Epidemiological News: Week 46, 2025
Non-Communicable Disease Developments: New Medicines
The European Medicines Agency’s Committee for Medicinal Products for Human Use concluded its November 2025 meeting with recommendations for ten new medicines, representing significant therapeutic advances across multiple disease areas. Among the most notable approvals, Teizeild (teplizumab) stands out as a first-in-class treatment capable of delaying the onset of stage 3 type 1 diabetes in adults and children from eight years of age who present with stage 2 disease. This medicine received support through EMA’s PRIME scheme, which provides enhanced scientific and regulatory assistance for promising therapies addressing unmet medical needs. The ability to intervene in the natural progression of type 1 diabetes before the development of severe hyperglycemia represents a paradigm shift in diabetes care.
Waskyra (etuvetidigene autotemcel) marks another milestone as the first gene therapy approved for Wiskott-Aldrich syndrome, a rare inherited disease affecting blood cells and immune system function almost exclusively in males. Gene therapy continues to expand its therapeutic reach, with this approval joining a growing portfolio of curative approaches for previously intractable genetic conditions. Similarly, Dawnzera (donidalorsen) offers new hope for patients with hereditary angioedema, providing routine prevention of recurrent swelling attacks that can affect the face, throat, limbs, and gastrointestinal tract in adults and adolescents aged twelve years and older.
The oncology portfolio expanded with Inluriyo (imlunestrant) for locally advanced or metastatic breast cancer with specific ESR1 gene mutations, while diagnostic capabilities advanced with GalenVita, a radionuclide generator producing gallium-68 chloride solution for positron emission tomography imaging of various tumor types. Preventive medicine saw the addition of Vacpertagen, an acellular pertussis vaccine addressing whooping cough across all age groups.
The committee also recommended two biosimilar medicines, Ondibta (insulin glargine) for diabetes mellitus and Osqay (denosumab) for osteoporosis and bone loss, which will increase treatment accessibility through competitive pricing. A generic version of teduglutide received positive opinion for short bowel syndrome, further expanding affordable treatment options. Extensions of therapeutic indications were granted for four existing medicines: Koselugo, Minjuvi, Veyvondi, and Xerava, broadening their clinical utility.
Three marketing authorization applications were withdrawn during the meeting. Insulin Aspart Injection for diabetes in adults and children, Nurzigma (pridopidine) for Huntington’s disease, and Ohtuvayre (ensifentrine) for chronic obstructive pulmonary disease all had their applications discontinued by the applicants. Additionally, following re-examination of Aqneursa (levacetylleucine) for Niemann-Pick type C disease, the committee confirmed its initial recommendation not to consider levacetylleucine as a new active substance. The marketing authorization holder for Rezurock (belumosudil) has requested re-examination of the negative opinion from October 2025, with the committee expected to issue a final recommendation after reviewing the grounds for this request.
Infectious Diseases: Global and EU Perspective
Respiratory and Droplet Transmission
Measles surveillance across Europe during September 2025 demonstrated an expected seasonal decrease, with 90 cases reported by 11 countries while 17 countries reported zero cases. However, the 12-month period from October 2024 through September 2025 saw 10,195 measles cases across 30 EU/EEA Member States, with 71.3% laboratory confirmed. The age distribution reveals vulnerability across the lifespan, with 40.5% of cases occurring in children under five years and 32.5% in individuals aged 15 years or above. Infants under one year experienced the highest notification rate at 336.4 cases per million population, followed by children aged one to four years at 174.6 per million. The overwhelming majority of cases occurred in unvaccinated individuals, who represented 81.1% of cases, while those with two or more vaccine doses comprised only 7% of cases. Eight deaths were reported during this period, with Romania accounting for five, France for two, and the Netherlands for one, yielding a case fatality rate of 0.074%.
Recent epidemic intelligence surveillance conducted on 13 and 14 November revealed an active outbreak in the Canary Islands with 21 cases across La Palma, Gran Canaria, and Tenerife. The outbreak, which began on 20 October with three cases including two children and a healthcare worker, has expanded to include seven new cases this week, five adults in La Palma and two cases in Gran Canaria. Epidemiological investigation traced the index case to contact with a case previously detected in Tenerife. The recent cases present with mild disease and are recovering without complications, though authorities continue active contact tracing. Spain overall reported 379 cases as of 9 November, representing an increase of 35 cases since 30 September, with 108 imported cases and 92 related to imported cases.
