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CHAPTER FIVE
116 accumulation of water bodies seen in the town and these could also serve as a best sites for mosquitoes to breed, 100% of the individual sampled for this study have the knowledge of the usefulness of insecticide treated net but only 26.9% of the individual make use of it (Egbuche et al., 2013).
However, this study recorded a reduced prevalence of 9.8% in Aguleri community irrespective of the environmental condition of the community, the community prevalence reported in this study is close to what was recorded by the National Malaria Indicator survey 2015 (NMEP et al., 2016). The reduction in prevalence in both selected health facilities and Aguleri community in Anambra state could be attributed to the integrated control measures effectively been executed in the state and thus could stand as evidence to buttress the achievement in the malaria control programme of the state thus far.
On the other hand the study recorded a high prevalence in Agura health care centre in Ikorodu, Lagos however, in Regina Mundi catholic Hospital Lagos, all the samples collected were negative. This basically indicates that malaria incidence in Lagos is more in the rural/
sub-urban area of the state. This is supported by a study done in Ibeshe community in Ikorodu Lagos state during the dry season which showed a prevalence of 14.7% (Aina et al., 2013). This study was carried out during the rainy season in Regina Mundi catholic hospital and Agura health centre with a prevalence of 35.5%; all positives seen were from Agura health centre. The high prevalence could be because of a high rate of transmission during the rainy season. This implies that intensive control measures should be implemented in areas such as this which are at the outskirt of Lagos metropolis.
Of all the human malaria species, Plasmodium falciparum has been identified as the most prevalent species (NMEP et al., 2016; WHO, 2017). This fact is further reaffirmed with the
117 findings from this study which showed that the 100% of human malaria cases encountered in this study were as a result of Plasmodium falciparum.
5.2 Discrepancy Significance between Parasite Density with automated WBC, WBC of 8,000cells/ml and 6,000cells/ml
There was also a need to look at the method of parasite density determination with assumed WBC count since some facilities might have to estimate WBC to determine parasite density where actual WBC is not available. Diagnostic quality is a core part of malaria control and possible elimination in Nigeria. The parasite density discrepancy between the parasitaemia obtained with actual WBC and assumed parasitaemia with WBC count of 8,000cells/mL and 6,000cells/mL has been a contending issue (Jeremiah and Uko, 2007; Omalu et al., 2008;
Alves-Junior et al., 2014). This study gives further insight on the deviation of these assumed parasite densities from the actual parasite density and how it could potentially affect the treatment and management of malaria cases.
Some studies suggest that assumption of WBC Count of 8,000 Cells/mL overestimates malaria parasite density (Jeremiah and Uko, 2007; Omalu et al., 2008; Alves-Junior et al., 2014) and a recommendation that 6,000 cells/mL be used in Nigeria which has been applied in some malaria studies (Udomah et al., 2016). This study however did not find any significant statistical difference in the Assumed parasitaemia calculated using a fixed WBC count of 8,000 cells/mL and 6,000 cells/mL, thus these computations can be used in place of parasitaemia calculated using actual patient’s WBC where the actual patient’s WBC is not available.
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5.3 Immune Markers
Cytokines are a relevant factor in patients with clinical malaria, both in severe and mild cases (Prakash et al., 2006). Cytokines have been identified in various studies to play specific roles in disease pathogenesis or protection against severe forms of the disease (Aucan et al., 2000;
Choudhury, et al., 2000; Kinyanjui et al., 2004; Iriemenam et al., 2009a; Medina et al., 2011;
Bostrom et al., 2012; Tran et al., 2012; Rovira-Vallbona et al., 2012).Malaria infection has been identified to result in the characteristic changes in cytokine production which are as a result of the host immune activity in response to the infection (Lyke et al., 2004).
The balance between pro- and anti-inflammatory cytokines are known to play vital role in immune responses and disease pathogenesis of malaria infection, although, the role of these markers in disease pathogenesis and relationship to host protection is still not well established (Prakash et al., 2006). This study profiled IgG which is known to confer protection against malaria and pro inflammatory cytokines IL-8, and TNF which plays different roles in the disease pathogenesis correlating and associating them with the disease presentation, age and sex of study participants.
5.3.1 IgG in Individuals with Symtomatic and Asymptomatic Malaria Infection
The Immune Profile of IgG, was seen to range from 69-202ng/ml with a mean of 97.3 ±24.5 SD in Symptomatic individuals while asymptomatic concentration range was from 92.0-267.7ng/ml with a mean of 127.4±42.2 SD with a p-value of <0.001 which is significant.
Though the mean of the symptomatic is seen to be relatively lower than that of the asymptomatic, however the parasite range shows that the concentrations are quite similar, this which agrees with some earlier study by Perlman and Troye-Blomberg, (2002). This is
119 possibly the case because Nigeria is a country that is endemic for malaria and most of the population would have some form of immunity to the disease.
Furthermore, mean IgG plasma level was seen to be higher among the parasitemic asymptomatic group (122.409ng/ml) than the parasitemic symptomatic group (85.206ng/ml), this could possibly be the reason why individuals from that group are without symptoms even with the presence of the malaria parasite which is supported by a study in Kenya that identified that asymptomatic infection and anti-VSA IgG antibodies are associated with protection against clinical malaria (Kinyanjui et al., 2004).
This study showed some strong significant association between Immunoglobulin G with the presentation of fever, both documented and reported and microscopy readings which was significant among the symptomatic group (Table 8). This could indicate that the increase in the concentration of IgG in this group could be an indication of its protective role since the antibody has recognized the presence of the disease organism and is set to clear the infection.
Other malaria associated symptoms which were assayed did not show any significant relationship with IgG (Table 8).
Studies have shown that adults have the highest concentration of IgG1 (5-12 mg/ml), followed by IgG2 (2 - 6 mg/ml), IgA1 (0.5 - 2 mg/ml), IgM (0.5 - 1.5mg/ml), IgG3 (0.5 - 1.0 mg/ml), IgG4 (0.2 - 1.0 mg/ml), IgA2 (0 - 0.2 mg/ml), IgD (0 - 0.4 mg/ml) and IgE (0 - 0.002 mg/ml) (Shakib and Stanworth, 1980; French, 1986). It has been noticed that individuals who have malaria parasites at the time when their antibodies are being measured usually have high levels of antibodies compared to those that do not have the parasite (Kinyanjui et al., 2007).
120 Among people living in endemic areas, levels of antibodies to malaria antigens are seen to vary with the level of malaria transmission that is, they are highest during the period of high transmission (usually rainy season) and lowest or undetectable during the periods of low transmission (Kinyanjui et al, 2007, Cavanagh et al., 1998). It is evident that Immunoglobulin G has a role to play in the boosting of the immune system though it has been implicated in to be associated with susceptibility to malaria (Riley et al., 2000). The major setback in the role played by immunoglobulin G in malaria is the fact that it has a short half-life (Kinyanjui et al., 2007).