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The impact of some environmental factors on malaria parasite prevalence was investigated in rural Bolifamba, Cameroon. The study population comprised 1454 subjects aged 0 – 65 years. Malaria parasite prevalence was higher in the rainy (50.1%) than in the dry season (44.2%) with a significant difference (P=0.001) in mean parasite density between seasons. Individuals <15 years old, had significantly higher malaria parasite prevalence (55.5%) than those >15 years (37.4%). Malaria parasite prevalence (P=0.001) and parasite density (P=0.03) were higher in the individuals of wooden plank houses than those of cement brick houses. Inhabitants of houses surrounded by bushes or garbage heaps and swamps or stagnant water showed higher malaria parasite prevalence and densities compared with those from cleaner surroundings. Anopheles gambiae (63.8%) and A. funestus (32.8%) were associated with perennial transmission of malaria. Our data indicates that poor environmental sanitation and housing conditions may be significant risk factors for malaria parasite burden in Bolifamba.
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RESEARCH ARTICLE
African Journal of Health Sciences, Volume 13, Number 1-2, January-June 2006
40
Environmental factors affecting malaria parasite prevalence in rural
Bolifamba, South- West Cameroon
Theresa Nkuo-Akenji *, Nelson N. Ntonifor, Maze B. Ndukum , Helen K. Kimbi , Edith L. Abongwa,
Armand Nkwescheu, Damain N. Anong, Michael Songmbe , Michael G. Boyo , Kenneth N.
Ndamukong and Vincent P.K. Titanji
Faculty of Science, Department of Life Sciences, University of Buea, P.O. Box 63, Buea, South West
Province, Cameroon
* Corresponding author; Email: WIFON@YAHOO.COM
SUMMARY
The impact of some environmental factors on malaria parasite prevalence was
investigated in rural Bolifamba, Cameroon. The study population comprised
1454 subjects aged 0 – 65 years. Malaria parasite prevalence was higher in the
rainy (50.1%) than in the dry season (44.2%) with a significant difference
(P=0.001) in mean parasite density between seasons. Individuals <15 years old,
had significantly higher malaria parasite prevalence (55.5%) than those >15
years (37.4%). Malaria parasite prevalence (P=0.001) and parasite density
(P=0.03) were higher in the individuals of wooden plank houses than those of
cement brick houses. Inhabitants of houses surrounded by bushes or garbage
heaps and swamps or stagnant water showed higher malaria parasite prevalence
and densities compared with those from cleaner surroundings. Anopheles
gambiae (63.8%) and A. funestus (32.8%) were associated with perennial
transmission of malaria. Our data indicates that poor environmental sanitation
and housing conditions may be significant risk factors for malaria parasite
burden in Bolifamba.
[Afr J Health Sci. 2006; 13:40-46]
Introduction
Malaria is prevalent throughout Cameroon
with transmission being affected by climate
and geography [1,2], increased drug resistance
and the lack of adequate vector control
measures [3]. Reduction in man-vector contact
may be achieved by the use of protective
clothing, insect repellents, bed nets,
insecticides or environmental management. In
Zambia, multiple control interventions,
including environmental management against
Anopheles larval stages and improvement in
hygiene and sanitation reduced the overall
malaria incidence and mortality rates by
approximately 50% [4]. In Europe and North
America, malaria was eliminated through use
of insecticides and manipulation of the
environment [5]. Preliminary studies in
Bolifamba indicate that malaria transmission is
perennial [6] with Anopheles mosquitoes
occurring throughout the year. Factors
favouring mosquitoes may include the bushes,
garbage heaps, swamps and stagnant pools of
water that surround many houses in the
village. The poor housing conditions may also
encourage man-vector contact.
The study reported here therefore had as
the objective to investigate the effect of
entomological and environmental factors on
malaria parasite prevalence and parasite
density and provide information that could be
used by the public health sector for improving
its malaria control strategy.
Materials and Methods
Study site
Bolifamba is a village in South West
Cameroon at 247.89oN and 58.24oE and an
altitude of 530 on the east slope of Mount
Cameroon, 25 km from the Atlantic Ocean.
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African Journal of Health Sciences, Volume 13, Number 1-2, January-June 2006 41
It has a relative humidity of 80%, a
temperature range of 18oC – 23oC and an
annual rainfall of 4090mm. It has an equatorial
climate with a rainy season from March to
October and a dry season from November to
February but the rainfall pattern is changing
with rains beginning in June. A slow flowing
permanent stream flows across the village. A
low-lying marshy area that permits the
persistence of anopheline breeding year round
bound the village on the Southwestern side.
The inhabitants are of several ethnic groups
and the main occupation is farming. There are
two main house types – cement brick and
plank (wood) houses.
Parasitological studies
For malaria prevalence studies, 1454 subjects
of both sexes aged 0 – 65 years were selected
at random. Informed consent was obtained
from the parents and guardians of all minors.
In August 2002 (the peak transmission period),
208 children aged 0-14 years were selected to
assess the impact of housing and
environmental conditions on malaria
prevalence and parasite density. Ethical
clearance was obtained from the Provincial
Delegation of Public Health. Thick smears
were prepared, stained with Giemsa solution
and observed under 100X objective. Slides
were reported negative for parasites only after
observing at least 50 fields. Parasite density
was determined by counting the number of
malaria parasites against 200 white blood cells
and expressing the resultant number of
parasites/µl blood assuming a white blood cell
count of 8000 per µl of blood [7].
