The DRC's Bundibugyo Ebola outbreak has reached 7,890 confirmed cases and 3,799 deaths (CFR 48.1%) across 63 health zones in seven provinces. Newly affected areas near South Sudan raise the risk of cross-border spread, and WHO rates the national risk very high. West Nile virus has caused 1,569 locally acquired cases in 16 European countries, led by Italy and Greece. The Netherlands has 28 cases and four deaths. The US has 813 cases, 607 of them neuroinvasive. Tick-borne encephalitis reached a record in Sweden (448 cases) and rose sharply in Austria (168). Chikungunya remains high in Brazil (66,592 cases, 53 deaths), Mauritius (6,928) and Nicaragua (3,109). Western Australia reported a third severe diphtheria case in Perth. Taiwan has 1,586 severe influenza cases and 304 deaths, and leptospirosis cases in the Philippines reached 10,936 after flooding. Ghana confirmed yellow fever after 21 unexplained deaths, and Togo declared measles outbreaks.
Ebola disease outbreak caused by Bundibugyo virus, Democratic Republic of the Congo
As of 23 September, the DRC has 7,890 confirmed cases and 3,799 deaths (CFR 48.1%). That includes 1,133 new cases since 11 September. The outbreak has reached 63 health zones in seven provinces. The newest areas are Sud Ubangi (Bulu) and Dungu in Haut-Uélé, which borders South Sudan, so the risk of cross-border spread is higher. Ituri remains the epicentre (6,032 cases), with incidence slowly declining. North Kivu peaked in mid-September and has the highest CFR (59.7%). Contact follow-up is at 83%. There is no approved vaccine or treatment. WHO rates the risk very high nationally, high for neighbouring countries and low globally, and advises against travel or trade restrictions.
West Nile virus, Europe, USA
Europe has 186 affected areas in 16 countries, six of them newly affected this week. Most are in Italy (65), Greece and Romania (22 each), France (21) and the Netherlands (13). This year, there are 1,569 locally acquired human cases, led by Italy (696), Greece (355), Spain (125) and France (102). In The Netherlands, a total of 28 autochthonous cases and four deaths across six province has been reported, and blood safety measures have been expanded. The US has 813 cases in 43 states, 607 of them neuroinvasive, with California reporting the most (149).
Tick-borne encephalitis, Sweden, Austria
Tick-borne encephalitis (TBE) cases are rising sharply in parts of Europe. In Sweden, 448 cases had been registered as of 14 September, the highest number ever recorded for this point in the year. That surpasses the previous record of 392 cases by the same date in 2023, and cases there have risen about 6% per year over the past decade. Austria recorded 168 TBE cases from January to August 2026, up sharply from 111 in the same period last year. Incidence depends on tick populations, host animals and climate, and vaccination is recommended in risk areas.
Diphtheria, Australia
A third case of severe respiratory diphtheria has been reported in the Perth metropolitan area, according to an outbreak update from Western Australia. Confirmed cases have also been identified in Roebourne and Karratha in the Pilbara region. Control measures include contact tracing, preventive antibiotic treatment for close contacts, and vaccination reviews. The report does not give exact overall case counts, so the full size of the outbreak is still unclear. Clinicians should stay alert for suspected cases and report them promptly.
Chikungunya, Nicaragua, Mauritius, Brazil
Chikungunya activity remains high in several regions in 2026. Nicaragua has reported 3,109 cases, 68% of them in the six weeks up to late September, with spread across the border into Costa Rica and suspected underreporting. Mauritius has 6,928 confirmed cases this year (6,826 on Mauritius, 102 on Rodrigues), with six new cases in the week to 19 September. In Brazil, Bahia recorded 10,364 probable cases and three deaths through 22 September, up 369% on 2025, with Alagoinhas worst affected. Nationally, Brazil has 66,592 cases and 53 deaths.
Yellow fever, Ghana
Confirmed cases of yellow fever have been rported from the Sissala East municipality in northwestern Ghana. These confirmed infections follow the registration of 21 mysterious deaths in the area. An alert is currently focused on the Sissala East region.
Epidemic reaches new peak with 1,586 severe cases and 304 deaths this season.
28 autochthonous cases and four deaths reported across six provinces in 2026.
In 2026 to date, 671 of West Nile virus disease have been reported in 42 states, of which 495 (74%) neuroinvasive
10,364 probable cases and three deaths reported in Bahia state between January and September.
Six new confirmed cases reported, bringing the year's total to 6,928 across two islands.
3109 cases reported in 2026, with recent surge and cross-border spread to Costa Rica.
190 locally acquired cases reported across six counties, predominantly DENV-2 in Hillsborough County.
Third case of severe respiratory infection reported in metropolitan Perth; vaccination reviews urged.
Confirmed cases reported in Roebourne and Karratha; contact tracing and preventive measures implemented.
114 confirmed cases and 11 deaths recorded across 31 health districts; vaccination recommended.
37 multistate cases linked to imported clams, alongside a Los Angeles County community-wide outbreak.
Outbreaks declared in Blitta and Ogou with at least four confirmed cases; vaccination underway.
835 confirmed cases, 164 hospitalizations, and 4 deaths reported across 39 counties in 2026
280 cases and 22 deaths reported across most health regions amid waning immunity.
Six deaths and 101,384 people treated for animal bites in Ho Chi Minh City.
168 cases recorded between January and August 2026, a significant increase from last year.
448 cases registered by mid-September, marking the highest historical figure for this period.
Confirmed cases reported in Sissala East municipality following 21 mysterious deaths in the region.
Hikers on the GR20 trail report vomiting and diarrhea indicative of an outbreak.
Flea-borne typhus outbreaks in Louisiana and Los Angeles, with multiple cases requiring hospitalization.
Confirmed case in a Washington County male, the state's third case in 2026.
23 cases and 5 deaths reported across 14 counties so far this year.
At least 53 human cases linked to sick cattle meat across three northern districts.
10,936 cases reported in 2026 following monsoon flooding, exceeding epidemic thresholds across ten regions.
1086 confirmed cases and 259 deaths reported in 2026 outbreak, with weekly incidence declining.
7,890 cases, 3,799 deaths (CFR 48.1%), 1,133 additional cases since 11 September, across 63 health zones and 7 provinces
The ESCMID-AUMC Epi Alert, a strategic collaboration between the ESCMID Emerging Infections Subcommittee and the Center of Tropical Medicine and Travel Medicine of Amsterdam University Medical Center (AUMC) that integrates expertise and resources to advance emerging infectious diseases surveillance and intelligence sharing. This collaboration integrates ESCMID's extensive international network and emerging infections expertise with AUMC's proven surveillance capabilities, led by Dr. Abraham Goorhuis and the AUMC team and other collaborators form European Institutions.
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