Since early May 2022, monkeypox has been detected in 94 countries with more than 40,000 infections and 12 deaths. Of these 94 countries 97% historically have not reported monkeypox earlier, indicating geographic spread with probability of variant form. United States has reported almost one-third of the cases with no death. In India so far 10 cases have been reported.
Monkeypox virus (MPXV) was first described in humans in 1970 in the Democratic Republic of Congo (formerly Zaire). Until May 2022, sporadic outbreaks of infection have been reported in Africa. Also limited secondary spread outside Africa typically originating from contacts with wildlife reservoirs (particularly rodent) were known. Genetic analysis of monkeypox virus have identified two distinct lineages of monkeypox – Central African (Congo Basin) clade and the West African clade. Typically, Central African monkeypox viruses are associated with more severe disease, higher mortality (1-10%), and more frequent human-to-human transmission. The current outbreak is the first multi-country epidemic without known epidemiological links to West or Central Africa. Monkeypox virus, in the current outbreak outside of Africa, has been confirmed to belong to a West African strain. This sudden appearance of monkeypox in several nonendemic countries indicates that there may be a period of undetected transmission, as well as recent expansion events.
MPXV belongs to family of orthopoxviruses which are most complex group of DNA viruses. It can be transmitted from human to human by close contact with lesions, body fluids, respiratory droplets and contaminated materials. With incubation period raging 5-21 days, infection with monkeypox virus is generally self-limited with symptoms such as: fever, myalgia, fatigue and headache, often followed by maculopapular rash at the site of primary infection that can spread to other parts of the body. Most of the cases have mild symptoms for 2-4 weeks. In severe cases who are mostly immunocompromised individuals may experience complications such as pneumonitis, encephalitis, keratitis, and secondary bacterial infections. Recent epidemiologic studies of human monkeypox infections have shown that younger children, pregnant women, and persons not vaccinated against smallpox may suffer from severe disease and complications.
Since monkeypox is clinically similar to chickenpox or smallpox it is often misdiagnosed. The major symptom distinguishing monkeypox (MPX) from smallpox is the lymph node enlargement caused by MPXV that often occurs at the onset of fever. Chickenpox lesions are usually more superficial in appearance with irregular borders and can be present at multiple stages on any one site on the body. Clinically suspected cases need confirmation by molecular tests such as Real Time PCR. Viral swabs can be collected from one or more vesicles or ulcers and transported in viral transport medium. Generally, Real Time PCR is positive within 5 days of appearance of symptoms; confirmed cases continue to test positive by Real Time PCR for 21 days after onset of the symptoms. Similarly it has been observed that 70% of high contact-areas such as blankets, bed, coffee machine, and computer can harbour virus for up to 20 days after onset of symptoms. Presently skin lesion/vesicles or ulcer swabs are preferred specimen type since viral loads in other specimen types such as blood/body fluids is very low. In India, Real Time PCR test is performed for clinically indicated high-risk travellers at ICMR nodal labs.
As per experts since the clinical presentation may be atypical in this outbreak, differential diagnosis must include monkeypox when a patient presents with a sexually transmitted infection (STI)-associated or STI-like rash. The very first monkeypox case in India was reported on 14th July 2022. Within 15 days, genome sequencing for first two cases in India was concluded by ICMR. Genome sequencing data indicates both these cases were infected with A.2 variant; whereas the current super-spreader in parts of Europe is B.1 variant. Also recent reports indicate the surge in cases globally could be due to asymptomatic or subclinical infections.
Agilus Diagnostics, a subsidiary of Fortis Healthcare Limited