Entomology
Mosquitoes were collected by human landing
catches and spray catch in the dry and rainy
seasons. Eight adult volunteers served as
mosquito collectors as well as human baits,
half caught mosquitoes using aspirators in two
6 hourly shifts from 6 pm to 6 am from 8
houses each month. Spray catches were done
in 4 rooms per sector in 4 sectors of the village
every month. Rooms were sprayed with a
pyrethrum-based insecticide. Ten minutes after
spraying, adult mosquitoes were collected
from floor sheets. Adult Anophelines were
identified using the Gilles and de Meillon
morphologic identification keys. Human biting
rate (HBR) per person per night was calculated
from the human landing catches and the hourly
night biting pattern determined. Rainfall data
for the Bolifamba area was obtained from the
Cameroon Tea Estate.
Statistical analysis
All parasitological and entomological data was
analyzed with the statistical package for social
sciences (SPSS) [8]. Proportions were
compared using the chi-square or t-test. Means
were compared using analyses of variance
(ANOVA) while significant levels were
measured at 95% confidence level with
significant differences recorded at p<0.05.
Results
Malaria prevalence and parasite density
Six hundred and forty one males and 813
females aged 0-65 years were examined. No
significant difference (p = 0.75) in the
prevalence of malaria parasite was observed
between males (46.1%) and females (47.0%).
Malaria parasite was prevalent throughout the
year but was significantly higher in the rainy
season [50.1% (284/567)] than in the dry
season [44.2% (392/887)] (χ2 =4.8; P = 0.028).
Parasite density ranged from 38 – 50252
parasites/µl blood. The geometric mean
parasite density was 470±9318 and 414±432
parasites/µl blood for the rainy and dry season
respectively, and this difference was also
significant (t = 0.86; df = 1; P = 0.001).
Malaria parasite prevalence and mean parasite
density declined after age 14 (Table 1).
Prevalence in children from 0-14 years was
55.5% and in adults 15-65 was 37.4%
(P<0.05). Mean parasite density was higher in
subjects aged 0-14 year than in those 15-65
years old (Table 1).
Entomological observations
A. gambiae and A. funestus were both
predominant through out the year but the
population of the former was higher during the
rainy season while the later was higher in the
dry season. Two thousand six hundred and
thirty mosquitoes were collected by the human
landing catches and 442 by the spray catch
technique (Table 2). The biting cycles of all
Anopheles species showed peak biting hours
between 1-2a.m. and 2-3a.m. irrespective of
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African Journal of Health Sciences, Volume 13, Number 1-2, January-June 2006
42
season (Fig 1A & 1B). Biting rates were
higher for A. gambiae than for other species.
The rainfall data is shown on Fig. 2 with peak
rainfall occurring in the months of July and
August. There was more biting during the
rainy season than in the dry season
Table 1: Malaria parasite prevalence and geometric mean parasite density (GMPD) by
age group.
Age group
(years)
Number
infected
Prevalence
(%)
GMPD
(Parasites/µl blood ± SD)
0-1 37(75)* 49.3 2915 ± 8727
2-5 173(261) 66.3 3469 ± 12069
6-9 96(193) 49.7 1437 ± 5233
10-14 95(190) 50.0 1081 ± 5673
15-65 275(735) 37.4 328± 777
Malaria prevalence: At 95% confidence level, χ2 = 67.44; df = 4; P = 0.00
Mean parasite density F = 2.94; df = 4, P = 0.0006
*(Total number of individuals tested per age group)
Table 2: Percent Anopheline abundance (n).
Seasons
Rainy season Dry season
Spray catch technique
A. gambiae 46.2* 41.4
(97)** (96)
A. funestus 52.4 56.0
(109) (130)
A. hankocki 1.4 2.6
(3) (6)
Total 100 100
(209) (2320
Human landing catch
technique
A. gambiae 66.8 44.5
(584) (66.2)
A. funestus 32.4 50.3
(283) (747)
A. hankocki 0.8 5.2
(7) (77)
Total 100 100
(874) (1486)
* (Percentage of mosquitoes caught)
** (Numbers caught)
Of the 117 houses examined, 31(26.5%) were
built with cement bricks and 86 (73.5%) with
wooden plank. The average number of
occupants per house was 7. Ceilings were
present in 20.5% cement brick and 11.9%
wooden plank houses. However, the presence
of a ceiling did not have any influence on
parasite density. The malaria parasite
prevalence for children living in wooden plank
and cement brick houses was 62.7% and
45.4% respectively and the difference was
significant (χ2 =13.56; P =0.00). The geometric
RESEARCH ARTICLE
African Journal of Health Sciences, Volume 13, Number 1-2, January-June 2006 43
mean parasite density was 5117±6682 and
3550±4622/µl blood for children living in
wooden plank and cement brick houses
respectively (χ2 = 9.5; P = 0.025). Children
living in houses in which bed nets were not
used had higher malaria parasite prevalence
than those who used bed nets (67.5% versus
45.5%;χ2=5.57;P=0.02).
