india

Updated: Apr 20, 2020 22:37 IST

The top official of Patna’s All India Institute of Medical Sciences (AIIMS) warned on Monday that Bihar could be missing out a large number of Covid-19 cases because of incorrect methodology of sample collection.

The disclosure came as Bihar reported 20 cases of coronavirus — the biggest spike in a day so far. Seventeen of the cases were reported from Biharsharif in Nalanda district and three from Jamalpur in Munger district during the last 24 hours.

The district administration had sealed Biharsharif and enforced containment measures, similar to a hotspot.

“Improper methodology of sample collection could be a reason for the large number of negative cases in the state,” AIIMS-Patna director Dr Prabhat Kumar Singh told HT

Follow coronavirus latest updates here.

Of the 11,319 samples tested so far, Bihar has reported only 113 positive cases.

Dr Singh cast aspersions on the acumen of non-AIIMS personnel in collecting nasopharyngeal and oropharyngeal samples for Covid-19 confirmatory test.

He raised this point after two recent samples, which tested positive at AIIMS, turned out to be negative at the ICMR’s Rajendra Memorial Research Institute of Medical Sciences (RMRIMS) here. Both are institutes of the Central government.

Dispelling any ambiguity in reporting samples at AIIMS, Dr Singh said, “We engage specialist doctors from the ENT department to collect nasopharyngeal and oropharyngeal samples of suspects. In our case, you will always get proper yield. I don’t think any other institute, which conducts RT PCR (real-time polymerase chain reaction) in the state, engages ENT specialists for samples. They mainly rely on technicians.”

Stressing that the government should emphasise on proper sample collection by specialists, he said, “If a sample tests positive, there is 99.9% probability of the sample actually being positive. However, if a sample tests negative, there is every possibility of the patient being positive (false negative), but the result being negative because the virus strand may not have been tapped due to improper sample collection. A large number of patients can thus be left out of the net,” he added.

A 32-year-old woman from Khajpura who tested positive at the AIIMS on April 18, had tested negative at the RMRIMS on Monday. Patna civil surgeon Dr Raj Kishore Choudhary confirmed this fact.

The AIIMS had collected nasopharyngeal sample of the woman that tested positive on April 18.

“The remaining extract of the woman’s nasopharyngeal sample, along with fresh oropharyngeal (throat swab) sample, collected on April 19 was sent to the RMRI. The nasopharyngeal extract of ours, tested positive at the RMRI as well. However, the oropharyngeal swab of the patient, collected by RMRI technicians, tested negative at the ICMR laboratory,” said Dr Neeraj Agarwal, dean of AIIMS-Patna and also the nodal officer of the institute for coronavirus.

“As such, Sunday we collected four samples — two nasopharyngeal and oropharyngeal swabs each —from the woman and sent them for re-tests at our laboratory as well as the RMRI to check for any discordant results,” he said.

Patna civil surgeon Dr Choudhary said, “The samples of recent tests, performed at RMRI, have tested negative, while we await results of tests done at AIIMS.”

Another 35-year-old patient from Raghopur block of Bihar’s Vaishali district who tested positive at the AIIMS on April 15, tested negative during a re-test at the RMRIMS and the AIIMS, less than 48 hours later. The patient died on April 17 before his second report tested negative later in the evening.

The AIIMS, however, said the patient died of “coronavirus” and “multi-organ failure”.

“In medical science, any test report is always based on probability. If a sample tests positive, the actual chance of positivity is 67%. Similarly, if a sample is negative, actual chance of the patient being negative is only 37%. It is for this reason that a Covid-19 patient is tested twice within 24 hours before he or she is discharged from any facility. Even after discharge, a patient is advised to be under 14-day home quarantine,” said Dr Agarwal.

The Khajpura woman did not have any travel history or prospects of having come in contact with any Covid-19 patient. In fact, 17 samples of those who came in contact with her, including her husband, have tested negative.

Efforts to reach out to Pradeep Das, director of the RMRIMS, about the veracity of his laboratory results, proved futile as he did not respond to this reporter’s phone calls or text message.