INTRODUCTION
Coronavirus disease 2019 (COVID-19) is a viral disease caused by a novel
coronavirus that can lead to severe acute respiratory failure. It was
first identified in December 2019. In a short time, it became a global
and emergent health problem [1].
Coronaviruses belong to a family of enveloped, single-stranded, zoonotic
RNA viruses that can be transmitted from animals to humans, mutate
rapidly and recombine. Severe Acute Respiratory Syndrome Coronavirus-2
(SARS-CoV-2) is transmitted by inhalation of respiratory droplets from
an infected person or by touching virus-contaminated surfaces. In
previous epidemics, pediatric cases accounted for 6.9% of total
SARS-2002-3 cases and 2% of Middle East Respiratory Syndrome (MERS)
cases. Data from the Centers for Disease and Prevention (CDC) show that
children accounted for 12.3% of all SARS-CoV-2 cases; 2.1% were 0-4
years old, and 10.2% were 5-17 years old [2].
COVID-19 infection may progress with a cytokine storm following viral
proliferation phase that may lead to acute respiratory distress syndrome
(ARSD), impaired cardiac function and death. Cytokine storm is due to
the dysregulated immune response of the host [3,4]. In this
infection, older age, male sex, chronic obstructive pulmonary disease,
hypercholesterolemia and diabetes are among the independent risk factors
associated with mortality. Recent studies have shown that aggravating
factors in the etiology of COVID-19 disease include genetic defects and
autoantibodies against type 1 interferon [5,6].
Mycobacterium tuberculosis is an immobile aerobic bacillus that causes
tuberculosis disease (TB). It is transmitted by infected droplets.
Whether infection develops after transmission depends on the frequency
and duration of the contact, distance to the contact, the amount and
virulence of the transmitted pathogen, and the susceptibility of the
exposed person. After inhalation of the bacillus, it usually settles in
the better ventilated upper regions of the lungs. In healthy
individuals, T-cells inhibit intracellular proliferation of the bacillus
3-4 weeks after the infection. In this way, the disease is brought under
control. Clinically significant TB may develop shortly after the
disease, particularly in children and immunosuppressed individuals
[7].
Tuberculosis remains a major cause of mortality and morbidity in
developing countries. More than 95% of tuberculosis-related deaths
occur in low- and middle-income countries. About one-third of the
world’s population has latent tuberculosis infection [8,9].
SARS-CoV-2 infection and immunosuppressive drugs may temporarily inhibit
immunologic system, then may lead to active tuberculosis by reactivation
or infection of M. tuberculosis [10]. Although studies showed an
increase in the frequency of tuberculosis in previous SARS, MERS and
H1N1 epidemics, no such information has yet been found for COVID-19
infections [11-15]. In this study, we aimed to investigate the
association between COVID-19 infection and increase in tuberculosis
cases during the pandemic.