Prevalence of malaria from peripheral blood smears examination: A 1-year retrospective study from the Serbo Health Center, Kersa Woreda, Ethiopia

Introduction 

Malaria afflicts 90 countries and territories in the tropical and subtropical regions and almost one half of them are in Africa, South of Sahara. About 36% of the world population (i.e., 2020 million) is exposed to the risk of contracting malaria. The World Health Organization estimates 300–500 million malaria cases annually, with 90% of this burden being in Africa. In addition, the estimated annual mortality attributed to malaria ranges from 700,000 to 2.7 million globally and >75% of them are African children and expectant mothers. Doubts have been expressed about reliability of these estimates because most of the hyper and holoendemic countries, especially in Africa, lack credible diagnostic facilities and reporting systems [1], [2].

Malaria is a major public health problem in Ethiopia. The diverse eco-climatic condition in the country makes the malaria transmission pattern seasonal and unstable usually characterized by frequent focal and cyclic widespread epidemics [3]. In Ethiopia, malaria was reported to be endemic first and foremost by the Italian and British scientists from the mid-1930s to the late 1950s. In 1953, severe outbreaks that devastated the lives of 7000 people was reported to occur in Dembia plain near Lake Tana [4] and more than 1 million cases were recorded in the recent epidemic year of 1998 [5]. In 2003 and 2004, there were serious malaria epidemics throughout the country, which affected 15 million persons in 3 federal regions [6].

An estimated 68% (50 million people) of the population lives in areas at risk of malaria. Malaria was reported as the primary cause of health problems in 2004–2005 accounting for 17% of outpatient visits, 15% of hospital admissions and 29% of inpatient deaths [7]. The main components of the malaria control approach in Ethiopia include diagnosis and treatment of cases, the application of selective vector control measures and strengthening the information system to facilitate the prevention, early detection and control of epidemics [8]. Currently, about 6–10% of the world population harbor malaria parasites in their bloodstream [9]. Especially, the physical consequences of infection with Plasmodium falciparum are the main causes of malaria morbidity and mortality in Africa [10]. Almost 3% of disability adjusted life years (DALYs) are due to malaria mortality globally [1].

Because of its dependence on human/vector (mosquito) contact, malaria is considered to be a disease of poverty. Underprivileged people in the rural endemic area become infected with malaria. Also it causes economical lost and impact on the social functions. Monitoring of the incidence of the disease can provide useful data for disease surveillance and control [11]. Health facility records are important sources of malaria data, because they are readily available, can provide useful indicators on the situation of malaria at a lower cost. They are useful not only for planning malaria control and evaluating the impact of health services, but also for epidemiological surveillance. If properly utilized, this information will urge the decision makers to act timely to intensify malaria control interventions effectively and efficiently [12].

Indeed, malaria imposes enormous socio-economic burden on humankind. Malaria remains a major public health problem which contributes to poverty and underdevelopment in sub-Saharan Africa particularly in country like Ethiopia. Currently, information regarding gender and age wise prevalence of malaria is quite inadequate in Ethiopia. Therefore, the purpose of the present investigation was to determine the prevalence of malaria from peripheral blood smear examination from the Serbo Health Center, Kersa Woreda an endemic area of Ethiopia. The present study outcome could serve as valuable resource for malaria surveillance and control strategy in the near future.

Materials and methods 

Results 

A total of 6863 blood smear was examined for the detection of malarial parasites during the study period. The overall prevalence of Plasmodium slide diagnostic yield was 43.8% (3009/6863), wherein P. falciparum was observed to be highest [64.6% (1946/3009 cases)] as compared with that of Plasmodium vivax 34.9% (1052/3009). During the study period, no case of Plasmodium malariae or Plasmodium ovale infection was observed. However, mixed infection with P. vivax and P. falciparum was identified (Table 1 and Fig. 1).

Table 1. Gender and age wise detection of malaria parasites from blood smear examination between July 2007 and June 2008 from the Serbo Health Center, Kersa Woreda in an endemic area of Ethiopia.

	Age group (years)	Total no. of blood film examined	No. of blood film −ve		No. of blood film +ve		Female cases			Male cases			p-Value
			Frequency	%	Frequency	%	Plasmodium vivax	Plasmodium falciparum	Mixed infection	P. vivax	P. falciparum	Mixed infection
	01–05	697	406	58.2	291	41.8	43	83	1	54	109	1
	06–10	785	448	57.1	337	42.9	31	74	0	52	179	1	χ2=28.1
	11–20	643	334	51.9	309	48.1	38	89	0	67	113	2	df=7
	21–30	1007	586	58.2	421	41.8	41	91	1	74	213	1	p=0.001*
	31–40	667	289	43.3	378	56.7	57	104	0	79	138	0
	41–50	1051	631	60.1	420	39.9	61	91	0	112	155	1
	51–60	1070	611	57.1	459	42.9	67	93	1	106	192	0
	≥61	943	549	58.3	394	41.7	51	73	1	119	149	1
	Total	6863	3854	56.2	3009	43.8	389	698	4	663	1248	7

* p<0.05 statistically significant.

View Large Image Download to PowerPoint

Figure 1. Distribution of malaria by species in percentage.

