Non-Communicable Disease and Healthcare System Developments
Cardiovascular Prevention: Two High-Impact Trial Analyses
Two clinically significant publications appeared in major journals this week. The VESALIUS-CV trial, published in JAMA (28 March 2026), examined the effect of the PCSK9 inhibitor evolocumab in a prespecified subgroup of 3,655 high-risk primary prevention patients without known significant atherosclerosis but with diabetes. With a median follow-up of 4.8 years, evolocumab reduced the hazard of a first three-component major adverse cardiovascular event by 31% (HR 0.69; 95% CI 0.52–0.91), with a corresponding 5-year absolute risk reduction of 2.1 percentage points (5.0% versus 7.1%). The four-component composite outcome showed a comparable effect (HR 0.69; 95% CI 0.55–0.86; absolute risk reduction 2.9%). These data extend the evidence base for PCSK9 inhibitor therapy earlier in the disease continuum—before significant atherosclerosis is established—specifically in the diabetic population, and are pertinent to ongoing discussions about primary prevention intensification in high-risk individuals currently not meeting criteria for PCSK9 inhibitor reimbursement in many EU member states.
A concurrent post-hoc analysis of the FINEARTS-HF trial, published in JAMA Cardiology (28 March 2026), characterised the clinical trajectories preceding sudden death in 6,001 patients with heart failure with mildly reduced or preserved ejection fraction (HFmrEF/HFpEF). The analysis found that the six months before sudden death were marked by modest worsening in New York Heart Association class, a clinically meaningful decline in patient-reported health status (approximately 8-point decrease in the KCCQ-TSS), and a gradual rise in NT-proBNP from approximately 1,800 to 2,000 pg/mL. Crucially, however, similar or more pronounced deterioration patterns preceded other modes of death—cardiovascular and non-cardiovascular—which limits the discriminative utility of these signals for sudden death prediction specifically. The finding that many sudden deaths in HFmrEF/HFpEF may not be entirely unexpected, and are preceded by detectable clinical deterioration, has implications for palliative care integration and for discussions of implantable cardioverter-defibrillator candidacy in these populations.
Dengue Vector Control: Landmark Efficacy Evidence from Singapore
Published in the New England Journal of Medicine (11 February 2026), the Project Wolbachia–Singapore cluster-randomised trial provides the strongest evidence to date for the population-level efficacy of Wolbachia-based biological vector control. The trial released male Aedes aegypti mosquitoes infected with the wAlbB strain of Wolbachia pipientis across eight intervention clusters (approximately 393,000 residents), exploiting cytoplasmic incompatibility to suppress wild-type female mosquito populations. At six months of exposure or more, the dengue positivity rate among residents was 6% in intervention clusters versus 21% in control clusters (protective efficacy 71–72%; odds ratio 0.28–0.29). Wild-type adult Aedes aegypti abundance declined from a baseline of 0.18 to 0.041 mosquitoes per trap in intervention areas, compared with a rise to 0.277 in controls. These findings are not immediately applicable to the Bulgarian or broader EU context—where Aedes aegypti is established only in Cyprus and select outermost regions—but are directly relevant to international dengue control strategy, particularly in high-burden tropical settings, and to the development pipeline for biological alternatives to chemical insecticide-based vector control.
Infectious Diseases: Global Perspective
Vector-Borne Transmission
Dengue
Global dengue activity through 23 March 2026 has surpassed 500,000 cases and 100 deaths, with 78 countries and territories reporting cases since January. While this represents a substantial absolute burden, it is lower than the extraordinary volume recorded in the equivalent period of 2025, which was one of the highest-burden years on historical record. The regional distribution reflects divergent trends. In the Americas, approximately 299,210 cases had been reported through epidemiological week 7, a figure 64% below the same period in 2025 and 57% below the five-year average, suggesting a return toward more typical interseasonal activity following the exceptional 2025 epidemic. In Timor-Leste, however, a tenfold increase relative to February 2025 is documented, with 2,105 cases in February 2026 following 1,281 in January. Vietnam accounts for a twofold year-over-year increase (27,365 cases through late February 2026), and Laos reports a 57% increase relative to the same period in 2025. Cambodia has reported 4,338 cases since January—a 211% increase over the 1,392 in the equivalent 2025 period—suggesting genuine epidemic amplification in the Mekong region. China has reported modestly elevated counts in January 2026 (93 cases, 84% above January 2025). Africa reports limited but real transmission in Mali, Mauritania, Senegal, and the Central African Republic (658 cases total). Within the EU/EEA, no autochthonous cases have occurred on the mainland; transmission continues in French outermost regions, particularly Martinique (high-level, fluctuating) and Réunion (a cluster in Saint-Leu driving recent increase). The risk for mainland EU/EEA populations remains linked to the importation of viraemic travellers into areas where competent vectors are established—Aedes albopictus across much of southern and central Europe, and Aedes aegypti in Cyprus.
