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MERS-CoV: For every reported case, 5-10 infections go undetected

Mers CovResearchers believe that for every one case reported at least five to ten cases of MERS-COV goes undetected. A scientific paper by European researchers also believes that the MERS-CoV is now being passed from one person to another in a sustained manner. In fact, the authors say based on the available evidence they cannot rule out the possibility that person-to-person spread is the main mode of transmission of the virus at this point. The other option, they say, is that the virus is spreading via a combination of animal-to-person and then person-to-person transfer.

'We conclude that a slow growing epidemic is underway, but current epidemiological data do not allow us to determine whether transmission is self-sustaining in man,' they write in the article, published in the journal Lancet Infectious Diseases.

The scientists are from Imperial College London, the University of Edinburgh and the Institut Pasteur in Paris. The work was done with funding from Britain's Medical Research Council, the Bill and Melinda Gates Foundation and other agencies.

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Till date there have been around 155 confirmed MERS-CoV cases and at least 65 of these infections have ended in deaths. All the cases trace back to infections in a handful of countries on the Arabian Peninsula: Jordan, Saudi Arabia, Qatar, the United Arab Emirates and Oman.

Dr Ram Shukla, a specialist in infectious diseases from the UAE tells us 12 important facts about the disease:

1. Spread by animals in contact with bats

Mostly carried by bats but also some other vertebrates, the MERS Coronovirus spreads very rapidly in animals when they are kept together in confined and crowded places like live-animal markets, slaughter houses and while transporting animals by ships. Close and prolong contact with infected animals, which may not show any symptoms, helps virus jump to human. As it happened in SARS most of the animal traders were found to have SARS antibodies without any symptoms. This is a stage of adaptation to a new host (Inter-species transfer) which led to possible viral genetic mutation to adapt to its new human host. Same may be true for MERS-CoV.

2. It doesn't spread rapidly among humans

MERS is not transmitted very readily from person-to-person. This may occur after close and prolonged contact with infected patient in closed environment like home, hospitals etc. Infection spreads by coughing, droplet infection. But it can become air borne, meaning spread by air in hospitals when infected patient is given pressurized oxygen, intubated or procedures like bronchoscopy or during the use of pressurized devises like dental drill etc making healthcare workers more susceptible.

3. Infection control in hospitals and clinics can prevent spread

Healthcare workers getting infected by MERS are reported on a regular basis which shows failure of observing stringent Infection Control Procedures in the hospitals. It is the responsibility of the hospitals to educate their staff, supervise and implement strict Infection Control and isolation procedures. Infected healthcare workers take the infection to their family and wider community.

4. Masks and other physical barriers will not help

Casual contact in open spaces is unlikely to transmit the virus. Using face masks or other such physical barriers is not of much benefit. But it is wise to observe meticulous hand hygiene by soap and water or hand alcohol rub. (Read: Lessons from the SARS chapter which will help us fight)

5. Simple measures can prevent spread

Infected patient spreads it by coughing out the virus particles known as droplet infection. These droplets spread to the distance of one to one and half meters. If patient does not cover his mouth, this may infect furniture, door knobs, lift buttons etc for few hours depending upon the environmental temperature, humidity, air flow etc. Hence, it is highly advised that good cough-etiquette be observed, meticulous hand hygiene should be maintained and contaminated surfaces be disinfected.

6. It takes 7-10 days for symptoms to develop

The long incubation period of MERS is good news. This helps public health authorities to identify those who may have got infected (contact tracing). These individuals are observed, isolated or quarantined, so as to break the chain of transmission.

7. The symptoms may not all be respiratory

Even though the most common symptoms are fever, cough and difficulty in breathing, it can also lead to kidney failure, septic shock, multi-organ failure and acute respiratory failure. These are usually the cause for the high death rate, nearly 60% (death rate of SARS was 8%).

8. The virus may not really affect the upper respiratory tract

The MERS virus enters by nose or mouth and uses certain receptors to enter human cells. These receptors are common in the lower respiratory tract but not in the upper respiratory tract that is why the virus causes illness in the lungs (pneumonia) rather than in the nose and throat as a cold virus or H1N1 would. These receptors are found in kidney too causing renal failure. So if we block these receptors by drugs, we can prevent infection by MERS. Even though certain anti-diabetic drugs are also known blockers of the same receptors, scientists have found that these drugs are not useful in blocking MERS virus. They hope to develop a drug or a vaccine to block the receptor to prevent MERS infection.

9. Improving your immunity could prevent the disease

All available cases data indicate that the people who are susceptible include those who are very old, very young, pregnant women, individuals with compromised immune system due to diseases, drugs and organ transplant patients. Young and healthy healthcare workers get infected in hospital settings because of the prolonged close contact with infected patients.

10. PCR tests can help diagnose MERS-CoV

There is a sophisticated test like PCR to diagnose it but this is only available in specialized laboratories. There is no quick test. There is no specific drug or treatment for MERS but only supportive treatment given in the hospital.

11. MERS-CoV cannot spread very fast

So far it fails to show epidemic potential. It is not easily transmissible from person to person. Its receptor is deep in the lungs so requires prolonged close contact with the infected patient. It has a long incubation period which makes public health interventions like contact tracing and isolation effective.

12. Screening at airports could help

Gulf sector is a very busy sector as millions of Indians are working in the Gulf countries. On top of that 1.7 million Indians will perform Haj this year. Airport screening is one of the methods to detect cases with fever by installing thermal scans or by manual methods. Education of travellers about the disease; explaining risks of getting infected, how to maintain good hygiene and what to do if symptoms develop after returning back home could also help.

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