Beyond Europe, Canada has lost its measles elimination status according to notification from the Pan American Health Organization, due to an ongoing multi-jurisdictional outbreak lasting more than 12 months. As of 10 November, Canada reported 5,162 cases including two deaths in congenitally infected pre-term infants. The United States reported 1,723 confirmed cases with three deaths across 43 jurisdictions, with 92% occurring in unvaccinated individuals or those with unknown vaccination status. Mexico’s situation remains severe with 5,257 confirmed cases and 23 deaths through week 43, predominantly concentrated in Chihuahua state with 4,440 confirmed cases and 21 deaths. Africa reported 129,680 cases with 1,110 deaths across 20 countries, yielding a case fatality rate of 0.79%.
Influenza surveillance indicates an earlier start to the 2025-2026 season compared to the previous two years, with circulation increasing three to four weeks ahead of typical patterns. During week 45, primary care surveillance detected 167 influenza cases, with the overwhelming predominance of influenza A accounting for 98.2% of detections. Among subtyped influenza A viruses, A(H3) represented 68% while A(H1)pdm09 comprised 32%, marking a shift in the dominant circulating subtype. Children aged five to fourteen years show the highest number of detections, consistent with typical epidemiological patterns. Genetic characterization of 83 viruses from weeks 40 through 45 revealed that A(H1)pdm09 viruses predominantly belonged to clade 5a.2a.1(D.3.1) representing 97% of characterized strains, while A(H3) viruses showed 86% belonging to clade 2a.3a.1(K). Despite increasing influenza activity, the impact on hospitalizations remains limited at this time, with 52 influenza detections in severe acute respiratory infection surveillance during week 45.
SARS-CoV-2 indicators demonstrate stable or decreasing trends across Europe, with 155 detections in primary care and 23 in hospital settings during week 45. Variant surveillance for weeks 43-44 showed continued dominance of the XFG variant accounting for 78% of detections across five countries, classified as a variant under monitoring. The NB.1.8.1 variant represented 8% of detections, while BA.2.86, classified as a variant of interest, accounted for 4%. The current levels of COVID-19 circulation remain substantially below those observed in autumn 2024, consistent with the transition to endemic patterns.
Respiratory syncytial virus circulation has increased in recent weeks but remains at low levels, with 17 detections in primary care and 21 in hospital settings during week 45. The cumulative data from weeks 40 through 45 shows 97 primary care detections and 111 hospital detections. RSV detections occur primarily in children under five years of age, and the temporal trends follow similar patterns to the previous season, suggesting a typical seasonal onset. Both RSV-A and RSV-B are circulating, with RSV-A representing between 33% and 75% of typed detections depending on surveillance setting.
Vector-Borne Transmission
West Nile virus transmission across Europe is concluding for the 2025 season, with the latest case onset date of 27 October reported among the cumulative 1,096 locally acquired human infections. Italy experienced the most intense circulation with 773 cases including 71 deaths, representing a case fatality rate of 9.2% within the expected range but marking the highest number of human infections Italy has reported at this time of year. The Lazio region served as the primary epicenter with 265 cases concentrated in Latina, Roma, and Frosinone provinces, while the Campania region reported 133 cases distributed across Napoli, Caserta, Salerno, and Avellino provinces. Other regions in Italy reported numbers similar to previous years, suggesting that the outbreak expansion primarily affected central regions.
The 2025 season introduced West Nile virus to 35 regions reporting human cases for the first time, including 17 Italian regions spanning from northern provinces like Genova and Sondrio to southern areas such as Reggio di Calabria and multiple Sicilian provinces. France reported first-time detections in 14 regions, notably including the Paris metropolitan area with cases in Paris proper and six surrounding departments, suggesting urban transmission. This urban detection pattern represents a significant epidemiological development, as West Nile virus has historically been associated with rural and wetland areas. Germany, Greece, Spain, Croatia, Kosovo, Romania, and Türkiye each reported first-time detections in one to three regions.
