JE FAQs - Prof. Lam S.K

In response to the many questions from medical personnels as well as the general public about the JE outbreak, I have decided to post some answers to these frequently asked questions.

1. Can JE be spread if I come into contact with an infected person?

Infected mosquitoes of the Culex family transmit JE after feeding on viremic animals, especially pigs. A mosquito feeding on a viremic person will not get infected because there is not sufficient virus in the blood to infect it. Man then is a dead end host for JE virus. One cannot be infected by JE through direct contact with an infected person.

2. I am staying in Seremban and not associated with pig farms. Should I be vaccinated?

The current policy of the Ministry of Health is to vaccinate those at high risk. These would be people working in pig farms, their families and those living within 2 kilometers of the farms since that is the flight range of the mosquito. Staying in an urban area such as Seremban does not constitute a high risk.

3. Is it necessary to receive 3 doses of the vaccines? Can I get away with only two?

Although the manufacturer recommends 2 doses within 1-2 weeks, it is best to get a 3rd dose 30 days after the first dose to get adequate protection. Two doses will give about 80% protection but 3 doses will provide up to 95% protection. Boosters are recommended every 3 years.

4. What is the best available test(s) to confirm a case? How long will it take to get the results?

Detection of JE IgM antibody is the best available test and in non-fatal cases, almost all patients should be positive within one week of disease onset. The test takes only a few hours to perform. In fatal cases, IgM serology may be negative. Other tests such polymerase chain detection of viral RNA or virus isolation are useful.

5. Is it possible to be infected with JE and not become sick?

Yes, one can get asymptomatic infection or a very mild disease. As a matter of fact, the ratio of symptomatic to asymptomatic is 1:300.

6. Can pigs die from JE? Is pork safe to consume?

This has not been documented. JE can cause spontaneous abortion in pregnant sows. Pork is safe to consume since the virus cannot survive in the meat and meat products.

7. Why are we seeing cases mainly in adults when we know that JE is usually associated with children?

This is an unusual feature of the current outbreak. In other outbreaks around the world, children are the victims. There is still a lot we do not understand about our JE outbreak.

8. Is the vaccine effective? Why are there deaths among those vaccinated?

The vaccine is effective in over 90% of those receiving 3 doses but there is still some who will not get protection. No vaccine is 100% effective. In those who died despite adequate vaccination, we have to prove that the cause of death is JE before we say that the vaccine failed to protect. It must be remembered other viruses and complications from underlying illnesses can be confused with JE.

9. Are the measures taken to control the outbreak adequate and appropriate?

JE is a zoonotic infection and transmitted by mosquitoes. The multiprong approaches taken to date are correct in an epidemic situation. However, implementation can pose problems. No new cases have been reported in Perak so there is hope that the control measures are effective.

10. Will the disease spread to other parts of the country?

We hope not. Strict measures are taken to prevent the movement of pigs and vector control is being stepped up in areas where the disease has not appeared. In addition, vaccination of humans and pigs are on-going.