and entered quarantine; the ship is undergoing disinfection. Preliminary genome sequencing analysis confirmed a high level of genetic similarity across isolates from confirmed cases, indicating an initial zoonotic spillover event—likely in Argentina, where Andes virus is endemic—followed by limited human-to-human transmission aboard the vessel. The natural reservoir for Andes virus (Oligoryzomys longicaudatus) is absent from Europe, precluding sylvatic transmission cycles. The risk to the EU/EEA general population from this outbreak is assessed as very low.
Avian Influenza A(H9N2) — China: New Human Case
On 15 May 2026, WHO and the Hong Kong Centre for Health Protection reported a new human infection with avian influenza A(H9N2) virus in a child under five years of age from Sichuan Province, China. Symptom onset (fever) occurred on 25 April 2026 and self-resolved without complications. The patient had documented exposure to a live poultry market prior to symptom onset, the characteristic exposure pathway for this subtype. No additional cases were detected among close contacts. Globally, 203 human cases of A(H9N2)—including 2 deaths (CFR 0.98%)—have been reported since 1998 from 11 countries; since 2015, China alone has reported 161 cases including 2 deaths. A(H9N2) typically causes mild upper respiratory illness in humans, and to date no clusters of human-to-human transmission have been documented, nor has the virus demonstrated evidence of acquired capacity for sustained human-to-human spread. The risk to human health in the EU/EEA is considered very low. HPAI H5N1 continues to circulate extensively in poultry and wild bird populations across multiple EU member states, including ongoing events in the Netherlands, Poland, Denmark, Lithuania, Sweden, and Finland as documented in WAHIS follow-up reports published this week, sustaining the background risk environment for avian-to-human spillover.
Vector-Borne Transmission
Chikungunya Virus Disease — French Guiana, France, 2026
An ongoing chikungunya virus outbreak in French Guiana, an overseas territory of France, has intensified to the epidemic phase in the Littoral ouest sector as of 23 April 2026—the highest alert level under French arbovirosis surveillance protocol, corresponding to the activation of level 3 (low-intensity epidemic) of the ORSEC emergency management plan. Since January 2026, 249 confirmed autochthonous cases have been identified (data as of 7 May), with a pronounced acceleration in case incidence in recent weeks: 15 in Week 15, 33 in Week 16, 61 in Week 17, and 40 in Week 18. The Littoral ouest sector, near the border with Suriname, accounts for 198 cases (80%); the Île de Cayenne sector is in the ‘outbreak clusters’ phase, while Maroni and Savanes are in sporadic transmission phases. Suriname, sharing a land border with the affected sector, reported 2,579 cases between January and mid-March 2026. Genomic characterisation identifies the circulating strain as the ECSA genotype, lacking the adaptive E1-A226V mutation that facilitated Aedes albopictus transmission during prior outbreaks, and showing close genetic relationship with recent Cuban and Brazilian sequences. The rainy season in French Guiana (January–July) favours Aedes mosquito proliferation and ongoing transmission. ECDC assesses the likelihood of infection for travellers to French Guiana as low, with the risk of onward transmission in mainland Europe following introduction by a viraemic traveller also characterised as low, though environmental conditions for Aedes activity in southern Europe are becoming progressively more favourable. Travellers should be advised to implement enhanced mosquito bite prevention, and vaccination may be considered according to national guidance.
Infectious Diseases: European Union / European Economic Area
Respiratory and Droplet Transmission
Measles — EU/EEA Multi-Country: Monthly Monitoring Update
The ECDC monthly measles surveillance update for March 2026, published in the Week 21 CDTR with complementary epidemic intelligence surveillance performed on 20 May 2026, documents a continued and intensifying pan-European measles situation. In March 2026, 12 of 30 reporting EU/EEA countries contributed 172 cases; case numbers increased compared with the preceding month, though this may be subject to retrospective revision. The highest case counts in March were reported by Bulgaria (52), Italy (44), Spain (24), France (15), and Germany (11).
