Breaking News
April 20, 2018 - Teva and Procter & Gamble Company terminate PGT Healthcare partnership
April 20, 2018 - People diagnosed with traumatic brain injury may have increased risk of Parkinson’s disease, shows study
April 20, 2018 - Researchers use smartphone to diagnose people infected with Loa loa worm
April 20, 2018 - College students with autism have high rate of suicidal thoughts
April 20, 2018 - Study sheds light on how the HSC niche is maintained
April 20, 2018 - Drug test spurs frank talk between hypertension patients and doctors
April 19, 2018 - Low-cost deworming drug improves female farmers’ physical fitness
April 19, 2018 - Genome editing identifies neural circuit behind leptin’s anti-obesity and anti-diabetes effects
April 19, 2018 - Many European countries lack comprehensive policy to eliminate viral hepatitis
April 19, 2018 - Young people with ADHD ‘more likely’ to come from deprived neighbourhoods
April 19, 2018 - SLU professor discovers new biomarkers for chlorine gas exposure
April 19, 2018 - Study proposes new mechanism that may contribute to gender differences in weight control
April 19, 2018 - Sleep restriction therapy does not interfere with insomnia patient’s driving ability, research shows
April 19, 2018 - Deep brain stimulation offers relief to UTHealth patient with treatment-resistant depression
April 19, 2018 - Study shows fatty fish and camelina oil boost HDL and IDL cholesterol
April 19, 2018 - FDA Alert: Euphoric Capsules by Epic Products: Recall
April 19, 2018 - Researchers identify peptide produced during cartilage deterioration as a potential source of osteoarthritis pain
April 19, 2018 - New breakthrough may allow scientists to orchestrate tissue regeneration in humans
April 19, 2018 - SYGNIS AG introduces new TruePrime apoptotic cell free DNA amplification kit
April 19, 2018 - Innovative device shows promise in capturing and releasing circulating tumor cells
April 19, 2018 - Researchers shed light on role of striosomal neurons in reinforcement learning
April 19, 2018 - Genetic make-up impacts long-term effectiveness of phobia treatment
April 19, 2018 - Novel biomarker can distinguish malignant lung nodules
April 19, 2018 - Study reports promising novel approach to treat therapy resistant pediatric brain tumors
April 19, 2018 - One-Hour Plasma Glucose Useful Predictor of Diabetic Retinopathy
April 19, 2018 - Hydroxychloroquine no more effective than placebo for relieving osteoarthritis hand pain
April 19, 2018 - Transplanted livers have a protective effect and reduce potential for organ rejection
April 19, 2018 - Researchers develop new method to study activity of inflammatory cells
April 19, 2018 - Researchers discover highly antibiotic resistant superbugs in Gulf States
April 19, 2018 - Smart-tooth technology shows promise in detecting certain diseases in high-risk patients
April 19, 2018 - Interaction between dioxin and HLA gene variant activates events associated with rheumatoid arthritis
April 19, 2018 - Eyes of adolescents could be associated with increased risk of cardiovascular disease in later life
April 19, 2018 - U.S. Women Less Likely Than Men to Get Statins After Heart Attack
April 19, 2018 - Health Canada grants cannabis cultivation license to High Park Farms
April 19, 2018 - Atypical brain development observed in preschoolers with ADHD symptoms
April 19, 2018 - SC Johnson releases annual Sustainability Report
April 19, 2018 - Positive attitudes about aging reduce risk of dementia in older adults
April 19, 2018 - Environmental pollutants found to worsen rheumatoid arthritis
April 19, 2018 - UT Southwestern scientists discover protein linked to metastatic breast cancer
April 19, 2018 - Study highlights need for further evidence to improve symptom management in end of life care
April 19, 2018 - Detecting diminished dopamine-firing cells inside brain could reveal earliest signs of Alzheimer’s
April 19, 2018 - Uniqsis offers high-power LED light unit for scalable flow photochemistry reactions
April 19, 2018 - Case study shows how intravascular ultrasound imaging helps detect acute aortic syndrome
April 19, 2018 - Research reveals new mechanism by which HIV evades the immune system
April 19, 2018 - Nanodisc-delivered cancer treatment helps eliminate tumors
April 19, 2018 - Functional connectivity MRI could help detect brain disorders and diseases
April 19, 2018 - Finding better way to quantify neuropathy symptoms and treatment efficacy
April 19, 2018 - Study examines effectiveness of caregiver education about sickle cell trait
April 19, 2018 - High-resolution images of tumor vasculature using new technology
April 19, 2018 - Lack of sleep may be linked to risk factor for Alzheimer’s disease
April 19, 2018 - Study finds neurotransmitter may play a role in alcohol relapse, addiction
April 19, 2018 - Researchers build molecular networks of calcific aortic valve disease
April 19, 2018 - Researchers develop highly specific apoptosis assay for pharmacodynamic analyses of tumor specimens
April 19, 2018 - Scientists decipher mechanism of chemotherapy induced female infertility
April 19, 2018 - New insight may allow researchers to design drugs that improve immune responses to vaccines
April 19, 2018 - FDA Approves Crysvita (burosumab-twza) for X-Linked Hypophosphatemia
April 19, 2018 - Researchers uncover origin of virus-fighting plasma B cells
April 19, 2018 - Study finds no evidence of lower intelligence in young children who had anesthesia
April 19, 2018 - Baboons break out of research facility briefly
April 19, 2018 - Study shows how deployment time increases risk of suicide attempt in soldiers
April 19, 2018 - Specific odors from malaria infected individuals attract more mosquitoes
April 19, 2018 - FDA Alert: Rhino 69 Extreme 50000 by AMA Wholesale: Recall
April 19, 2018 - Top HIV cure research team refutes major recent results on how to identify HIV persistence
April 19, 2018 - Experts propose new solutions to increase benefit, affordability of targeted cancer medicines
April 19, 2018 - Deficiency of innate immune adaptor TRIF shortens survival time of ALS mice
April 19, 2018 - New machine learning method offers better way to detect heart disease
April 19, 2018 - CNIO researchers determine structure of protein complex related to cell survival
April 19, 2018 - Faith-based diabetes support program launched by UTSA research team
April 19, 2018 - Volumetric Laser Endomicroscopy Helps ID Barrett’s Regions
April 19, 2018 - Engineered cartilage template to heal broken bones
April 19, 2018 - New computational framework accurately predicts drug-drug and drug-food interactions
April 18, 2018 - Some human cancers may be result of evolutionary accidents, research finds
April 18, 2018 - Higher levels of education linked to lower dementia risk in older African Americans
April 18, 2018 - Smoking Puts Blacks at Higher Risk for Heart Failure
April 18, 2018 - Physiotherapist contributes to guidelines for knee cartilage treatment
April 18, 2018 - Researchers use ‘top-down proteomics’ strategy to get new insights into cancer
April 18, 2018 - Physician assistants less likely to accurately diagnose early stage skin cancers
April 18, 2018 - New faster, streamlined method for bowel cancer detection and treatment
April 18, 2018 - Researchers identify new Listeria species in Costa Rica
April 18, 2018 - Novel interactive diagram shows many facets of mild traumatic brain injury
Researchers shine new light on hookworm-malaria co-infections