Effect of environmental conditions on
malaria parasite
Malaria parasite prevalence and parasite
density was higher in children living in houses
surrounded by bushes/garbage and
swamps/stagnant pools of water (Tables 3 and
4 respectively) when compared with those
inhabiting cleaner environments. There was a
high positive correlation between swamps and
stagnant pools and malaria parasite prevalence
(r = 0.82; P = 0.001) while bushes and garbage
were not highly positively correlated (r = 0.56;
P= 0.001).
Fig. 1. Anopheles species peak biting hours in the rainy (A) and in the dry (B) seasons
A
A
A
B
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
2
6-7pm
8-9pm
9-10pm
10-11pm
11-12pm
12-1am
1-2am
2-3am
3-4am
4-5am
5-6am
Hour interval
Biting cycle (mosquito/man/hour)
An. funestus
An. gambiae
An. hankocki
0
0.2
0.4
0.6
0.8
1
1.2
6-7pm
8-9pm
9-10pm
10-11pm
11-12pm
12-1am
1-2am
2-3am
3-4am
4-5am
5-6am
Hour inte rval
Biting cycle (mosquito/ man /hour)
An. funestus
An. gamb iae
An. hankock i
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African Journal of Health Sciences, Volume 13, Number 1-2, January-June 2006
44
Table 3: Association of environmental factors with malaria parasite prevalence.
Environmental Factor 1Present
2Absent χ2 d.f. P
Bushes/garbage *69.7%(69/99) 47.7%(52/109) 10.31 3 0.00
Swamps/Stagnant pools
of water
72.6%(61/84)
48.4%(60/124)
12.09
3
0.00
Bushes/garbage and
swamps/Stagnant pools
of water
60.5%(26/43)
35.0%(7/20)
6.0
3
0.04
1Presence of environmental condition
2Absence of environmental condition
*Malaria prevalence
Table 4: Association of environmental factors with parasite density
Swamps/stagnant pools of
water
Bushes/garbage Swamps/ stagnant pools
of water and
bushes/garbage
Parasite
density
Present Absent
Present Absent
Present Absent
> 10.000 28*(45.9%) 10(16.7%) 20(29.0%) 18(34.6%) 10(38.5%) 0(0.0%)
> 1000 2(3.3%) 13(21.7%) 8(11.6%) 7(13.5%) 6(23.1%) 3(42.9%)
> 400 12(19.7%) 27(45.5%) 30(43.5%) 9(17.3%) 7(26.9%) 2(28.6%)
1-399 19(31.1%) 10(16.7%) 11(15.9%) 18(34.6%) 3(11.5%) 2(28.6%)
Total 61 60 69 52 26 7
χ2
d.f.
25.14
3
10.99
3
5.0
3
P 0.001 0.012 0.015
* Number of positive cases
Relationship between anopheles species
abundance with malaria
A high Anopheles species population
corresponded with higher malaria parasite
prevalence and parasite density. A positive
correlation was recorded between total
Anopheles population and malaria parasite
prevalence (r = 0.50; P = 0.001) as well as
mean parasite density (r = 0.51; P= 0.001).
Discussion
Malaria parasite prevalence differed between
age groups with the highest prevalence in
children less than 15 years old (55.5%). Lower
mean parasite densities were recorded in
adults than in children. This accord with
similar studies conducted in Bamenda, Douala
and Yaounde, [9] and has been attributed to
protective immunity as a result of previous
exposure to malaria.
Entomological surveys conducted in our
study revealed that A. funestus and A. gambiae
were the predominant Anopheles species and
malaria transmission vectors in Bolifamba. In
many areas of Africa, Anopheles gambiae is
found together with an equally important
vector A. funestus [10]. A. gambiae accounted
for about 68% of adult human bait catches, in
both the rainy and dry seasons. A. funestus was
the most populated species caught during
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African Journal of Health Sciences, Volume 13, Number 1-2, January-June 2006
45
spray catches (done indoors) for both seasons.
A low A. hankocki population was recorded in
this study. This species has been reported to be
a secondary vector in malaria transmission and
will effect transmission in the presence of the
main transmission vectors [11].
The seasonal variation in malaria parasite
prevalence in Bolifamba can be attributed to
changes in Anopheles abundance during the
year. High rainfall in the rainy season (Fig. 2)
produced pools and swamps due to poor
drainage, producing suitable conditions for
mosquitoes. In the dry season, the formation of
water pools around some public water taps due
to poor drainage, coupled with much sunlight
was conducive to breeding of A. gambiae
[12,2]. Thus the persistence of some swamps,
together with the existence of bushes or
plantains that surround many households
which serve as resting sites for these
mosquitoes during the dry season leads to high
exposure to mosquito bites and risk of malaria
parasite infect all year round.
Houses built with plank had breaks and
crevices on the walls and ceiling boards that
provided refuges and allowed for easy passage
of mosquitoes. This may explain why more
mosquitoes were caught in plank houses than
brick houses and the higher malaria parasite
prevalence in children living in plank versus
brick houses.
Bed nets were shown to be protective
but most of them were old and some torn,
which explain why children in houses where
bed nets were used still had relatively high
malaria prevalence. None of the bed nets were
treated with insecticides. The presence of
ceiling boards in some houses did not reduce
malaria parasite prevalence as the boards did
not completely cover the roof or had cracks in
them, which served as passage ways for
mosquitoes
Figure 2. Mean rainfall data (mm) for 2001 and 2002.