Over the most recent 12-month period (1 April 2025–31 March 2026), EU/EEA countries collectively reported 3,607 measles cases, 85.9% laboratory confirmed. Of cases with documented vaccination status (3,029 individuals; 84.0% of all cases), 78.2% were unvaccinated, 10.6% had received one dose of a measles-containing vaccine, and only 9.9% had received two or more doses—a distribution that unambiguously identifies incomplete vaccination as the primary driver of ongoing transmission. Age distribution shows 31.7% of cases in children under five years and 45.1% in individuals aged 15 or above, reflecting both the vulnerability of unvaccinated young children and the accumulation of susceptibles in adult cohorts who were not vaccinated or did not mount durable immunity. Notification rates were highest among infants under one year (90.8 per million), who are too young to receive their first vaccine dose and depend entirely on community immunity for protection. Five measles deaths were reported to ECDC over the 12-month period by France (3), the Netherlands (1), and Romania (1), yielding a case fatality ratio of 0.139% among reported cases—almost certainly an underestimate of true mortality given case ascertainment limitations.
By epidemic intelligence surveillance on 20 May 2026, active outbreaks are confirmed in Bulgaria, France, and Portugal. Spain reports 118 cases through 17 May 2026 (including 10 imported and 25 import-linked); Germany reports 82 cases in weeks 1–21; Latvia reports 49 outbreak-linked confirmed cases; Lithuania 7 cases; Poland 17 cases; Sweden 5 cases. Globally, the measles situation is severe: Mexico has reported 10,945 confirmed cases and 13 deaths in 2026, with Jalisco state (9,847 cases) most affected; the United States reports 1,893 cases and 27 outbreaks through 14 May 2026, 93% outbreak-associated and 92% in unvaccinated individuals; Canada reports 1,018 cases in an ongoing multijurisdictional outbreak; and Bangladesh has reported 57,856 children with measles-like symptoms, including 8,067 confirmed cases and 481 deaths since 15 March 2026. The FIFA World Cup 2026 co-hosting by Canada, Mexico, and the United States—countries all currently in active transmission—elevates the risk of measles importation into EU/EEA countries during the summer travel season.
Respiratory Viruses — EU/EEA: Inter-Seasonal Baseline
All respiratory virus indicators in the EU/EEA remain at baseline or inter-seasonal levels as of Week 20 data. Influenza positivity in primary care was 0.4% (pooled median; IQR 0–0%); influenza was at baseline intensity in 18 countries and low in one, with seven countries reporting no activity, nine sporadic, one local, and one regional. RSV test positivity has returned to baseline inter-seasonal levels in both primary care and hospital settings. SARS-CoV-2 primary care positivity was 2.1% (IQR 0–0%), with hospital positivity at 0.6%. An important surveillance system note: the European Surveillance System (TESSy) is being decommissioned and replaced by EpiPulse Cases. ERVISS data cannot be updated during this transition, and weekly publication will resume on 22 June 2026. Data for subsequent weeks may be delayed or incomplete, and this transition period should be considered when interpreting any apparent changes in EU/EEA respiratory virus trends.
Infectious Diseases: Bulgaria
Surveillance data for Week 21 (18–24 May 2026) are drawn from the NCIPD weekly operational analysis and the ZRZ/NCOZA district-level breakdown. As previously noted in this series, measles in Bulgaria is reported through the ZRZ/NCOZA district system and does not appear in the NCIPD operational analysis; the ZRZ data for Week 21 typically reflect activity one week prior to the NCIPD report. All data are provisional and subject to revision.
Respiratory and Droplet Transmission
Measles
The ZRZ district-level data for Week 21 documents 41 measles cases distributed across five districts: Pleven (18), Vracha (12), Lovech (5), Montana (5), and Sofia-grad (1). This geographic distribution confirms the continued concentration of active transmission in north-central Bulgaria—the Pleven-Vracha-Lovech cluster that emerged in Week 19—while the appearance of Montana cases represents a southward extension of the outbreak’s geographic footprint. The Sofia-grad case adds an element of metropolitan exposure risk. Nationally, the cumulative total through Week 20 is 277 cases since the outbreak’s onset on 19 March 2026, with the Vracha region alone accounting for 150 cases, followed by Pleven (48) and Lovech (18). According to ECDC monthly surveillance data, the majority of Bulgarian cases are in children (189 of 225 with known age), consistent with the pattern of accumulation of susceptibles in unvaccinated birth cohorts. Over 28,000 MMR vaccine doses have been administered in outbreak response, a scale of reactive vaccination that reflects the severity of the immunity gap in affected communities. Bulgaria reported only two measles cases in all of 2025; the 2026 outbreak represents a dramatically different epidemiological trajectory. The outbreak’s concentration in districts with documented low MMR coverage, predominantly affecting unvaccinated children, demands sustained reactive vaccination, active case-based surveillance, and rapid laboratory confirmation of all suspected cases to detect any shifts in geographic or demographic distribution.