Researchers shine new light on hookworm-malaria co-infections

image_pdfDownload PDFimage_print

A study released today from an international team of researchers shines new light on “co-infections,” infectious diseases that attack the immune system simultaneously. The findings offer insights for treating malaria and worm infections and can help public health officials disentangle how infectious diseases compete in the human body.

Princeton ecologists Andrea Graham and Sarah Budischak examined data from an Indonesian study of 4,000 patients who had two parasitic infections: malaria and hookworm. They focused on the malaria patients who also received deworming treatment and discovered previously unknown interactions between the species. Their ecological perspective proved vital to teasing apart the data and realizing that the co-infecting species are fighting over a shared resource: red blood cells.

“Co-infecting agents can interact within the ecosystem of the body just as species interact on the savannah, via resource competition — predation and all,” said Graham, an associate professor of ecology and evolutionary biology and co-director of the Program in Global Health and Health Policy at Princeton University. “Ecologists, thinking about species interactions within the body holistically, can shed light on human health.”

When most people think of ecology, they think about the food pyramid of the rainforest or the Serengeti, said Graham, but the same resource battles that explain lion-wildebeest-grass ecosystems can apply to parasites within the human body.

By taking competition for red blood cells into account, she and her colleagues revealed that removing worms from patients who also had malaria allowed their malaria to grow to nearly three-fold higher densities. Conversely, the presence of the bloodsucking worms reduced the density of malaria parasites by over 50 percent. In other words, deworming can exacerbate malaria infections, potentially causing more severe symptoms and increasing the risk of transmitting malaria to other people. They published their findings Feb. 15 in the journal Ecology Letters.

“Whether and how infections interact has important implications for human health and disease spread,” said Budischak, a postdoctoral researcher in Graham’s lab who is the first author on the paper.

