Prion diseases are transmissible, untreatable, and fatal brain diseases of mammals. Their cause is highly unusual: The host’s normal prion protein can, for unknown reasons, malfunction and assemble into structured aggregates called prions that cause infectious brain disease. This process – which can be underway for years before symptoms appear – likely causes the most common form of prion disease in people, sporadic Creutzfeldt-Jakob disease (CJD). Other forms of human prion diseases include variant CJD, fatal familial insomnia, Gerstmann-Straussler-Scheinker Syndrome and Kuru.

In livestock and wildlife, prion diseases such as scrapie (sheep), chronic wasting disease (deer, elk, moose), and mad cow disease (cattle) can spread by casual contact or contamination of feeds or the environment. Prions also can be infectious if inadvertently transferred from person to person by invasive medical procedures.

Prion disease symptoms reflect the brain being destroyed and can range from memory loss and unstable movement to being unable to sleep or realize the need to eat.

NIAID scientists have focused research on prion structures, biochemistry, cell biology, pathogenesis, diagnostics, and therapeutics. NIAID also is exploring similarities between prion diseases and other protein misfolding diseases, such as Alzheimer’s and Parkinson’s diseases, Lewy body dementia, and chronic traumatic encephalopathy.

Plague, caused by the bacterium Yersinia pestis, is a disease that affects humans and other mammals. People typically get infected after being bitten by a rodent flea that is carrying the bacterium or by handling a plague-infected animal. Although the disease killed millions in Europe during the Middle Ages, antibiotics effectively treat plague today. Without prompt treatment, plague can cause serious illness or death. Human plague infections continue to occur in the western United States, but significantly more cases occur in parts of Africa and Asia.

Why Is the Study of Plague a Priority for NIAID?

Plague is a category A pathogen which are those organisms/biological agents that pose the highest risk to national security and public health because they can be easily disseminated or transmitted from person to person, result in high mortality rates and have the potential for major public health impact, might cause public panic and social disruption, and require special action for public health preparedness.

How Is NIAID Addressing This Critical Topic?

NIAID conducts and supports research on the diagnosis, prevention, and treatment of infections caused by microbes, including those that have the potential for use as biological weapons. The research program to address biodefense includes both short- and long-term studies targeted at designing, developing, evaluating, and approving specific tools (diagnostics, drugs, and vaccines) needed to defend against possible bioterrorist-caused disease outbreaks.

Gonorrhea is a sexually transmitted infection (STI) caused by the bacteria Neisseria gonorrhoeae. N. gonorrhoeae infects the reproductive tract, including the cervix, uterus, and fallopian tubes in women, and the urethra in women and men. N. gonorrhoeae can also establish infection in the mouth, throat, eyes, and rectum. It is becoming more difficult to treat gonorrhea, as strains have been isolated that are resistant to the last antibiotic approved for treatment. NIAID supports a comprehensive, multidisciplinary program of research on N. gonorrhoeae that includes basic research on pathogens, improved diagnostics, preventive vaccines, and additional alternative treatments. 

Schistosomiasis, also known as bilharzia or snail fever, is an acute and chronic disease caused by parasitic flatworms called schistosomes or blood flukes. Most human infections are caused by Schistosoma mansoni, S. haematobium, or S. japonicum. The parasites spend part of their lifecycle in freshwater snails. The infectious, larval form emerges from the snail and contaminates water.

People who contact contaminated water during recreational, agricultural, or domestic activities become infected when the fork-shaped larval worms penetrate their skin, travel to blood vessels, and develop into adults. The release of eggs from female worms triggers symptoms in infected people, which can include abdominal pain, diarrhea, and blood in the urine. In children, repeated infections may cause anemia and stunted growth. Chronic infections frequently result in serious damage to the liver, intestines, and bladder. Women who are exposed to infested water through such routine tasks as clothes washing can develop urogenital schistosomiasis, which may result in tissue damage that increases the risk of HIV transmission.

Why Is the Study of Schistosomiasis (Bilharzia) a Priority for NIAID?

Although the parasites that cause human schistosomiasis are not found in the United States, at least 220 million people are infected worldwide, particularly in rural communities where people routinely collect water from lakes, rivers or small bodies of water for household or agricultural use. Among parasitic diseases, schistosomiasis is second only to malaria in terms of the high disease and economic burden it imposes

How Is NIAID Addressing This Critical Topic?

NIAID-supported investigators study many aspects of schistosomiasis to find new ways to prevent and treat the disease. Research is directed at the various life-stages of parasite itself as well as the freshwater snails that serve as an intermediate host.

Like other so-called neglected tropical diseases (NTDs), schistosomiasis generally impacts the world’s poorest people. Learn about NIAID research efforts on other NTDs.

The NIAID-funded Schistosomiasis Research Center provides investigators with a number of resources to advance their studies, including egg and larval parasites, snails and molecular reagents and other tools needed to conduct research.

This video describes the resources available from the Schistosomiasis Research Center.

VIDEO: Scientists studying schistosomiasis rely on NIAID for an unusual research resource—snails.

Hepatitis is an inflammation of the liver. Viruses are the most common cause of hepatitis, but the condition can also be caused by other infections, heavy alcohol use, toxins, certain medications, and autoimmune disease. There are five main virus types that cause hepatitis---type A, B, C, D, and E. Hepatitis A and E are typically caused by ingesting contaminated food or water. Hepatitis B commonly occurs through contact with infected blood, semen or other bodily fluid through sex, sharing needles or other drug-injection equipment or from mother to baby at birth. Hepatitis C is a blood-borne virus that is largely spread by sharing needles or other drug injection equipment. Hepatitis D, which is transmitted through contact with infectious blood, occurs only among people with hepatitis B infection.

Hepatitis B, C, and D afflict more than half a billion people worldwide and are responsible for more than a million deaths a year. Chronic infection with these viruses can lead to cirrhosis of the liver, end-stage liver disease, and liver cancer.

Hepatitis Research

NIAID supports and conducts research on each of the five known hepatitis viruses—A, B, C, D, and E. During the past 60 years, NIAID-supported investigators have been involved in many important advances in hepatitis research, including:

• Discovery of the hepatitis A and E viruses
• Development of one of the first diagnostic tests for hepatitis A
• Studies that led to the creation of the hepatitis A vaccine
• Studies that laid the foundation for advanced development of a hepatitis E vaccine.

NIAID’s research program emphasizes the study of hepatitis B and C viruses due to the large magnitude of medical burdens that they impose. Studies focus on understanding the immune response to infection, the course of disease development, and developing new therapeutics and vaccines for these viruses.