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Threats of Ebola, polio, other emerging infectious diseases persist

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AFP PHOTO / UNICEF / MARK NAFTALIN /

*Speedy tests mean health workers can now diagnose EVD in hours, instead of days
*Virologists use ‘genetic trees’ to evaluate intervention strategies, researchers find
*Nigeria on alert as poliomyelitis re-emerges in Venezuela nearly 30 years after eradication

Despite reports that the ongoing outbreak of Ebola Virus Disease (EVD) in the Democratic Republic of Congo (DRC) is under control, the World Health Organisation (WHO), health officials and the Nigeria Centre for Disease Control (NCDC) are cautiously optimistic.

They are still worried that the virus could spread across the DRC and Central Africa. Some cases may have gone undetected, which could lead to resurgences of the disease. And for the first time in the DRC, cases have occurred in an urban area: Mbandaka, a city of more than a million people and a major travel hub.

WHO deputy director-general of emergency preparedness and response, Dr. Peter Salama, in a webcast on Twitter, said: “The outbreak is ongoing.” Salama said he is “cautiously optimistic.”

Chief Executive Officer (CEO) of NCDC, Dr. Chikwe Ihekweazu, yesterday assured that Nigeria is prepared to contain any possible outbreak of the virus and the Centre is taking also the measures needed.

Also, a report published Monday in the journal Nature noted that the DRC outbreak, which is mainly centered in remote regions of Équateur Province in the north west of the country, is still relatively small, with 38 lab-confirmed cases, 14 probable cases, and 14 suspected; and as of June 9, 28 of those people had died.

Salama’s optimism arises from the fact that there have been no new reports of illness in Mbandaka, the Equateur province capital, which boasts a population of 1.2 million.

“What this is telling us is the response (the WHO’s vaccination programme) is having an impact in those two locations,” said Salama.

Since the launch of the vaccination programme on May 21, 1,826 people have been vaccinated, the Ministry of Health of the DRC reported Wednesday. This figure includes 673 people in Mbandaka, 398 in Bikoro, 725 in Iboko, and 30 in Ingende, also located in the Equateur province.

Ebola virus disease, which causes fever, severe headache and in some cases haemorrhaging, most commonly affects people and nonhuman primates, such as monkeys, gorillas and chimpanzees.

According to WHO, the current outbreak is caused by the Zaire ebolavirus, one of five separate subtypes and the one with the highest mortality rate, ranging from 60 per cent to 90 per cent.

Meanwhile, scientists have developed speedy tests that can now diagnose Ebola in hours, instead of days.

Health workers fighting the Ebola epidemic that swept West Africa several years ago waited days, even a week, for the results of laboratory tests to detect the deadly virus. But in an Ebola outbreak that began in early April in the DRC, this waiting time has shrunk to hours — thanks to a genetic test that was developed in response to the 2014-2016 West African epidemic.

Researchers and health officials credit the faster tests with helping to contain the spread of Ebola in the DRC, by allowing those infected to be isolated and their contacts traced promptly. And should sparks from this outbreak light new fires in neighbouring countries, the nimbler test could help to avert a repeat of the devastating West African epidemic.

The test involves a small machine called the GeneXpert, which is widely used across Africa to diagnose tuberculosis. The DRC’s government has made the GeneXpert its primary method of testing for Ebola in the current outbreak.

Head of laboratory networks for the WHO Health Emergencies Programme, Mark Perkins, told Nature: “Labs have been set up with two to three days’ notice in new transmission zones, whereas in West Africa it took months and months to get facilities up and running. It is a remarkable change.”

Also, according to the Pan American Health Organization (PAHO), a regional apparatus of the WHO, a child has been diagnosed with polio in Venezuela, where the infectious viral disease has been eradicated since 1989. The Western Hemisphere has been certified polio-free since 1994.

The diagnosis comes as Venezuela, with an estimated population of 31.3 million, experiences political and economic turmoil, resulting in a humanitarian and health care crisis.

According to the WHO, poliomyelitis, known as polio, is a highly infectious viral disease that invades the brain and spinal cord and causes permanent paralysis in a small proportion of patients. There is no cure and it can be deadly. The virus, which mainly affects young children, spreads from person to person and can also be transmitted through contaminated food and water.

According to the PAHO statement, the Venezuelan child with polio is 2 years and 10 months old and first experienced paralysis on April 29. As of May 31, the child continued to experience crippling symptoms. Part of an indigenous community in Venezuela’s northeastern state of Delta Amacuro, the child had not been vaccinated against polio, the statement noted.

The situation has put Nigeria on red alert because she is one of the three countries- Pakistan and Afghanistan- that has never interrupted polio virus transmission. The last cases of the virus were detected in Internally Displaced Persons (IDPs) Camp in August 2016 nearly two years plus when the last cases were reported in July 2014.

The WHO had hoped to achieve global eradication of polio by 2018.
With the two cases found in North-East of Nigeria, the countries window period was extended from the day those two cases were detected in August 20I6 for another compulsory three years of window period which means Nigeria’s zero polio case status certification will now be in 2019 if no more incidences of polio is recorded.

Also, the WHO on Monday certified Paraguay as having eliminated malaria, the first country in the Americas to be granted this status since Cuba in 1973.

In 2016, WHO identified Paraguay as one of 21 countries with the potential to eliminate malaria by 2020. Through the “E-2020 initiative,” WHO is supporting these countries as they scale up activities to become malaria-free. Other E-2020 countries in the Americas include Belize, Costa Rica, Ecuador, El Salvador, Mexico and Suriname.

