Abstract
Previous serologic surveys show >80% of infants in Chile have anti-Pneumocystis antibodies by 2 years of age, but the seroepidemiology of Pneumocystis infection beyond infancy is unknown. We describe the sero-epidemiology in infants, children, and adults at different locations in Chile. Serum samples were prospectively obtained from 681 healthy adults (age ≥ 17 years) and 690 non-immunocompromised infants/children attending eight blood banks or outpatient clinics (2 in Santiago) in Chile. ELISA was used to measure serum IgM and IgG antibodies to Pneumocystis jirovecii major surface antigen (Msg) constructs MsgA and MsgC1. Serologic responses to Pneumocystis Msg showed a high frequency of reactivity, inferring infection. Among infants/children increasing age and the proportion with detectable IgM responses to MsgA, and IgG responses to MsgA, and MsgC1 were positively associated. Among adults there was almost universal seropositivity to one or more Pneumocystis Msg constructs. In infants and children rates of detectable IgM responses to MsgC1 and MsgA were greater than IgG responses. In Santiago, rates of seropositivity among infants/children were greater in clinics located in a more socio-economically deprived part of the city. In Chile, a serological response to Pneumocystis Msg constructs was common across ages regardless of geographical location and climatic conditions. Observed higher rates of IgM responses than IgG responses is consistent with concept of recent/ongoing exposure to Pneumocystis in children and adults. Higher rates of seropositivity in infants/children residing in more densely populated areas of Santiago infers crowding poses an increased risk of transmission.
Highlights
We report a high frequency of anti-Pneumocystis antibodies in healthy infants, children, and adults attending hospital outpatient clinics distributed along Chile, suggesting Pneumocystis is prevalent and widely distributed at various geographical locations
There was evidence of a high frequency of asymptomatic infection, as demonstrated by serologic responses to Pneumocystis major surface glycoprotein (Msg) constructs. Among both infants/children and in adults, the frequency of IgG MsgA responses were greater than MsgC1 responses (χ2 = 208.9; p < 0.001, and χ2 = 102; p < 0.001, respectively), whereas IgM responses to MsgA
This study describes the sero-epidemiology of Pneumocystis infection among infant, children and adult populations in different cities in Chile
Summary
Pneumocystis provokes a severe fungal disease known as Pneumocystis pneumonia (PcP)in immunocompromised patients in Central and South America [1,2,3,4,5,6,7,8,9], in low- and middleincome countries in Africa or Europe [10,11,12], and in the more industrialized world [13,14].Serologic surveys for anti-Pneumocystis antibodies do not correlate with incidence of PcP.they have contributed to documenting the widespread occurrence of Pneumocystis in humans. Pneumocystis provokes a severe fungal disease known as Pneumocystis pneumonia (PcP). Serologic surveys for anti-Pneumocystis antibodies do not correlate with incidence of PcP. They have contributed to documenting the widespread occurrence of Pneumocystis in humans. They lead to a better understanding of the epidemiology and may reveal predisposing conditions and be useful to describe the efficacy of strategies of control or prevention. Serologic surveys show that seroconversion resulting from the primary infection is common in children [15,16,17].
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