Monkeypox in a Traveler Returning from Nigeria — Dallas, Texas, July 2021

Findings

On July 13, 2021, an emergency department (ED) physician in Dallas evaluated an early middle-aged man* with a 2-week history of fever, cough, and fatigue, followed by onset of a diffuse rash. Less than 1 week earlier, the patient had been in Nigeria for a large social gathering. Because of the extensive pustular rash on his face, hospital staff members immediately placed the patient in an airborne isolation room, where he was managed with airborne and contact precautions plus eye protection. After reviewing CDC’s Travelers’ Health destination webpage for Nigeria,^† the ED physician suspected monkeypox, and public health authorities were immediately notified. The following day, the Dallas County Health and Human Services Laboratory Response Network laboratory confirmed, by real-time polymerase chain reaction (PCR), the presence of nonvariola orthopoxvirus DNA from lesion swabs. Subsequent testing by species-specific real-time PCR at CDC confirmed West African clade Monkeypox virus.

Interviews revealed that the patient had arrived in Nigeria on June 25 and stayed in three urban centers during his trip (Figure). By June 30, he began experiencing diarrhea, vomiting, cough, subjective fever, and fatigue, all characteristic signs and symptoms of the monkeypox prodrome, which also mark the onset of transmissibility of the virus to others (e.g., through infected body fluids or respiratory droplets). On July 8, 1 day before boarding the first of two return flights, the patient developed a purulent rash confined to a covered part of his body. After a brief layover in the Atlanta airport, he took a domestic flight to Dallas, and then a ride-share vehicle to his residence, where he lives alone. The next day, the rash had worsened and was visible on his face, prompting a friend to drive him to the hospital on July 13. Like many persons his age, the patient had never received the smallpox vaccine, which would have provided cross-protection against monkeypox (2) but has not been routinely administered following the eradication of smallpox in 1980 (3).

Public Health Response

CDC, state and local public health authorities, and the treating clinicians launched an intensive investigation during July 13–September 4. Investigators reviewed what is known about orthopoxviruses and, through iterative discussions, categorized exposures as high, intermediate, low/uncertain, or no risk (Table). Exposures were ascertained through information collected from airport video surveillance, the patient’s report of his activities and interactions with others, and flight seating assignments. This activity was reviewed by CDC and was conducted consistent with applicable federal law and CDC policy.^§

Notifications were immediately issued to the public via press releases; clinicians through the Health Alert Network; country national focal points, including those in Nigeria, under guidelines of the International Health Regulations (2005); public health officials via an Epi-X^¶; and a call with state health departments. Airline and federal partners provided information for flight contacts. Simultaneously, investigators discussed disinfection of potentially contaminated surfaces. Transmission to passengers on subsequent flights was considered unlikely because the disinfectants used between flights included a label claim for inactivation of Vaccinia virus, suggesting effective inactivation of Monkeypox virus. Airport bathrooms used by the patient were confirmed to have been regularly cleaned with similarly effective products. The owners of the two cars used by the patient were instructed to disinfect high-touch surfaces in the car with such products.

A total of 223 contacts were identified. A 24/7 CDC monkeypox call center was established to coordinate daily monitoring from 21 U.S. jurisdictions where contacts resided and to provide clinical consultations to physicians who suspected additional cases. Recommendations about monitoring and PEP were strongest for persons with high (no persons) or intermediate (34 persons) risk. Some exposures were categorized or recategorized to a higher or lower risk level because of circumstances unique to this event. For example, typically, persons who used the same lavatory as the patient would be categorized as no risk; however, because the patient used the mid-cabin aircraft lavatory while he had a purulent rash on his body, investigators included passengers who used that same lavatory in the “low/uncertain” risk group. Similarly, persons seated adjacent to the patient on the domestic flight (<3 hours) had increased opportunities for contact with the patient’s skin or contaminated materials (e.g., shared arm rest); however, because it was uncertain whether this exposure had occurred, investigators categorized these as “low/uncertain” risk. Reaching identified travel contacts was challenging; some travelers were non-U.S. residents, had already departed the United States, or had provided inaccurate telephone numbers to airlines, all of which hindered timely contact tracing.

Approximately 1 week after the investigation began, investigators learned that early in the patient’s hospitalization, clinical specimens from the patient had been sent from the hospital to a laboratory in Utah for additional diagnostics. Conversations with the laboratory’s biosafety manager revealed that instrumentation used to process these specimens during July 13–19 might have resulted in aerosol generation outside of a biosafety cabinet where personnel were not wearing respirators; six laboratory personnel were accordingly added to contact monitoring.

Most (189; 85%) contacts were categorized as having “low/uncertain” risk. All monitoring of known contacts concluded on September 4, 2021, and no secondary cases in the United States were identified, including among persons with suspected cases reported by clinicians to the CDC call center. ACAM2000, the orthopoxvirus vaccine recommended after exposure to smallpox (4), might be helpful after exposure to Monkeypox virus and was available for this potential indication through a CDC Investigational New Drug Protocol. Local public health officials were recommended to consider ACAM2000 for the 34 contacts with intermediate risk; no contact for whom ACAM2000 was offered received the vaccine. The patient completed a 32-day hospitalization that included treatment with tecovirimat because of severe disease. Hospital discharge had been delayed until a remaining lesion tested negative for Monkeypox virus DNA by PCR; this ensured no infectious risk upon discharge but extended the hospitalization. Procedures for disinfection of his home were extrapolated from guidance previously developed by CDC for smallpox** and by Public Health England for monkeypox.^†† Whole genome sequencing confirmed that the Monkeypox virus strain was closely related to strains known to circulate in Nigeria. No specific source of his infection was identified in Nigeria; local staff members dispatched to the urban centers visited by the patient found no reported cases linked to him.

