E-ISSN: 2814 – 1822; P-ISSN: 2616 – 0668
ORIGINAL RESEARCH ARTICLE
A. Sani1* and 1M.H.I. Doko
1Department of Microbiology, Faculty of Life Sciences, Ahmadu Bello University, Zaria, Nigeria
Correspondence: aminasani1992@gmail.com;08106502875
Malaria is a public health problem in Nigeria and other developing countries. It is endemic in Nigeria, for which reason individuals are constantly exposed to it, with many of the cases presenting symptomatically or asymptomatically. This study aims to establish an association between the prevalence of asymptomatic and symptomatic malaria with risk factors in order to help develop strategies for management. In this study, blood samples were collected; from apparently healthy individuals and patients having symptoms of malaria attending Ahmadu Bello University Teaching Hospital, Zaria. Thick and thin blood smears were prepared and stained with Giemsa stain observed microscopically. Parasite densities were estimated on positive slides. The prevalence of Plasmodium infection among asymptomatic participants in this study was 15.6%. Type of housing, amongst other risk factors, was one of the factors significantly associated with malaria in this study. The study emphasizes the use of treated mosquito bed nets to further reduce the incidence of malaria.
Keywords: Asymptomatic, Symptomatic, Malaria, Plasmodium falciparum, Risk, Demographic, Prevalence
The parasitic protozoan Plasmodium causes malaria and It is a debilitating infectious disease, threatening half of the world’s population. It is the leading cause of death yearly, predominantly among children in Africa (Benjamin et al., 2019). Fifteen countries in sub-Saharan Africa and India carried almost 80% of the global malaria burden, but five countries, Nigeria (25%), Democratic Republic of Congo (11%), Mozambique (5%), India (4%), and Uganda (4%)) accounted for nearly half of all malaria cases worldwide.
Asymptomatic malaria is the lack of symptoms in the presence of the asexual stage of the malaria parasite in the peripheral blood (Ibrahim et al., 2023). It has remained a global public health issue, which is highly prevalent in endemic areas like Sub-Sahara Africa, mostly among adults who are seen as a reservoir for the transmission of the parasite (Ibrahim et al., 2023).
Research has shown that social, demographic, environmental, cultural, and behavioural factors may dictate the frequency, outcome, and severity of the disease (Benjamin et al., 2019). However, a research gap comparing the prevalence of asymptomatic and symptomatic malaria in association with risk factors exists. Therefore, this study aimed at detecting Plasmodium spp in blood samples of febrile patients and apparently healthy individuals in Ahmadu Bello University Teaching Hospital, Zaria.
The study was conducted in Zaria, Kaduna State, Nigeria. Zaria is an ancient city in northern Kaduna State, Nigeria (Oladimeji and Ojibo, 2012) located on latitude 11ﹾ04’54”N and longitude 7ﹾ 42’57”E (Latlog.net, 2012)
The study population included apparently healthy males (individuals who did not have symptoms of malaria, which included headache, fever, chills, sweat, or treated malaria in the last week) and non-pregnant females and individuals with symptoms of malaria (as mentioned above) that consented and children≥ 1 year of age.
The study was cross-sectional and hospital-based, and convenience sampling was used to recruit the study participants. A total of two hundred and seven individuals (207) were sampled in two groups of (53) fifty-three (25.6%) symptomatic individuals (i.e., with symptoms of malaria) and (154) hundred and fifty-four (74.4%) asymptomatic individuals (apparently healthy)
For this study, a prevalence rate of 14.1%, as reported from a study conducted in Zaria, Kaduna State, Nigeria (Inabo et al., 2011), was used to determine the sample size at 95% confidence interval. A total of 207 blood samples were collected for this study.
A total of 5ml blood samples were collected aseptically into an Ethylenediaminetetraacetic acid (EDTA) container from the participants under study. Samples collected were transported in cold packs to the Department of Microbiology, Faculty of Life Sciences, Ahmadu Bello University, Zaria, for analysis. Thick and thin blood films were made on clean – grease-free slides. The smears were stained using 2% Giemsa solution for the thick film for detection of the parasite and thin film for the identification and speciation of the parasite, respectively (Ojo et al. 2006). A slide was negative if no Plasmodium parasite (having a blue chromatin dot and pinkish-red cytoplasm, thin or thick) was found after scanning 100 high-power fields. The parasite count was against one hundred white blood cells. A white cell count of 8000/µl was used in the analysis (Ojo et al. 2006).
The parasite density was estimated using the formula below: -
Number of parasites per ul of blood=WBC count (8000) x Parasites counted against 100 WBC
The number of white Blood Cells Counted
The socio-demographic and risk factors, including age, gender, occupation, marital status, Type of housing, presence of bushes, use of insecticides, and use of bed nets, were collected using a questionnaire.
Data obtained from the result was analyzed using Chi-square and Fisher’s exact test (for distributions having 0 value) for association of malaria to socio-demographic and risk factors with P at 0.05 as a significant level using SPSS software version 23. All data were summarized in tables.
