The unmet need in researching and preventing HIV and Toxoplasmosis co-infection
By David Miller and Chris Romano
The International AIDS Society (IAS) held the world’s largest scientific gathering on HIV science in Paris, France this year, a country where 37% of patients with AIDS have evidence of toxoplasmic encephalitis.
Toxo has been reported as the most common opportunistic infection in HIV/AIDS in developed countries and the most common cause of focal brain lesions, coma and death. It commonly causes encephalitis in HIV-postive patients and increases the risk of HIV Associated Neurological Disorders (HAND) by 60%.
HAND is becoming increasingly prevalent as Anti-Retroviral Therapy (ART) allows HIV patients to live longer lives. Several poster sessions at IAS 2017 discussed the issue of HAND.
Ei Kinai from the National Center for Global Health and Medicine in Tokyo, Japan presented on The Impact of Age and Time of Disease on HAND. The study concluded that, “Older patients are more likely to have neurocognitive decline at early stages of HIV infections.” It is also known that the prevalence of Toxo increases with age, an aspect that was not addressed in the study.
Galia Manuelle Aurora Santos from Lausanne University Hospital Center in Lausanne, Switzerland presented on the link between depressive symptoms and HAND. This study suggests that addressing depressive symptoms, especially in HIV positive-women, might potentially improve the neurocognitive outcome of HIV-positive patients. Toxo has been linked to depression in numerous studies.Vincent Senecal of the Centre de Recherche du CHU de Quebec, Centre de Recherche en Infectiologie, Quebec, Canada shed light on HAND pathogenesis by studying the interactions of HIV with the anti-inflammatory chemokine, fractalkine (FKN). The results indicated that HIV reduced FKN receptor expression in microglia/macrophages which could have important implications in chronic inflammation and immune activation for HAND. It has been found in separate studies that Toxo also down-regulates FKN after 24 hours of infection.
HAND continues to be a major concern in HIV patients and the connection between HAND and toxo is an understudied issue that may help to better understand and potentially treat HAND. New studies to determine if toxo has a causative effect contributing to neurocognitive decline in people living with HIV are essential.
Toxo infects approximately 1.1 million people each year in the United States. The global prevalence is estimated between 2 and 3 billion and there is no cure. Acute infection in the immune compromised is often deadly if not aggressively treated with Pyrimethamine (Daraprim). In 2014, the CDC designated Toxo a Neglected Parasitic Infection (NPI), targeting it for public health action based on the number of people infected and the severity of the disease. Less than a year later, Martin Shkreli, then CEO of Turing Pharmaceuticals, acquired the rights to Daraprim and raised the price of the now 64 year old drug 5000%, a notorious move that increased an annual prescription to $634,500 for patients weighing more than 60 kilograms (132 pounds).
Without an available cure and considering the unfavorable treatment options at hand, our only immediate hope to alleviate the burden of toxo is to prevent human exposure to the offending pathogen causing the initial disease.
Toxo can only complete its life cycle and produce infectious spores on cat feces. Most people and animals become infected by unknowingly ingesting or inhaling these spores which makes cleaning a cat’s litter box a high-risk activity, particularly to those who are immune- compromised. Simple precautions should be taken that can eliminate the risk of toxo infection.
Toxo is also transmitted by consuming the raw or rare meat of previously infected animals and is a leading cause of death from foodborne illness in the United States. The general public is warned of toxo risk by the mandated menu advisory, “Consuming raw or undercooked meats, poultry, seafood, shellfish, eggs or unpasteurized milk may increase your risk of foodborne illness,” But public awareness on how to prevent toxo infections is otherwise extremely limited.
With more than one third of the U.S population sharing their homes with pet cats, the responsibility to provide the warnings and resources necessary to protect the general public from the burdens of toxo and create a safer environment for both humans and cats, should be a high priority of our public health d healthcare systems.
viable solutions to reducing the risk of toxo are essential. One such alternative to using masks and gloves when changing kitty litter is a self-contained cat waste disposal system (created by Toxoplasmosis Solutions, an enterprise of BetterBox) which allows cat owners to safely contain and dispose of domestic cat waste without exposing themselves or their environment to toxo’s infectious spores. Additional tools that the public can utilize including public service announcements on how to properly handle and prepare raw meet, are needed.
Toxo’s life cycle is dependent on cat waste contaminating the environment of its future hosts. Considering that the majority of cats in the U.S. are domesticated and living in human homes, mechanically blocking the life cycle of this devastating disease by implementing responsible cat waste disposal procedures is an effective option.
Legislators in the U.S. need to be encouraged to develop a national toxoplasmosis bill supporting the additional research, education, prevention, and treatment efforts. The latest scientific findings regarding “latent” toxo along with the compelling epidemiology to inform legislators, public health officials, and health insurance providers that an investment towards designing public awareness has great potential to reduce healthcare costs and disease burden in the United States and globally.