India has surpassed Brazil to become the country with the second highest number of coronavirus cases, as the virus continues to spread through the country of 1.3 billion at the fastest rate of anywhere in the world.

India recorded more than 90,000 cases overnight, bringing the number of infections in the country past 4.2 million and overtaking Brazil, which with 4.1 million cases had been the second worst-affected country for several months.

India now only lags behind the United States, which has had 6.2 million cases so far. However, while cases in the US have begun to level off, the rate of infection in India is worsening by the day, with no signs of when it will hit the peak, and experts are predicting the south Asian country will soon tally the most cases in the world.

The death toll stands at 71,000, equating to 50 deaths per million, which is relatively low compared with the US and Brazil but is still rising at around 1,000 aday.

India is now carrying out more than 1m tests a day, but per capita the testing levels still remain very low. Concerns have also been raised over the accuracy of the tests, as over half were rapid antigen test, which have a far higher percentage of false negatives.

The steep climb in infections also coincided with the country almost completing its reopening after months of lockdown and restrictions, which doctors said they feared was leading to a culture of complacency around the virus just as the situation was at its worst.

In March, India imposed one of the strictest lockdowns in the world, but over the past few months has gradually reopened after the lockdown took a heavy economic and humanitarian toll.

State borders opened up, domestic flights have resumed and restaurants and bars have opened their doors. Even the metro system in Delhi resumed service this week after being closed for over five months. Only schools remain closed and international travel is still restricted.

Dr Harjit Singh Bhatti, a doctor on the Covid-19 ward of Manipal hospital in Delhi, described the situation in India as “very worrisome. Since the government loosened lockdown, they have taken no proactive measures to stop the spread of the virus, which is why we are seeing cases go up and up.”

The virus was initially concentrated in major urban metropolises such as Delhi and Mumbai. But while cases in Delhi have increased by 50% in just the last month, the fastest spread of the infection is now in rural areas, where two-thirds of new cases are being reported. Bhatti said doctors were being told to prepare for cases to keep rising until at least the end of November.

“Rural areas have had very little healthcare investment, they are poorly equipped, there are very few doctors and poor transport into the cities, so the spread of the virus into these communities will have very serious consequences and we are likely to see much higher coronavirus casualties,” said Bhatti.

He added: “The quackery in those rural areas is also very high, you see a lot of untrained professionals who are treating patients there, and this can cause a worrying mismanagement of the infection and higher rates of mortality.”

The virus has already taken a heavy toll on India’s already overworked and over-burdened healthcare workers. According to Amnesty International, India has one of the highest Covid death tolls for healthcare workers in the world, with 573 deaths since the pandemic arrived in India.

“Healthcare workers in India are already exhausted, we’re not only overworked but we have suffered a lot of mental trauma because a lot of our colleagues have died,” said Bhatti. “The next few months are going to be very challenging for us all if things get much worse.”

India is also grappling with rising coronavirus figures amid both a security crisis on its border with China and an economy that lies in tatters. In June, rising tensions between Indian and and Chinese troops on the border in the Himalayan region of Ladakh led to a face-to-face battle, where 20 Indian soldiers lost their lives.

Multiple rounds of diplomatic and military-level talks have failed to resolve the situation, which once again came to a head last week when both India and China accused each other of violating sovereign territory.

The Indian government is also having to deal with the economy shrinking by almost 24% over the last quarter, the greatest recession it has suffered since records began in 1996. It was mainly due to the impact of coronavirus lockdown, though followed an earlier period of decline.