The between longitude 340 E and 350 E.

The study will
be carried out in two sub Counties of Homa
Bay County namely; Rangwe and Karachuonyo sub Counties. The study targets
local communities residing within the Oluch-Kimira irrigation scheme and the
neighboring communities. Homa Bay County is located in the southern part of former
Nyanza Province and lies between latitude 0.150S and 0.520
S and between longitude 340 E and 350
E. (Appendix II). According to 2009 Kenya National Population Census, Homa
Bay County covers an area of approximately 3183.3 Km2 and has a
population of about 963,794 people. Homa Bay County experiences semi-arid
climatic conditions where daily temperatures range between 260C and
340C during cold months (April and November) and hot months (January
to March) respectively. The County receives rainfall ranging between 250mm and
1200mm annually. It has two rainy seasons; Long rains (March-April) and short
rains (September- November). With establishment of irrigation scheme and
construction of dams, local communities have adopted mixed crop farming. Some
grow rice, water melon, maize, while others plant vegetables.


The study area will be sub-divided into three
transmission zones based on proximity to irrigation scheme. The three
transmission zones include; High transmission zone denoted “H” (areas within
irrigation schemes), medium transmission zones “M” (areas located 2-3 KM away
from the irrigation scheme and low transmission zones “L” (areas located 5-10
km away from the scheme. (Appendix III). The region experience perennial
malaria transmission (MOH, 2014; Mohajan, 2014; MOH, 2016b, 2016a).


3.2. Study design

The study will be both cross-sectional and
longitudinal in survey. Cross-sectional survey will be conducted three times per
year for two years. It will be carried out in the dry season (January-February 2018), long
rain season (April-May) and short rain season (October-November). The same
cycle will be repeated in the year 2019 (Appendix IV). Study participants aged
6 months and above in every household will be recruited. During each survey,
finger prick blood sample from each study participant will be collected.
The sample will be examined for infections with Plasmodium spp. and gametocyte carriage using microscopy and PCR.


During longitudinal survey
(active case detection), finger prick blood sample for both microscopy and
molecular examination will be collected after every two weeks for one year in all
study clusters. For each study participant, parasitaemia density, anaemia
and body temperature will be determined. Before commencement of the survey,
community members will be recruited into the study. Each household will be
registered into the study after explaining the study purpose, rationale and
methods to the household heads and their family members. Written informed
consent will be sought from the head of the household, while verbal consent
will be obtained from other family members to participate in the study.
Following enrollment, all households will be geo-located using GPS (Garmin,
Switzerland) instruments with up to 5 m of accuracy. Demographic information
such as age, level of education, source of income and gender will be collected
from the head of the family.

3.3. Sampling technique

Cluster sampling will be used to divide the study area
into clusters. A Swiss cheese pattern of clusters within the catchments will be
defined based on geographic and land characteristics (e.g., a group of isolated
houses, villages or sections of a township) and the boundary of each cluster
marked. Cluster radii will vary from 0.25 – 0.5 km and with populations ranging
from 100-250 residents. A malaria risk index will be computed for each cluster
based on proximity to breeding sites, vegetation coverage, and other ecologic
factors. A total of 12 clusters will be identified. The study area will be
classified into three transmission sites (high risk area, medium risk area and
low risk area) based on risk index. For instance, high risk area (within the
irrigation scheme), medium risk area (2-3 KM to the irrigation scheme) and low
risk area (5-10 KM to the irrigation scheme). Four clusters will be identified
within each transmission site. In each cluster, fifty households will be
enrolled into the study.