Vaccine target for devastating livestock disease could change lives of millions - Science Daily

Posted: 27 May 2021 09:02 AM PDT

The first ever vaccine target for trypanosomes, a family of parasites that cause devastating disease in animals and humans, has been discovered by scientists at the Wellcome Sanger Institute. By targeting a protein on the cell surface of the parasite Trypanosoma vivax, researchers were able to confer long-lasting protection against animal African trypanosomiasis (AAT) infection in mice.

The study, published today (26 May 2021) in Nature, is the first successful attempt to induce apparently sterile immunity against a trypanosome parasite. A vaccine was long thought impossible due to the sophisticated ability of the parasites to evade the host immune system. As well as a strong vaccine target for AAT, the findings raise the possibility of identifying vaccine targets for trypanosome species that cause the deadly human infections sleeping sickness and Chagas' disease.

Animal African trypanosomiasis (AAT) is a disease affecting livestock in Africa and, more recently, South America. It is caused by several species of Trypanosoma parasite, which are transmitted by tsetse flies, causing animals to suffer from fever, weakness, lethargy and anaemia. The resulting weight loss, low fertility and reduced milk yields have a huge economic impact on the people who depend on these animals. The disease has been said to lie at the heart of poverty in Africa1.

In humans, a disease called sleeping sickness is caused by infection with another trypanosome species, Trypanosoma brucei. Although control efforts have reduced the number of infections each year considerably, 65 million people remain at risk. In South America, the potentially life-threatening infection Chagas' disease is caused by Trypanosoma cruzi and affects at least 6 million people living in endemic areas2.

All trypanosome species have developed sophisticated anti-immune mechanisms that allow the parasites to thrive in their host. For example, African trypanosomes display a protein on their surface that constantly changes and prevents host antibodies from recognising the pathogen. Until now, it was thought impossible to vaccinate against trypanosome infection for this reason.

In this study, scientists at the Wellcome Sanger Institute analysed the genome of T. vivax to identify 60 cell surface proteins that could be viable vaccine targets. Each protein was produced using mammalian cell lines and then used to vaccinate mice to determine if the host immune system had been instructed to identify and destroy the T. vivax parasite.

One cell surface protein, named 'invariant flagellum antigen from T. vivax' (IFX), was observed to confer immunity against infection in almost all vaccinated mice for at least 170 days after experimental challenge with T. vivax parasites.

Dr Delphine Autheman, first author of the study from the Wellcome Sanger Institute, said: "Scientists have been searching for a way to vaccinate against animal African trypanosomiasis (AAT) since the parasite and vector were first discovered in the early 20th century. We've heard a lot about vaccines recently, but compared to a virus protozoan parasites have a huge number of proteins, making it very difficult to identify the right targets. Several of the 60 targets we tested elicited a partial immune response, but only one conferred the long-lasting protection that makes it a promising vaccine candidate."

Though drugs exist to prevent or treat AAT, many communities that require them live in remote locations that are difficult to access. Reliance on a handful of drugs, and a lack of professional expertise in their administration, are thought to be contributing to increased drug resistance in the parasites3. An effective vaccine would help to overcome some of these practical barriers.

Dr Andrew Jackson, a senior author of the study from the University of Liverpool, said: "It was considered impossible to vaccinate against trypanosome parasites because of the sophisticated immune-protective mechanisms they have evolved, so I'm delighted that we have been able to demonstrate that this can be done. Beyond the obvious benefit of a strong vaccine candidate for animal trypanosomiasis, the genome-led vaccine approach we outline in this study is one that could potentially be applied to other trypanosome species and other parasite families."

The next step will be to validate the results using a cattle model. If successful, work could begin on developing a vaccine for AAT that would be an important tool for tackling poverty in affected regions.

Dr Gavin Wright, a senior author of the study from the Wellcome Sanger Institute and the University of York, said: "This study is an important first step toward relieving the burden of animal African trypanosomiasis (AAT) on both animals and humans in Africa and South America. The protective effect of the vaccine target we identified will first need to be replicated in a cattle model, but I think we can be cautiously optimistic that in a few years' time we will have made substantial progress against this devastating disease."

Michael Pearce, AAT Programme Officer at livestock vaccine organisation GALVmed, said: "Trypanosomiasis remains a major disease challenge for livestock and farmers in Asia, Africa and South America, and is a significant human health problem in Africa and South America. Options for control and treatment of trypanosomiasis are very limited and resistance to currently available medicines is an increasing problem. These novel results from the Sanger Institute are a very important and welcome development, opening up the possibility of successful vaccine development for the prevention and control of trypanosomiasis in both humans and animals."