From the veterinary perspective, 178 outbreaks among equids and 345 outbreaks among birds have been reported across Europe in 2025. The temporal distribution showed outbreak activity from mid-January through late October, with the earliest equid outbreak starting 15 January in Germany and the earliest bird outbreak beginning 16 February in Italy. Italy dominated both animal surveillance categories, accounting for 86 of 178 equid outbreaks and 318 of 345 bird outbreaks, reflecting intensive surveillance capacity alongside favorable ecological conditions for virus circulation. Belgium reported West Nile virus for the first time with three bird outbreaks in August 2025 involving Eurasian jackdaws and carrion crows in the Mechelen and Halle-Vilvoorde administrative units. The Netherlands also reported its first equid outbreak to the Animal Disease Information System in October 2025, though the virus had been previously detected in mosquitoes, birds, and humans since 2020.
Bird species surveillance identified carrion crows as associated with the highest number of outbreaks at 95, followed by common magpies with 59 outbreaks and common wood-pigeons with 30 outbreaks. These corvid species serve as particularly sensitive sentinels for West Nile virus circulation due to their high susceptibility and the visibility of mortality events. As temperatures decline across Europe and mosquito activity diminishes, only sporadic human cases are expected in the coming weeks, with the 2025 transmission season effectively concluded.
Dengue surveillance globally documented over 4.5 million cases and more than 3,000 deaths from 103 countries and territories since the beginning of 2025. The Americas region reported 3.9 million cases through week 40, representing a 68% decrease compared to the same period in 2024 but remaining 9% above the five-year average. Cases peaked during weeks 12-14 of 2025 before entering a declining trend. All four dengue virus serotypes continue to circulate with varying geographic distributions across countries. Brazil maintains the highest burden with cases reported across all regions, though a declining trend from June through October suggests seasonal contraction. Cuba’s outbreak affects all 14 provinces with decreasing febrile syndrome cases suggesting disease control measures are achieving impact.
In Asia, dengue case numbers reached 136,233 representing a 31.5% decrease compared to the same period in 2024, with Southeast Asia bearing the greatest burden. Bangladesh demonstrates continuing increasing trends since August, with 6,235 new cases reported during the week of 27 October through 2 November, and cumulative 2025 figures exceeding those from the same period in 2024. Vietnam shows an increasing trend with 122,979 cases and 23 deaths as of 17 October. China reported 5,280 cases through the end of September, lower than the same period in 2024, though the monthly number of cases increased from 1,702 in August to 2,321 in September. The Guangdong province continues as the primary affected area. Singapore’s outbreak, which began in early August with initial cases associated with travelers returning from Guangdong, has continued through September and October.
Within the EU/EEA, seasonal dengue surveillance recorded 29 autochthonous cases in France and four in Italy as of 5 November. This week saw no new cases reported to ECDC, and all clusters are currently closed. The outermost regions demonstrate varying transmission patterns. Guadeloupe continues epidemic phase 2 level 1 with isolated outbreaks and DENV-3 as the predominant serotype. Martinique, Saint Martin, and Saint Barthélemy maintain epidemic phase 1 with sporadic cases at lower levels. French Guiana confirmed nine dengue cases in weeks 43-44, bringing the year-to-date total to 293 cases with 97% of serotyped samples identified as DENV-2. Mayotte has reported 30 cases through 8 September with no recent detections. Réunion’s 44 cases year-to-date include 17 confirmed, with the last autochthonous case identified in week 17 at the end of April.
Chikungunya surveillance globally documented 458,840 cases and 146 deaths from 24 countries and territories in 2025. October saw 44,295 new cases representing a 108% increase from September’s 21,266 cases, though with only one associated death compared to ten in September. The Americas region accounts for 266,165 cases and 118 deaths, showing a 35.2% decrease compared to the same period in 2024. Brazil maintains transmission across all regions with recent epidemiological weeks showing highest numbers in Centro-Oeste and Sudeste regions, particularly in Mato Grosso do Sul, Minas Gerais, and São Paulo federal units. Cuba’s outbreak affects all 14 provinces with decreasing febrile syndrome trends suggesting epidemic control. Bolivia reported cases in six of nine departments with Santa Cruz accounting for over 80% of cases and all deaths, including documented cases of Guillain-Barré syndrome associated with chikungunya infection.
