The Future of Infectious Diseases

Last post for MICR3350! This semester's been a wild ride!

We've come a long way in diagnosis and treatment of infectious diseases. Diseases that used to be major causes of death and disability are not as bad today, and one (smallpox) has been eradicated entirely (well, unless you count smallpox samples in labs). That being said, there's always room for improvement with regards to diagnosis, treatment, prevention and eradication.

Diagnosis

The quicker we diagnose something, the quicker we can give appropriate treatment. Therefore, we are always looking to find ways to diagnose diseases more rapidly.

Sepsis

Traditional diagnosis of sepsis ("a toxic inflammatory condition arising from the spread of bacteria or bacterial toxins from the focus of infection") relies on culture, which normally takes at least 24-48 hours. Possible rapid diagnostic tests that can be done instead include direct detection of biomarkers and point-of-care testing. Point-of-care testing might be done at a dedicated point-of-care lab that is closer than a central diagnostic lab, or it might be done at the bedside via a range of hand-held devices. For example, a portable "microscope" has been developed that sends light through a blood drop and can detect the interaction of light with blood components. Another possible device is the CD64 biochip which detects CD64 expression on neutrophils. The CD64 biochip can provide results after around 30 minutes.

Tuberculosis

Conventional TB diagnosis requires chest X-ray as well as sputum microscopy and culture. Since mycobacteria take a long time to grow, quicker tests, such as urine and breath tests, are being developed. Urine tests can be done to detect lipoarabinomannan (LAM), a component of the M. tuberculosis cell wall. These tests can give results in 25 minutes. Breath tests can look for metabolic products of M. tuberculosis, such as naphthalene derivatives, benzene and alkanes. Such breath tests can give results in six minutes- a far cry from the weeks required to culture M. tuberculosis!

Treatments

Unfortunately, not much has happened in the way of developing new antibiotics, despite new technologies for drug discovery, such as "iChips." One antibiotic that has been developed using the "iChip" is teixobactin, which was derived from soil microbes. Another relatively recent antibiotic is Baxdela, or delafloxacin, which is a fluoroquinolone.

Prevention

Public health campaigns and other preventative measures such as vaccines have helped to bring down the rate of infectious diseases. Unfortunately, there are many diseases that we don't have vaccines for yet, such as HIV/AIDS. HIV is highly mutable and very variable, making it difficult to produce a vaccine. There is also a lack of natural immunity to HIV that can be exploited with a vaccine. Other production issues for an HIV vaccine include a lack of an animal model, non-antigenicity of heat-killed HIV-1, and safety concerns with a live attenuated vaccine.

Eradication

As you most likely know, smallpox has been declared eradicated. Factors contributing towards smallpox eradication include an effective vaccine, good surveillance and the fact that humans are the only host. (If animals are also hosts, then you have to vaccinate all of the animals too, which can be tricky.) There are current global eradication programs for polio, malaria, Guinea worms and Yaws (caused by T. pallidum pertenue). Wild poliovirus type 2 has already been eradicated worldwide and type 3 hasn't been seen since 2012 (so it may be declared eradicated soon), but type 1 is still circulating in some countries, notably Pakistan, Nigeria and Afghanistan. The Democratic Republic of the Congo and Syria have also experienced outbreaks.

And that's it for MICR3350!! Good luck in the exam!