Appendices

■101

5.A

METHODS FOR LITERATURE SEARCH

5.A.1

Literature search strategy and selection criteria

Here, we present the main tools used in the literature search and analysis. These in-

clude:

• Web of Science

• Google Scholar

• Vos-viewer

• Snowballing

• Expert knowledge

A systematic literature review was performed through the Web of Science, using the option

“all databases”. No constraints were placed on publication type, dates of publication (see

Appendix 5.A), publication status and study location. The search strategy fetched publi-

cations mentioning each of the following concepts in their subject heading, keywords list,

title or abstract: acquired immunity to malaria, malaria model and malaria parasite density.

Additional articles were found through snowballing [83] (backward and forward) literature

search, utilizing the Google Scholar database and also through expert knowledge. The ab-

stracts of all returned candidate studies were assessed for suitability. Papers that mentioned

“(acquired) immunity” to malaria, malaria model or malaria parasite density, (anti-malaria)

drug resistance or intervention in their abstracts were selected for full-text review. Full-text

articles describing the model of acquired immunity to infectious diseases other than malaria

and other than human-malaria, were excluded. Also, papers majorly describing vaccine in-

duced immunity and the co-infection of malaria with some other infections such as HIV

are excluded.

5.A.2

Outcome of literature search

Altogether, 120 literatures were included for answering the research questions. Forty

models of naturally acquired immunity to malaria were explicitly studied with the key

characteristics of each model in relation to quantifying the effect of immunity on malaria

prevalence identified. The remaining 80 papers were included based on the insights they

provided into the properties and underlying mechanisms of acquired immunity, and are

essential to the interpretation and evaluation of the modelling papers. A network visual-

ization of the most common terms addressed and/or used in the titles and abstracts of the

included papers was created (Figure 7) with Vosviewer [14]. It appears that there are three

main clusters of topics/terms addressed by the included papers:

• Immunity to malaria, its stages of acquisition and its level of protection with age and

exposure to parasite infection (left-bottom).

• Malaria transmission and prevalence, based on transmission intensity in different

settings/areas (right).