Notes to Editors:

1 For more details, see the Food and Agriculture Organisation of the United Nations website.

2 For more information on trypanosomiasis in humans, see the WHO website.

3 For more information on attempts to understand, control and prevent AAT, see the University of Glasgow website

Trichomoniasis testing and diagnosis: Options - Medical News Today

Posted: 27 May 2021 02:51 AM PDT

We include products we think are useful for our readers. If you buy through links on this page, we may earn a small commission. Here's our process.

Anyone who thinks that they might have trichomoniasis should get a test for this condition. Without treatment, trichomoniasis can increase the risk of a person contracting HIV.

Trichomoniasis, which people often refer to as "trich," can also increase the risk of pregnancy complications, such as premature labor or low birth weight.

This article discusses what trichomoniasis is and how tests for the infection work. It also lists some of the tests available to purchase online and explains when to see a doctor.

Trichomoniasis is one of the most common sexually transmitted infections (STIs) in the United States, affecting about 3.7 million people. It is particularly common in females.

Although 70–85% of people with trichomoniasis have very few or no symptoms, the infection can still spread from them to others. Due to this, access to a convenient trichomoniasis test is important for people who are sexually active.

The cause of trichomoniasis is a parasite that spreads easily through sexual activity, including:

vaginal sex
sharing sex toys
touching the genitals with the hands after touching fluid that contains the infection
vulva-to-vulva contact

The majority of people with trichomoniasis do not have symptoms. If symptoms do appear, they can take until 5–28 days after exposure to trichomoniasis to develop. It can be easy to mistake the symptoms as being due to another condition, such as a urinary tract infection or yeast infection.

Possible signs of trichomoniasis include:

When people test positive for trichomoniasis, they and any sexual partners should receive treatment for the condition. Antibiotics called nitroimidazoles are the standard treatment for trichomoniasis. This medication, which people take either in one large dose or twice a day for 7 days, is generally effective.

The first step in a trichomoniasis test is collecting a sample, which could be in the form of a urine sample or, for females, a swab of vaginal secretions.

The following are common methods for analyzing samples in a trichomoniasis test:

Nucleic acid amplification tests (NAATs): The Food and Drug Administration (FDA) has approved this molecular detection process for analyzing vaginal swabs and urine samples from females.
Antigen tests: This test, which doctors only use on female samples, is particularly fast and can provide results in 45 minutes.
Wet prep: Although it is potentially the most common testing process, it is not the most sensitive. This method requires analysts to use microscopes to look for parasites in samples.
Culture: Growing cultures from samples may yield high quality test results, but it can take up to 7 days to get results.

A trichomoniasis test can be either positive, negative, or unclear. If the results are positive, and a person has the infection, healthcare professionals can help them get treatment and take action to treat the infection.

Whether people undergo testing at a clinic or take an at-home test, they should discuss the test results with a licensed healthcare professional.

A follow-up test may be necessary if the results are not clear. If the test comes back negative, experts recommend that people use barrier methods, such as condoms, during sexual activity and undergo regular testing for STIs.

Please note that the writer of this article has not tried these products. All information is purely research-based.

Home tests, which connect consumers to certified labs, are available through these companies:

LetsGetChecked

LetsGetChecked offers at-home tests for coronavirus, wellness, and other health concerns, including sexual health.

Three of its sexual health tests — the Basic 3, Standard 5, and Complete 8 — include a trichomoniasis test.

Users receive their tests, collect their samples, and mail them in. They can check their results in a secure online location in 2–5 days. A doctor will review the results, and a nursing team member will then contact the user to discuss the next steps.

EverlyWell

This online health diagnostics company offers 30 test panels, covering everything from allergies to thyroid function.

The trichomoniasis test uses a urine sample. The kit contains a urine cup, sample tube, pipette, bio-hazard bag, and prepaid shipping labels. Users register their kits, collect their samples at home, send them off, and receive doctor-reviewed results securely online within days. If the results are positive, a board-certified doctor will contact the user to discuss the test and the next steps.

The specific test that the company uses is the NAAT, which EverlyWell says is an effective trichomoniasis test for both males and females.

People who have symptoms of trichomoniasis, such as genital irritation, itching, unusual discharge, or discomfort, should consider asking a doctor about getting a trichomoniasis test.

However, because this STI often does not produce symptoms, people should also speak with a doctor or get a test if they have:

received a diagnosis of a different STI
a sexual partner who has tested positive for trichomoniasis or other STIs
had unprotected sex with someone without knowing their sexual history

Trichomoniasis, or trich, is one of the world's most common STIs, especially for females. The symptoms can include itching, discomfort, swelling, soreness around the genitals, and unusual discharge. However, these symptoms resemble those of many other conditions, and most people who get trichomoniasis do not get any symptoms.

The only way to be sure whether someone has this STI is to get a trichomoniasis test. People can get tests from healthcare professionals or use at-home tests. It is important to speak with a doctor to confirm the diagnosis and get appropriate treatments.

Search This Blog

Parasitic Diseases