In Asia, the 136,233 cases with no associated deaths represent a 31.5% decrease compared to the same period in 2024, with Southeast Asia most affected. China’s outbreak, continuing since the first case in July 2025, shows concentration in Guangdong province, particularly Jiangmen, Foshan, and Guangzhou cities. Weekly case numbers demonstrate a decreasing trend during epidemiological weeks 41-43, though October’s total increased compared to September. Hong Kong Special Administrative Region and Guangxi province have also reported cases, initially associated with imported cases from Guangdong. Pakistan’s year-round transmission concentrated in southwestern provinces shows 109 cases over the last 60 days with no deaths, representing a 37% increase in October compared to September. Singapore’s cases reported since early August include initial outbreak cases associated with travelers returning from Guangdong, with continued transmission through September and October.
For the EU/EEA, seasonal chikungunya surveillance documented 776 cases in France and 384 in Italy as of 12 November. This week France did not report surveillance data, with reporting expected in week 47. Italy reported ten new locally acquired cases, bringing the cumulative total to 384 cases distributed across six clusters, with three clusters currently active. The largest cluster is located in Carpi, San Prospero, Soliera, Novellara, Cavezzo, Modena, Nonantola, Correggio, Novi di Modena, and Cesenatico in the Emilia-Romagna region.
Fecal-Oral Transmission
The most significant global development in week 46 concerns poliomyelitis, with Germany reporting detection of wild poliovirus type 1 in a wastewater sample from Hamburg. The sample, collected during calendar week 41 as part of a research project to establish poliovirus detection methodology, represents the first such finding in a country that has maintained polio-free status as part of the WHO European Region since 2002. Genome sequencing revealed strong similarity to a genetic cluster circulating in Afghanistan, where wild poliovirus type 1 continues to circulate alongside Pakistan. No clinical cases of poliomyelitis have been reported in Germany, and the Robert Koch Institute emphasizes that the risk to the general population remains very low due to high vaccination coverage of approximately 88% for three doses of inactivated polio vaccine.
This detection, while unusual, was not unexpected given the continuing global circulation of wild poliovirus and the presence of under-vaccinated populations within European countries. The virus spreads primarily through the fecal-oral route, with infected individuals shedding virus in their feces for several weeks even when asymptomatic, making wastewater surveillance a sensitive early warning system. The majority of poliovirus infections produce no visible symptoms, approximately 24% cause minor non-specific illness, and fewer than 1% progress to paralytic poliomyelitis with its characteristic acute flaccid paralysis. The German authorities have assessed that while the risk to the general population is very low, the occurrence of a clinical case in unvaccinated individuals cannot be completely ruled out. This finding follows previous detections of circulating vaccine-derived poliovirus type 2 in German wastewater since late 2024, emphasizing the importance of maintaining high vaccination coverage and robust environmental surveillance.
Contact and Sexual Transmission
Mpox surveillance revealed significant developments in transmission patterns during week 46, with 88 new cases reported from eight EU/EEA countries since 9 October. Spain led with 29 cases, followed by Germany with 19, Portugal with 16, France with 12, Netherlands with nine, and Greece, Hungary, and Norway with one case each. The cumulative burden since the outbreak began has reached 25,609 confirmed cases across 29 EU/EEA countries, with Spain accounting for 9,110 cases, France 4,552, and Germany 4,540. Ten deaths have been reported from five countries during the entire outbreak period.
The emergence of mpox clade I in Europe continues with 50 total cases reported as of 13 November, including 46 cases submitted to The European Surveillance System and four additional cases from Spain reported through event-based surveillance. Germany has reported 15 clade I cases, while Belgium and the Netherlands each reported seven cases. The distribution includes Spain with six cases, Ireland and Italy with four cases each, France with four cases, and Portugal, Greece, and Sweden with one case each. All cases involve clade Ib except the first Irish case, which was caused by clade Ia.
The most significant epidemiological development concerns the identification of 14 clade Ib mpox cases among men who have sex with men, with 12 cases lacking any travel links to countries with known mpox clade Ib transmission. The Netherlands reported seven cases among men who have sex with men, Spain reported five cases, Belgium one, and Greece one. The cases in Belgium and Greece were imported, but the remaining cases in Spain and the Netherlands occurred in individuals without travel history. Geographic distribution shows cases in Madrid and Barcelona for Spain, while the Netherlands cases are distributed across the country. All cases among men who have sex with men except the Greek case had symptom onset in October 2025, indicating very recent transmission events.
