2014-09-12

Ebola 14: False negative ebola tests - denials, wrong analytical methods or criminal falsification of results

1.1.0

Further to my other ebola posts, here I will be collecting only reports on the low sensitivity of ebola tests, that is their false negative results (read more about these medical terms here), which are doubly deadly for the unsuspecting carers.

Let's start with Sierra Leone:


On July 19, Moussa Kotuneh fell sick after returning to Pujehun from a trip to Kenema. Immediately, the ambulance was called, and he was taken to the testing site in Daru, 25 kilometers away. He was tested and declared free of the disease. He was sent home with a document declaring him Ebola free. The staff suggested he be observed for the next 21 days in case he got worse.
Kenema hospital cum lab

Jefrey Morison is a trained community health worker who grew up in Pujehun. He spoke with people after Kotuneh came back. “There was lots of confusion about what to do,” he said. The document said he did not have Ebola, but Jefrey urged everyone in the town to be vigilant. “I said, ‘You must continue to isolate him.’”

Kotuneh got worse, and he died soon after returning to Pujehun.
 ...
a close friend of Kotuneh’s died, and the villagers called the ambulance team again. This time, the ambulance took six suspected contacts away to isolation. Days later, they were all dead.

...
“They should have never [let Kotuneh] back to Pujehun,” Jefrey said. 

Who was right? The doctors who gave the "free from ebola" stamped fancy certificate or the hard common-sense instincts of self-preservation shown by the suspecting villagers?

Dr. Brantly first felt ill [with ebola on] July 23 but tested negative.
[source] 

He was not alone here:
Rev. Brother Patrick Nshamdze: On the 17th of this month, his specimen was taken and the result, which came on the next day (July 18), proved negative...
The ailing Catholic hospital director decided to seek further treatment abroad, but his trip was subjected to Ebola test... he did another test on Tuesday, July 29, 2014, which proved positive, contrary to the first test he underwent.
and then:

Following the [Patrick and Princess] Sawyers death health workers at the hospital began to show signs of the deadly virus, but denial again reigned. Sources say when the healthcare workers at the hospital began to notice that Brother Nshamdze was showing signs of the disease, they admonished him to do a test to find out whether he had the virus, since in fact he had come in contact with the Sawyers.

But he was also in denial and because of that, did not show the true outcome of the first test that came out positive. But, how a negative result was pronounced that came back two weeks later as positive is still a puzzle that Liberians are trying to piece together.

Sources tell FrontPageAfrica that after the result came back negative, the Catholic brother told his colleagues that all was well and they kept caring for him because they felt he was suffering from a heart disease that was his known medical condition. It was when a second test was done on him that came out positive after he tried to leave the country while critically ill did his colleagues begin to cut off contact with him but it was too late. He died on August 2, 2014 and the death roll continued after that.
Source


Read also my separate post about another case of  "miraculous death" of a medic


Some of the tests currently used to diagnose EBOV might fail to work in the presence of these genetic changes—meaning they could give false negative test results in some people who are actually infected with the virus.
Source: Using Genomics to Follow the Path of Ebola


Ebola is generally detected in a patient’s blood specimen by RT - PCR by the third day of symptoms. Testing too early could result in a false negative test.
Laboratory Bio safety Considerations for Handling Specimens from Patients Designated as “Suspect Ebola”

This latency is confirmed in medical literature:
It can test negative in early stages.
[Source: Pathology of Experimental Aerosol Zaire Ebolavirus Infection in Rhesus Macaques]

Some of the ebola tests: are all performed at once?


Asymptomatic patients

The health worker had a temperature of 99.5 Fahrenheit (37.5 Celsius) before she boarded her flight, he added.
Health care workers who had been exposed to Duncan were undergoing self-monitoring. They were allowed to travel ...

The risk of exposure to the passengers who were on the plane with Vinson is low [my comment: and thus exists!], since she did not yet have symptoms, health officials said Wednesday.

Source


8 OCT: 
Vinson flew from Dallas-Fort Worth to Cleveland a week ago, on October 8, said Toinette Parrilla, director of the Cleveland Department of Public Health.

10 OCT:
Frontier Airlines, however, said she traveled to Ohio on October 10 -- and specifically asked people who may have been on a flight on that date to contact the CDC at 1-800-CDC-INFO (1-800-232-4636).

13 OCT: 
The woman "exhibited no symptoms or sign of illness while on Flight 1143, according to the crew," Frontier Airlines said in a statement.
...
The CDC, in a joint news release with Frontier, said it wanted to speak only with passengers on the October 13 flight. The CDC later confirmed to CNN that it is "only interested" in the passengers on Flight 1143.

16 OCT: CDC is also "interested" in the passengers etc. on the previous flights of this nurse and on the subsequent flights of the same aircraft. In practice, health authorities arrest (quarantine) some staff and passengers. "She may have been symptomatic after all", claims CDC.



