title: Considering causality: a response to Muula.
authors.forename: Janet S
authors.initials: JS
authors.lastname: St Lawrence
mesh_terms: D015984:Causality; D004866:Equipment Contamination; D005260:Female; D015658:HIV Infections / Q000453:epidemiology / Q000635:transmission*; D006679:HIV Seropositivity / Q000453:epidemiology*; D006801:Humans; D007267:Injections / Q000009:adverse effects*; D011247:Pregnancy; D015995:Prevalence; D015024:Zambia / Q000453:epidemiology