These findings demonstrate ongoing local transmission of mpox clade I within sexual networks of gay, bisexual, and other men who have sex with men in the EU/EEA, representing a significant shift from the earlier outbreak phase when all clade I cases were either imported or directly related to imported cases with heterosexual and household transmission patterns. Notably, none of the clade I mpox cases reported among men who have sex with men required hospitalization, and three cases occurred in vaccinated individuals, though vaccine effectiveness data for clade I remain limited. Seven individuals overall have been hospitalized for treatment during the clade I outbreak, all from the earlier heterosexual and household transmission phase.
The epidemiological pattern suggests that mpox clade I has established transmission chains within European sexual networks independent of travel-related importation. This development prompted ECDC to publish a Threat Assessment Brief on 24 October, assessing the risk of MPXV clade Ib infection as moderate for men who have sex with men and low for the general population in the EU/EEA. The moderate risk assessment for men who have sex with men reflects the documented local transmission, while considerable uncertainties remain regarding the transmissibility and severity of clade Ib relative to clade IIb, which has been circulating in Europe since 2022.
Confirmed secondary transmission events from imported clade I cases have been reported by Germany, Belgium, and Ireland among household or other close contacts, demonstrating that the virus maintains transmission capability beyond sexual networks when close contact occurs. The presence of both sexual network transmission and household transmission underscores the need for comprehensive public health responses addressing multiple risk groups and transmission contexts.
Infectious Diseases: Bulgaria
Respiratory and Droplet Transmission
Bulgaria’s surveillance during week 46 documented significant increases in vaccine-preventable respiratory diseases consistent with autumn seasonal patterns. Varicella reported 420 cases, representing an increase of 83 cases from the previous week, a 24.6% rise that reflects the characteristic autumn-winter seasonality of this highly contagious virus. The case distribution included 45 possible, 305 probable, and 70 confirmed cases, with the highest numbers in Varna with 63 cases, and Sofia-oblast and Sofia-grad each reporting 60 cases. The year-to-date total of 18,538 cases represents a 20.3% decrease compared to the 23,271 cases during the same period in 2024, suggesting that the current season follows a more moderate trajectory than the previous year. Varicella predominantly affects children, and the characteristic vesicular rash that appears in successive crops creates the typical clinical picture. While generally a mild disease in healthy children, varicella can cause severe complications in immunocompromised individuals, pregnant women, and adults who escaped childhood infection.
Scarlet fever demonstrated substantial increase with 84 cases during week 46, rising by 34 cases from the previous week. The case distribution included 20 possible, 33 probable, and 31 confirmed cases, with Plovdiv reporting the highest number at 26 cases. The year-to-date total of 3,060 cases represents a dramatic 60.7% decrease compared to the 7,793 cases during the same period in 2024, continuing a declining trend that has characterized the entire year. Scarlet fever results from Group A Streptococcal pharyngitis with production of erythrogenic toxin, causing the characteristic sandpaper-like rash, strawberry tongue, and circumoral pallor. The disease primarily affects children aged five to fifteen years, and while usually mild with appropriate antibiotic treatment, can lead to serious complications including acute rheumatic fever and post-streptococcal glomerulonephritis if untreated.
Pertussis surveillance recorded one confirmed case during week 46, bringing the year-to-date total to 84 cases, representing a 96.9% decrease compared to the 2,678 cases during the same period in 2024. This dramatic decline likely reflects the cyclical nature of pertussis epidemics, which typically occur every three to five years, with 2024 representing a peak year across much of Europe. Pertussis, caused by Bordetella pertussis, produces characteristic paroxysmal coughing with inspiratory whoop in classic presentations, though the disease spectrum varies by age with adolescents and adults often presenting with prolonged cough without typical features. The disease poses greatest risk to infants too young for complete vaccination, in whom severe complications including apnea, pneumonia, seizures, and encephalopathy can occur.
