Antagonism between two intestinal parasites in humans: the importance of co-infection for infection risk and recovery dynamics

Abstract

Co-infection may affect transmission and recovery from infection, but remains an understudied element of disease ecology, particularly with regard to antagonism between parasites sharing a host. Helminth and giardia infections are often endemic in the same populations and both occupy the small intestine; yet few studies have examined interactions between these parasites. We report on helminth -giardia co-infections in a panel study of forager -horticulturalists in the Bolivian lowlands. Parasites were identified in faecal samples from 3275 participants, collected during 5235 medical exams over 6 years. Longitudinal co-infection patterns were examined using logistic mixed and multi-state Markov models. The most prevalent infections were hookworm (56%), Giardia lamblia (30%) and Ascaris lumbricoides (15%). Cross-sectionally, hookworm and A. lumbricoides were negatively associated with G. lamblia (OR ¼ 0.60; OR ¼ 0.65, respectively). Longitudinally, giardia infection was less likely in helminth-infected individuals (HR: 0.46). Infection with helminths was also less likely for individuals infected with giardia (HR: 0.71). Finally, treatment with mebendazole reduced subsequent hookworm infections, but resulted in a marginal increase in the odds of G. lamblia infection. Our results provide evidence for an antagonistic relationship between helminths and giardia, and suggest that co-infection should be considered in disease transmission models and treatment decisions.

Water from fruit or the river? Examining hydration strategies and gastrointestinal illness among Tsimane’ adults in the Bolivian Amazon

“…Tsimane' children and adults have a 56-80 % prevalence of parasitic helminthic infections (10,11) . Infectious diseases, including GI infection, historically have accounted for more than 50 % of all deaths (45) .…”

“…The paper focuses on Tsimane' because they lack access to clean water, yet are highly active and live in a hot, humid environment, creating high water needs. Additionally, previous research has documented high prevalences of water-related diarrhoeal diseases and parasitic infection (10,11) . …”

Interspecific competition in honeybee intracellular gut parasites is asymmetric and favours the spread of an emerging infectious disease

“…In turn, these can have significant impacts on epidemiology [8][9][10][11][12], with major repercussions for disease control in humans [13,14] and other animal hosts [15]. For example, rodents infected with multiple Plasmodium sp.…”

Unusual Enterobius-Hookworm Co-Infection Presenting With Severe Anaemia in an Apparently Immunocompetent Patient: A Case Report

“…Although albendazole or mebendazole have been the mainstay of therapy against hookworm since times long past, a study by Blackwell et al concluded that antiprotozoal agents may provide short-term benefits, but do not appear to have lasting effects due to constant reinfection. 15 An effective treatment for either parasite is not likely without a coalition of short-term therapy and long-term improvements in sanitation systems and access to clean drinking water besides health awareness amongst the masses. …”