Clinical Review

Monkeypox: Another emerging threat?

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What do we know about this infection, and how do we treat it during pregnancy?



CASE Pregnant woman’s husband is ill after traveling

A 29-year-old primigravid woman at 18 weeks’ gestation just returned from a 10-day trip to Nigeria with her husband. While in Nigeria, the couple went on safari. On several occasions during the safari, they consumed bushmeat prepared by their guides. Her husband now has severe malaise, fever, chills, myalgias, cough, and prominent submandibular, cervical, and inguinal adenopathy. In addition, he has developed a diffuse papular-vesicular rash on his trunk and extremities.

  • What is the most likely diagnosis?
  • Does this condition pose a danger to his wife?
  • What treatment is indicated for his wife?

What we know

In recent weeks, the specter of another poorly understood biological threat has emerged in the medical literature and lay press: monkeypox. This article will first review the epidemiology, clinical manifestations, and diagnosis of this infection, followed by a discussion of how to prevent and treat the condition, with special emphasis on the risks that this infection poses in pregnant women.


The monkeypox virus is a member of the orthopoxvirus genus. The variola (smallpox) virus and vaccinia virus are included in this genus. It is one of the largest of all viruses, measuring 200-250 nm. It is enveloped and contains double-stranded DNA. Its natural reservoir is probably African rodents. Two distinct strains of monkeypox exist in different geographical regions of Africa: the Central African clade and the West African clade. The Central African clade is significantly more virulent than the latter, with a mortality rate approaching 10%, versus 1% in the West African clade. The incubation period of the virus ranges from 4-20 days and averages 12 days.1,2


Monkeypox was first discovered in 1958 by Preben von Magnus in a colony of research monkeys in Copenhagen, Denmark. The first case of monkeypox in humans occurred in the Democratic Republic of Congo in 1970 in a 9-year-old boy. Subsequently, cases were reported in the Ivory Coast, Liberia, Nigeria, and Sierra Leone. The infection was limited to the rain forests of central and western Africa until 2003. At that time, the first cases in the United States were reported. The US cases occurred in the Midwest and were traced to exposure to pet prairie dogs. These animals all came from a single distributor, and they apparently were infected when they were housed in the same space with Gambian rats, which are well recognized reservoirs of monkeypox in their native habitat in Africa.1-3

A limited outbreak of monkeypox occurred in the United Kingdom in 2018. Seventy-one cases, with no fatalities, were reported. In 2021 another US case of monkeypox was reported in Dallas, Texas, in an individual who had recently traveled to the United States from Nigeria. A second US case was reported in November 2021 from a patient in Maryland who had returned from a visit to Nigeria. Those were the only 2 reported cases of monkeypox in the United States in 2021.1-3

Then in early May 2022, the United Kingdom reported 9 cases of monkeypox. The first infected patient had recently traveled to Nigeria and, subsequently, infected 2 members of his family.4 On May 18, the Massachusetts Department of Public Health confirmed a case of monkeypox in an adult man who had recently traveled to Canada. As of July 7, 6,027 cases have been reported from at least 39 countries.5 Eight states in the United States reported cases. To date, 73 deaths have occurred in this recent outbreak of infections (case fatality rate, 4.5%).4-6

The current outbreak is unusual in that, previously, almost all cases occurred in western and central Africa in remote tropical rain forests. Infection usually resulted from close exposure to rats, rabbits, squirrels, monkeys, porcupines, and gazelles. Exposure occurred when persons captured, slaughtered, prepared, and then ate these animals for food without properly cooking the flesh.

The leading theory is that the present outbreak originated among men who had sex with men at 2 raves held in Spain and Belgium. The virus appears to have been spread by skin-to-skin contact, by respiratory droplets, by contact with contaminated bedding, and probably by sperm.2,4,6

Continue to: Clinical manifestations...


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