Legionnaires disease is a serious pneumonia caused by Legionella bacteria. During November 2022-June 2024, CDC was notified of 12 cases of Legionnaires disease among travelers on two cruise ships; eight on cruise ship A and four on cruise ship B. CDC, in collaboration with the cruise lines, initiated investigations to ascertain the potential sources of on-board exposure after notification of the second potentially associated case for each ship. Epidemiologic data collected from patient interviews and environmental assessment and sampling results identified private hot tubs on selected cabin balconies as the most likely exposure source. To minimize Legionella growth, both cruise lines modified the operation and maintenance of these devices by removing the heating elements, draining water between uses, and increasing the frequency of hyperchlorination and cleaning. Hot tubs offer favorable conditions for Legionella growth and transmission when maintained and operated inadequately, regardless of location. Private hot tubs on cruise ships are not subject to the same maintenance requirements as are public hot tubs in common areas. Given the range of hot tub-type devices offered as amenities across the cruise industry, to reduce risk for Legionella growth and transmission, it is important for cruise ship water management program staff members to inventory and assess private balcony hot tubs and adapt public hot tub maintenance and operations protocols for use on private outdoor hot tubs.

BACKGROUND: Cruise travel contributed to SARS-CoV-2 transmission when there were relatively few cases in the United States. By March 14, 2020, the Centers for Disease Control and Prevention (CDC) issued a No Sail Order suspending U.S. cruise operations; the last U.S. passenger ship docked on April 16. METHODS: We analyzed SARS-CoV-2 outbreaks on cruises in U.S. waters or carrying U.S. citizens and used regression models to compare voyage characteristics. We used compartmental models to simulate the potential impact of four interventions (screening for COVID-19 symptoms; viral testing on two days and isolation of positive persons; reduction of passengers by 40%, crew by 20%, and port visits to one) for 7-day and 14-day voyages. RESULTS: During January 19-April 16, 2020, 89 voyages on 70 ships had known SARS-CoV-2 outbreaks; 16 ships had recurrent outbreaks. There were 1,669 RT-PCR-confirmed SARS-CoV-2 infections and 29 confirmed deaths. Longer voyages were associated with more cases (adjusted incidence rate ratio, 1.10, 95% CI: 1.03-1.17, p < 0.0001). Mathematical models showed that 7-day voyages had about 70% fewer cases than 14-day voyages. On 7-day voyages, the most effective interventions were reducing the number of individuals onboard (43-49% reduction in total infections) and testing passengers and crew (42-43% reduction in total infections). All four interventions reduced transmission by 80%, but no single intervention or combination eliminated transmission. Results were similar for 14-day voyages. CONCLUSIONS: SARS-CoV-2 outbreaks on cruises were common during January-April 2020. Despite all interventions modeled, cruise travel still poses a significant SARS-CoV-2 transmission risk.

On March 14, 2017, the County of San Diego Health and Human Services Agency (COSD HHSA) notified CDC of a measles case in an adult airline passenger (patient A), with recent travel to Indonesia. The patient had developed rash and swollen eyes during a flight from Hong Kong to Los Angeles on March 8, followed by conjunctivitis and cough after arrival; the patient proceeded to an urgent care clinic, but a measles diagnosis was not considered. On March 9, patient A visited the clinic again, at which time measles was confirmed by polymerase chain reaction (PCR) testing on March 14. Patient A reported having received 1 dose of measles, mumps, and rubella (MMR) vaccine. CDC identified 22 contacts from the flight, involving seven U.S. states and two countries; potentially exposed flight crew were notified on March 15. COSD HHSA identified 483 community contacts, 81 of whom received self-quarantine recommendations because they lacked presumptive evidence of immunity.*

An estimated 30 million passengers are transported on 272 cruise ships worldwide each year* (1). Cruise ships bring diverse populations into proximity for many days, facilitating transmission of respiratory illness (2). SARS-CoV-2, the virus that causes coronavirus disease (COVID-19) was first identified in Wuhan, China, in December 2019 and has since spread worldwide to at least 187 countries and territories. Widespread COVID-19 transmission on cruise ships has been reported as well (3). Passengers on certain cruise ship voyages might be aged >/=65 years, which places them at greater risk for severe consequences of SARS-CoV-2 infection (4). During February-March 2020, COVID-19 outbreaks associated with three cruise ship voyages have caused more than 800 laboratory-confirmed cases among passengers and crew, including 10 deaths. Transmission occurred across multiple voyages of several ships. This report describes public health responses to COVID-19 outbreaks on these ships. COVID-19 on cruise ships poses a risk for rapid spread of disease, causing outbreaks in a vulnerable population, and aggressive efforts are required to contain spread. All persons should defer all cruise travel worldwide during the COVID-19 pandemic.

