The CoviD-19 saga: IMPORTED CASE vs LOCAL TRANSMISSION vs COMMUNITY TRANSMISSION

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Imported case, and local and community transmissions are not exactly exclusive to CoViD-19 cases.  These are terminologies widely used in epidemiology to describe outbreaks or contagion. But in line with the recent pandemic, we’ll be differentiating each in the context of CoviD-19.

IMPORTED CASE

The Centers for Disease Control and Prevention’s  defines imported case with vector-borne infections such as Dengue and Zika is one when a person travels to an an affected area and gets bitten and subsequently infected. An imported case of CoviD-19 happens when a person infected with CoviD-19 travels to a place without any known infection.

For example, a patient in Wuhan travels to the Philippines (which has no known infections yet) is considered an imported case. Another example would be when a Repatriate OFW who is infected with CoviD-19 returns to the province, where the province records it as a case but is then labelled imported.

In other words, the source of the disease is not within the locality but from outside coming in.

LOCAL TRANSMISSION

According to the World Health Organization, local transmission is when the source of the disease is not from imported cases but within the “locality” or the area. A local transmission can easily be from an imported case who infected people when they travelled there.

Local transmission is usually isolated to a small area, like a household, and the origin of the disease can be traced back towards the imported case.

An example of local transmission would be within the household, a relative returning home would infect a member of the household, and that member infects the rest of the household. While the relative who returned is an imported case, the member infected by the imported case and subsequently infected the rest of the household is what is known as local transmission.

COMMUNITY TRANSMISSION

Community transmission is when people start contracting the disease but cannot be traced back to any source, may it be local transmission or imported cases.

An example would be cases that have no travel history or have no known contact with people who are infected. This does not mean that a person independently developed the disease, but somehow acquired it unknowingly from a person who also unknowingly acquired it somewhere else, as there is always a source for the disease, albeit this time it’s untraceable.

These three types of transmissions can also be described as the three stages of spread.  In the first stage, a contagion is carried by imported cases to a place (like our country, which was CoviD-19 free before, and became bombarded initially by imported cases from tourists, travelers and returning OFWs). 

The second stage is when an imported case started to infect a person or persons and subsequently that person infected a group, from as small as a household to as big as a bank corporation. Subsequently when cases start to appear and cannot be traced to any source, it can be labeled as a community transmission or aptly the third stage of spread.

The importance of preventive measures such as hygiene, masks, isolation, mass testing and contact tracing are enough to alleviate further spread if done religiously.

There are cases of suspected community transmissions that are actually imported cases (like patients who didn’t reveal travel history) thus completely undermining prevention efforts as contact tracing is a global initiative.

Countries will need to note that an imported case is from them as it will also help them in their prevention efforts.

The terminologies are important, yes, but at the end of the day, may it be good or bad government policies, we as individuals have a responsibility in disease prevention.

Wear masks, wash hands, never touch the face, and keep social distancing.

The Philippines have cases of community transmission and the safest mindset we can come up with is that everybody is infected.

Stay safe.

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