The impact of environmental surroundings on
malaria prevalence was potentially important
the highest malaria prevalence being recorded
in children living in houses surrounded by
bushes and swamps. High Anopheles species
populations were caught from these
environments. A reduction of malaria
transmission in this area might be achieved by
control interventions involving environmental
management alongside the use of bed nets [4].
Implementation of an environmental control
programme could be achieved by improving
drainage of flooded areas and swamps and
through campaigns to clear bushes and
disposal of garbage (such as building local
incinerators). House improvements should
take into consideration the sealing off of
crevices and breaks in the walls and roof.
0
5
10
15
20
25
30
J. F. M. A. M. J. J. A. S. O. N. D. J. F. M. A. M. J. J. A. S. O. N. D.
Months
Mean rainfall(mm)
Mean rainfall(mm)
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African Journal of Health Sciences, Volume 13, Number 1-2, January-June 2006
46
Acknowledgements
We thank the University of Buea for providing
a malaria research laboratory for our team.
Thanks also go to the Chief and the entire
population of Bolifamba for participating in
the study. This investigation received financial
support from UNDP/World Bank/WHO
Special Programme for Research and Training
in Tropical Diseases.
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... The intensity and duration of malaria transmission is greatly influenced by climate and geography. In many endemic biotopes, the situation is further worsened by increased drug resistance in Plasmodium falciparum, the prevailing parasite species, inconsistent allocation and inadequate use of vector control measures, the occurrence of a vast plethora of permissive and efficient vectors of P. falciparum [5,6], and the occurrence and spread of insecticide resistance in the major vectors [7,8]. Of the 52 Anopheles species described so far in Cameroon, 17 have been reported to support the development and propagation of malaria parasites, amongst which are six major species (Anopheles gambiae, Anopheles coluzzii, Anopheles arabiensis, Anopheles funestus, Anopheles nili and Anopheles moucheti). ...
... Houses with openings at the level of eaves, walls, windows, doors and/or ceilings will enhance mosquito entry, exposing its occupants to higher risks of malaria [32][33][34][35]. Earlier studies in Cameroon revealed higher malaria parasite prevalence and density amongst individuals living in poorly constructed houses (wooden plank houses) compared to those in cement and brick houses [7]. ...
... All holes on the roofs and walls were closed using same type of material used during initial construction by the house owners. Figures 5,6,7,8,9 and 10 show some of the improvements that were done on the house structures. ...
Preprint
Full-text available
Background This study evaluated the effectiveness of improved housing on indoor residual mosquito density and exposure to infected Anophelines in Minkoameyos, a rural community in southern forested Cameroon. Methods Following the identification of housing factors affecting malaria prevalence in 2013, 218 houses were improved by screening the doors and windows, installing plywood ceilings on open eaves and closing holes on walls and doors. Monthly entomological surveys were conducted in a sample of 21 improved and 21 non-improved houses from November 2014 to October 2015. Mosquitoes sampled from night collections on human volunteers were identified morphologically and their parity status determined. Mosquito infectivity was verified through Plasmodium falciparum CSP ELISA and the average entomological inoculation rates determined. A Reduction Factor (RF), defined as the ratio of the values for mosquitoes collected outdoor to those collected indoor was calculated in improved houses (RFI) and non-improved houses (RFN). An Intervention Effect (IE=RFI/RFN) measured the true effect of the intervention. Chi-square test was used to determine variable significance. The threshold for statistical significance was set at P < 0.05. Results A total of 1113 mosquitoes were collected comprising Anopheles sp (58.6%), Culex sp (36.4%), Aedes sp (2.5%), Mansonia sp (2.4%) and Coquillettidia sp (0.2%). Amongst the Anophelines were Anopheles gambiae sensu lato (s.l.) (95.2%), Anopheles funestus (2.9%), Anopheles ziemanni (0.2%), Anopheles brohieri (1.2%) and Anopheles paludis (0.5%). Anopheles gambiae sensu stricto (s.s.) was the only An. gambiae sibling species found. The intervention reduced the indoor Anopheles density by 1.8-fold (RFI=3.99; RFN=2.21; P=0.001). The indoor density of parous Anopheles was reduced by 1.7-fold (RFI=3.99; RFN=2.21; P=0.04) and that of infected Anopheles by 1.8-fold (RFI=3.26; RFN=1.78; P=0.04). Indoor peak biting rates were observed between 02am to 04am in non-improved houses and from 02am to 06am in improved houses. Conclusion Housing improvement contributed to reducing indoor residual anopheline density and malaria transmission. This highlights the need for policy specialists to further evaluate and promote aspects of house design as a complementary control tool that could reduce indoor human–vector contact and malaria transmission in similar epidemiological settings.
... The intensity and duration of malaria transmission is greatly influenced by climate and geography. In many endemic biotopes, the situation is further worsened by increased drug resistance in Plasmodium falciparum, the prevailing parasite species, inconsistent allocation and inadequate use of vector control measures, the occurrence of a vast plethora of permissive and efficient vectors of P. falciparum [5,6], and the occurrence and spread of insecticide resistance in the major vectors [7,8]. Of the 52 Anopheles species described so far in Cameroon, 17 have been reported to support the development and propagation of malaria parasites, amongst which are six major species (Anopheles gambiae, Anopheles coluzzii, Anopheles arabiensis, Anopheles funestus, Anopheles nili and Anopheles moucheti). ...