Scarlet Fever
Week 21 registered 65 scarlet fever cases, a 28-case increase over Week 20 (+76% week-over-week)—the largest single-week increase in this indicator during 2026. The year-to-date cumulative total of 1,439 cases is 32% below the 2,110 cases recorded in the same period of 2025, confirming that the 2026 season is running substantially below last year’s burden at the population level. The abrupt week-over-week surge from an estimated 37 cases in Week 20 to 65 in Week 21 therefore represents a sharp local fluctuation rather than a change in the season’s overall trajectory. Scarlet fever, caused by Group A Streptococcus pyogenes toxin-producing strains transmitted via the respiratory route, typically peaks during the school term and declines over the summer holidays; the May spike may reflect within-school transmission prior to the end of the academic year. The ZRZ district distribution documents cases across multiple districts, with Sofia-grad (22), Plovdiv (9), and Ruse (10) as the largest contributors. The week-over-week magnitude of this increase justifies monitoring over the following two weeks to determine whether the upward trend persists or resolves with school closure.
Varicella
Varicella registered 594 cases in Week 21, an increase of 18 cases over Week 20 (+3% week-over-week), which falls below the 20% threshold for signal inclusion. The year-to-date cumulative total of 12,820 cases is only 1.7% above the 12,606 cases recorded in the corresponding period of 2025. Overall, the 2026 varicella season remains closely tracking the prior year’s level. The Sofia-grad district continues to account for the largest share of national case volume (166 cases in Week 21), consistent with its large paediatric population.
Fecal-Oral Transmission
Campylobacteriosis
Campylobacteriosis registered 13 confirmed cases in Week 21, unchanged from Week 20 (0% week-over-week change). The year-to-date cumulative total of 228 cases represents a 98% excess over the 115 cases recorded in the same period of 2025. This near-doubling of year-on-year campylobacteriosis burden has been sustained consistently since Week 1 of 2026, making it one of the most epidemiologically prominent trends in the Bulgarian surveillance year. Campylobacter spp. are the most commonly identified bacterial cause of foodborne gastroenteritis in the EU, primarily acquired through undercooked poultry, contaminated water, and contact with animal reservoirs. The persistently elevated incidence in 2026 continues to suggest either a genuine increase in poultry-associated or environmental contamination, improved testing and reporting sensitivity, or both. The ZRZ Week 21 data documents campylobacteriosis cases in Varna (2), Plovdiv (5), Sofia-grad (5), and Stara Zagora (1), with a distribution consistent with broader geographic circulation rather than a single outbreak focus.
Gastroenteritis and Enterocolitis
The week-over-week change in gastroenteritis and enterocolitis was a decline of 17 cases (−9%), falling below the 20% inclusion threshold. However, the year-to-date total of 3,186 cases is 4% above the 3,066 cases in the corresponding 2025 period. Breakdown by confirmation category (83 possible, 86 probable, 8 confirmed) reflects the syndromic and mixed-aetiology nature of this reporting category. The year-over-year excess, while modest, is consistent across the surveillance year and may reflect the same epidemiological pressures driving campylobacteriosis and hepatitis elevations. No action threshold has been formally exceeded, and this signal is noted for situational awareness.
Vector-Borne Transmission
Lyme Borreliosis
Week 21 registered 7 confirmed cases of Lyme borreliosis, a three-case increase over Week 20 (+75% week-over-week). The year-to-date total of 71 cases is 11% below the 80 cases recorded in the corresponding period of 2025. The week-over-week surge is consistent with expected seasonal dynamics: May–June represents the peak questing period for Ixodes ricinus ticks in Bulgaria, and week-over-week increases of this magnitude are typical of the tick season onset. The ZRZ data for Week 21 documents cases in Gabrovo (3) and Shumen-area districts (2 in Kyustendil-coded area per page 1 data), with additional cases in other districts. The modest year-to-date deficit relative to 2025 may reflect inter-annual variation in tick activity or ascertainment rather than a genuine reduction in transmission risk. Lyme borreliosis—caused by Borrelia burgdorferi sensu lato and presenting primarily as erythema migrans in uncomplicated cases, with the risk of disseminated nervous system, cardiac, and joint manifestations if untreated—warrants continued clinical vigilance as tick season intensifies.
