Researchers develop quick, inexpensive leptospirosis test

Leptospirosis is a danger that comes with the rainy season. Initial symptoms are not specific. It can be similar to other infectious diseases, such as dengue fever and influenza, causing infected people to be misdiagnosed. Normally, diagnosis is done with expensive equipment and generally takes one or two weeks to know the result. As a consequence, leptospirosis is not treated properly or timely and may cause severe symptoms, and risk of internal organ failure and death.

A research team led by Assoc. Prof. Kanittha Pattarakul, M.D., Department of Microbiology, Faculty of Medicine, Chulalongkorn University has developed an innovative lateral flow strip test for leptospirosis screening that is quick and easy to use so that patients can be diagnosed and treated properly to avoid life-threatening dangers. 

Leptospirosis – a serious threat that comes from water and the animals around you

According to Assoc. Prof. Dr. Kanittha Pattarakul "leptospirosis is a serious threat during the rainy season. Most people tend to think that leptospirosis is carried only by 'rats' and found only in fields or flooded areas. The disease is transmitted from animals to humans and caused by 'leptospira' bacteria which is found in the kidneys of a wide variety of animal reservoirs such as rats, pigs, goats, sheep, cattle, buffaloes, dogs, and cats. These animals may or may not show signs of illness, but can spread the disease through their urine that contaminates the water and soil. The bacteria can live for months in wetland or waterlogged areas such as puddles, ditches, waterfalls, rivers, canals."

To prevent infection, Assoc. Prof. Dr. Kanittha recommends starting with keeping the house clean and avoid walking barefoot or soaking feet in stagnant water, because bacteria may enter the body through pruney skin from prolonged soaking, wounds, and even scratches on the skin. If it is unavoidable, or for those who have to work in stagnant water, protective footwear, such as ankle boots should be worn. If it is necessary to come into contact with these animals, protective equipment such as gloves should be used. Moreover, leptospira bacteria can also enter the body through the conjunctiva or the mouth when coming into contact with contaminated water like swimming, or drinking. So good hygiene is very important. 

Symptoms and treatment guidelines for leptospirosis

Symptoms normally begin to show within one-two week after infection and are divided into two phases as follows:

In the early or acute stage during the first week after infection, the bacteria are in the bloodstream. Patients have nonspecific symptoms such as fever, muscle aches, nausea, vomiting, and a rash. This stage of illness can be treated with antibiotics.

In the second stage, the bacteria spreads through various organs causing inflammation in many systems, such as nephritis which can lead to acute renal failure, hepatitis, jaundice, pneumonia, infection, and bleeding in the lungs, coughing up blood, myocarditis. meningitis, eye inflammation, internal organ failure, and disability which can be life-threatening. For treatment at this stage, the doctors will use intravenous antibiotics along with symptomatic treatment for visceral complications, such as dialysis for kidney failure, a ventilator for respiratory failure. For acute cases, the mortality rate is as high as 25 – 40 percent.

Diagnosis of leptospirosis -- the sooner, the better 

Currently, the standard method for leptospirosis diagnosis requires a specialist in a reference laboratory performing a blood test to detect the pathogen's antibodies which can cost as high as 1,200–1,500 baht per sample. The test takes at least one-two week to obtain results. Other self-test kits that are currently available are antibodies tests. But in the early stage, the body still does not produce any antibodies. Therefore, the test results are often negative. Testing for infectious DNA requires expensive reagents and equipment, so patients may not get an accurate diagnosis from the start.

"It is best to detect the disease early on," said Assoc. Prof. Dr. Kanittha in discussing the importance of the innovative lateral flow strip test. It detects leptospira antigens in the blood, therefore, the infection can be detected in the early stages of the disease. The test strip set was developed by a team of researchers, including Asst. Prof. Amornpun Sereemaspun, M.D Department of Anatomy, Faculty of Medicine, Chulalongkorn University, Prof. Dr. Tanapat Palaga, Department of Microbiology, and Asst. Prof. Dr. Rojrit Rojanathanes, Department of Chemistry, both from the Faculty of Science, Chulalongkorn University, and Prof. Tararaj Dharakul, M.D. from the National Nanotechnology Center, the National Science and Technology Development Agency (NSTDA).

Test strip yields fast results 

The leptospirosis test strip is a stick similar to a pregnancy test that's easy to use. The result is available within 15-20 minutes, and it costs under 200 baht per set. The result can be read with naked eyes, enabling doctors to diagnose quickly even in the acute stage.

"The test strip will report the results in nanometer gold particles. If infected, the strip will appear purple or two red lines on the Test line (T) and the Control line (C). If the result is negative, only one line will appear on the control line (C)," said Assoc. Prof. Dr. Kanittha. She further stressed that the test strip has to be used under the supervision of doctors and used together with a medical history, physical examination results, lab results, and other history and surrounding risk factors, such as occupation, living environment, and history of contact with water sources.