Sacra, a family physician from Worcester, Massachusetts, wasn’t treating Ebola patients when he got infected. He was helping pregnant women. Like Writebol and Brantly before him, when a fever came on, he desperately hoped it was malaria and not Ebola. 
NBC


One of the patients receiving treatment after testing positive to the deadly Ebola Virus, was wrongly diagnosed and did not have the virus, the Minister of Health, Onyebuchi Chukwu, said Monday.
[source]



During both outbreaks we identified some individuals in direct contact with sick patients who never developed symptoms.

FINDINGS: 11 of 24 asymptomatic individuals developed both IgM and IgG responses to Ebola antigens, indicating viral infection. Western-blot analysis showed that IgG responses were directed to nucleoprotein and viral protein of 40 kDa. The glycoprotein and viral protein of 24 kDa genes showed no nucleotide differences between symptomatic and asymptomatic individuals. Asymptomatic individuals had a strong inflammatory response characterised by high circulating concentrations of cytokines and chemokines.

INTERPRETATION: This study showed that asymptomatic, replicative Ebola infection can and does occur in human beings.

Interestingly, we have observed a similarly strong inhibition phenomenon [impeding positive identification of ebola] with plasma from a moribund patient with acute Ebola hemorrhagic fever from Gulu, Uganda ...



False-negative RT-PCR results are likely to occur for patients with severe viral hemorrhagic fevers, especially in the acute phase of the disease where a rapid confirmation is required. Their plasma may contain large amounts of RT-PCR inhibitors, probably resulting from the decay of tissue.


Between 26 June and 1 September 2014, 138 patients were discharged from the Kailahun Ebola case management centre (CMC) in Sierra Leone, as non-Ebola virus disease (EVD) cases, because they tested negative for the virus by polymerase chain reaction (PCR). Of these, 15 returned to the CMC within 21 days of their first admission and subsequently nine tested positive for Ebola virus. This raised the question as to whether CMCs could be acting as potential amplifiers of infection even though appropriate infection control measures are being followed. 

Eurosurveillance


They tell us about a survivor in their community. He came back from the treatment centre, but despite testing negative for the virus infected his girlfriend, who died.
Source: BBC


The American doctor is thought to have contacted it while having dinner with another health worker that was developing a fever.

source

Times scales vary for all of this [period of being infecting] from a few days from beginning to recover until virus negative (except semen) and a few weeks.  
Guardian, interview with surviving doctor



AP: But I think back, too, what happened with the baby at the hospital—whose mother came in and died, and the baby was in a box. They tested the baby and the baby was negative. But I think the symptoms in babies and the disease progression in babies is different than adults.

MD: Right.

AP: So the nurses would pick up and cuddle the baby. And they were taking care of the baby in the box. And then twelve of them got Ebola. And one survived.

MD: Because they couldn't just watch a baby sitting alone in a box.

By the time we had arrived more than 20 nurses had died from Ebola. 

source


  
[A heroic doctor] contracted Ebola from a patient who went into cardiac arrest. [...] this patient didn’t have any of Ebola’s usual symptoms, McDonald said: No fever. No vomiting or diarrhea. No bleeding. No reason to suit up. So when the man’s heart stopped, Brisbane went in without the full protective gear health workers touching Ebola patients should wear. He did CPR. He ventilated him. He hooked him up to the usual series of tubes and wires. “And that’s what happened,” McDonald said, tearing up, as she described the last case Brisbane worked on.
...
Source - an eye-opening Buzzfeed article.

The virus mutates rapidly

Thursday’s study also details hundreds of genetic mutations that make the current Ebola outbreak different from any in the past. Some of those changes have the potential to affect the accuracy of diagnostic tests or the effectiveness of vaccines and treatments under development for the disease.
There are many, too many, ebola strains by now
source

The diagnostic tests now in use, as well as drugs and vaccines under consideration, are based on the Central African strain and might not work well on this outbreak. For example, a diagnostic test in use now might not give a clear positive if a victim had a low viral load early in an infection.
source

Falsified tests:
Breaking News: Mr. Musa Bangura the lab technician who was arrested in Kenema government hospital in Sierra Leone for manipulating Ebola data – changing sample results from positive to negative and charging patients for as little as Le30,000 ($6.00) has escaped from custody.
[Source]


President of the Sierra Leone Laboratory Association (SLLA) has distanced his organization from the alleged falsification of Ebola test results by one of its members at the Kenema Government Hospital. Laboratory Technician, Musa Bangura is alleged to have demanded cash payment from patients tested to manipulate their test results.
[Source]

Results falsified by infected politicians: the case of the vile Patrick Sawyer:

There is no evidence to suggest that the employee has been infected. Under the Ministry of Health guidelines, the employee is being monitored on a daily basis and will continue to do so for a period of 21 days. [...] Doctors say the risk of potential transfer to any member of the ArcelorMittal staff or contractors is very low. [...] The deputy minister personally admitted approving the trip in an online discussion forum, where some Liberian citizens raised questions about his action and competence."
[source]



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