Marseille Fever
Four cases of Mediterranean spotted fever (Marseille fever, Rickettsia conorii) were registered in Week 21, consistent with Week 20 (0% week-over-week change). The year-to-date total of 11 cases is 35% below the 17 cases recorded in the same period of 2025. Activity is expected to increase progressively through summer as tick (Rhipicephalus sanguineus) populations expand.
Healthcare-Associated and Environmental Transmission
Legionellosis
Week 21 registered 2 confirmed cases of Legionnaires’ disease, a 2-case increase from 0 cases in Week 20. The year-to-date total of 7 cases is 133% above the 3 cases recorded in the corresponding period of 2025, though the absolute numbers remain small. Legionella pneumophila, primarily transmitted via inhalation of contaminated aerosols from water systems (cooling towers, hot water systems, decorative fountains), causes severe pneumonia with a case fatality ratio of 5–10% in treated community-acquired cases and substantially higher in healthcare-associated infections. The appearance of two confirmed cases in a single week following a zero-case week, combined with the elevated year-to-date figure, merits prompt case-based investigation to identify potential point sources—particularly shared accommodations, healthcare facilities, or hotel water systems—and exclude a common-source cluster.
Contact and Sexual Transmission
Gonorrhea
Week 21 registered 5 confirmed cases of gonorrhea, a two-case increase over Week 20 (+67% week-over-week). The year-to-date total of 97 cases represents a 203% excess over the 32 cases recorded in the same period of 2025—the most extreme sustained proportional year-over-year increase of any monitored infection in Bulgaria’s 2026 surveillance year. This three-fold annual excess has persisted without attenuation since Week 1 and, as documented throughout this report series, constitutes a structural change in the epidemiology of gonorrhea in Bulgaria that has not been formally explained. Neisseria gonorrhoeae is transmitted through sexual contact and frequently causes asymptomatic infection, particularly in women, making routine surveillance systematically likely to underestimate true incidence. The clinical and public health significance is amplified by the global context of emerging extensively drug-resistant gonorrhea: routine surveillance data in Bulgaria do not include antimicrobial susceptibility profiles alongside case notifications, representing a critical gap in an era when treatment failure with cephalosporins has been documented in multiple European countries and WHO has designated gonorrhea as a priority antimicrobial resistance pathogen.
Urogenital Chlamydial Infection
Eight confirmed cases of urogenital chlamydial infection were registered in Week 21, five fewer than in Week 20 (−38% week-over-week). The year-to-date total of 138 cases is 146% above the 56 cases recorded in the same period of 2025—a sustained near-doubling of the prior year’s cumulative burden that has been consistent throughout 2026. As with gonorrhea, this excess almost certainly reflects a combination of genuine transmission increases and improvements in testing and reporting completeness. Chlamydia trachomatis is the most frequently reported sexually transmitted infection in EU/EEA countries, with the highest burden in young adults aged 15–24 years; systematic under-ascertainment due to asymptomatic infection in a large proportion of cases means that surveillance figures represent only a fraction of true incidence. Potential complications of untreated infection—pelvic inflammatory disease, tubal factor infertility, epididymo-orchitis, and neonatal conjunctivitis—carry substantial reproductive health implications.
Syphilis
Week 21 registered 9 confirmed cases of syphilis, five more than Week 20 (+125% week-over-week). The year-to-date total of 151 cases is 11% above the 136 cases in the corresponding period of 2025. The week-over-week surge mirrors a similar spike documented in Week 19 (14 cases) and warrants monitoring to determine whether it reflects a genuine acceleration in transmission or a consolidation of delayed case reports. Congenital syphilis recorded one confirmed case in Week 21, bringing the year-to-date total to 17 cases—42% above the 12 cases in the corresponding period of 2025. Congenital syphilis is an entirely preventable condition contingent on antenatal screening and timely treatment of maternal syphilis; a sustained year-over-year excess in this indicator is a direct measure of antenatal care system performance and warrants specific investigation of the clinical and demographic characteristics of affected cases.
HIV
Six confirmed HIV cases were registered in Week 21, two more than in Week 20. The year-to-date total of 96 cases is 21% below the 122 cases recorded in the corresponding period of 2025—a decline that may reflect improved earlier diagnosis in prior years (reducing the pool of detectable late-presenting infections), or reporting delays. The interpretation of HIV surveillance data in the Bulgarian context is constrained by the high proportion of late-stage diagnoses historically documented in the national programme, which limits the sensitivity of case notification counts as a proxy for current incidence.