A Study Of The Immunity To Malaria Among The San People In The Tsumeb Area Of Oshikoto And Kavango Regions Of Namibia

Abstract

The San people are indigenous minorities in Namibia that are known for their hunting and gathering lifestyle. From personal observations, discussions, interviews, raw data from Tsintsabis clinic and results obtained from the research, one had to assume that the San people are immune to malaria. It is unclear how the disease does not affect them although they live in endemic areas. The objective of this study was to investigate how the San have survived without a major outbreak of malaria as well as the mechanism underlying this immunity. The sample consisted of two hundred participants that included the San and the other ethnic groups (“the other ethnic groups” in this study refers to tribes other than the San that lived in the same regions studied).

Questionnaires were administered and focus group discussions were conducted to both groups in Oshikoto and Kavango Regions to determine their knowledge of malaria. The presence of malaria parasites and the structure characteristics of the red blood cells in the blood samples of the San and other ethnic groups were examined microscopically by using thin and thick blood smears. Full blood cell count was measured and the role of nutrition played in the immunity boosting against malaria was investigated. The results were analyzed through descriptive and inferential statistics that included t-test and for indicator variables for the San and the other ethnic groups at 5% level of significance. Chi-square and t-test were used to evaluate differences between the shapes of red blood cell and presence of malaria parasites in the blood of the San and the other ethnic groups.

The results showed that the control groups had better knowledge of malaria (56%) compared to the San people who showed no knowledge of malaria. All San people

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(100%) took traditional medicinal herbs but not specifically against malaria disease compared to 12% in the other ethnic groups. The chi square test indicated that the shapes of the red blood cells of the San (80%), displayed spikes and 2% showed mixed shape on the surface of the erythrocytes compared to the other ethnic groups of which 20% showed spikes and 1% showed a mixed shape. The t-test showed significant differences in the mean numbers of RBC, Hb, MCV, WBC, MON, BAS, LIC between the San and other ethnic groups. A t-test of the haemoglobin indicated that LAIcCHBbI (p=0.003) was significantly higher than the other Hb variants. The mean of the WBC of the San was significantly higher than that of the ethnic groups which suggested that the San are more likely immune to the malaria parasite. There were phenotypic variations in the San red blood cells which most likely as a result of genetic influences.

Food samples of the San analyzed showed the means of the following; 73.88% moisture; 0.83mg/100g Iron; 0.39mg/100g Zinc; 12.37mg/100g Vitamin C; 0.48mg/100g Antioxidants and 0.83mg/100g Flavonoids were all slightly higher than in the other ethnic groups of Sorghum biocolor and Pennisetum glaucum. Pennisetum glaucum had the highest content in Zinc 3.2mg/100g compared to that of the San food.

A study on the presence of fungi on the food of the San people was carried out and the following species were identified R. stolonifer, S. cerevisiae, P. notatum, A. pezia, A. niger. The fungi were possibly producing secondary metabolites that boost immunity against bacterial and some protozoan infections like malaria parasites.

The statistics above explain the immunity of the San, which have not been studied before and for which there is dearth of data in this regard. This knowledge could be useful in determining and developing interventions against transmission of malaria.

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Among others, the significant contribution to the field of malariology is that the San people have a distinct morphology in haemoglobin C whereby 63.1% of the San people showed the presence of HbC and 36.9% in the other ethnic groups. Spiculated RBC, HbC and nutritional elements helped build immunity against malaria parasites in the San people. It is recommended that IgG of the San can be used to test for acquired immunity and development of vaccine in animal studies and therefore can be used to form basis for antimalarial vaccines and drugs.