Chikungunya
Chikungunya virus disease (CHIKVD) continues to affect multiple countries across the Americas, Africa, and Asia in 2026. Through 28 February 2026, 32,758 cases and nine deaths had been reported from 18 countries, with February case counts substantially higher than January (approximately 28,397 versus 4,361). Brazil remains the dominant source in the Americas, with cases reported across all five geographic regions and the 20–29 age group and females disproportionately represented. Bolivia, Cuba, and Mexico are also reporting sustained transmission. Seven countries—Colombia, Cuba, Guatemala, Guyana, Mauritius, Peru, and Saint Lucia—reported CHIKVD cases for the first time in 2026, with Saint Lucia recording its first autochthonous case since 2021. In Africa, transmission is concentrated in East Africa; Mauritius is experiencing an outbreak with an increasing trajectory; and Seychelles authorities report that chikungunya has become more prevalent than other arboviruses on the archipelago—a development directly relevant to EU/EEA travellers given the well-documented importation chain into EU countries. In Europe, all previously reported autochthonous clusters in France and Italy are now closed, and no new EU/EEA mainland cases have been reported to ECDC this week. Chikungunya cases in French Guiana represent the first autochthonous cases there since 2015, and Mayotte has seen increasing case counts since week 3 of 2026.
Infectious Diseases: European Union/European Economic Area
Respiratory and Droplet Transmission
Influenza and Respiratory Virus Surveillance
Respiratory virus activity in the EU/EEA has continued its post-season decline through Week 12 (the most recent data available in the ECDC Communicable Disease Threats Report for Week 13). Primary care consultation rates for influenza-like illness and acute respiratory infections are at baseline levels in most reporting countries, with five countries at baseline and one at low intensity. Influenza test positivity in primary care stands at a pooled median of 4.7% (IQR 5.5; 1.4–9.1%), down from the elevated levels observed during the peak weeks of the 2025–26 season. Influenza subtypes A(H1)pdm09 and A(H3) are now co-dominant; during the season overall, A(H3) accounted for 60% of subtyped influenza A specimens, with subclade 2a.3a.1(K) comprising 90% of characterised A(H3) viruses. Hospitalisation rates for severe acute respiratory infections (SARI) attributable to influenza are declining across all age groups.
RSV continues to circulate at elevated levels despite the seasonal trend toward resolution, with a hospital test positivity rate of 16% (IQR 13; 7.2–23%), with children under five years accounting for the majority of admissions. SARS-CoV-2 activity remains low in all age groups (primary care positivity 1.8%; hospital positivity 1.5%), and circulating variants are dominated by BA.3.2, classified as a variant under monitoring and detected at approximately 30% distribution in reporting countries.
Measles — Latvia Outbreak
Latvia has reported its first measles outbreak since 2018, with 28 cases identified as of 26 March 2026, of which 27 are laboratory-confirmed. The index case is an 11-year-old girl who developed rash on 6 March following attendance at an international public event in Riga on 21–22 February, where exposure to a symptomatic traveller from abroad is reported. The outbreak has concentrated in unvaccinated school contacts of the index case, with 19 paediatric cases and 9 adults; more than 100 children at the affected school are reported to be unvaccinated—a vaccine coverage gap directly enabling this outbreak. Genotyping of the first ten specimens identified measles virus genotype D8, supporting a single imported transmission chain. Over 1,000 contacts have been placed under follow-up; self-collection of specimens is being used to minimise healthcare facility exposure. ECDC assesses national risk in Latvia as moderate to high, particularly among non-immune individuals and given the scale of contact tracing underway. Measles risk across the EU/EEA remains as characterised in ECDC’s threat assessment brief of 14 February 2026: very low for immunised persons; moderate for infants under 12 months, young children, and immunocompromised individuals; and low to moderate for older unvaccinated persons. The spring travel season and the seasonal peak of measles transmission compound the risk of further importation events across the region.
