DNA Explainer: Understanding two strains and four stages of monkeypox

Monkeypox is fast spreading across the globe with more than 300 suspected and confirmed cases of the infection from across Europe and other countries. For the first time, the viral infection has spread to over 20 countries outside tropical areas of west and central Africa, where it predominently exists. 

In the latest addition, Ireland and Mexico on Saturday confirmed their first cases of the monkeypox after Argentina. Monkeypox has been around for years. The first human case was recorded in 1970 in the Democratic Republic of the Congo. Typically, monkeypox occurs in central and west Africa.  

Read | Fact check: Myths about the monkeypox viral infection busted

Monkeypox starts with fever, then general body aches, malaise and muscle aches. The first symptoms are similar to influenza. Those usually precede the development of a rash. According to the Centers for Disease Control and Prevention (CDC), the incubation period, that is from infection to symptoms, for monkeypox is usually 7 to 14 days, but it can range from 5 to 21 days.

Monkeypox is transmitted through close person-to-person contact with lesions, body fluids and respiratory droplets, and through contaminated materials such as clothing or bedding. Here we try to understand the general order of occurrence for monkeypox symptoms so that people become more aware of the disease and can seek doctor's help immediately. 

Stages of monkeypox symptoms

1. Prodromal period

Once a person catches the infection, there is an incubation period which lasts on average 7-14 days. The development of initial symptoms like fever, malaise, headache, weakness marks the beginning of the prodromal period. These symptoms are linked to the upper respiratory system and are very similar to flu.

2. Lymph nodes

Feature that distinguishes monkeypox infection with smallpox is the development of swollen lymph nodes or lymphadenopathy. Swelling of the lymph nodes may be generalised (involving many different locations on the body) or localised to several areas (neck and armpit).

3. Rashes

Shortly after the prodrome and lymph, a rash appears. The lymphadenopathy or occurrence of lumps may then progresses to a rash often found on the hands, feet, face, mouth, or even genitals, experts say.

4. Raised bumps or painful puss-filled red papules

In the final stage of monkeypox disease, these rashes usually transform into raised bumps or painful puss-filled red papules. The severity of illness can depend upon the initial health of the individual, the route of exposure, and the strain of the infecting virus (West African vs. Central African virus genetic groups, or clades). 

Different strains of monkeypox

There are two predominent strains of the infecting monkeypox virus, west African and central African virus genetic groups or clades.

West African monkeypox is associated with milder disease, fewer deaths, and limited human-to-human transmission in comparison.

Human infections with the central African monkeypox virus clade are typically more severe compared to those with the west African virus.

The central African monkeypox virus has a higher mortality. Person-to-person spread is well-documented for central African monkeypox virus.