Amref Health Africa in Kenya

1 May 2020

Malaria prevalence and mean parasite density in asymptomatic population of western Kenya

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Tabitha Abongo | AMREF Kenya AMREF International conference Safari Park Hotel Nairobi 24 th -26 th November 2014

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1 May 2020

Presentation Outline

      

Background Information Objectives Methodology Results Discussion Conclusion Recommendation

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Background Information

• Worldwide between one and three million deaths, mostly of children, are attributed to malaria.

• There is a greater potential risk for malaria epidemics at high altitude in several countries in sub-Saharan Africa .

• Kenya’s malaria disease burden is demonstrated by about 70 % of the population living in malaria endemic regions and is at risk of infection.

• This study was conducted to determine malaria incidence and prevalence , and mean parasite densities (MPD) at Kopere village, western Kenya.

1 May 2020 • Malaria prevalence in western Kenya stands at 37% 4

1 May 2020

Research Objectives

•

This study was conducted to determine malaria incidence and prevalence levels.

•

Establish the Mean Parasite Densities (MPD) at Kopere village, western Kenya

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1 May 2020

Study Area

• This study was conducted at Kopere village in the sugar belt area of malaria endemic Kano Plain (Fig 1).

• The area forms a corridor through which malaria emanates to cause epidemics in neighborhood highland district of northern Rift Valley Province of Kenya.

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Study Area

• The area forms a corridor through which malaria emanates to cause epidemics in neighborhood highland district of northern Rift Valley Province of Kenya.

• This study was conducted at Kopere village in the sugar belt area of malaria endemic Kano Plain (Fig 1).

1 May 2020 Fig. 1: The location of study area in Kenya and the cluster of

homesteads

utilized for data collection

1 May 2020

Methodology

• This was a longitudinal survey with study households selected using two-stage sampling procedures.

• The sampling frame comprised all households in Kopere village.

• A sample size of 127 volunteers obtained for the study using the formula; n=z²pq/d² (Fisher, 1971).

• Study Approval -Joint Institutional Research and Ethics Committee (IREC) of School of Medicine-Moi University and MTRH.

• Volunteers were recruited after consenting to the study by signing consent forms.

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1 May 2020

…Methodology

• where minors were involved, both assent and consent were obtained before the specimens were taken.

• Blood smears (BS) were examined at three-monthly • intervals. Data was analyzed using Statistical Package for Social Scientists (SPSS) version 12.

• The incidence rates and MPD compared to identify a more sensitive indicator for monitoring short-term malaria control.

• Malaria incidences, the MPD, and two-year malaria prevalence were determined.

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Results

Age groups BS Asexual(%) Gametes(%) MP(%)

0-11 months 11 12-23 months 12 2-4 years 5-9 years 10-14 years ≥15 years Total 45.5

41.7

137 63.5

177 55.9

181 43.1

330 31.2

848 44.5

9.1

16.7

5.8

4.5

0 0.6

2.2

45.5

58.8

67.2

61.6

44.2

31.5

46.8

MPD/ μℓ blood

104 1844 3744 1952 680 232 568

Where; BS= blood smear, MP= malaria prevalence, and MPD= mean parasite density

Results

• Malaria prevalence of 46.8% (397/848) was obtained from 848 repeat blood smears.

• Non-uniform significant difference in three-monthly interval

incidence rates

were detected (t=5.771, df=6,

p=0.029

). • The MPD for children 2-9 years and other age-groups differed significantly (t=3.356, df=6,

p=0.015

), probably due to differences in immune response to malaria.

• Children 12-23 months old were most gametogonic (16.7%, 2/12); • While those 2-4 year olds had high prevalence (67.2%; 92/137) and an MPD of 3,744-parasites/µℓ blood.

Discussion

• The malaria prevalence of about 47% found in this study compares favorably to an average of 42% reported in Nyanza region in 2012 (Malaria by Numbers, 2012).

• Children 2-4 years were asymptomatic, carrying a mean parasite densities ( 3,744 )in excess of critical threshold of more than 1000 parasites/µℓ blood compared to infants and children ≥15 years.

• Children 2-4 years were the population at Kopere Village.

main malaria reservoir

in the • The findings indicate that

Malaria transmission is stage specific and density-dependent,

and is at peak when critical parasite densities are in excess of 1,000-parasites/µℓ blood.

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Conclusion

• The Malaria prevalence of about 47% was obtained among asymptomatic population in Kopere village.

• Mean parasite density determined for children 2-4 years exceeds the critical threshold of 1,000 parasite/µℓ blood, above which gametogony is initiated.

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Recommendations

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Targeted control

, which lowers the asexual parasite densities below the critical threshold are required to reduce malaria transmission.

• We propose that the MPD can be used to evaluate short-term malaria control; • However a

more controlled study design

is required to confirm the ability of MPD as a sensitive tool, which can be used to monitor short-term malaria control.

1 May 2020

Acknowledgments

• Andrew A. Obala • Tabitha M. Abongo • Helen L. Kutima, • Henry D. Nyamogoba • Ann W. Mwangi • Barasa Khwa-Otsyula • John H. Ouma • Provincial Administration Kopere village • Moi University • Research Foundation of SUNY 15

End

Thank you

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