One case of measles was reported from the Pernik region during week 46. As discussed in the European section above, measles remains a concern across the continent despite high vaccination coverage in most areas, with outbreaks occurring when the virus is introduced into communities with immunity gaps. The highly contagious nature of measles, with basic reproduction numbers of 12-18 in susceptible populations, means that vaccination coverage must exceed 95% to prevent community transmission. The isolated case reported in Bulgaria emphasizes the importance of rapid response including contact tracing, vaccination verification, and targeted vaccination campaigns in affected communities.
Bacterial meningitis and meningoencephalitis surveillance recorded one case in Plovdiv region during week 46. The surveillance system captures meningitis caused by various bacterial pathogens including Streptococcus pneumoniae, Neisseria meningitidis, Haemophilus influenzae, and other bacteria. The clinical presentation typically includes fever, headache, neck stiffness, and altered consciousness, progressing rapidly over hours to days. Immediate empiric antibiotic therapy is essential given the high mortality and morbidity associated with delayed treatment. The relatively low case count reflects the success of conjugate vaccine programs targeting the most common bacterial causes of meningitis in children and adults.
COVID-19 surveillance documented 121 confirmed cases during week 46, representing a decrease of 41 cases from the previous week, a 25.3% reduction that suggests declining transmission. The geographic distribution showed Sofia-oblast reporting the highest number with 29 cases, followed by Plovdiv with 11 cases and Varna with four cases. The year-to-date total of 2,774 cases represents an 81.2% decrease compared to the 14,776 cases during the same period in 2024, reflecting the transition to endemic circulation patterns with substantially lower disease burden than during the pandemic years. The stable mortality suggests that population immunity from vaccination and prior infection, combined with less virulent circulating variants, has reduced disease severity at the population level.
Vector-Borne Transmission
Lyme borreliosis reported five confirmed cases during week 46, with stable numbers compared to the previous week. Cases were distributed across Gabrovo, Lovech, Stara Zagora, and Pleven regions, reflecting the widespread geographic distribution of tick vectors throughout Bulgaria. The year-to-date total of 368 cases represents a slight increase of four cases compared to 364 during the same period in 2024, suggesting stable endemic transmission. Lyme disease, caused by Borrelia burgdorferi sensu lato complex transmitted by Ixodes tick species, typically presents with early localized disease characterized by the pathognomonic erythema migrans rash, a slowly expanding red patch with central clearing. If untreated, infection can progress to early disseminated disease with multiple erythema migrans lesions, neurological manifestations including facial palsy and meningitis, or cardiac involvement. Late disease manifests as arthritis, typically affecting large joints, or chronic neurological symptoms. The disease responds well to antibiotic therapy when recognized early, emphasizing the importance of clinical awareness and prompt diagnosis.
Legionnaires’ disease surveillance recorded one confirmed case during week 46, representing an increase of one case from the previous week. The year-to-date total of 12 cases shows an increase of two cases compared to the ten cases during the same period in 2024. Legionnaires’ disease results from inhalation of aerosols containing Legionella pneumophila bacteria, typically from contaminated water systems including cooling towers, hot tubs, decorative fountains, and plumbing systems. The disease presents as severe pneumonia with high fever, cough, and systemic symptoms, requiring specific antibiotic therapy. Environmental investigation of potential sources is essential for each case to prevent additional exposures and identify systems requiring remediation.
Q fever reported one confirmed case during week 46 in Sofia-oblast, representing an increase of one case from the previous week. The year-to-date total of 37 cases shows a decrease of six cases compared to 43 during the same period in 2024. Q fever, caused by Coxiella burnetii, is a zoonotic disease with cattle, sheep, and goats serving as primary reservoirs. Transmission typically occurs through inhalation of aerosols from contaminated environments, particularly during birthing of infected animals when organisms are shed in high concentrations in placental tissues and birth fluids. Occupational exposure represents the primary risk factor, with farmers, veterinarians, and abattoir workers at elevated risk. Acute Q fever presents as a febrile illness that may include pneumonia or hepatitis, while chronic Q fever manifests as endocarditis or vascular infections, particularly in individuals with pre-existing valvular disease or vascular abnormalities.