Out of the two hundred and seven (207), thirty-five (35) tested positive, giving an overall prevalence of 16.9%. Of the one hundred and fifty-four (154) asymptomatic participants, twenty-four (24) were positive, giving a prevalence of 15.6%. Similarly, eleven (11) out of the fifty-three (53) symptomatic were positive, with a percentage prevalence of 20.8%.
Parasitemia among the asymptomatic and symptomatic participants ranges from 95.62 – 9931 parasites/ul and 489 – 13000 parasites/ul, respectively. The highest level of parasitemia recorded was 13000 parasites/ul among the symptomatic patients, whereas the least (95.62 parasites/ul) was observed among the asymptomatic participants as shown in Table 1.
More females were positive among the symptomatic. No individual of age twenty years or less was positive. More individuals between ages 21- 30 years between31-40 years were positive as compared to individuals aged 41 and above. More married individuals were positive. Among the four farmers tested, none tested positive and more civil servants were positive. Also, more of those staying in self-contained were positive among symptomatic participants as shown in Table 2.
More participants who did not have bushes around their houses were positive, and more of those who did not use insecticides were positive. Participants who did not use treated mosquito bed nets had more positive individuals as shown in Table 3.
Out of the one hundred and fifty-four asymptomatic tested, twenty-four were positive, five males and nineteen females. More people within the age range of 31-40 and ≥ 41 were positive, and one widower. More students tested positive next, unemployed civil servants then self-employed lastly, only one farmer tested positive. More participants who lived in self-contained apartments tested positive as shown in Table 4.
More people who have bushes around their house are positive, and more people who do not use insecticides are positive. Also, more people who do not use insecticide-treated mosquito bed nets are positive as shown in Table 5.
Table 1: Level of Parasitemia among Asymptomatic and Symptomatic Participants who Tested Positive for Plasmodium Infection (n=35)
| Level of parasitemia | Asymptomatic No. of Samples Examined |
Symptomatic Total No. of Samples Examined |
|---|---|---|
Low Intermediate High Total |
1 23 - 24 |
9 32 2 2 11 35 |
Low: PD≤100parasites/ul Intermediate: 100<PD<10,000parasites/ul
High: PD≥ 10,000parasites/ul (Awosolu et al., 2021).
Key: PD-Parasite Density.
Table 2: Relationship between Plasmodium Infection and some Demographic Factors among the Symptomatic Study Participants
| Demographic factors | No. examined | No. positive Prevalence% | χ2 /FET | P value | |
|---|---|---|---|---|---|
| Sex | |||||
| Male | 17 | 5 | 29.41 | 1.015 | 0.314 |
Female Total |
36 53 |
6 11 |
16.67 20.8 |
||
| Age(years) | |||||
| ≤10 | 2 | 0 | 0.0 | 4.283 | 0.334 |
| 11-20 | 9 | 0 | 0.0 | ||
| 21-30 | 12 | 4 | 33.33 | ||
| 31-40 | 14 | 4 | 28.7 | ||
≥41 Total |
16 53 |
3 11 |
18.75 20.8 |
||
| Marital Status | |||||
| Married | 40 | 10 | 25 | 1.7870 | 0.1813 |
Single Total |
13 53 |
1 11 |
7.69 20.8 |
||
| Occupation | |||||
| Civil servant | 13 | 5 | 38.46 | 5.634 | 0.191 |
| Farmer | 4 | 0 | 0.0 | ||
| Self employed | 9 | 3 | 33.33 | ||
| Student | 15 | 1 | 6.67 | ||
Unemployed Total |
12 53 |
2 11 |
25 20.8 |
||
| Type of housing | |||||
| Compound house | 26 | 5 | 19.23 | 0.0721 | 0.7884 |
Self-contained Total |
27 53 |
6 11 |
22.22 20.8 |
||
Table 3: Relationship of Plasmodium Infection with some Risk Factors Associated with Exposure among Symptomatic Study Participants
| Risk Factors | No. examined | No. positive Prevalence% | χ2 | P value | |
|---|---|---|---|---|---|
| Presence of Bushes | |||||
| Yes | 19 | 2 | 10.52 | 1.8840 | 0.1699 |
| No | 34 | 9 | 26.47 | ||
Total Use of insecticides Yes NO Total Use of ITN Yes No Total |
53 32 21 53 37 16 53 |
11 6 5 11 7 4 11 |
20.8 18.75 23.8 20.8 18.91 25 20.8 |
0.1973 0.2511 |
0.6569 0.6163 |
Keys: χ2=Chi square, %=percentage, ITN= Insecticide Treated Bed Nets
Table 4: Relationship between Plasmodium Infection and some Demographic Factors among the Asymptomatic Study Participants
| Demographic factors | No. examined | No. positive % Prevalence | χ2 | P value | |
|---|---|---|---|---|---|
| Sex | |||||
| Male | 59 | 5 | 8.47 | 3.675 | 0.055 |
Female Total |
95 154 |
19 24 |
20 15.6 |
||
| Age(years) | |||||
| ≤10 | 47 | 2 | 4.25 | 77.924 | 0.059 |
| 11-20 | 18 | 3 | 16.67 | ||
| 21-30 | 25 | 5 | 20 | ||
| 31-40 | 23 | 6 | 26.09 | ||
≥41 Total |
41 154 |
8 24 |
19.51 15.6 |
||
| Marital Status | |||||
| Married | 68 | 15 | 22.05 | 4.246 | 0.119 |
