Cabo Verde Travel Outbreak, RSV Mortality, and TB Findings: April 2026 Roundup

Overview

Several distinct disease developments are demanding public health attention this April. The most urgent is an ongoing multi-country outbreak of shigellosis and related gastrointestinal infections traced to travel to Cabo Verde, the Atlantic archipelago off the coast of West Africa. Case counts have crossed four digits with no sign of tapering off. Simultaneously, new clinical data quantify the lethal toll that respiratory syncytial virus (RSV) is extracting from hospitalized older adults — a burden long underappreciated relative to influenza. And a novel ultrasensitive diagnostic test has surfaced a surprisingly high rate of tuberculosis DNA in routine respiratory samples from two Boston hospitals, raising questions about what standard screening has been missing. Together, these developments paint a picture of a global disease landscape where familiar pathogens continue to outpace the assumptions built around them.

Current Situation

shigellosis bacteria lab culture Image: Pexels/Edward Jenner

As of mid-March 2026, the European Centre for Disease Prevention and Control (ECDC) reported over 1,000 confirmed and probable cases of shigellosis and other gastrointestinal infections — including salmonellosis — among travellers returning from Cabo Verde. Cases have been identified in multiple nations across the European Union and European Economic Area (EU/EEA), as well as in the United Kingdom and the United States. The ECDC notes that new cases were still being reported at the time of the epidemiological update, meaning the final count is expected to climb further.

Shigellosis is caused by Shigella bacteria and produces a dysenteric illness characterized by bloody diarrhea, fever, and severe abdominal cramps. Even a small infectious dose — as few as ten to a hundred organisms — can cause disease, which makes it notably easy to transmit through contaminated food, water, and person-to-person contact. The overlap with salmonellosis in the same travel cohort suggests a shared environmental source, most likely food or water at tourist-facing establishments, though the precise vehicle has not been publicly identified.

On the respiratory front, a new analysis published in mid-April and covered by CIDRAP delivers sobering numbers on RSV outcomes in hospitalized adults. Among patients aged 60 and older admitted with RSV infection, the 30-day mortality rate was 12% and the 90-day mortality rate reached 19%. These figures place the short-term death toll of severe RSV in older patients firmly in the range associated with serious influenza hospitalizations — a comparison that should sharpen clinical and policy attention on the virus heading into the next respiratory season.

The 2025–2026 influenza season, meanwhile, appears to be receding. CDC surveillance data from early April show outpatient visits for influenza have dropped below the national baseline and weekly hospital admissions are declining week over week. However, four additional pediatric influenza deaths were reported in the most recent reporting week, bringing continued grief even as the broader epidemic curve flattens. Pediatric flu fatalities remain a sobering reminder that seasonal influenza is not a benign illness, particularly for children with underlying conditions.

Affected Regions

The Cabo Verde outbreak is geographically dispersed across the destination countries of European and North American tourists. Cabo Verde has become a popular package-holiday destination, particularly for travellers from the United Kingdom, Scandinavia, and other parts of Northern and Western Europe. The ECDC’s epidemiological update does not name individual EU member states with the largest caseloads, but the breadth of affected countries underscores how quickly travel-associated outbreaks can seed cases across an entire continent within weeks.

Within the United States, cases remain linked to international travel rather than indicating domestic community transmission of the outbreak strain. That distinction matters: there is no current evidence that the Cabo Verde-linked strains are spreading person-to-person in the US general population at this time, though secondary household transmission from returning travellers is plausible given shigellosis’s low infectious dose.

The RSV mortality findings are drawn from a clinical dataset rather than a geographically bounded outbreak, making them relevant globally wherever aging populations are in contact with respiratory viruses. The TB DNA finding is more geographically specific: the elevated detection rate — up to 16% of respiratory samples testing positive for tuberculosis DNA — was recorded at two major hospitals in Boston, Massachusetts, according to CIDRAP’s coverage of the study. Whether this signal reflects genuine subclinical TB burden, environmental DNA contamination of the samples, or a feature specific to that hospital’s patient population remains under investigation, but the finding has drawn significant attention from infectious disease specialists.

