“Community Transmission”(CT) and “Categorisation of diseases”

What is the News?

India is registering the highest number of cases globally every day. But the World Health Organization(WHO) Report mentions, India is yet to label itself in the category of community transmission(CT).

Note: Currently, India has labelled itself in the category of ‘cluster of cases’ category.

About Categorisation of diseases: 

In general, the World Health Organization (WHO) uses the following categories to describe transmission patterns:

• Sporadic cases,
• Clusters of cases
• Community transmission.

What is the category of the Sporadic case?

• These are a small number of cases (one or more) either imported or detected locally  

What is the Cluster of Cases category?

• Cluster transmission has been used by Indian authorities to identify infections that are largely concentrated in a limited locality. The disease concentration is often within a family and its extended circle.
• Under this, cases detected in the past 14 days are predominantly limited to well-defined clusters. Further, the disease detected will not directly be linked to imported cases.

What is Community Transmission(CT)?

• It means that the epidemic has become so widespread in a community. Further, it gets difficult (if not impossible) to determine who is passing on the infection to whom.
• In simple terms, Community Transmission is classified when the source of the infection is not known.
• CT will happen when new cases in the last 14 days cannot be traced to those who have an international travel history or to any specific cluster.

Stages of Community Transmission: WHO guidelines suggest four subcategories within the broader definition of CT:

• CT1: Low incidence of locally acquired cases detected in the past 14 days
• CT2: Moderate incidence of locally acquired cases detected in the past 14 days
• CT3: High incidence of locally acquired cases in the past 14 days
• CT4: Very high incidence of locally acquired cases in the past 14 days.

Countries classified under Community Transmission:

• Countries such as the United States, Brazil, United Kingdom, France have labelled themselves as being in ‘community transmission’.
• However, among the countries with the most number of confirmed cases, Italy and Russia do not label themselves as being in community transmission.

Government policy based on Categorisation:

• India’s refusal to describe itself as being in community transmission had an effect on how the authorities addressed the pandemic.
• Under Cluster Transmission, the government gives priority to testing, contact tracing and isolating to prevent further infection.
• On the other hand, under community transmission, the government prioritises treatment and observing advisories to stay protected.

Source: The Hindu

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