RT Journal Article
SR Electronic
T1 Co-infections determine patterns of mortality in a population exposed to parasite infection
JF Science Advances
JO Sci Adv
FD American Association for the Advancement of Science
SP e1400026
DO 10.1126/sciadv.1400026
VO 1
IS 2
A1 Woolhouse, Mark E. J.
A1 Thumbi, Samuel M.
A1 Jennings, Amy
A1 Chase-Topping, Margo
A1 Callaby, Rebecca
A1 Kiara, Henry
A1 Oosthuizen, Marinda C.
A1 Mbole-Kariuki, Mary N.
A1 Conradie, Ilana
A1 Handel, Ian G.
A1 Poole, E. Jane
A1 Njiiri, Evalyne
A1 Collins, Nicola E.
A1 Murray, Gemma
A1 Tapio, Miika
A1 Auguet, Olga Tosas
A1 Weir, Willie
A1 Morrison, W. Ivan
A1 Kruuk, Loeske E. B.
A1 Bronsvoort, B. Mark de C.
A1 Hanotte, Olivier
A1 Coetzer, Koos
A1 Toye, Philip G.
YR 2015
UL http://advances.sciencemag.org/content/1/2/e1400026.abstract
AB Many individual hosts are infected with multiple parasite species, and this may increase or decrease the pathogenicity of the infections. This phenomenon is termed heterologous reactivity and is potentially an important determinant of both patterns of morbidity and mortality and of the impact of disease control measures at the population level. Using infections with Theileria parva (a tick-borne protozoan, related to Plasmodium) in indigenous African cattle [where it causes East Coast fever (ECF)] as a model system, we obtain the first quantitative estimate of the effects of heterologous reactivity for any parasitic disease. In individual calves, concurrent co-infection with less pathogenic species of Theileria resulted in an 89% reduction in mortality associated with T. parva infection. Across our study population, this corresponds to a net reduction in mortality due to ECF of greater than 40%. Using a mathematical model, we demonstrate that this degree of heterologous protection provides a unifying explanation for apparently disparate epidemiological patterns: variable disease-induced mortality rates, age-mortality profiles, weak correlations between the incidence of infection and disease (known as endemic stability), and poor efficacy of interventions that reduce exposure to multiple parasite species. These findings can be generalized to many other infectious diseases, including human malaria, and illustrate how co-infections can play a key role in determining population-level patterns of morbidity and mortality due to parasite infections.