On TB vaccines, a large phase 3 trial conducted in India — enrolling 12,717 household contacts of recently diagnosed TB patients — evaluated two candidate vaccines, VPM1002 and Immuvac, and found that both offered only limited protection. This result is a setback for TB prevention efforts in high-burden settings.

Risk Assessment

hospital workers PPE respiratory care Image: Pexels/Max Mishin

For the Cabo Verde shigellosis outbreak, the primary risk population is travellers who have recently visited or are planning to visit the islands. The risk to the general public in affected destination countries is low unless there has been direct exposure to a returned traveller’s illness or to implicated food products. Shigella strains circulating in this outbreak have not been publicly characterized for antibiotic resistance at this stage, but drug-resistant shigellosis has been increasing globally, and clinicians should be aware of this possibility when managing returning travellers with dysenteric illness.

Travellers who have recently returned from Cabo Verde with gastrointestinal symptoms — particularly bloody diarrhea — should seek medical evaluation promptly and inform their provider of their travel history.

The RSV data represent a population-level risk assessment revision rather than an active outbreak. The high 90-day mortality among hospitalized older adults — 19% — underscores that RSV is not merely a pediatric illness and that older adults, particularly those with cardiopulmonary comorbidities, face a genuinely serious threat from infection. Adults aged 60 and over are the highest-risk group for severe RSV outcomes.

The unexpected tuberculosis DNA findings from Boston hospitals warrant cautious interpretation. A positive result on an ultrasensitive assay does not necessarily equate to active TB disease. However, if the signal reflects real subclinical or paucibacillary infection that standard diagnostics have been missing, it could indicate that TB burden in urban US hospitals is higher than current surveillance captures. This has significant implications for infection control and screening protocols.

Prevention & Response

For the Cabo Verde outbreak, the ECDC update serves as a formal alert to clinicians across affected countries to maintain heightened suspicion for shigellosis and salmonellosis in patients with recent travel to the islands. Standard management of shigellosis includes supportive hydration and, in moderate-to-severe cases, antibiotic therapy — though treatment choice should account for local resistance patterns.

Travellers to Cabo Verde should follow standard food and water precautions: drink bottled or treated water, avoid raw produce washed in tap water, and exercise caution at buffet-style or street food settings. Hand hygiene is a cornerstone of prevention given Shigella’s low infectious dose and ease of person-to-person spread.

On RSV, FDA-approved RSV vaccines for adults aged 60 and older are available and have been recommended by the US Advisory Committee on Immunization Practices (ACIP). The new mortality data reinforce the case for uptake in this age group ahead of the next respiratory virus season. Nirsevimab, the monoclonal antibody prophylactic for infants, addresses the pediatric side of the RSV burden.

The TB vaccine trial failure highlights the continued unmet need for an effective post-exposure or adult TB vaccine. BCG, the only currently licensed TB vaccine, offers limited protection in adults and adolescents. The VPM1002 and Immuvac results add to a history of phase 3 disappointments in TB vaccinology and suggest that novel immunological approaches will likely be needed. In the meantime, contact investigation, rapid diagnosis, and directly observed therapy remain the primary tools for TB control in high-burden settings.

For the Boston TB DNA findings, hospital infection control teams at the studied institutions are likely reviewing their protocols. At the population level, the takeaway is that next-generation diagnostics may reshape understanding of TB’s footprint even in low-incidence countries — and that public health agencies will need to determine how to act on signals that fall outside the current diagnostic framework.

Sources

European Centre for Disease Prevention and Control (ECDC) — Epidemiological update: Shigellosis and other gastrointestinal infections in travellers returning from Cabo Verde (March 18, 2026)
CIDRAP — RSV tied to high complication, death rates in hospitalized older adults (April 13, 2026)
CIDRAP — CDC data suggest flu is on the way out (April 3, 2026)
CIDRAP — Ultrasensitive test detects tuberculosis DNA in unexpected number of US patients (April 15, 2026)
CIDRAP — TB vaccine candidates offer limited protection in phase 3 trial (April 13, 2026)