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COVID-19 and Other Seasonal Co-Infections

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COVID-19 and Other Seasonal Co-Infections

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

Medically reviewed by

Dr. Ajmera Jail Singh

Published At November 5, 2020
Reviewed AtMay 2, 2023


COVID-19 and its variants have affected almost all countries in the world. With the symptoms of COVID-19 not being 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:

  • High fever.

  • Cough.

  • Tiredness.

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 two to three 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 -

  • Chills and tremors.

  • High fever.

  • Headache.

  • Vomiting and nausea.

  • Profuse sweating.

  • Stomach pain.

  • Diarrhea.

  • Anemia.

  • Muscular pain.

  • Convulsions.

  • Bloody stools.

  • Coma.

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


  • Altered sensorium - Alteration in the mental status.
  • Acidosis hypoglycemia - Inborn errors of carbohydrate metabolism leading to fasting hypoglycemia.
  • ARDS (acute respiratory distress syndrome) - Lung injury allowing fluid to leak into the lungs.

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 four to seven days after getting bitten by the infected mosquito. The signs and symptoms are -

  • High fever of 104 °F.

  • Bone, muscle, and joint pain.

  • Headache.

  • Nausea and vomiting.

  • Swollen lymph nodes.

  • Skin rashes.

  • Pain behind the eyes.

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 -

  • Severe stomach pain.

  • Severe vomiting.

  • Nosebleeds and bleeding from gums.

  • Blood in vomit, stools, and urine.

  • Bruising.

  • Rapid breathing.


  • Hypotensive shock - Condition that occurs due to sudden loss of fluids or blood from the body.
  • Bleeding - Loss of blood either inside or outside the body.
  • Metabolic derangement - It is a cluster of conditions that increase the risk of diabetes, heart disease, and stroke.

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 three to seven days after getting bitten by an infected mosquito -

  • Fever as high as 104 °F.

  • Joint and muscle pain.

  • Headaches.

  • Skin rashes.

  • Joint swelling.

  • Nausea and vomiting.

  • Conjunctivitis (rarely).

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


  • Cardiovascular decompensation - Inability to accommodate blood within the normal physiological pressure levels.
  • Myocarditis - The middle layer of the heart wall becomes inflamed.
  • Renal failure - Failure of one or both kidneys.
  • Hemorrhage.
  • Meningoencephalitis - Due to the infection, inflammation of the brain occurs.

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 one to four days. The infected person exhibits -

  • Fever.

  • Cough.

  • Runny nose.

  • Sore throat.

  • Body pain.

  • Tiredness.

  • Headaches.


  • ARDS (acute respiratory distress syndrome).
  • Myositis - Inflammation in muscles.
  • Rhabdomyolysis - Direct or indirect muscle injury.
  • Acute MI (myocardial infarction).
  • Myocarditis.

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 -

  • High fever.

  • Chills or rigors.

  • Muscle pain.

  • Headaches.

  • Yellowish skin and sclera.

  • Red eyes.

  • Stomach pain.

  • Diarrhea.

  • Skin rashes.


  • Acute respiratory distress syndrome (ARDS).
  • Uveitis - Inflammation of the eye.
  • Optic neuritis - Inflammation of the optic nerve.
  • Peripheral neuropathy - Damage to the nerves, especially the hands and feet.
  • Myocarditis.
  • Rhabdomyolysis.

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 -

  • High fever.

  • Chills.

  • Muscle and body pain.

  • Eschar - A dark lesion at the site of the bite.

  • Confusion.

  • Coma.

  • Enlarged lymph nodes.

  • Skin rashes.

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 the 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.


  • Fever that starts low, increases daily, and reaches as high as 104.9 F.
  • Fatigue and weakness.
  • Headache.
  • Weight loss and loss of appetite.
  • Dry cough.
  • Sweating.
  • Rashes.
  • Stomach ache and swollen belly.
  • Constipation or diarrhea.