| Single | 81 | 8 | 9.87 | ||
Widowed Total |
5 154 |
1 24 |
20 15.6 |
||
| Occupation | |||||
| Civil servant | 27 | 4 | 14.81 | 1.462 | 0.833 |
| Farmer | 3 | 1 | 33.33 | ||
| Self employed | 15 | 3 | 20 | ||
| Student | 76 | 10 | 13.15 | ||
Unemployed Total |
33 154 |
6 24 |
18.81 15.6 |
||
| Type of housing | |||||
| Compound house | 97 | 10 | 10.31 | 5.543 | 0.018 |
Self-contained Total |
57 154 |
14 24 |
24.56 15.6 |
||
Keys: Significant at p≤0.05χ2=Chi square, %=percentage No= number
Table 5: Relationship between Plasmodium Infection and Risk Factors among Asymptomatic Study Participants
| Risk Factors | No. examined | No. positive % Prevalence | χ2 | P value | |
|---|---|---|---|---|---|
| Presence of Bushes | |||||
| Yes | 36 | 9 | 25 | 3.166 | 0.075 |
| No | 118 | 15 | 12.71 | ||
Total Use of Insecticides Yes NO Total Use of ITN Yes No Total |
154 110 44 154 124 30 154 |
24 16 8 24 16 8 24 |
15.6 14.54 18.81 15.6 12.90 26.67 15.6 |
0.316 3.478 |
0.574 0.062 |
Keys:χ2=Chi square percentage, ITN= Insecticide Treated Bed Nets
The prevalence of malaria in this study was 16.9%. This shows that malaria prevalence is gradually declining as a result of increased awareness of malaria and its preventive measures. This is lower than the prevalence reported by Idoko et al. (2015), 46.5%, Benjamin et al. (2016), 28.3%, Okogwu et al. (2018), and 25.3% each in Kaduna State. The prevalence of asymptomatic malaria in this study was 15.6%, indicating that the prevalence of asymptomatic malaria is declining gradually. This value is lower than the 20.5% reported by Osue et al. (2013) in Kaduna State.
The prevalence of asymptomatic malaria was higher in females than in males. This is in contrast to that reported by Ojo et al. (2006) but in agreement with the report of Sulabha et al. (2012) that clinical malaria is predominant among males as compared to females, mostly from adolescence; this could be due to socio-behavioral factors and sex hormones though parasite-positivity was independent of sex.
Asymptomatic malaria was found to be higher among individuals who were 41 years of age and above. This could be explained by the fact that adults have been more exposed to the infection than children, so immunity has been developed. This is in contrast to Ojo et al. (2006) and Constant et al. (2018), who found asymptomatic malaria to be more common among children between ages 0-5 years. In agreement with this is a report by Toure et al. (2016) with children 5-10 years of age having the lowest prevalence. More students were positive among the asymptomatic participants. This could be because most of the participants were students.
There was an association between type of housing and prevalence of Plasmodium infection among the asymptomatic study participants, such that more participants staying in self-contained apartments were positive compared to those in compound houses. This could be because people staying in self-contained are not frequently exposed to mosquito bites and, therefore, have low parasite density, which protects against clinical malaria and could represent pre-munition due to previously high parasite density.
The participants who used insecticide-treated mosquito bed nets had a significantly lower prevalence of malaria as compared to those who did not. This is due to the fact that the use of mosquito bed nets prevents the bite of mosquitoes, therefore reducing the incidence of malaria. This is in agreement with the findings by Yusuf et al. (2010) and Sunil (2014), which report that the use of insecticide-treated mosquito bed nets has reduced the incidence of malaria.
The prevalence of malaria was 16.9%, asymptomatic parasitemia was 15.6%, and symptomatic malaria was 20.8% among the study population. This study also shows that the type of housing (P value= 0.018) significantly affects the prevalence of malaria.
There should be more awareness of malaria as well as asymptomatic parasitemia; this could help in reducing the incidence of malaria.
More emphasis should be placed on control measures like the use of treated mosquito bed nets to further reduce the incidence of malaria.
Control measures should also include taking good care of the environment, constant washing of the gutter, clearing bushes around the house and avoiding stagnant water to prevent breeding of mosquitoes. This should reduce the incidence of asymptomatic parasitemia.
Individuals living in self-contained should also use insecticides for the environment so when relaxing outside, there would be no mosquito bites and mosquito nets should also be used when sleeping outside the house.
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