Avian Influenza A(H9N2) — Italy, First EU/EEA Case
A single human case of avian influenza A(H9N2) has been confirmed in the Lombardy region of Italy in a returning traveller from a non-European country where A(H9N2) has been documented in poultry. This is the first human case of A(H9N2) ever reported in the EU/EEA and therefore constitutes a notable epidemiological threshold, even though sporadic human infections with this subtype have been documented internationally since 1998—a total of 195 cases in 10 countries across Asia and Africa, with only two fatalities. A(H9N2) is a low-pathogenicity avian influenza virus widely distributed in poultry globally; it does not sustain human-to-human transmission, and direct contact with infected birds or contaminated environments remains the predominant exposure route. The patient, who has co-existing medical conditions, is in hospital isolation and receiving treatment. Italian authorities have initiated contact tracing. ECDC currently assesses the population-level risk in the EU/EEA as very low based on the established epidemiology of A(H9N2) and the absence of evidence for onward transmission. The event will be closely monitored and risk re-assessed as additional information becomes available.
Contact and Droplet Transmission
Invasive Meningococcal Disease — Kent, England
The most operationally urgent infectious disease event of this reporting period is an outbreak of invasive meningococcal disease (IMD) serogroup B centred on the University of Kent and a nightclub in Canterbury (Club Chemistry). As of 26 March 2026, UKHSA has confirmed 23 cases: 22 in the United Kingdom (20 laboratory-confirmed; two deaths) and one exported laboratory-confirmed case in France in an individual who had attended the University of Kent before returning to France. All UK cases are young adults with a median age of 19 years; 20 of 23 cases have an epidemiological link to the Canterbury nightclub during the exposure period of 5–7 March. The earliest case onset was 9 March and the latest 16 March—meaning one full incubation period of 10 days has elapsed since the last case without a new case, a reassuring epidemiological signal regarding outbreak containment.
IMD is caused by Neisseria meningitidis, a gram-negative diplococcus that colonises the human nasopharynx and is transmitted via respiratory droplets and close contact. In its invasive form—meningitis and/or septicaemia—it carries a case fatality rate of 10–15%, with permanent sequelae including limb amputation, deafness, and neurological disability in a substantial proportion of survivors. Serogroup B accounts for the majority of IMD in the UK and EU/EEA (55–57% of cases in 2023 and 2024 respectively). All 20 laboratory-confirmed cases in this outbreak are serogroup B; 17 have been subtyped as P1.12-1,16-183, with whole genome sequencing identifying sequence type 485 in clonal complex ST-41/44—the predominant UK lineage contributing approximately 40% of invasive disease. ECDC molecular analysis confirms the outbreak isolates cluster closely together but do not cluster with any other isolates from international genomic databases, supporting a single local transmission source. MenDeVAR index analysis indicates the isolate is covered by both MenB vaccines licensed in the UK and EU (Bexsero and Trumenba). UKHSA has administered approximately 10,969 vaccinations and over 13,514 doses of antibiotic prophylaxis as of 24 March. ECDC assesses that no specific recommendations for EU/EEA countries beyond the affected cluster are warranted at this time, given the localised epidemiological profile.
Vector-Borne Transmission
Dengue Vector Surveillance — Switzerland and Luxembourg
Two entomological surveillance findings have been reported this week with implications for the ongoing northward range expansion of dengue-competent vectors in Europe. In Switzerland, a pool of Aedes mosquitoes collected in Basel-City canton in 2024 has tested positive for dengue virus serotype 4—the first published identification of dengue virus in mosquitoes north of the Alps, although autochthonous dengue transmission occurred in the Paris region in 2023, which lies slightly further north. Aedes albopictus is established in Basel-City; it is probable that the positive specimen had fed on an infected viraemic traveller. No local dengue cases were reported in the area during the collection period, though mild or asymptomatic infections would not be detected by passive surveillance. In Luxembourg, DNA of Aedes aegypti—a more efficient dengue vector than Aedes albopictus—was detected in ovitrap eggs collected in July 2025 at a highway station in Berchem (the largest petrol station in Europe). A prior detection of Aedes aegypti environmental DNA was made approximately five kilometres away in Bettembourg in 2023. No adult mosquitoes have been recovered; the probability of establishment is considered low given Aedes aegypti’s limited cold tolerance. Taken together, these two findings reinforce the trajectory of progressive northward vector range expansion under climate change and the importance of maintaining sensitive entomological surveillance, particularly at ports of entry, to detect early establishment before transmission events occur.