Malaria and soil-transmitted worm infections remain two of the most common and co-occurring types of human infectious diseases, but if and how they interact is a longstanding debate, Budischak said. Using their ecological expertise, she and Graham were able to solve this malaria-worm mystery by recognizing that malaria parasites and certain worm species rely on the same resource within the host ecosystem: red blood cells, the oxygen-carrying workforce of the human circulatory system.

The key to uncovering this strong but hidden effect was changing perspectives, Graham said. The immunologists were looking from a top-down view, focusing on how the immune system attacked the different parasites. That’s like looking at the Serengeti and thinking lions determine the populations of herbivores like zebras and wildebeests. That’s true in some cases — but more often, both predators and food availability are important.

“Malaria parasites are ecologically in a similar position to those herbivores,” Graham said. “They’re depending on resources below them on the food chain — for herbivores it’s the greenery, for malaria parasites it’s the red blood cells — and then all of them are subject to predation from above. For herbivores it’s predators like lions, for parasites it’s the immune system.” Worms are in a similar position in the food chain: they are at risk from immunological “predators,” and hookworms eat red blood cells (though other worms instead eat food within the host’s belly). Because only some worms compete with malaria parasites for red blood cells, this study highlights the importance of distinguishing among parasite species in terms of how they function and which resources they use.

“Of particular interest in this study is that it is the application of ecological thinking that has enabled the elucidation of the helminth [hookworm]-malaria relationship,” said Joanne Lello, a senior lecturer in biosciences at Cardiff University who was not involved in the research. “If resource competition had not been considered, helminths would continue to be treated as a single group and the relationship between these parasites might never have been clarified. The wider implication of this work is therefore in its promotion of ecological thinking and approaches in the field of medical research.”

Just like other animals, some disease-causing species are better competitors than others. The bloodsucking hookworms outcompete one species of malaria, Plasmodium vivax. Interestingly, the other species of malaria, P. falciparum, can outcompete hookworms, especially when they are newly infecting a previously dewormed individual.

The ecologists determined that the difference in the reaction to deworming is a function of how “picky” the malaria species are. “If the hookworms are reducing the number of red blood cells that are around, the vivax, which is pickier in which red blood cells it can use, just doesn’t have enough to replicate as quickly,” Budischak said. “But the falciparum, which use any red blood cell around, can find enough red blood cells to replicate. So the worms slow down the vivax because it’s a really finicky eater, whereas the falciparum, which will eat anything, outcompetes the worms.”

Previous studies had missed this competitive hierarchy because all malaria and worm species were lumped together. Graham and Budischak’s focus on species resource needs was key to sorting the data and discovering that deworming allows vivax malaria populations to increase by as much as three times.

“Although deworming may still provide net health benefits to this human population, our study suggests it has the potential to exacerbate the severity of some malaria infections,” said Budischak.

“If you mass administer deworming pills, you risk making individuals who have vivax malaria hiding in their blood cells sicker — and you also might make the mosquitos more likely to pick up malaria and pass it on from those individuals,” said Graham. “So, if logistics and cost permit it, we would advise a ‘test and treat’ policy, where you tailor what you do to your patient. If it’s a child who’s got a lot of worms, definitely deworm. But if it’s a kid with a light worm burden, then we’d suggest weighing in the malaria risk — in the neighborhood, in that season of the year. Is deworming worth the malaria risk? Weigh up the costs and benefits.”

Graham met one of the principal researchers on the Indonesian clinical deworming trial, Maria Yazdanbakhsh, at a conference in Brazil that Graham co-organized three years ago. Graham recalled Yazdanbakhsh and her collaborator Erliyani Sartono, parasitologists from the Leiden University Medical Center in the Netherlands, coming up afterward to discuss their clinical trial that might just have the data necessary to address this disease interaction question. Graham, Sartono and Yazdanbakhsh decided to put their heads together and this study is the fruit of their collaboration.

Graham had spent years testing her theories in mice. “In mouse experiments, you can control the dose and the timing of interaction between malaria and worms,” she said. “Repeatedly, in the mice, we saw that red blood cell competition, rather than the immune response, seems best to explain the outcome of worm-malaria co-infection. So this [collaboration] allows us to ask, ‘Wow, this resource competition that we observed in the mouse system, can we also observe it in humans?'”

Graham and Budischak hope that their discovery encourages more public health researchers to collaborate with ecologists. “Infectious disease clinicians don’t necessarily realize that they might learn something from ecologists,” said Graham. “But ecologists, coming in laterally into a clinical trial context — thinking holistically about what is regulating the size of the malaria population inside a person’s body — were able to make more sense of the health outcomes than the more standard, immunological-based approach.”

Source:

https://www.princeton.edu/

Tagged with:

About author

Related Articles