Mortaza had first tested positive of being infected by Coronavirus last month.
Mortaza, 36, having retired from Tests and T20Is, had earlier this year resigned from ODI captaincy. He first tested COVID-19 positive last month, a piece of news he had confirmed via a Facebook post on June 20.
"There is no reason to panic. He will give another test on eighth (8 July) and he might be cleared at that point of time. In most cases, the patient is cleared by 14 days but that is not mandatory. Someone might take more time," Chowdhury was quoted as saying by Cricbuzz.
Mashrafe is regarded as Bangladesh's greatest captain. Under his leadership, the team reached the quarterfinal of the 2015 World Cup in foreign conditions in Australia and New Zealand and taking great confidence from that, started winning consistently against top teams, especially at home.
The inspirational figure of Mashrafe, someone who has had multiple injuries and comebacks throughout his career, worked as a guiding light for youngsters in the team, before he decided to relinquish the post and hand it over to another Bangladesh great Tamim Iqbal.
Tamim's brother, former Bangladesh cricketer Nafees Iqbal, has tested COVID-19 positive.
Last month, Nazmul Islam, who was involved in distributing food and other supplies in his hometown Narayanganj - one of the worst-hit areas in Bangladesh - was also found proven of being infected by the disease.