  • The patient may become delirious (disturbed state of mind).
  • Typhoid state- The patient lies motionless and exhausted with the eyes half-closed.
  • Life-threatening condition.

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 iCliniq.com.

Frequently Asked Questions


Is COVID- 19 a Cause of Bronchitis?

Viruses that cause colds and the flu typically cause them. However, it might also be a sign of COVID-19. Bronchitis can be brought on by coronaviruses and other viruses that affect the respiratory system. This can occasionally result in pneumonia, an infection of the lungs' small air sacs.


What Seasonal Illnesses Are There?

Children's illnesses like measles, diphtheria, chickenpox, fecal-oral infections like cholera and rotavirus, vector-borne illnesses like malaria, and even sexually transmitted gonorrhea are among the human diseases contagious throughout certain seasons.


How Can Seasonal Illnesses Develop?

Seasonal variations in the number of vectors, such as mosquitoes, ticks, snails, fleas, and flies, are well-known factors contributing to the seasonality of vector-borne diseases. Changes in weather and environmental conditions can impact the transmission and survival of pathogens. For instance, low humidity during the winter months can lead to dry nasal passages, making individuals more susceptible to respiratory infections.


What Viruses Are the Seasonal Flu Viruses?

Seasonal flu epidemics, sometimes known as the flu season, are caused by the influenza A and B viruses. Antigenic drift and antigenic shift are two different ways influenza viruses can alter.


How to Define Seasonal Viral Fever?

Viral fever refers to acute viral illnesses brought on by environmental and seasonal variations. The most typical sign is an increase in the body's normal temperature. People of all ages may be affected by this during the monsoon. The virus raises the body temperature above normal.


When Does Adenovirus Occur?

Adenovirus can be transferred by droplets when an infected person coughs or sneezes. Poop can spread infection through polluted water, filthy diapers, and inadequate hand washing. Adenovirus outbreaks at summer camps relate to tainted water in lakes and swimming pools.


How to Tell if the Infection Is Bacterial or Viral?

Infections with microorganisms are the result. Viruses cause viral infections. Antibiotics do not treat viruses but kill or prevent many bacterial' growth. Some viruses are removed from the body by antiviral medications.


How Is Seasonal Fever Managed?

Rest and a lot of fluids are typical for a person to recover from the flu. However, if a person has a severe infection or is more likely to experience complications, the doctor may advise using an antiviral drug to treat the flu.


Can Seasonal Allergies Cause a Fever?

In a nutshell, allergens do not directly cause fevers. The body is likely fighting a viral or bacterial infection when a person has a fever. Because a fever is a symptom of a sinus infection, allergies can occasionally result in a sinus infection, which can then cause a fever.


What Safeguards Can Be Put in Place to Stop the Spread of COVID-19?

Simple precautions like social distancing, wearing a mask at all times, and limiting travel can help people lower their risk of catching COVID-19. Emphasize the importance of frequent handwashing with soap and water for at least 20 seconds, or using hand sanitizer with at least 60 percent alcohol when soap and water are not readily available. This helps to remove any potential virus on the hands.


What Are the Covid-19's Five Preventative Measures?

The following activities aid in limiting the transmission of influenza, other coronaviruses, and COVID-19:
- When inside in public, put on a face mask.
- Keep a minimum of six feet distance between two people.
- Stay away from large crowds.
- Socializing outside.
- As soon as qualified, get vaccinated.


What Distinguishes COVID- 19 From Other Viral Infections?

COVID-19 has significantly higher infectivity than Middle East respiratory syndrome (MERS) and severe acute respiratory syndrome (SARS). The global spread of COVID-19 has also been substantially faster than other coronavirus infections.


How to Recognize COVID- 19?

Fever, exhaustion, and a dry cough are the most typical signs of COVID-19. In addition, aches and pains, runny nose, sore throat, and diarrhea can affect patients. Usually minor, these symptoms appear gradually. Some people contract an infection but do not show any signs of illness or discomfort.
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Dr. Ajmera Jail Singh
Dr. Ajmera Jail Singh

General Practitioner


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