Infectious Diseases: Bulgaria
Respiratory and Droplet Transmission
Varicella
Varicella registered the most striking week-over-week increase of any condition in the Bulgarian national NCIPD report for Week 13, with 784 cases—an increase of 265 cases over the 519 recorded in Week 12, representing a 51% single-week surge. This is the highest single-week varicella count of 2026 and one of the more substantial short-interval increases observed in any condition in recent weeks. The year-to-date total of 7,860 cases through Week 13, however, remains 5% below the 8,264 cases registered in the same period of 2025, indicating that the current acceleration has not yet translated into a year-over-year excess on a cumulative basis. The district-level breakdown from the ZRZ report (reflecting Week 13 activity) confirms nationwide distribution: Sofia-grad reports the largest share (193 cases), followed by Blagoevgrad (58), Varna (72), V. Tarnovo (22), and Plovdiv (44), with cases distributed across virtually all 28 districts. The biological mechanism driving this surge is most consistent with accumulation of susceptibles within the school-age population as the academic term progresses, given varicella’s R₀ of approximately 10–12 in non-immune groups and the absence of universal childhood vaccination in Bulgaria. The observation that absolute case counts remain below 2025 levels on a year-to-date basis likely reflects a cohort effect from higher transmission during the equivalent period of the prior year. Given that varicella complications—bacterial superinfection, pneumonia, and encephalitis—disproportionately affect adults, immunocompromised individuals, and neonates, clinicians in paediatric and general practice settings should anticipate elevated consultation volumes in coming weeks.
Scarlet Fever
Week 13 recorded 99 cases of scarlet fever—nine more than the 90 cases in Week 12—representing a modest 10% week-over-week increase that approaches but does not exceed the 20% reporting threshold. The year-to-date cumulative total of 987 cases through Week 13 is 26% below the 1,335 cases registered in the same period of 2025, confirming that the 2026 scarlet fever season is unfolding at substantially lower intensity than the preceding year. Of the 99 weekly cases, 25 were classified as possible, 46 as probable, and 28 as confirmed. Geographically, Varna (18 cases) and Sofia-grad (21 cases) account for the largest district-level totals. Scarlet fever, caused by group A Streptococcus pyogenes producing erythrogenic toxin, is typically a disease of school-age children characterised by pharyngotonsillitis, a diffuse erythematous rash, and strawberry tongue; it remains sensitive to penicillin and amoxicillin in the Bulgarian context, though global vigilance regarding invasive GAS disease is maintained.
Fecal-Oral Transmission
Gastroenteritis and Enterocolitis
Non-specific gastroenteritis and enterocolitis registered 189 cases in Week 13—an increase of 75 cases over the 114 recorded in Week 12, representing a 66% single-week surge. This is the largest single-week increase in this category in the 2026 surveillance year to date, and clearly meets the reporting threshold. Of the 189 cases, 82 were classified as possible, 98 as probable, and only 9 as confirmed, a distribution that is typical for this syndromic category and reflects the operational realities of microbiological case ascertainment for undifferentiated gastrointestinal illness. The year-to-date cumulative total of 1,791 cases is approximately 1% above the 1,772 cases registered in the same period of 2025—a negligible year-over-year difference that contextualises this week’s surge as a short-interval deviation rather than a sustained trend shift. The ZRZ district-level data identify Sofia-grad (26 cases), Pleven (18 cases), Plovdiv (30 cases), Varna (17 cases), and Kyustendil (8 cases) as the highest-burden districts this week. The aetiological drivers of this increase cannot be determined from aggregate surveillance data; the case classification distribution is consistent with norovirus or other viral gastroenteritis, though bacterial and parasitic causes cannot be excluded. Rotavirus gastroenteritis, tracked separately, was stable at 18 confirmed cases this week (unchanged from Week 12), with a year-to-date total of 188 cases—28% below the 262 cases in the same period of 2025, consistent with the declining trend that has characterised rotavirus in 2026.
Campylobacteriosis
Eight confirmed cases of campylobacteriosis were registered in Week 13, representing a decline of 10 cases from the 18 recorded in Week 12 (a 56% week-over-week decrease). Despite this single-week decline—which returns weekly counts to levels closer to the 5–8 case range characteristic of earlier weeks in 2026—the cumulative year-to-date total of 134 cases remains dramatically elevated relative to the 49 cases in the same period of 2025, representing a 173% year-over-year excess. Campylobacter spp., primarily C. jejuni and C. coli, are zoonotic pathogens transmitted predominantly via consumption of undercooked poultry and unpasteurised dairy products, with secondary transmission via contaminated water or environment. This persistent year-over-year excess, now extending through 13 consecutive weeks of 2026, continues to require structured epidemiological investigation and engagement with food safety authorities, as previously flagged in this series.
