Human Monkeypox Explained

Dr.  Bibus Amatya

Human monkeypox is a disease transmitted from animals to humans and is caused by the monkeypox virus. The virus belongs to the genus Orthopoxvirus, which also causes smallpox, camelpox and cowpox.

Epidemiology

The disease originated in sub-Saharan Africa where rodents are believed to be the primary hosts. Humans and monkeys are suggested to be incidental hosts. The disease was first reported in a 9 month old child from Zaire in 1970. Since then, it has primarily been concentrated in parts of Central and West African countries. 

However, the disease has started spreading globally in recent weeks. The World Health Organization (WHO) released a statement on Sunday (May 26) confirming 257 cases with a further 120 cases under observation. 

The cases have been identified in 23 member countries where the disease is not endemic. One death due to monkeypox has been reported from Nigeria. 

The virus is usually transmitted to humans after contact with the infected animal’s body fluids or lesions. Person to person contact can occur through broken skin surface, respiratory droplets or through the eyes, nose or mouth. It may also be transmitted through sexual contact. 

What are the signs and symptoms?

After an incubation period of 10-14 days, the onset of the disease is characterized by fever, malaise (feeling of being unwell) and swollen lymph nodes. Other symptoms include headache, backache, sore throat, cough and shortness of breath. 

The lymph nodes predominantly involved are the submandibular (below the jaw line), cervical (neck) and inguinal (groin) lymph nodes. Involvement of the lymph nodes helps the clinician to distinguish it from smallpox where there is no lymphadenopathy.

After 1-3 days, a body rash appears starting from the trunk and gradually spreading peripherally to involve the limbs. The rash may be raised reddish lesions or fluid filled lesions usually less than 1 cm in diameter. The typical progression of lesions over 2-4 weeks is from a reddish discolouration, to elevated reddish lesions, followed by formation of fluid filled lesions, drying of the lesions to form scabs and ultimately complete healing. 

The lesions may also be observed on the mouth, tongue and on the 

genitals.There may be involvement of the lungs (12%), eyes (4-5%) and the brain (1%). Death occurs in 1 out of 10 individuals during the second week of the disease. 

How do we diagnose monkeypox?

The diagnosis rests on detaile d clinical evaluation. Although the virus or antibodies against it may be detected by electron microscopy, IgG and IgM ELISA, the tests are nonspecific. Definite diagnosis is through isolation of the virus using PCR. 

Once the virus has been diagnosed, quarantine and vaccination are the only effective public health measures. Although there is no specific vaccine for monkeypox, the smallpox vaccine provides around 85% protection. 

Prevention

Eradication of monkeypox is not possible because of the presence of animal reservoirs. The Centers for Disease Control and Prevention (CDC) recommends vaccination with smallpox vaccine for health workers, animal handlers and laboratory workers. 

The vaccine can also be given within 14 days (but preferably within 4 days) after contact with a confirmed case. There is no currently licensed antiviral therapy for monkeypox infection. The disease usually heals on its own in 2-3 weeks. 

Should We Be Worried?

As the disease is not highly transmissible and most of the reported cases are mild, the probability of a COVID-19 scale pandemic is unlikely. We should still exercise caution and have a contingency plan to procure smallpox vaccine if the need arises. 

(The writer is dermatologist at PHECT Nepal, Kirtipur Hospital. bibush.amatya@gmail.com)