The high case fatality status of malaria in hyper endemic regions of sub-Saharan Africa including Nigeria is of public health importance (WHO, 2003). Programs aimed at reducing the incidence of this disease excluded the screening for parasitemia before transfusion. The prevalence of 15.8% parasitemia (Table 1) reported in this study among blood donors calls for immense concern as it reflects the high risk of transfusion transmitted malaria. In a similar study, Uneke et al., (2006) reported a prevalence of 40.9%, whereas Okocha et al., (2005) reported 30.2% prevalence within the same South East locality. Other similar studies done within African region among blood donors reported prevalence of over 30.0% (Achidi et al., 1995, Kinde-Gazard et al., 2000 and Ali et al., 2005).The reason for the lower prevalence reported in our study over that of other authors could be attributed to apparent compliance to the “Roll back malaria” program currently going on in Ebonyi state.
Despite the lower prevalence in our study over that of others, the risk posed by it is still a threat to the success of the fight against malaria since the recipients of infected blood are the most vulnerable group to malaria and include, children below five years of age, pregnant women, splenectomised or immune compromised patients (Chadramohan and Greenwood, 1998, Migot et al., 1996)
A significant relationship exists between age and parasitemia among donors as reported in our study. The prevalence of malaria declined randomly across age groups with highest parasitemia occurrence shown among individuals of 23-27 years age group (Table 1).The results of the study would have shown a vertical decline if not for the Variations observed in two age groups (18-22 and 43-47 years groups). The reason for this was not clear. The cause of the highest prevalence of parasitemia observed among the former age group was not also clearly asserted. However, since the blood donors showed variations in their compliance to the “Roll back malaria” program (Table 4-5), it could possibly be the reason for the variability in parasitemia as observed. Also with the exception of the variation mentioned in the two age groups above, our findings showed that the younger members of the study population were more infected than the older age groups.
This is in consonance with that reported by WHO, (2003) in sub-Saharan African communities with Nigeria inclusive, and also with that reported by Uneke et al., (2006) and Okocha et al., (2005) in South Eastern Nigeria. The findings of Camargo et al., (1999) in Brazil in this regard were also affirmative. This trend of infection was suggestively explained by Uneke et al., (2006) to result from more involvement of the younger members of Sub-Saharan African communities to occupational and social nocturnal activities that predispose them to the vectors more than the older members of the community.
Although not statistically significant, the prevalence of Plasmodium parasitemia was higher among male donors (16.19%) than females (11.63%). Our findings on this higher prevalence among male donors is in agreement with that (64.6%) reported by Cerrutti et al., (2007) in Brazil and also that (41.3% and 82.2%) reported in Nigeria by Uneke et al., (2006) and Okocha et al., (2005) respectively. The reason for this higher prevalence among males could probably be due to greater exposure of males to occupational and nocturnal activities which also expose them to the vectors than the females. We therefore recommend that individuals in endemic areas should wear protective clothing when undertaking night duties.
Our study also revealed that for commercial blood donation, only male donors were found. The reason for this could be attributed to social, psychological and physiological factors which do not restrict men unlike women who are affected by these factors in this part of the globe. Regrettably, the commercial blood donors were mostly males of lower social class who live in vector infested areas. The greater participation of this group in the study increased the prevalence of Plasmodium parasitemia among them. This calls for renewed effort of health care workers in screening every pint of blood from commercial donors for parasitemia prior to transfusion. In accordance with our finding, two similar studies by Bruce-Chwatt (1982) and Enosolease et al.,(2004) established that blood donation from commercial sources accounted for higher occurrence of transfusion malaria in communities where they are practiced.
Geographical locations have been established to affect the distribution of malaria (Greenwood et al., 2002). In this study, the plasmodium parasitemia was higher in the rural areas than in the urban (Table 2). Our finding on the higher prevalence of parasitemia among the rural dwellers is in agreement with that reported by Van et al., (2005) and Keisez et al., (2004) in Vietnam and African communities respectively. The reason for the above higher prevalence could be attributed to occupational and environmental factors that predispose the rural dwellers to the bites of the vectors more than those in the urban areas. Other reasons could also be due to less compliance of rural dwellers to the preventive measures of malaria, absence of health care facilities in many rural areas and poverty. Consequently we suggest that efforts should be increased in the fight against malaria through the provision of health care services and good environmental sanitation.