Meanwhile, according to a May 2018 report by the Foundation for Innovative New Diagnostics in Geneva, Switzerland, one of the biggest lessons of the West African epidemic — in which around 29,000 people were infected and 11,000 died in Sierra Leone, Guinea and Liberia — was the need to diagnose cases of Ebola more quickly. Better lab tests could have averted 30–70 per cent of cases and saved thousands of lives and billions of dollars.

Most Ebola lab diagnostics detect genetic sequences that are specific to the virus in blood, serum and other bodily fluids. During the West African epidemic, these manual tests required highly trained scientists working in sophisticated, highly secure labs that were often far from outbreak zones.

In the DRC, by contrast, GeneXpert is performing the same tests more rapidly, nearer to transmission zones and in an automated manner. The machine uses custom cartridges for different diseases and was developed for resource-poor settings. In response to the 2014–16 epidemics, the firm developed a cartridge, Xpert Ebola, to test for the Zaire strain of Ebola, which is behind the current DRC outbreak. The turnaround time from taking a sample to receiving a diagnosis in the outbreak is usually a matter of hours or at most a day, Perkins says.

Officials say should further regional outbreaks occur, GeneExpert machines would continue to be a big help. There are already around 150 of the machines in DRC and several hundred in nearby countries for testing for tuberculosis and other diseases. By swapping in Xpert Ebola cartridges, a large Ebola testing network could be quickly created, says Perkins.

That has provided that there are enough Ebola test cartridges. No countries have purchased stockpiles of Xpert Ebola cartridges, and the DRC had none when the outbreak started, says Iain Sharp-Paul, a marketing director at Cepheid, the Sunnyvale, California Company that makes the machines. It shipped 3,600 Xpert Ebola cartridges to the DRC in less than two days after being alerted to the outbreak, and a further 4,000 cartridges are on their way.

Other Ebola diagnostics are also being field-tested in the DRC outbreak. Public health officials are keen to have access to screening tests, which, unlike GeneXpert, do not require electricity or refrigeration and can be distributed to affected areas in large numbers to get on-the-spot results within minutes. These tests work by detecting Ebola proteins using the same analytical technique as over-the-counter pregnancy tests.

Researchers plan to evaluate two such tests in the DRC outbreak. One is the OraQuick Ebola Rapid Antigen Test made by medical device company OraSure Technologies in Bethlehem, Pennsylvania. OraQuick has been approved by the WHO for emergency use in testing patients’ blood samples — as well as the oral fluids of corpses — for the Zaire strain of the virus. Also being tried out is a more-experimental test, QuickNavi-Ebola, produced by diagnostic company Denka Seiken in Tokyo. Oraquick has sent 2,000 tests to DRC, and Denka Seiken 1,500.

Outbreak responders aim to use the tests to investigate suspect deaths reported in remote and difficult-to-access regions, says Perkins. This will help confirm tests carried out by GeneXpert and provide a better idea of the tests’ performance. Lack of field data has been a barrier to the adoption of such tests.

Thanks to lessons learned from the West African outbreak, “a new paradigm for Ebola virus detection and diagnosis is taking shape”, says Mara Jana Broadhurst, an Ebola diagnostics expert at Stanford University in California. “It is critical that this process is guided by careful field studies.”

Meanwhile, although the 2014 epidemic has now passed, but researchers are wondering which intervention strategies would have been most effective in containing the disease.

With the genetic data of 1,610 samples from Ebola patients, researchers from the Rega Institute at KU Leuven mapped the spread of the Ebola virus in West Africa between 2013 and 2016.

Prof. Guy Baele from KU Leuven, Belgium, said: “We created a genetic family tree of the epidemic, in time as well as space, with the oldest DNA sample from early 2014 in Guinea, a sample of the virus when it entered Sierra Leone in March or April 2014, and so on.”

KU Leuven is Europe’s most innovative university in the latest Reuters ranking. Located in Belgium, it is dedicated to research, education, and service to society.

The researchers connected the family tree of the epidemic to other information, such as geographical information and transportation.

Postdoctoral researcher Simon Dellicour from KU Leuven said: “Long-distance transportation, such as air travel by contaminated people, doesn’t appear to have been important in spreading the virus.

“Contrary to what happens during a flu epidemic, the Ebola epidemic spread due to short-distance travelling. The epidemic stepped up its pace once the virus had reached Conakry, Freetown and Monrovia – the capitals of Guinea, Sierra Leone and Liberia, respectively. These capitals attracted the virus, so to speak, and played a key role in spreading it.”

The findings also reveal which policy measures can successfully slow down or, conversely, accelerate the spread of the Ebola virus.

Baele continued: “Guinea, Sierra Leone and Liberia have each closed their international borders at a different moment in time. These interventions are visible in our phylogenetic tree of the Ebola virus and we also see how the virus continued to evolve afterwards. Closing the borders was an effective way to prevent Ebola from becoming an international epidemic. That’s important to know, as this type of intervention strategy obviously has major economic and social consequences. Preventive measures within one city or district would have made little difference: we believe that a coordinated approach would have had a bigger impact.

“This research method gives us a quick and accurate view of the key times and locations of the Ebola epidemic. That teaches us where and when we should have intervened.

“This information is also useful for on-going epidemics. For one thing, we want to apply this phylogenetic inference-based technique to rabies, a disease that still kills 60,000 people each year in Asia and Africa.”

This research was funded by Research Foundation – Flanders (FWO), the European Research Council (Consolidator Grant no. 725422-ReservoirDOCS) and the Wellcome Trust (Grant 206298/Z/17/Z).


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