Among patients who underwent diagnostic testing for malaria, males [63.8% (1918/3009 cases)] were more prone to have a positive malaria smear than females [36.2% (1091/3009 cases)]. Chi-square statistical analysis clearly revealed that there was a statistically significant association found between male cases and number of positive blood smear (χ2=28.1; df=7; p-value=0.001). The most affected age group was 31–40 years [56.7% (378/667 cases)] (Table 1 and Fig. 2). Two hundred and twenty-eight patients admitted and treated as inpatients and rest of them were treated as outpatients. 74.5% (170 malaria admission/228 total admission) of inpatients were received treatment for malaria.

View Large Image Download to PowerPoint

Figure 2. Prevalence of malaria by age and gender between July 2007 and June 2008 from the Serbo Health Center, Kersa Woreda in an endemic area of Ethiopia.

Discussions 

Malaria has accompanied humankind since antediluvian period. Modern humans, Homo sapiens, began to emerge in Africa approximately 200,000 years ago [14], [15] and developed during a period overlapping with the current genetic form of P. falciparum [16]. Humans first emigrated out of Africa between 100,000 and 40,000 years ago to colonize Asia, Europe, and Oceania [17]. The four species of malaria that infect humans today (P. vivax, P. ovale, P. malariae, and P. falciparum) arose from an ancestral form 200 million years ago [18]. Malaria is the largest single component of disease burden; epidemic malaria in particular, remains a major public health concern in tropical countries. In many developing countries, and especially in Africa, malaria exacts an enormous toll in lives, in medical costs, and in days of labor lost [19].

The present study chi-square test result revealed that there was a significant association between male patients and number of positive blood smears smear (χ2=28.1; df=7; p-value=0.001). This could be explained by the fact that males are more active outdoors during early evening hrs than females. The present study results are similar reported by Jamaiah et al. [20]. The least affected age group was 41–50 years (39.9%). This might possibly in this part of the world the elderly population mostly stay back in the villages besides their outdoor activities are relatively restricted than young male individuals. Thus, contract with malarial infection is reasonably minimal.

The majority of cases occurred between the age group 31–40 years age group (56.7%) followed by 21–30 years age group (48.1%). The finding of this study similar with a study conducted in Malaysia that the majority of cases found between the age group 20–29 years (43%) [21]. This could be because this age group people are the bread winners as a result they spend outdoors in the evening when peak biting activities of malaria vector mosquitoes are high than other age group individuals. Besides, they prefer to offer any available personal protection materials in particular bed nets to their family members mainly for children's and pregnant women rather than their own personal use.

In the present study P. falciparum constituted the most predominant [64.6% (1946/3009 cases)], while P. vivax confirmed with 34.9% (1052/3009) cases. The findings were relatively comparable with earlier reports, which were found that infections with P. falciparum (>60%) and P. vivax (about 40%) have been consistently reported in many parts of the Ethiopia [22], [23]. Another study which was carried out in the same study area found that the two most important causes of malaria were P. falciparum and P. vivax, comprising of 51.5% and 32.3% of the case, respectively [12]. Ethiopia has the highest proportion of P. vivax malaria on the continent, accounting for approximately 40% of all infection in the country [24]. Similarly few earlier studies also reported regarding high incidence of vivax malaria in Ethiopia, Yewhalaw et al. [25] reported that the predominant species was P. vivax followed by P. falciparum. Similarly, in central Ethiopia, Woyessa et al. [26] reported the predominance of P. falciparum during October while P. vivax tends to dominate during November.

It is interesting to note that the dominant malaria in Africa is caused by P. falciparum, accounting for nearly 100% of malaria cases in most of the sub-Saharan countries. This phenomenon is currently explained by the lack of Duffy receptors on the erythrocytes of Africans, which makes them resistant to infection by P. vivax, the more common species in the rest of the world [27]. Ethiopia is an exception in this respect, since it is a meeting place between Semitic and African races, and 25–35% of malaria cases in Ethiopia are due to P. vivax [28], [29].

In the present study no case of P. malariae or P. ovale infection was observed. In addition, 0.5% of mixed malarial infection of both P. falciparum and P. vivax were also identified. A similar result was reported in a previous study [26]. It is estimated that there are 300–500 million clinical cases of malaria each year worldwide; infection with P. vivax accounts for about 25% of these cases and infection with P. falciparum primarily accounts for the rest. There are 1.4–2.7 million deaths attributable to malaria each year. Most of these deaths occur in African children and are caused by P. falciparum infections [1], [2].

Conclusions 

Indeed, malaria is frequently referred to as a disease of the poverty. Evidently, poorest countries of the world, in particular those in sub-Saharan Africa are major victims for this malicious and merciless killer. Malaria is a leading cause of morbidity and mortality in Ethiopia. Besides, it's a one of major obstacle to socio-economic development as the main transmission periods coincide with peak agricultural and harvesting period. The present study results clearly revealed that the catchment area of Serbo Health Center is extremely prone to epidemic malaria and the situation is quite deteriorating.

Recommendation 

Currently, although we are not equipped with magic bullet for malaria, effective low-cost strategies are available for its treatment, prevention, and control. Therefore, active health education campaign should be instigated among the underprivileged section of the society about importance of regular deployment of insecticide-treated nets (ITNs), malaria treatment, prevention, and control in order to reduce the intolerable burden of malaria. In addition, introduction of integrated malaria vector control strategy in the catchment area of Serbo Health Center could bring the constructive outcome in the near future.

Conflict of interest 

Funding: The authors would like to acknowledge Jimma University Student Research Programme (SRP) for pursuing this research work by providing fund.

Competing interests: None declared.

Ethical approval: Not required.