Gastrointestinal and Fecal-Oral Transmission
Gastroenteritis and enterocolitis surveillance documented 147 cases during week 46, representing a decrease of 18 cases from the previous week. The case distribution included 47 possible, 96 probable, and four confirmed cases, with Plovdiv reporting 32 cases, Varna 22 cases, and Pleven ten cases. The year-to-date total of 8,506 cases represents a 5.9% decrease compared to 9,038 cases during the same period in 2024. This broad surveillance category captures gastroenteritis of multiple etiologies including viral, bacterial, and parasitic causes. The predominance of probable cases reflects the syndromic nature of surveillance, where clinical presentations suggest gastroenteritis but specific pathogen identification is not always performed. The autumn-winter increase in cases reflects seasonal patterns associated with increased norovirus transmission in colder months and increased rotavirus circulation.
Rotavirus gastroenteritis reported 19 cases during week 46, representing an increase of 11 cases from the previous week. The case distribution included one probable and 18 confirmed cases, demonstrating the high proportion of laboratory-confirmed diagnoses for this pathogen. The year-to-date total of 668 cases shows a slight decrease of 39 cases compared to 707 during the same period in 2024. Rotavirus remains the leading cause of severe gastroenteritis in children under five years of age globally despite vaccine availability. The virus causes profuse watery diarrhea, vomiting, and fever, with dehydration representing the primary complication requiring medical intervention. The seasonal increase during autumn and winter months reflects optimal transmission conditions and increased person-to-person contact in indoor environments.
Salmonellosis recorded four confirmed cases during week 46, representing a decrease of two cases from the previous week. The year-to-date total of 622 cases shows a 28.8% decrease compared to 874 cases during the same period in 2024. Salmonella bacteria cause gastroenteritis through consumption of contaminated food, particularly poultry, eggs, and unpasteurized dairy products, though a wide variety of foods can serve as vehicles. The infection typically causes diarrhea, fever, and abdominal cramps beginning 12 to 72 hours after exposure, with illness duration of four to seven days in most cases. While most individuals recover without specific treatment, invasive disease can occur, particularly in young children, elderly individuals, and immunocompromised persons.
Dysentery, specifically shigellosis, reported two confirmed cases during week 46 in Dobrich and Kyustendil regions, representing an increase of one case from the previous week. The year-to-date total of 53 cases shows a decrease of 22 cases compared to 75 during the same period in 2024. Shigella bacteria cause dysentery characterized by diarrhea containing blood and mucus, abdominal cramps, fever, and tenesmus. The infection spreads through the fecal-oral route with a very low infectious dose, meaning that person-to-person transmission occurs readily, particularly in settings with inadequate hand hygiene. Shigellosis represents an important cause of healthcare-associated diarrhea and outbreaks in institutional settings.
Campylobacteriosis documented 14 confirmed cases during week 46, representing an increase of five cases from the previous week. The year-to-date total of 421 cases shows a substantial 43.7% increase compared to 293 cases during the same period in 2024. Sofia-oblast reported the majority of cases with ten. Campylobacter bacteria, particularly Campylobacter jejuni, represent the most common bacterial cause of gastroenteritis in many developed countries. Infection typically results from consumption of undercooked poultry or cross-contamination from raw poultry to other foods, as well as consumption of unpasteurized milk. The illness produces diarrhea that may be bloody, fever, and abdominal pain, typically lasting less than one week. Post-infectious complications including reactive arthritis and, rarely, Guillain-Barré syndrome can occur.
Escherichia coli infections causing colitis, specifically escherichiosis, reported four confirmed cases during week 46, representing a decrease of four cases from the previous week. The year-to-date total of 287 cases compares to 328 during the same period in 2024. Various pathotypes of E. coli cause gastrointestinal disease through different mechanisms, including enteropathogenic, enterotoxigenic, enteroinvasive, enteroaggregative, and enterohemorrhagic strains. The clinical presentations range from watery diarrhea to bloody diarrhea depending on the pathotype involved. Enterohemorrhagic E. coli, particularly serotype O157:H7, causes particular concern due to the risk of hemolytic uremic syndrome, a severe complication causing acute kidney injury.