Bloodborne Transmission
HIV
Eight confirmed HIV cases were registered in Week 13, one more than the seven in Week 12 (+14% week-over-week). The year-to-date total of 62 cases is 21% below the 78 cases registered in the same period of 2025, a year-over-year reduction that may reflect declining transmission, changes in testing uptake or reporting completeness, or both. Given HIV’s long and variable latency between acquisition and diagnosis, caution is warranted in interpreting year-over-year differences in a surveillance series without disaggregated data on new diagnoses by estimated transmission category, CD4 count at diagnosis, or time since estimated infection.
Contact and Sexual Transmission
Gonorrhea
Eight confirmed cases of gonorrhea were registered in Week 13—two fewer than the 10 cases in Week 12 (−20% week-over-week), a modest single-week decline. The cumulative year-to-date total of 66 cases through Week 13 is 267% above the 18 cases registered in the same period of 2025, sustaining the dramatic year-over-year excess that has been a consistent feature of Bulgarian STI surveillance throughout 2026. Neisseria gonorrhoeae causes urogenital, rectal, and pharyngeal infection and is of heightened public health concern given rising international rates of multidrug resistance and the potential for serious reproductive complications. The absence of systematically reported antimicrobial susceptibility data alongside case notifications in the Bulgarian surveillance system represents a limitation directly relevant to treatment guidance and to understanding whether resistance contributes to this observed increase.
Urogenital Chlamydial Infection
Three confirmed cases of urogenital chlamydial infection were registered in Week 13—a decrease of 11 cases from the 14 reported in Week 12 (−79% week-over-week), the most pronounced single-week decline for any notified condition in this reporting period. Despite this reduction, the year-to-date total of 85 cases through Week 13 is 130% above the 37 cases registered in the same period of 2025. The magnitude of the year-over-year excess for both gonorrhea and chlamydia in 2026 may partially reflect improved testing and reporting capacity, but genuine increases in transmission among sexually active populations cannot be excluded and should be evaluated through sexual health service utilisation data and partner notification rates. The frequently asymptomatic course of chlamydial infection—particularly in women—and the risk of long-term sequelae including tubal infertility and ectopic pregnancy underscore the importance of continued screening, especially in reproductive-age populations.
Syphilis
Eight confirmed cases of syphilis were registered in Week 13, unchanged from Week 12 (0% week-over-week change). The year-to-date total of 87 cases is 14% below the 101 cases in the same period of 2025, indicating that unlike gonorrhea and chlamydia, syphilis in Bulgaria has not demonstrated a year-over-year increase in 2026. Congenital syphilis through Week 13 totals six cases in 2026, against nine in the same period of 2025, reflecting a marginal reduction in vertical transmission events; this burden, while small in absolute terms, remains entirely preventable through antenatal screening and treatment and warrants continued vigilance.
Vaccine-Preventable Disease: Measles
The ZRZ district-level report for Week 13 records 21 confirmed or probable measles cases across Bulgaria—an epidemiologically significant finding, given that measles was not reported in the preceding Week 13 national NCIPD aggregate at the time of this analysis. The district distribution reveals concentration in Vraca (19 cases) with single cases in Kyustendil and Pleven. The Vraca cluster in particular warrants urgent investigation as a potential localised outbreak. Measles (Morbillivirus hominis), transmitted via respiratory droplets and aerosols with an R₀ of 12–18, requires population immunity exceeding 95% to interrupt transmission. It is the most contagious infectious disease known, and its resurgence in communities with incomplete vaccination coverage—as documented in Latvia this week at the European level—illustrates the speed at which chains of transmission can establish in susceptible cohorts. The Bulgarian national immunisation programme recommends two doses of measles-mumps-rubella (MMR) vaccine, but coverage data and the extent of susceptible populations in affected districts are not available from the current surveillance reports. This cluster should be treated as a priority for public health field investigation, contact tracing, and immunisation response.
Legionellosis
One confirmed case of Legionella pneumophila infection (Legionnaires’ disease) was registered in Week 13—an increase from zero in Week 12. The year-to-date total of three cases is comparable to the two cases registered in the same period of 2025. Legionellosis is caused by Legionella pneumophila, a gram-negative intracellular bacterium that proliferates in warm aquatic environments and is acquired through inhalation of contaminated aerosols from cooling towers, hot water systems, or nebulising devices. It is not transmitted person-to-person. While single sporadic cases are expected in any surveillance period, confirmed cases should prompt environmental investigation of the probable exposure source, particularly given the potential for point-source amplification in building water systems.