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■Bio-mathematics, Statistics and Nano-Technologies: Mosquito Control Strategies

Table 5.1: Glossary of definitions for commonly-used special terms

Innate immunity

Inborn protective mechanisms which are the first line of defense

against infection. It is not dependent on any previous infection

[11], [199].

Adaptive

or

naturally

ac-

quired immunity (NAI)

Immunity that is gained through exposure [11], [199]. It consti-

tutes anti-disease immunity, anti-parasite immunity and premu-

nition, all of which develop in parallel, reducing the probability

of experiencing symptomatic malaria upon each subsequent in-

fection.

Clinical or anti-disease immu-

nity

Immune responses that reduce the frequency and severity of clin-

ical disease [200], [11], [211].

Anti-parasite or parasitologi-

cal immunity

Immunity, that is responsible for parasite clearance from the

body [200], [211].

Premunition

A functional immunity that reduces the frequency and severity

of clinical disease but does not necessarily eliminate infections

but rather allows them to remain at low density [212]. This is

usually seen in endemic areas and comprises age dependent and

haplotype-independent effects on parasite densities, which re-

flect the strength of maturity of the immune system [35], [170]

and gradual acquisition with exposure [168], [169].

Pre-erythrocytic

(erythro-

cytic) immunity

Immunity against liver-stage (blood-stage) malaria parasites;

also known as liver-stage (blood-stage) immunity [34].

Asymptomatic

A case of no obvious symptoms in an individual who is a carrier

of a disease[202]. Regarded as a misnomer due to the significant

health and societal consequences of chronic infections which in

reality are associated with considerable non-acute burden with

mild symptoms [117].

Sterile immunity

Immunity that completely suppresses an innoculum of a

pathogen [201]. This can be thought of as the highest attainable

peak of acquired immunity which is probably never achieved.

Non-sterile immunity results in persistence of the pathogen, but

no symptoms of disease.

Parasitemia

Characterizes the density of parasites within a host [38]. Lower

parasite density tends to confer milder symptoms but could be

dangerous if not detected and treated, since it adds the number

of new cases occurring within a period of time (incidence), and

can become very symptomatic later [15]

Superinfection

The imposition of a second infection on a first before it has died

out [88], [165]

5.2.1

Misleading binary view on malaria immunity

The early compartmental models are simplistic and oriented towards understanding

how to eradicate the disease, using the transmission threshold criterion, R0 (see Table 5.2)

with little or no detail on the immune mechanism. The use of mathematical modeling in

the study of malaria originated from the seminal works of Ross [95] well over a century

ago. His work suggests that reducing the mosquito population to below a certain thresh-

old can engender successful malaria eradication. The Ross Macdonald model [96] simply