Interestingly, there is a significant relationship in our study between malaria infection and occupation (P<0.05). Farmers were the most affected (Table 3). A similar affirmative finding was reported in Brazil by Cerrutti et al., (2007). High exposure to bite of mosquito among farmers was reported by the scholars to be the major cause of malaria within the study area. (Cerrutti et al., 2007) They also reported high prevalence (14%) among students who were helping their parents in farming activities and were thus exposed to mosquito bites. The occurrence of malaria parasite (14.93%) among student blood donors in our study was almost of the same magnitude. However, whether the students were also involved in farming activities or not was not studied. The reason for higher prevalence among farmers in our study could be due to the fact that most farmers in Ebonyi state are also rural dwellers who live very close or within their farmlands where the vectors find conducive to breed and increase in population. Farmers should therefore be encouraged to comply with the control measures so as to reduce the disease burden among them. Another occupational group that recorded a relatively high prevalence is the civil servants (15.65%), while the clergy had the least parasitemia (12.0%). The reason for these results could be attributed to the mode of settlements and variability in compliance to the use of control and preventive measures. The reason for lower prevalence of plasmodium parasitemia observed among traders (13.41%) and drivers (12.6%) was not clear. Consequently, a further study to confirm or refute these findings is imperative.
Concerning the use of insecticide and insecticide treated nets (ITN), there was no significant relationship observed between the use of insecticides and prevalence of malaria parasites among the blood donors (P>0.05). However, significant relationship was found to exist between plasmodium parasitemia and the use of insecticide treated nets (P<0.05). Currently, several preventive measures have been initiated globally due to continued increase in the prevalence of malaria. Most common among them are the use of insecticide treated bed nets and indoor residual spraying (IRS). Our findings revealed poor patronage and compliance to these preventive measures among the blood donors. Hull and Kelvin (2006) and Bachou et al., (2006) also reported poor compliance to their use in many malarious region of Africa. In our study, only 2 and 5 donors reported strict compliance to the use of insecticides and insecticide treated nets respectively and they had zero prevalence (Table 4). On the other hand, highest prevalence of plasmodium parasitemia of 18.2% and 16.2% were reported respectively among the donors who did not use them. In a similar study Uneke et al., (2006) reported an age specific non compliance to the use of these preventive methods among individuals in their early twenties that presented with malaria parasites in South-Eastern Nigeria. Our finding with reference to non compliance to the use of ITN is significant due to its associated high progression to disease condition, accelerated morbidity and mortality. We therefore call for mass sensitization of the people living in endemic areas like our setting on the need for strict compliance with the use of these preventive measures.
In assessing the role of prophylaxis in transfusion transmitted malaria, our study revealed a significant statistical relationship between plasmodium parasitemia and the use of antimalarial prophylaxis (P<0.05). According to Kaur et al.,(2005), the infection of individuals by many species of plasmodium has given rise to many asymptomatic carriers in endemic regions of the world who serve as reservoirs for the parasite. The use of antimalarial prophylaxis as reported by Frey-Wettstein (2001) and Adepoju-Bello and Ogbeche (2003) in Switzerland and Nigeria respectively reduces the risk of transfusion malaria from asymptomatic carriers to blood recipients. Our findings in agreement with the above studies revealed that blood donors who engaged in quarterly use of antimalarial prophylaxis had the least prevalence of malaria parasite (5.08%). Whereas donors who did not take any prophylaxis at all recorded the highest prevalence of 18.86%. The principles and mechanisms of these prophylactic agents were not studied in our work. However, it has been established that the agents cause the disruption of the exo-erythrocytic stage of the merozoites (Olaniyi, 19889). This could be the reason for the lower prevalence reported in our study. Thus, it will be helpful to administer antimalarial prophylaxis to potential blood recipients to reduce the risk of transfusion transmitted malaria.
In evaluating the form of antimalarial therapy used by donors in our study, it was revealed that individuals who made use of Artemisinine based combination therapy ACT (Table 5) had the least (4.72%) parasitemia. The report of Eckstein-Ludwig et al.,(2003) on the low prevalence of plasmodium due to ACT therapy over other forms of antimalarial therapy is in consonance with our finding. Also reported in our study was a higher prevalence (20.21%) of Plasmodium falciparum among single antimalarial users (Table 5). The reason for the lower prevalence of parasitemia among blood donors who treat malaria with ACT could be attributed to the synergistic effects of the individual drug components contained in the combination. Consequently, there is need for a call on the strict compliance to the use of ACT in the treatment of uncomplicated malaria especially among blood donors. This will reduce the risk of transmission to vulnerable patients.
Although there was no statistical significant relationship between parasitemia and Hospitals used for the study, individuals who visited EBSUTH to donate blood showed the highest prevalence (17.65%, P>0.05). Other hospitals also recorded a slightly lower prevalence when compared to that from the former (Table 6). This showed that parasitemia among donors was independent of the hospitals visited. The implication of this is quite obvious and of epidemiological importance.