... Houses with openings at the level of eaves, walls, windows, doors and/or ceilings will enhance mosquito entry, exposing its occupants to higher risks of malaria [31][32][33][34]. Earlier studies in Cameroon revealed higher malaria parasite prevalence and density amongst individuals living in poorly constructed houses (wooden plank houses) compared to those in cement and brick houses [7]. ...
Article
Full-text available
Background: This study evaluated the effectiveness of improved housing on indoor residual mosquito density and exposure to infected Anophelines in Minkoameyos, a rural community in southern forested Cameroon. Methods: Following the identification of housing factors affecting malaria prevalence in 2013, 218 houses were improved by screening the doors and windows, installing plywood ceilings on open eaves and closing holes on walls and doors. Monthly entomological surveys were conducted in a sample of 21 improved and 21 non-improved houses from November 2014 to October 2015. Mosquitoes sampled from night collections on human volunteers were identified morphologically and their parity status determined. Mosquito infectivity was verified through Plasmodium falciparum CSP ELISA and the average entomological inoculation rates determined. A Reduction Factor (RF), defined as the ratio of the values for mosquitoes collected outdoor to those collected indoor was calculated in improved houses (RFI) and non-improved houses (RFN). An Intervention Effect (IE = RFI/RFN) measured the true effect of the intervention. Chi square test was used to determine variable significance. The threshold for statistical significance was set at P < 0.05. Results: A total of 1113 mosquitoes were collected comprising Anopheles sp (58.6%), Culex sp (36.4%), Aedes sp (2.5%), Mansonia sp (2.4%) and Coquillettidia sp (0.2%). Amongst the Anophelines were Anopheles gambiae sensu lato (s.l.) (95.2%), Anopheles funestus (2.9%), Anopheles ziemanni (0.2%), Anopheles brohieri (1.2%) and Anopheles paludis (0.5%). Anopheles gambiae sensu stricto (s.s.) was the only An. gambiae sibling species found. The intervention reduced the indoor Anopheles density by 1.8-fold (RFI = 3.99; RFN = 2.21; P = 0.001). The indoor density of parous Anopheles was reduced by 1.7-fold (RFI = 3.99; RFN = 2.21; P = 0.04) and that of infected Anopheles by 1.8-fold (RFI = 3.26; RFN = 1.78; P = 0.04). Indoor peak biting rates were observed between 02 a.m. to 04 a.m. in non-improved houses and from 02 a.m. to 06 a.m. in improved houses. Conclusion: Housing improvement contributed to reducing indoor residual anopheline density and malaria transmission. This highlights the need for policy specialists to further evaluate and promote aspects of house design as a complementary control tool that could reduce indoor human-vector contact and malaria transmission in similar epidemiological settings.
... [29] The high malaria prevalence observed in the current study could be attributed to the presence of environmental factors including the presence of bushes and stagnant water around residential areas, which favors the breeding of mosquitoes. [27,30] The prevalence of malaria in the current study is also similar to the national prevalence of 29%. [6] Malaria prevalence in this study was highest in children (≤10 years), which is in line with other studies conducted in the area. ...
... [6] Malaria prevalence in this study was highest in children (≤10 years), which is in line with other studies conducted in the area. [28,30] In this study, P. falciparum was the only parasite species identified by microscopy as causing malaria in the study population. P. falciparum has previously been reported as the main cause of clinical malaria in Cameroon. ...
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Background: Malaria and human immunodeficiency virus (HIV) account for significant morbidity and mortality in Cameroon. Studies on malaria and HIV coinfection in the Southwest Region of the country are few. The aim of this study was to determine the prevalence of malaria and HIV coinfection as well as the association between HIV and severe malaria (SM), in febrile patients attending the Regional Hospital of Buea. Materials and Methods: In this cross-sectional study, 218 febrile patients were enrolled from the Outpatient Department/Emergency Unit of the Regional Hospital of Buea. Their vital signs were collected, and the consulting physician examined them. Their HIV and malaria statuses were determined by serology and Giemsa microscopy, respectively. SM was classified according to the WHO criteria. Results: The participants' age ranged between 2 weeks and 79 years, and the majority were females (59.2%). The prevalence of malaria, HIV, and coinfection with malaria and HIV were 30.7%, 6.9%, and 2.3%, respectively. Malaria prevalence was significantly higher in children 10 years and below (P = 0.018); meanwhile, HIV prevalence was significantly higher in participants between 31 and 40 years (P = 0.005). The mean hemoglobin concentration was significantly lower while the malaria parasite density was significantly higher in malaria and HIV-coinfected group. The rate of SM was 13.8%, and this was higher in children ≤10 years (P = 0.037). The association between HIV and SM was not statistically significant (P = 0.308). Conclusion: In general, a low prevalence of coinfection with malaria and HIV was observed, and HIV infection was not found to be associated with SM in this study. Further studies in other populations from Cameroon are required to shed more light.
... Insecticide-treated nets were proven to have a powerful impact on reduction of vector-borne diseases including malaria when used correctly and consistently Roll Back Malaria [22]. Of particular importance is the users' choice of mosquito net in terms of shape and colour as well as practice to mend them when damaged [23]. This was a major problem in the use of, especially the rectangular ITNs/LLIN. ...
