Fighting Rabies: New Testing Methods on the Horizon

Rabies is a serious disease caused by a virus that affects the central nervous system, leading to death if not treated quickly. The majority of human rabies cases come from infected dogs, accounting for about 99%. The virus spreads mainly through bites. It can also be transmitted through scratches or open wounds that come into contact with the saliva of an infected animal. Even though rabies can be prevented with a vaccine, it remains a troubling health issue, especially in countries with limited resources.

Each year, over 59,000 people die from rabies worldwide, resulting in a significant economic loss estimated at around $8.6 billion. The Philippines is a major hotspot for rabies, reporting about 200 to 300 cases each year. In response to this ongoing issue, the government established the Anti-Rabies Act in 2007. Unfortunately, despite these efforts, the number of rabies cases did not decrease significantly from 2006 to 2015.

#The Importance of Early Detection

Early detection and treatment play a crucial role in reducing the chances of death from rabies. The most commonly used method for detecting rabies in animals is called the direct fluorescent antibody test (dFAT). This test requires Brain Tissue to find rabies virus. While it is known for being fast and accurate, its effectiveness decreases when the brain tissue decomposes, which is a significant concern in hot climates like the Philippines.

In tropical conditions, brain Samples can spoil quickly, making them unsuitable for testing. Research indicates that when brain tissue is stored at high temperatures, the ability to detect the virus diminishes rapidly. However, viable RNA from brain samples can be identified for a longer period even at elevated temperatures.

#Advancements in Rabies Testing

To improve rabies testing, scientists are looking into new methods that offer better sensitivity and speed. One promising approach is the use of Reverse Transcription Polymerase Chain Reaction (RT-PCR). This technique can detect the rabies virus in tissues that may have low levels of the virus, such as saliva or skin biopsies.

While traditional RT-PCR methods can sometimes yield false positives due to contamination, newer versions of this test have increased accuracy. The LN34 Pan-Lyssavirus assay is one popular RT-PCR method that detects a wide range of rabies viruses and exhibits a high degree of sensitivity.

#Gathering Samples for Testing

To conduct rabies research, scientists need to gather samples. For this, they collect brain tissue, as well as other tissues like nose skin and skin follicles from dogs. These samples are then stored at freezing temperatures until they are ready for analysis.

Collecting brain samples involves a detailed process. It starts with carefully removing the skull to access the brain. Researchers take samples from specific areas of the brain known to carry higher amounts of the virus.

Other samples, like the follicle sinus complexes and nasal planum, require different techniques. For these, small incisions are made to collect tissue.

#Extracting RNA for Testing

Once the samples are collected, researchers need to extract RNA, which is a copy of the virus's genetic material. This involves breaking down the tissue and using special kits to isolate the RNA. The extracted RNA is then kept at ultra-low temperatures until it is needed for testing.

Using the RNA extracted from positive brain samples, scientists conduct RT-qPCR tests to detect the rabies virus. Positive control samples are used to ensure that the tests work correctly.

#Setting Up the RT-qPCR Test

The RT-qPCR tests require specific conditions. This includes finding the right temperature for the test, as well as the correct amount of primers and probes needed to detect the virus. Researchers experiment with different temperatures and concentrations to find the optimal setup for the test.

During this process, they observe how well the assay works by creating a standard curve. This curve helps to determine how efficiently the assay can detect the virus at different concentrations.

#Validating the Test for Accuracy

Validation is crucial in testing new methods. During this process, the assay is tested against known positive and negative samples to measure its accuracy. The tests aim to ensure that the assay correctly identifies rabies and does not mistake it for other canine viruses.

Researchers also need to check that the assay can give similar results when conducted by different people or using different machines. Consistent results help in confirming the reliability of the test.

#Results from Testing

After extensive validation, the optimized RT-qPCR assay showed promising results. It demonstrated the ability to detect rabies virus RNA in both positive brain samples and alternative non-brain samples. In fact, all tested samples showed reliable results, which is good news for ongoing rabies surveillance efforts.

However, a few challenges were identified. Some samples previously labeled as negative did return positive results. This discrepancy might occur due to low levels of the virus that were undetectable by other testing methods, pointing to a need for continuous improvement in testing accuracy.

#The Path Ahead for Rabies Control

Public health organizations worldwide are working towards eliminating rabies, with a target to achieve zero dog-mediated rabies deaths by 2030. Improving diagnostic methods is a key part of this goal. The newly developed RT-qPCR assay can help accelerate testing and enhance rabies monitoring efforts.

However, the current assay is somewhat limited to specific sample types. Future research needs to explore other potential sample sources for rabies testing. Moreover, new testing methods should be developed to reduce costs to make them more widely accessible.

#Conclusion

Rabies poses a significant threat to public health, especially in places where dog bites are common. Although there are vaccines available, rabies continues to claim thousands of lives annually. Enhanced testing methods, like the new RT-qPCR assay, present a way forward. This test can aid in quicker and more efficient detection of rabies, ultimately contributing to better disease management and control.

As we strive toward a world free of rabies, continued research and innovation will be essential to overcoming the challenges that lie ahead. After all, we could all use a world where we can walk our furry friends without worrying about rabies.