Sexually Transmitted Infections
Syphilis surveillance documented 14 cases during week 46, representing an increase of nine cases from the previous week. The case distribution included one probable and 13 confirmed cases. The year-to-date total of 323 cases shows a 9.9% increase compared to 294 cases during the same period in 2024. Syphilis, caused by the spirochete Treponema pallidum, produces complex clinical manifestations progressing through distinct stages if untreated. Primary syphilis presents with a painless chancre at the inoculation site, while secondary syphilis causes systemic symptoms including rash, lymphadenopathy, and mucocutaneous lesions. Latent syphilis produces no symptoms despite persistent infection, and tertiary syphilis can affect multiple organ systems including cardiovascular and central nervous systems. The disease responds well to penicillin therapy, and screening programs targeting sexually active individuals enable early detection and treatment.
Congenital and infant syphilis reported one confirmed case during week 46, representing an increase of one case from the previous week. The year-to-date total of 34 cases shows a concerning 183% increase compared to 12 cases during the same period in 2024. Congenital syphilis results from transplacental transmission of Treponema pallidum from an infected mother to the fetus, with transmission risk highest during primary and secondary maternal infection but possible during latent infection. Congenital syphilis can cause fetal death, stillbirth, prematurity, and a wide spectrum of clinical manifestations in surviving infants including skeletal abnormalities, hepatosplenomegaly, rash, and neurosyphilis. The substantial increase in congenital syphilis cases indicates failures in the prenatal care system, as universal screening during pregnancy combined with prompt treatment of infected women prevents congenital transmission. This finding warrants urgent public health investigation to identify gaps in prenatal screening, obstacles to accessing care, or failures in partner treatment that perpetuate maternal infection.
Urogenital chlamydia infection reported two confirmed cases during week 46, representing a decrease of four cases from the previous week. The year-to-date total of 169 cases shows a 79.8% increase compared to 94 cases during the same period in 2024. Chlamydia trachomatis causes the most common bacterial sexually transmitted infection globally, though most infections produce no symptoms, particularly in women. When symptomatic, infection causes urethritis in men and cervicitis in women, with complications including pelvic inflammatory disease, ectopic pregnancy, and infertility in women, and epididymitis in men. The asymptomatic nature of most infections emphasizes the importance of screening programs targeting sexually active young adults to enable detection and treatment before complications develop.
Gonorrhea documented two confirmed cases during week 46, stable compared to the previous week. The year-to-date total of 107 cases shows a 28.9% increase compared to 83 cases during the same period in 2024. Neisseria gonorrhoeae causes urethritis in men and cervicitis in women, though like chlamydia, many infections produce no symptoms, particularly in women. Complications include pelvic inflammatory disease in women and epididymitis in men, and disseminated gonococcal infection can cause arthritis and dermatitis. The increasing global prevalence of antimicrobial-resistant gonorrhea represents a major public health concern, with resistance documented to penicillins, tetracyclines, fluoroquinolones, and macrolides, and emerging resistance to extended-spectrum cephalosporins.
HIV surveillance reported five confirmed cases during week 46, representing a decrease of three cases from the previous week. The year-to-date total of 272 cases shows a 9.7% increase compared to 248 cases during the same period in 2024. HIV infection progresses through stages from acute infection with high viral loads, through chronic infection where viral replication continues but at lower levels, to advanced HIV disease characterized by severe immunodeficiency enabling opportunistic infections. Antiretroviral therapy has transformed HIV from a rapidly fatal disease to a manageable chronic condition, with early treatment initiation enabling life expectancies approaching those of uninfected individuals. Treatment also prevents transmission, as individuals with suppressed viral loads on effective antiretroviral therapy do not transmit the virus sexually. The continued new infections emphasize the importance of prevention programs including pre-exposure prophylaxis for individuals at substantial risk, post-exposure prophylaxis after potential exposures, and comprehensive sexual health services.
Conclusion
Week 46 of 2025 illustrates both the progress achieved in infectious disease control and the persistent challenges requiring sustained public health attention. The detection of wild poliovirus in Germany despite decades of polio-free status demonstrates that as long as pathogens circulate anywhere in the world, reintroduction risk persists everywhere. The emergence of mpox clade I transmission in European sexual networks shows how pathogens can establish new transmission patterns in susceptible populations, requiring adaptive public health responses. Bulgaria’s surveillance reveals expected seasonal patterns for respiratory infections alongside concerning increases in sexually transmitted infections and viral hepatitis that warrant investigation and intervention.