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COVID-19 and Other Seasonal Co-Infections

Published on Nov 05, 2020 and last reviewed on May 03, 2022   -  7 min read


This article discusses the onset of disease, symptoms, complications, and warning signs to differentiate COVID-19 from various other seasonal co-infections.

COVID-19 and Other Seasonal Co-Infections


COVID-19 and its variants has affected almost all the countries in the world. With the symptoms of COVID-19 not very specific and the prevalence of other seasonal infections every year, it is becoming a challenge to diagnose patients who present with influenza-like illnesses (ILI). Diseases like malaria, dengue, seasonal flu, chikungunya, leptospirosis, etc., can mimic COVID-19 or may coexist in patients affected by the coronavirus. This makes clinical and laboratory diagnosis of COVID-19 challenging and also affects the management and outcomes. This article will provide information on the signs and symptoms of various seasonal co-infections and ways to differentiate them from COVID-19.

Symptoms of COVID-19:

COVID-19 patients may present with:

The other symptoms include:

The symptoms are not very specific, and various other seasonal infections can mimic COVID-19. If a COVID-19 patient is co-infected with any other disease, he or she will still exhibit the same symptoms, which may lead to difficulty in diagnosis. Knowledge about the onset of disease, symptoms, complications, and warning signs can help differentiate COVID-19 from these infections.

What Are the Possible Seasonal Co-Infections?

The following co-infections should be suspected in moderate to severe COVID-19 cases if they are not responding to treatment:

1) Malaria - It is a life-threatening viral infection transmitted through the bite of an infected Anopheles mosquito. These mosquitoes carry the Plasmodium parasite. This parasite gets released into the bloodstream when they bite. Once inside the body, these parasites reach the liver and mature. The mature parasites enter the bloodstream again and infect red blood cells. In 2 to 3 days, the parasites inside the red blood cells multiply and destroy the cell. The parasites continuously infect other red blood cells and cause symptoms. It is common in tropical and subtropical climates.


The symptoms develop within 10 to 14 days of the mosquito bite. The symptoms include -

The warning signs of malaria include high-grade intermittent fever, tiredness, vomiting, and low urine output.


2) Dengue - It is also a mosquito-borne viral infection, commonly seen in tropical and subtropical areas of the world. These viruses are spread to humans through the bites of infected Aedes species mosquitoes. Dengue fever is common in Southeast Asia.


Usually, children and teens might not experience any symptoms during mild dengue fever. In case symptoms occur, they begin 4 to 7 days after getting bitten by the infected mosquito. The signs and symptoms are -

Sometimes, the blood vessels get damaged, and the platelet numbers fall, resulting in hemorrhage and is called dengue hemorrhagic fever or dengue shock syndrome or severe dengue. The warning symptoms include -


3) Chikungunya - Chikungunya is also a viral infection transmitted by the same mosquitoes that transmit the dengue virus, Aedes aegypti, and albopictus. They usually bite during the day and also at night. This infection should be suspected during monsoon in places where chikungunya endemics are common.


The following symptoms of chikungunya generally begin in 3 to 7 days after getting bitten by an infected mosquito -

The warning signs of chikungunya are high fever with increasing joint and muscle pain.


4) Seasonal Influenza - Infection with the influenza virus, most commonly with types A and B, results in seasonal influenza or the flu. The transmission occurs through infected droplets spread and touching infected surfaces, similar to COVID-19. As both COVID-19 and seasonal influenza are Influenza-Like Illness (ILI), patients with these symptoms should be evaluated for COVID-19 and seasonal influenza.


The onset of symptoms takes 1 to 4 days. The infected person exhibits -


5) Leptospirosis - It is a rare bacterial infection caused by the bacteria Leptospira. It is transmitted to humans when skin wounds are exposed to water or soil contaminated with infected animals' urine. It is commonly seen in tropical and subtropical countries and in both urban and rural settings, mostly during or after the monsoon.


The following symptoms might take 2 to 26 days to be apparent -


6) Scrub or Bush Typhus - It is a disease caused by the bacteria Orientia tsutsugamushi. The bacteria spread to humans through bites of infected larval mites (chiggers). This bacterial infection is prevalent in Southeast Asia, China, Indonesia, Japan, India, and northern Australia.


People infected with this bacteria might show the following symptoms, approximately 10 days of being bitten -

If left untreated, organ failure and internal bleeding can result in death.

7) Bacterial Co-Infections - Apart from these infections, patients with COVID-19 pneumonia can experience any secondary bacterial infection. So it is essential to test and treat all possible infections along with COVID-19 to improve prognosis.

8) Enteric Fever- (Also known as typhoid or paratyphoid fever). It is caused by infection due to bacteria, namely Salmonella typhi, and Salmonella paratyphi. The infections are transmitted through contaminated food and water.



How to Differentiate COVID-19 From These Infections?

As the symptoms of the commonly occurring seasonal infections are so similar, the only certain way to differentiate them is by testing. The following signs might help differentiate the conditions to an extent.

COVID-19 and Other Seasonal Co-Infections

What Are the Preventive Strategies for COVID-19 and Other Seasonal Co-infections?

Even though the preventive strategies of seasonal co-infections and COVID-19 are different, there is a synergy in the prevention of these diseases. Basic preventive measures for COVID-19 like getting vaccinated, maintaining physical distance, avoiding large gatherings, cough etiquette, and hand hygiene must be ensured at all times.

Vector control is needed to reduce mosquito breeding sites. The use of approved insect repellents is effective against vector-borne diseases, including scrub typhus. The preventive measure against leptospirosis includes wearing protective clothing for people at occupational risk, such as rice-paddy, sanitation workers, sugarcane workers, etc., and avoiding swimming in contaminated water. High-risk groups and all health care workers should be vaccinated for seasonal influenza. In addition, community support and awareness on COVID-19 and other seasonal diseases must be ensured.


One or more infections can coexist in moderate to severely ill COVID-19 patients, which makes it crucial to differentiate and diagnose these conditions to prevent complications, including death. So, proper and reliable testing is needed.

For more information, consult a doctor online at

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Last reviewed at:
03 May 2022  -  7 min read




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