... Malaria transmission is influenced by climate and geography. The endemicity is worsened by increased drug resistance and inadequate use of vector control measures (7,8). In 2013, Malaria was responsible for 28.7% of consultations and 49.8% of hospitalizations. ...
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Background: Malaria control faces several threats. Alternative strategies to complement Long Lasting Insecticide-treated Nets and antimalarial therapy are therefore mandatory. This study evaluated the effectiveness of improved housing on indoor residual mosquito density and exposure to malaria-carrying Anophelines in Minkoameyos, a rural community in the center region of Cameroon. Methods: Following the identification of housing factors affecting malaria prevalence in 2013, 218 houses were improved (screening of doors and windows, installing plywood ceilings on open eaves, closing holes on the walls and doors). Quarterly surveys were conducted in a sample of 21 improved and 21 non-improved houses from November 2014 to October 2015. Mosquitoes sampled by night collections on human volunteers were identified morphologically. Their parity status determined. Mosquito infectivity was verified through Plasmodium falciparum CSP ELISA. The average entomological inoculation rates were determined. A Reduction Factor (RF), defined as the ratio of the values for mosquitoes collected outdoor to those collected indoor was calculated in improved houses (RFI) and non-improved houses (RFN). An Intervention Effect (IE=RFI/RFU) measured the true effect of the intervention. Chi-square test was used to determine variable significance. The threshold for statistical significance was set at P < 0.05. Results: A total of 1113 mosquitoes were collected comprising: Anopheles (58.6%), Culex (36.4%), Aedes (2.5%), Mansonia (2.4%) and Coquillettidia (0.2%). Amongst the anophelines were An. gambiae s.l. (95.2%), An. funestus (2.9%), An. ziemanni (0.2%), An. brohieri (1.2%) and An. paludis (0.5%). An gambiae s.s. was the only Anopheles gambiae sibling found. The intervention reduced the indoor Anopheles density by 1.8 fold (RFI=3.99; RFN=2.21; P=0.001 ). The indoor density of parous Anopheles was reduced by 1.7 fold (RFI=3.99; RFN=2.21; P=0.04 ) and that of infected Anopheles by 1.8 fold (RFI=3.26; RFN=1.78; P=0.04 ). Indoor peak biting rates were observed between 02am to 04am in non improved houses and from 02am to 06am in improved houses. Conclusion: Housing improvement reduced indoor residual anopheline density and malaria transmission. This highlights the need for Standardization and promotion of similar interventions to prevent malaria in comparable contexts.
... It is also noteworthy that the age group ≥ 41 had the least parasitaemia load despite having the highest prevalence recorded. A similar report was documented by Nkuo-Akenji et al. (33). This occurrence is thought to be a result of the build-up of matured immunity due to persistent exposure as reported by several authors in many endemic regions of sub-Saharan Africa (19,34). ...
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Background: The connection between malaria-associated morbidities and farming activities has not been succinctly reported. This study aimed to address the connectivity between farming activities and malaria transmission. Methods: The study took place in the agricultural setting of Nigeria Edu local government (9° N, 4.9° E) between March 2016 and December 2018. A pre-tested structured questionnaire was administered to obtain information on their occupation and malaria infection. Infection status was confirmed with blood film and microscopic diagnosis of Plasmodium falciparum was based on the presence of ring form or any other blood stages. Individuals who are either critically ill or lived in the community less than 3 months were excluded from the study. Results: Of the 341 volunteers, 58.1% (52.9% in Shigo and 61.4% in Sista) were infected (parasitaemia density of 1243.7 parasites/μL blood). The prevalence and intensity of infection were higher among farmers (71.3%, 1922.9 parasites/μL blood, P = 0.005), particularly among rice farmers (2991.6 parasites/μL blood) compared to non-farmer participants. The occurrence and parasite density follow the same pattern for sex and age (P < 0.05). Children in the age of 6 to 10 years (AOR: 2.168, CI: 1.63-2.19) and ≥ 11 years (AOR: 3.750, CI: 2.85-3.80) groups were two-and four-fold more likely to be infected with malaria. The analysis revealed that the proximity of bush and stagnant water to the farmer (73.9%, AOR: 3.242, CI: 2.57-3.61) and non-farmer (38.1%, AOR: 1.362, CI: 1.25-1.41) habitations influence malaria transmission. Conclusion: This study highlights farming activities as a risk factor for malaria infection in agro-communities. Integrated malaria control measures in agricultural communities should therefore include water and environmental management practices.
... The AG vectors for instance mostly live in sympatry with AA and AF with all of them sustaining the perennial inoculation of malaria parasite [54,108]. In such sympatry, AG and AF mostly dominate other vectors year-round with peak population in the rainy and dry season respectively [109,110]. ...
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A comprehensive literature review was conducted to create a new database of 197 field surveys of monthly malaria Entomological Inoculation Rates (EIR), a metric of malaria transmission intensity. All field studies provide data at a monthly temporal resolution and have a duration of at least one year in order to study the seasonality of the disease. For inclusion, data collection methodologies adhered to a specific standard and the location and timing of the measurements were documented. Auxiliary information on the population and hydrological setting were also included. The database includes measurements that cover West and Central Africa and the period from 1945 to 2011, and hence facilitates analysis of interannual transmission variability over broad regions.
