New Tuberculosis drug and a TB refresher

Tropical medicine, international health and diseases of poverty all go together…we should know this by now. A new drug to combat Multi-Drug Resistant Tuberculosis (MDRTB) recently got United States Food and Drug Administration (FDA) approval. A relatively unbiased and superficial article about the new drug can be found here:

http://www.washingtontimes.com/news/2012/dec/31/new-tb-drug-fights-tougher-strain-but-carries-risk

A press release from MSF/Doctors Without Borders can be read here: http://www.doctorswithoutborders.org/press/release.cfm?id=6519&cat=press-release

Why we need to know TB management in remote and international settings

Working in international and remote settings, I often care for both imports and locals. Contractors, ex-patriots, visitors, etc are the people that bring me there. Providing care for the local patient population is often done for a variety of reasons ranging from public health control and generating “good will” to the fact that they are employed by another entity. Screening and managing tuberculosis is a skill that is often overlooked by the docs and paramedics who work in these settings. Sure we are good at malaria, trauma and managing high blood pressure…We need to be good at this too!

Tuberculosis Basics

Condition: A mycobacterial disease that is common in developing nations. 70% of disease effects the lungs while 30% is extra-pulmonary. This disease has made a recent “comeback” with immunocompromised states caused by HIV/AIDS.

Infectious Agent: Mycobacterium Tuberculosis complex consisting of Mycobacterium tuberculosis, M. africanum and M. canettii. This is an Acid fast bacillus.

Signs and Symptoms: Fatigue, fevers, night sweats, hemoptysis and sputum producing cough, weight loss

Diagnosis: A PPD (purified protein derivative) and/or chest x-ray are commonly used tools to diagnose. The PPD is also known as a Mantoux skin test. Positive skin tests should be followed with a chest x-ray. The skin test is “read” 48-72 hours after the subcutaneous injection is given and examined for induration/swelling. Positive results range from 5-15 mm in size. More on test interpretation can be found here from the CDC: http://www.cdc.gov/tb/publications/factsheets/testing/skintesting.htm . False positives are common.

Chest x-ray showing tuberculosis in the patients right upper lobe (left upper section of picture)

Transmission: Exposure to TB in aerosolized respiratory droplets (1-5 microns in diameter); Health care workers are at high risk

Treatment: For most susceptible cases a 4 drug cocktail of Isoniazid, Rifampin, Pyrazinamide and Ethambutol is used for the first two months of treatment then just Isonaziad and Rifampin for 4 months. A total of 6 months of treatment is advised and should be tailored to sputum culture results and sensitivity. I remember this because TB effects your RESPIratory tract (Rifampin, Ethambutol, Streptomycin, Pyrazinamide and Isoniazid)

Prevention: Strict control of positive and suspected cases, Directly Observed Therapy (DOT) to ensure patients take medication, approved face masks to prevent droplet inhalation

Epidemiology: Found worldwide, the disease is associated more with poverty and immunocompromised persons.

As doctors and paramedics working in areas where TB is possible, we need to promptly identify and treat this illness, we need to know how to administer a PPD and read it. Most people are comfortable with giving a sub-cutaneous injection but here is an expert video from the CDC on how to do it. This is a multi-part series and I have linked to the injection section of the video although viewing them all is a great idea as there is a lot of good education, review and information in all the sections.

Providing medical care in a remote or austere location means you have to know a lot about many different things. Often we get focused on trauma, common infectious diseases and basic primary care. I hope this review made us more ready to recognize, diagnose and treat TB.

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