In December 2016, U.S. Customs and Border Protection notified the CDC Honolulu Quarantine Station of a crewman on a commercial fishing vessel who was hospitalized with suspected tuberculosis (TB); the crewman, in his mid-30s, was unconsciousness, intubated, and dependent upon mechanical ventilation to maintain his respiratory status. He was a native of a high TB-burden country (one with TB incidence exceeding 10 cases per 100,000 population per year)* in the Pacific region. Nine days earlier, he had been hospitalized in Hawaii following a 1-month history of headache, fever, night sweats, chills, fatigue, weight loss, breathing difficulties, and cough and recent onset of abdominal pain, vomiting, dizziness, and blurred vision. Brain computerized tomography (CT) and magnetic resonance imaging scans showed lesions in the left basal ganglia and left temporal lobe; chest CT showed multiple bilateral lung opacities with central cavitation. Pathology results from a lung biopsy demonstrated acid-fast bacilli with molecular and culture tests positive for Mycobacterium tuberculosis complex, susceptible to all first-line drugs. Cerebrospinal fluid demonstrated low glucose (23 mg/dL), elevated protein (247 mg/dL), and elevated white blood cell count (298 cells/uL) with a relative lymphocytic predominance (50%), consistent with TB meningitis. Testing for human immunodeficiency virus infection was negative, and the patient had no medical comorbidities. The Hawaii Department of Health (Hawaii DOH) was contacted to assist with the investigation.

The U.S. Code of Federal Regulations (42 §71.21) requires that the master of a ship destined to a U.S. port of entry report certain illnesses, as well as any death onboard to the nearest CDC Quarantine Station (1). On December 30, 2015, the U.S. Coast Guard notified CDC of the death of a crew member of a foreign cargo vessel off the coast of Puerto Rico. Four days earlier, on December 26, the patient, a man aged 50 years from India, developed abdominal pain, headache, and fever (103.0°F [39.4°C]), followed by loose stools and pruritus. On December 28, a vesicular rash appeared on his face, neck, and shoulders. Medical consultants suspected varicella and recommended shipboard isolation. On December 29, the vesicles had begun to dry and scab, and he developed a nonproductive cough and reported chest congestion. On December 30, he had difficulty breathing and collapsed; cardiopulmonary resuscitation was unsuccessful. The Puerto Rico Department of Health was contacted to liaise with the medical examiner. Lung tissue and skin lesion specimens collected at autopsy were positive for varicella-zoster virus DNA by polymerase chain reaction at CDC. The cause of death was reported as varicella pneumonia. No other medical conditions were reported. | Per CDC recommendations, all 24 shipmates were considered contacts of the index patient; the master of the ship instituted daily temperature and rash surveillance for 21 days (i.e., one incubation period) after the death. On days 13 and 16 of surveillance, two crew members were sent home because of emergencies unrelated to varicella. San Juan and Houston CDC Quarantine Stations coordinated varicella vaccination for the 22 remaining and five new crew members boarding after the end of the 21-day surveillance, all of whom had unknown varicella immunity. Acyclovir was procured by the ship for treatment of possible additional cases; however, none occurred.

On June 2, 2015, CDC was notified that a male airline passenger, aged 41 years, with a fever of 105.4 degrees F, headache, nausea, photophobia, diarrhea, and vomiting, which began approximately 3 hours after departure, was arriving to San Francisco, California, on a flight from Frankfurt, Germany. His symptoms reportedly started with neck stiffness 1 day earlier. Upon arrival, the patient was immediately transported to a local hospital, where he was in septic shock, which was followed by multisystem organ failure. Cerebrospinal fluid, obtained approximately 12 hours after initiation of treatment, was Gram stain- and culture-negative. Blood cultures, which were drawn before antibiotic treatment, were positive for Neisseria meningitides of indeterminate serogroup. A review of the patient's medical records revealed a history of paroxysmal nocturnal hemoglobinuria and current biweekly eculizumab (Soliris) therapy.