... Another example of major health losses in SSA is from the prevalence of malaria. The complex factors contributing to malaria risk in urban areas are not fully understood but there is evidence that the urban poor are at significant high risk from malaria (Donnelley et al, 2005) 9 and there was generally a positive correlation between malaria prevalence and the environmental conditions of households, showing a strong correlation for households surrounded in filth and improper waste and sewerage channels (Nkuo-Akenji et al, 2006). In Dar es Salaam, for example, de Castro et al. (2004) found that a large number of breeding sites for the anopheles mosquito were concentrated in lower elevation parts of the city or near drains that require cleaning or rehabilitation, and that entomologic inoculation rates (i.e. the number of infective bites per person per year) were likely to be significantly higher in informal settlements and marginal localities near the periphery. ...
... Bolifamba is semi-rural community in Buea located at 530 m asl. Buea has a mean relative humidity of 80%, average rainfall of 4000 mm and a temperature range of 18-27 °C [26]. All medical facilities selected for the study are government-owned institutions that offer antenatal care, preventive, curative and delivery services at affordable costs and are highly accessible facilitating utilization of ANC services [27]. ...
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Background: Growing concerns about the waning efficacy of IPTp-SP warrants continuous monitoring and evaluation. This study determined coverage of IPTp-SP and compared the effectiveness of the 3-dose to 2-dose regimen on placental malaria (PM) infection and low birth weight (LBW) in the Mount Cameroon area. Methods: Consenting pregnant women were enrolled consecutively through a cross-sectional survey at delivery at four antenatal clinics, two each from semi-rural and semi-urban settings from November 2016 to December 2017. Reported IPTp-SP use, demographic and antenatal clinic (ANC) data of the mothers and neonate birth weights were documented. Maternal haemoglobin concentration was measured using a haemoglobinometer and PM infection diagnosed by placental blood microscopy. Logistic regression analysis was used to model study outcomes. Results: Among the 465 parturient women enrolled, 47.0% (203), 34.7% (150), 18.3% (79) and 7.1% (33) reported uptake of ≥ 3, 2.1 dose(s) and no SP, respectively. Uptake of ≥ 3 doses varied significantly (p < 0.001) according to type of medical facility, timing of ANC initiation and number of ANC visits. The prevalence of PM was 18.5% where uptake of ≥ 3 SP doses (AOR = 2.36: 95% CI 1.41-4.87), primiparity (AOR = 2.13: 95% CI 1.19-3.81), semi-rural setting (AOR = 1.85: 95% CI 1.12-3.04) increased odds of infection. Also, three or more dosing was associated (p < 0.001) with increased PM density notably among women from semi-urban areas. Compared with third trimester, ANC initiation in the second trimester (AOR: 0.39: 95% CI 0.20-0.74) lower odds of infection. The prevalence of LBW infants was 7.3% and were generally those of anaemic (AOR: 4.6: 95% CI 1.03-20.57) and semi-rural (AOR: 5.29: 95% CI 1.73-16.15) women. Although ≥ 3 (AOR: 0.31: 95% CI 0.11-0.87) and 2 (AOR: 0.32: 95% CI 0.11-0.93) doses of SP was associated with lower odds of LBW, ≥ 3 doses were not associated with additional increase in birth weight nor maternal haemoglobin levels when compared with 2 doses. Conclusion: In the Mount Cameroon area, reported uptake of IPTp with ≥ 3 SP doses did not provide observable prophylactic benefits. SP resistance efficacy studies are necessary.
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A research infrastructure was established in two ecological zones in southern Ghana to study the variables of malaria transmission and provide information to support the country's Malaria Action Plan (MAP) launched in 1992. Residents' beliefs and practices about causes, recognition, treatment and prevention of malaria were explored in two ecological zones in southern Ghana using epidemiological and social research methods. In both communities females constituted more than 80% of caretakers of children 1-9 years and the illiteracy rate was high. Fever and malaria, which are locally called Asra or Atridi, were found to represent the same thing and are used interchangeably. Caretakers were well informed about the major symptoms of malaria, which correspond to the current clinical case definition of malaria. Knowledge about malaria transmission is, however, shrouded in many misconceptions. Though the human dwellings in the study communities conferred no real protection against mosquitoes, bednet usage was low while residents combatted the nuisance of mosquitoes with insecticide sprays, burning of coils and herbs, which they largely considered as temporary measures. Home treatment of malaria combining herbs and over-the-counter drugs and inadequate doses of chloroquine was widespread. There i s a need for a strong educational component to be incorporated into the MAP to correct misconceptions about malaria transmission, appropriate treatment and protection of households. Malaria control policies should recognize the role of home treatment and drug shops in the management of malaria and incorporate them into existing control strategies.
