Our Research
Our collaborative is the product of more than 30 years of intellectual, technological and personnel exchanges between CWRU, the Gonçalo Moniz Research Center of the Oswaldo Cruz Foundation Bahia and now Tulane University. Our objective is to integrate basic research with fieldwork in diseases whose transmission is associated with human fecal contamination of surface waters. We want our work to directly contribute to the tools and knowledge available for use by agents and agencies of public health in the control of these diseases. Major areas of focus currently are schistosmiasis and antibiotic resistance.
For SCHISTOSOMIASIS we place population genetics at the service of public health by understanding the mechanisms for persistence in the presence of repeated treatment, identifying the genetic indices associated with extinction and evaluating the effect of control measures at the parasite population level. At present, our primary tool is microsatellite analysis of DNA from the pool of eggs contained in whole stools from infected individuals. We have projects in rural areas, but also recognize that with ever increasing urbanization, urban disease is increasingly important.
ANTIBIOTIC RESISTANCE is now as much a concern in the community as in hospital settings. Where sanitation is poor, surface waters both reflect and serve as a conduit for transmission of antibiotic resistance between bacteria as well as humans. We investigate the contribution of human and animal fecal contamination to this problem. We explore the significance of these hypotheses through microbial source tracking, antibiotic profiling of human feces and surface waters plus analysis of resistance plasmids.
Antibiotic resistance: effects of sanitation
Antibiotic resistance is a major threat to human health globally. As a threat, it has as much importance for low-income as high-income countries. In some cases, low- or middle-income countries have lower antibiotic use, but similar or greater problems with resistance. Some of this paradox (lower antibiotic use/higher antibiotic resistance) may be explained by poor sanitation that allows for greater horizontal gene transfer and human exposure.
Schistosomiasis: a negelected tropical disease
Schistosomiasis (a.k.a snail fever, bilharzia) is caused by parasitic flatworms of the genus Schistosoma. There are 3 main species: Schistosoma mansoni, S. haematobium, S. japonicum. Schistosomiasis affects more than 250 million people worldwide. An estimated 200,000 people die from it each year. Millions more suffer more subtle morbidities. The disease is found in Africa, Asia, and South America. In South America, the highest prevalence is in Brazil with >6 million infected. Around 700 million people, in more than 70 countries, live in areas where the disease is common. In tropical countries, schistosomiasis is second only to malaria among parasitic diseases with the greatest economic impact. The success of treatment and improving sanitation conditions in some areas has lead to the erroneous impression that the disease has been conquered.
Adult worms reside in the veins draining the intestines or the urinary tract, depending on the species. Symptoms include abdominal pain, diarrhea, bloody stool or bloody urine. Those who have been infected chronically may experience liver damage, esophageal varices, anemia, kidney failure, infertility, or bladder cancer. In children, it may cause poor growth and learning difficulty. More rarely the condition may be associated with paralysis or pulmonary hypertension. Acutely, some may experience a skin rash (swimmer’s itch) or an acute febrile illness (Katayama fever).
Schistosomiasis is ultimately a disease of human fecal, animal fecal (S. japonicum) or human urinary (S. haematobium) contamination of surface waters. The disease is spread by contact with fresh water where there are snails infected with the parasite. The infective form (cercaria) is released from the snail host in response to bright light. Cercariae find and penetrate the skin of humans who enter these waters. Diagnosis is by observing eggs of the parasite in a person's stool or urine .
Methods to prevent the disease include interrupting contamination of surface waters with human or animal (S. japonicum) waste, improving access to clean water and reducing the number of snails. Praziquantel is the treatment recommended by the WHO.
(Heavily modified from Wikipedia April 2018)