A substantial portion of the cases I see in the clinic are prospective overseas workers who test positive on screening for infectious diseases during their pre-employment screening. While being diagnosed with an infectious disease you didn’t know about is stressful enough, this is further exacerbated by the possibility of not being able to leave. In addition, most patients have already spent a substantial sum of money on their training and preparation for deployment.

Three of the most common infections that get flagged and need clearance from an infectious diseases specialist are: syphilis, hepatitis B, and latent tuberculosis.

Syphilis is a sexually transmitted infection caused by the bacterium Treponema pallidum. There are multiple stages of syphilis, and I recently discussed these in my article on venereal diseases from last week. Most of the syphilis that I see in the clinic is in the late latent stage. Many are shocked that they tested positive on the test since they don’t have any symptoms. Diagnosis of syphilis is with a blood screening test like an RPR or VDRL, coupled with a confirmatory test like a TPHA, anti-TP, TPPA, or FTA-ABS. I usually ask the patient for a full sexual history to estimate when he or she might have gotten infected.

If someone has a positive RPR and a negative TPHA, there are two possibilities. If he or she had a new sexual partner recently, then this could be a very early infection, and we can treat with a single dose of penicillin and repeat the TPHA at a later date to see if it turns positive. If there was no new sexual partner and there wasn’t any recent sexual activity, it is more likely that the RPR is a false positive and the patient can be cleared even without treatment.

If someone has a positive RPR and a reactive TPHA, then this is a confirmed syphilis infection. If it has been more than one year since infection, the treatment will be three weekly injections of benzathine benzylpenicillin. Otherwise, one injection will suffice. This is considered curative, and the patient can be cleared right away after the course is completed. There is no need to repeat the RPR before deployment since it takes six months to one year for it to go down substantially. It can be repeated prior to the next clearance cycle to ensure that the titers are going down and that there have been no new infections. TPHA and other confirmatory tests will remain positive for life and are not used for subsequent clearance. While most countries understand this scenario and will accept a clearance note from an infectious disease physician, there are some countries that will not take anyone who tests positive for syphilis on a confirmatory test, even if they have received adequate treatment and have been cleared.

Hepatitis B is another common reason for clearance. Hepatitis B is caused by a virus that attacks the liver and significantly increases the risk of liver cancer. While some people with hepatitis B can develop liver failure and jaundice (yellowing of the skin), most patients that we diagnose on pre-employment screening have no symptoms and are surprised to learn they are infected. Hepatitis B has historically been highly prevalent in the Philippines, with some studies showing infection rates of up to 16 percent of the population. More recent data shows that this has improved to around 10 percent and continues to go down, but that is still a high number compared with most countries.

There are two main routes of hepatitis B infection: from mother to child, which is also known as vertical transmission, and sexual transmission. Most hepatitis B cases in the Philippines are vertically transmitted, which is problematic because a child’s immune system is unable to properly clear the virus, and that person develops chronic hepatitis B. Chronic hepatitis B is asymptomatic early on but can lead to cirrhosis and liver cancer. In contrast, hepatitis B acquired through sexual transmission can usually be cleared by an adult immune system.

Hepatitis B during the preemployment examination is diagnosed when a patient tests positive for HBsAg. HBsAg stands for hepatitis B surface antigen, which is a protein found on the surface of the hepatitis B virus. HBsAg usually remains positive for life in chronic hepatitis B, even if someone is started on treatment. HBsAg can clear spontaneously in cases of sexually transmitted hepatitis B, although it can take months. It is not expected to disappear among those infected as children, who will most likely develop chronic hepatitis B. Treatment is with antiviral medications such as tenofovir or entecavir, which, once started, needs to be continued for life in most cases. Treatment is not curative and only needs to be started when there are beginning signs of liver damage, or the virus is causing damage in other organs, or there is a family history of cirrhosis and liver cancer.

Overseas employers are reluctant to accept someone with chronic hepatitis B, even if they look healthy. Many shipping companies employing seafarers will say no outright. There are exceptions, especially when a seafarer has a high rank or has essential skills. In these cases, however, the companies may ask us to start antiviral treatment right away. The patient is also required to bring enough medication for them to take on board for the duration of the contract.

The Philippines has one of the highest rates of tuberculosis in the world. Many Filipinos are exposed to tuberculosis during childhood, but this does not automatically result in active tuberculosis. Most people who do get exposed are able to mount an adequate response to contain the infection, but the body is unable to completely get rid of the bacteria. This results in a condition known as latent tuberculosis, where one is infected but does not manifest any symptoms. People with latent tuberculosis are not considered infectious, unlike those with active tuberculosis.

Latent tuberculosis is asymptomatic and can only be diagnosed with either a PPD (purified protein derivative) skin test or a Quantiferon test. In non-endemic countries like the United States, people who convert from a negative PPD or Quantiferon test to a positive one have a high rate of developing active tuberculosis within one year. Therefore, the common practice in non-endemic countries is to treat latent tuberculosis with one or two of the usual four drugs used to treat active tuberculosis.

In endemic countries like the Philippines, we do not treat latent tuberculosis routinely except in special cases, since most people are more likely remotely infected and are unlikely to develop active tuberculosis in the near term. Unfortunately, when someone tests positive on PPD or Quantiferon on pre-employment screening, many countries now require that we treat them before deployment, regardless of whether they come from an endemic or non-endemic country. Since latent tuberculosis is not infectious, we can clear patients for work as long as they have started the treatment regimen and bring enough medication to complete the course onboard.

The duration of treatment depends on the medication used, with isoniazid requiring six to nine months, rifampicin needing four months, and combination rifampicin and isoniazid requiring only three months. The latter is associated with higher rates of liver toxicity, and so we check liver function tests in patients at baseline and two weeks after they start the medication before we give final clearance.

There are other diseases that we detect on pre-employment checkup such as HIV, salmonellosis, and worm infestation, but these are less common than the three that were discussed. It is important to take steps to prevent infection or to mitigate the risk of progression of a disease, especially if you are planning to work abroad. This can make or break the dream of a prospective overseas Filipino worker, so it is worth paying attention to.