Discussion

This was the first travel-associated monkeypox case in the United States, and the seventh such case worldwide, since a large 2017 outbreak in Nigeria (5,6). Case recognition launched a large public health response involving extrapolation of limited data about monkeypox to develop a framework for managing potentially exposed persons and preventing additional cases.

The reservoir for Monkeypox virus has not been identified but is suspected to be a rodent or other small mammal or mammals (2). Before the 2017 Nigeria outbreak, most human monkeypox cases occurred in rural, forested areas of Africa; however, in Nigeria, monkeypox cases have occurred in urban areas, suggesting novel risk factors (1). Two distinct clades of Monkeypox virus circulate in Africa: the West African clade, which is endemic in west Africa, and the Congo Basin clade, which occurs in central Africa (2). Complicating the public health response, cases in Nigeria, although confirmed to be caused by the West African clade, have clinically been distinct: the West African Clade is historically believed to cause milder human disease, few deaths, and limited human-to-human transmission. However, some cases in Nigeria have been severe, even resulting in death, most commonly in persons with HIV infection (1,7). In addition, epidemiologic and genomic analyses have shown multiple human-to-human transmission events in Nigeria, including within households and a prison; secondary cases occurred in a health care provider and in family members of one patient whose illness was diagnosed in the United Kingdom (1,7,8).

Fortuitously, mask use during the ongoing COVID-19 pandemic ensured that contacts, including fellow airline passengers and crew members, community contacts, and health care providers, were at reduced risk for being infected with Monkeypox virus from this patient. Sparse data on Monkeypox virus epidemiology, increasing numbers of immunocompromised persons in the United States (9) (e.g., from chemotherapy and other therapeutics), and waning of immunity to orthopoxviruses since the eradication of smallpox and cessation of routine smallpox vaccination (2) led investigators in this situation to take a cautious approach. Clinical laboratory personnel are typically not at risk for exposure to Monkeypox virus; however, use of specific laboratory instruments near persons not wearing adequate personal protective equipment caused investigators to be concerned about exposure to aerosols. The possible presence of Monkeypox virus on the patient’s covered body during lavatory use similarly prompted a guarded approach; passengers who used that lavatory were monitored in the “low/uncertain” risk group. Most exposures occurred during airline flights that, relative to the time the patient was in the community and admitted to the hospital, were brief.

Four months after this case, an eighth travel-associated monkeypox case in a traveler from Nigeria occurred, also in the United States, prompting CDC to issue a Level 1 (Watch) Travel Health Notice for travel to Nigeria.^§§ Multiple reasons have been proposed for continued human cases in Nigeria, including population growth, increased human interaction with Monkeypox virus reservoirs because of deforestation and climate change, accumulation of unvaccinated cohorts, and declining smallpox vaccine immunity (1,10). The Nigerian Federal Ministry of Health continues to work to prevent, detect, and investigate monkeypox cases in Nigeria, but as cases continue to occur, U.S. public health and hospital authorities might consider developing local strategies for responding to future imported cases. Early clinical suspicion facilitated by elicitation of a complete travel history, use of appropriate infection control precautions, and timely identification of activities performed during the period of infectivity were among the most critical actions taken. Understanding the types of exposures that are most concerning for Monkeypox virus transmission, knowing contaminated surfaces need to be quickly identified and decontaminated, and anticipating potentially long hospitalizations and contact monitoring periods might also aid in planning for future cases (Box).

July 2021 Monkeypox Response Team

Asma’u Aminu-Alhaji, CDC; Lauren Andersen, CDC; Matthew Arduino, CDC; Nicolette Bestul, CDC; Megan Bias, CDC; Mary J. Choi, CDC; Crystal Gigante, CDC; Madison Harkey, CDC; Kate Hendricks, CDC; Yonette Hercules, CDC; Farah Husain, CDC; Oladipupo Ipadeola, CDC; Robynne Jungerman, CDC; Theodora Khan, CDC; Grishma Kharod, CDC; Amber Kunkel, CDC; Amanda MacGurn, CDC; Audrey Matheny, CDC; Timothy McCleod, CDC; Faisal S. Minhaj, CDC; Jenna Mink, CDC; Clint Morgan, CDC; Yoshinori Nakazawa, CDC; Donovan Newton, CDC; Eddy Ortega, CDC; Lalita Priyamvada, CDC; Kay Radford, CDC; Joseph Rehfus, CDC; Muhammad Muhammad Saleh, CDC; Michael B. Townsend, CDC; Rita Traxler, CDC; Florence Whitehill, CDC; Xianfu Wu, CDC; Hui Zhao, CDC; Michelle Carruthers, Dallas County Health Department, Texas; Ivory Gomez, Dallas County Health Department, Texas; Samantha Groppell, Dallas County Health Department, Texas; Juan Jaramillo, Dallas County Health Department, Texas; Daniel Serinaldi, Dallas County Health Department, Texas; Jose Serrano, Dallas County Health Department, Texas; Joey Stringer, Dallas County Health Department, Texas; Jenna Gettings, Georgia Department of Public Health; Jessica Pavlick, Georgia Department of Public Health; José David Retana, Texas Department of State Health Services; Shelley Stonecipher, Texas Department of State Health Services; Rachael Straver, Texas Department of State Health Services; Inger-Marie Vilcins, Texas Department of State Health Services; Leisha D. Nolen, Utah Department of Health.