For for the second time this year, the United States has an imported case of monkeypox. A traveler from Maryland who has just returned from Nigeria has been diagnosed with the dangerous disease, the Centers for Disease Control and Prevention said on Wednesday.
The unidentified person is isolated in Maryland, the CDC said in a statement. The Maryland Department of Health said in a statement that the individual has mild symptoms and is not in the hospital.
The earlier U.S. case this year occurred in Texas in July, also at a person who traveled to Nigeria. There were no secondary cases of the Texas patient, although more than 200 people who had contact with the individual were monitored.
The CDC said it is working with the airline on which the passenger was traveling, as well as with state and local health authorities in the Washington area to identify other passengers and people who may have been in contact with the infected person.
But the agency said it believes the risk of transmission while traveling will be lessened because people on flights are currently forced to wear masks.
In recent years there have been a number of reports of exported smallpox cases around the globe. Here are some facts about this rare disease:
Monkeypox is caused by a virus that is related to smallpox; both are Orthopox viruses. Smallpox, once a common pest, was declared extinct in 1980.
Its name suggests that it comes from monkeys, but that is actually not the case. The first time the virus was seen to cause an outbreak was in 1958, in a colony of research monkeys, the true reservoir of the virus remains unknown. Some African rodent species may be sensitive to the virus and have been seen as involved in its transmission. (More on that later.)
The disease in humans
The incubation for the disease – the time of exposure until the onset of disease – varies from five to 21 days. People who are infected initially develop a mild, flu-like illness – headache, fever, chills and swollen lymph nodes. But a few days later, a rash will appear, often starting on the face. The rash will usually spread to other parts of the body, although mainly to the extremities. Palms of the hands and soles of the feet are often affected.
Scar lesions will form at a stage of the disease, which can last between two and six weeks.
The disease can be fatal. In Africa, monkeypox was fatal in about 1 in 10 cases, with severe disease and death more likely among children.
Spread to and among people
The virus is transmitted to humans from infected animals, entering through cuts in the skin, the respiratory tract or the mucous membranes around the eyes or in the nose and mouth.
A major outbreak in the United States in 2003 – the first time monkeypox was reported outside Africa – saw 47 confirmed and probable cases reported from six different states. The outbreak was linked to infected exotic pets imported from Ghana, which in turn infected a number of prairie dogs sold as pets.
Person-to-person transmission can occur, and is thought to occur mostly through virus-laced droplets. But direct contact with injuries or body fluids of an infected person, or indirect contact with contaminated clothing or linen, can also result in transmission.
Where it is located
The virus appears to be present in a zone of countries in West and Central Africa, with locally obtained cases reported from Sierra Leone, Liberia, Ivory Coast, Nigeria, Cameroon, Gabon, Central African Republic, the Republic of the Congo, and the Democratic Republic of the Congo.
The United States, the United Kingdom, Israel, Benin, South Sudan, and Singapore have reported imported cases of monkeypox.
Unintended consequence of smallpox extermination
The WHO suggests that the risk of contracting monkeypox in countries where it is found may be greater in middle-aged and younger people – people who have not been vaccinated against smallpox in childhood.
The eradication of smallpox has led to the cessation of routine smallpox vaccination around the world, which may have contributed to the increase in human cases in Nigeria that has been observed since 2017, Australian scientists suggested in an article published earlier this year.