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We conducted a three-year entomologic study in Dielmo, a village of 250 inhabitants in a holoendemic area for malaria in Senegal. Anophelines were captured on human bait and by pyrethrum spray collections. The mosquitoes belonging to the Anopheles gambiae complex were identified using the polymerase chain reaction. Malaria vectors captured were An. funestus, An. arabiensis, and An. gambiae. Anopheles funestus was the most abundant mosquito captured the first year, An. arabiensis in the following years. The annual entomologic inoculation rates calculated by enzyme-linked immunosorbent assay were 238, 89, and 150 for the first, second, and third years, respectively. Each year there was a peak of transmission at the end of the rainy season, but transmission occurred year round. The heterogeneity of transmission was found at four different levels: 1) the relative vector proportion according to the place and method of capture, 2) the human biting rate and relative proportion of vectors by month and year, 3) the infection rate of each vector by year, and 4) the number of infected bites for all vectors, and for each species, for the year. Our data show that even in areas of intense and perennial transmission, there exist large longitudinal variations and strong heterogeneity in entomologic parameters of malaria transmission. It is important to take these into account for the study of the variations in clinical and biological parameters of human malaria, and to evaluate this relationship, a very thorough investigation of transmission is necessary.
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A research infrastructure was established in two ecological zones in southern Ghana to study the variables of malaria transmission and provide information to support the country's Malaria Action Plan (MAP) launched in 1992. Residents' beliefs and practices about causes, recognition, treatment and prevention of malaria were explored in two ecological zones in southern Ghana using epidemiological and social research methods. In both communities females constituted more than 80% of caretakers of children 1-9 years and the illiteracy rate was high. Fever and malaria, which are locally called Asra or Atridi, were found to represent the same thing and are used interchangeably. Caretakers were well informed about the major symptoms of malaria, which correspond to the current clinical case definition of malaria. Knowledge about malaria transmission is, however, shrouded in many misconceptions. Though the human dwellings in the study communities conferred no real protection against mosquitoes, bednet usage was low while residents combatted the nuisance of mosquitoes with insecticide sprays, burning of coils and herbs, which they largely considered as temporary measures. Home treatment of malaria combining herbs and over-the-counter drugs and inadequate doses of chloroquine was widespread. There is a need for a strong educational component to be incorporated into the MAP to correct misconceptions about malaria transmission, appropriate treatment and protection of households. Malaria control policies should recognize the role of home treatment and drug shops in the management of malaria and incorporate them into existing control strategies.
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Human intervention in the Brazilian Amazon region promotes contacts between humans and vectors that may favor the propagation of anopheline mosquitoes and the spread of malaria in the absence of planning and infrastructure to control this disease. Vector ecology studies were carried out to determine the risk areas. These data should help in designing appropriate malaria control measures. Data from 14 different regions are reported. Vectors are able to adapt to different environments, which made it necessary to study each area. The parameters studied were Anopheles breeding sites, species distribution, incidence, feeding preferences, hours of maximum activity of adult mosquitoes, seasonality, resting places, and the presence of Plasmodium. Species complexes were also studied. Anopheles darlingi may be responsible for maintaining malaria in human populations in this region. A reduction in the population density of A. darlingi in a particular geographic area can sometimes cause the disappearance of malaria. This species feeds at night but has a peak of activity at the beginning of the evening and another at dawn. Other species are mainly crepuscular and all anophelines demonstrated pronounced exophilia. The timing of feeding activities was found to vary in areas altered by human intervention and also depended on the time of the year and climatic conditions. The larvae were more abundant in the rivers with a less acidic pH and rural areas showed the highest larval index.
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In support of ongoing immunologic studies on immunity to Plasmodium falciparum, demographic, entomologic, parasitologic, and clinical studies were conducted in two Cameroonian villages located 3 km apart. Simbok (population = 907) has pools of water present year round that provide breeding sites for Anopheles gambiae, whereas Etoa (population = 485) has swampy areas that dry up annually in which A. funestus breed. Results showed that individuals in Simbok receive an estimated 1.9 and 1.2 infectious bites per night in the wet and dry season, respectively, whereas individuals in Etoa receive 2.4 and 0.4 infectious bites per night, respectively. Although transmission patterns differ, the rate of acquisition of immunity to malaria appears to be similar in both villages. A prevalence of 50-75% was found in children < 10 years old, variable levels in children 11-15 years old, and 31% in adults. Thus, as reported in other parts of Africa, individuals exposed to continuous transmission of P. falciparum slowly acquired significant, but not complete, immunity.
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Malaria draws global attention in a cyclic manner, with interest and associated financing waxing and waning according to political and humanitarian concerns. Currently we are on an upswing, which should be carefully developed. Malaria parasites have been eliminated from Europe and North America through the use of residual insecticides and manipulation of environmental and ecological characteristics; however, in many tropical and some temperate areas the incidence of disease is increasing dramatically. Much of this increase results from a breakdown of effective control methods developed and implemented in the 1960s, but it has also occurred because of a lack of trained scientists and control specialists who live and work in the areas of endemic infection. Add to this the widespread resistance to the most effective antimalarial drug, chloroquine, developing resistance to other first-line drugs such as sulfadoxine-pyrimethamine, and resistance of certain vector species of mosquito to some of the previously effective insecticides and we have a crisis situation. Vaccine research has proceeded for over 30 years, but as yet there is no effective product, although research continues in many promising areas. A global strategy for malaria control has been accepted, but there are critics who suggest that the single strategy cannot confront the wide range of conditions in which malaria exists and that reliance on chemotherapy without proper control of drug usage and diagnosis will select for drug resistant parasites, thus exacerbating the problem. An integrated approach to control using vector control strategies based on the biology of the mosquito, the epidemiology of the parasite, and human behavior patterns is needed to prevent continued upsurge in malaria in the endemic areas.
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