Malaria infection and anaemia in HIV-infected children in Mutengene, Southwest Cameroon: a cross sectional study

Malaria is a life threatening disease especially in children whose immune systems are not yet fully developed. The human immunodeficiency virus/acquired immunodeficiency syndrome (HIV/AIDS) infection further worsens the situation in children that are co-infected with both diseases. Unfortunately, HIV/AIDS geographically overlaps malaria infections in sub-Saharan Africa including Cameroon [1]. Approximately two-thirds of the global HIV/AIDS infected population lives in this area [2] and in 2013 an estimated 210,000 of infected persons were children [3]. More so, an estimated 163,000 malaria cases have been reported in children in sub-Saharan Africa [4]. Both infections are known to negatively impact each other. HIV-infected individuals are exposed to malaria infection on a daily basis [5] and have a higher risk of recurrent malaria episodes [6]. Malaria has also been associated with increased HIV replication in co-infected individuals [7]. Children are generally susceptible and vulnerable to malaria [8] and with HIV co-infection they may be at a higher risk of severe malaria infection. Such a co-infection may also retard the age-related acquisition of natural immunity to malaria in children [6] and lead to higher parasite densities thereby increasing the risk of anaemia [2, 5, 9, 10]. One of the major outcomes of HIV infection is also anaemia. There have been reports of high prevalence of childhood anaemia in the Mount Cameroon area [11] and Mutengene is one of the towns found in the area. Since malaria and HV/AIDS remain health concerns in this area, there is a need for constant monitoring of both diseases in all age groups.

Although there have been some reports on malaria in HIV patients in Cameroon [12‐16], none of them has specifically focused on factors influencing the prevalence of malaria and anaemia in HIV-infected children. Such data remains very scanty in the country in general and the South West Region in particular. Baseline data on the prevalence of malaria and anaemia in this high risk group of patients is of utmost importance as this will help inform the design of interventions that can reduce the burden of both diseases. Against this background, this study was aimed at determining malaria parasite prevalence, density and anaemia in HIV-infected children attending the Care and Treatment Centre of the Mutengene Baptist Hospital, Southwest Cameroon.

Malaria and HIV co-infection in children is a condition of great public health significance as both infections have devastating effects on the health of children especially those less than 5 years old. Both infections lead to anaemia which can lead to serious consequences if not treated on time. The overall malaria parasite prevalence was 24.8 % in HIV-infected children. This value is similar to the 20.3 % malaria parasite prevalence reported in Uganda in both HIV-exposed and unexposed children [21]. The value is however less than that reported in some studies carried out in apparently healthy school children ≤15 years (33.8 % and 33.0 %) in the Mount Cameroon region [22, 23]. This discrepancy may be attributed to some state policies and strategies that have recently been implemented to fight HIV/AIDS and malaria in Cameroon. These include the free distribution of ART to HIV/AIDS patients in the country as the main control measure to improve their immune status and slow down the deteriorating effect of the virus. The number of care and treatment centres for HIV/AIDS distributing ART has increased in the last decade. Antimalarial strategies include the free distribution of LLINS, free treatment of malaria in children less than five years old and increased access to artermisinin-based combination therapies (ACTs) as well as malaria rapid diagnostic tests at subsidized rates. These measures have been relatively helpful especially in people living in urban areas. Similar measures contributed to reductions in malaria-related morbidity and mortality in HIV patients, particularly those living in urban settings in Mozambique [24]. Despite the involvement of the state and other development partners in the fight against HIV/AIDS in Cameroon, the coverage rate of antiretroviral treatment is still relatively low [25]. Unfortunately, malaria still remains a major cause of morbidity and mortality in Cameroon, especially among children and pregnant women, accounting for over 40 % hospital attendance [26].

Malaria parasite prevalence in this study was higher in children of younger age groups when compared with those of the older age groups. In malaria endemic areas acquired immunity to malaria is known to be both exposure- and age-dependent. Hence, older children might have developed some degree of immunity as a result of repeated malaria infections. This is in agreement with studies carried out in the Mount Cameroon region [22].

The study showed that females were significantly more infected with malaria parasites than males. This is in contrast with other studies [22, 27], which reported higher malaria prevalence rates in males. This may be due to the large proportion of females involved in this study. This could also be due to the fact that HIV is more common in females because of their biology and consequently leading to a lower level of immunity in them.

Children on ART were more likely to be infected with the malaria parasites than those who were not. This is in contrast with other studies which showed that the prevalence of malaria parasites was lower in patients who were on ART than in those who were not [28]. This discrepancy may be due to lack of adherence to therapy by the patients. Adherence to ART is a special issue in pediatrics because many of the drugs are not child friendly [29]. Adherence is important not only for individual patient responses to ART, but also because lack of adherence to prescribed regimens and sub-therapeutic levels of antiretroviral medications, particularly protease inhibitors, may enhance development of drug resistance and the likelihood of virologic failure. It may also be related to the relatively small sample size (22.2 %) of the patients who were not yet on ART in the study population. However, these findings were similar to one which showed that patients on ART had a slightly higher malaria prevalence than those who were not on ART [15]. On the other hand, GMPD was comparable in patients who were on ART and those who were not on ART. This finding is contrary to studies of other authors who reported that certain ARVs such as lopinavir/ritonavir can inhibit malaria parasite growth and reduce the incidence of malaria [28, 30, 31]. Although it was not investigated, it is worth noting that co-trimoxazole is generally prescribed for prophylaxis against opportunistic infections in HIV patients in treatment centres in Cameroon and it is also known to have anti-malaria properties [32].

When the vector control methods implemented by the participants in the study were all pulled together, it was observed that those who implemented at least three preventive methods had the least malaria prevalence, while those who did not implement any vector control method had the highest. This finding lends credence to the efficiency of possible integrated vector control methods against malaria infection. This needs to be encouraged in HIV-infected individuals.

The prevalence of anaemia in children in the study population was 49.6 %. This result was lower than values reported by Sumbele et al. [11] and Ruhinda et al. [33]. This may be due to the wide scale use of anti-malaria preventive measures that caused the decrease in the prevalence of malaria infections in these children and also the use of co-trimoxazole prescribed along with ART which has been associated with reduced anaemia in HIV infected children [34]. This confirms the fact that malaria is one of the major contributing factors to anaemia in children [35]. That probably also explains why GMPD was significantly higher in those who were anaemic as compared with their non-anaemic counterparts.

This study recorded a high prevalence of anaemia in the HIV-infected children who had lower CD4 T cell counts as well as those at clinical stage IV. This may be due to chronic inflammation by the HIV infection or it may be due to other opportunistic infections [36]. Sullivan et al. [37] and Mocroft et al. [38] associated anaemia to advancing HIV disease. The observed results could be due to the increasing viral burden which could cause anaemia through increased cytokine-mediated myelosuppression, and/or a higher burden of comorbidities. The use of ART in such patients usually leads to improvement in haemoglobin and other related haematological indices, even without specific additional treatment targeting anaemia [30]. It could possibly be linked to the kind of ART that the patients were taking as some of them have been reported to cause anaemia. Kimbi et al. [15] also reported high anaemia prevalence in patients who had CD4 T cells less than 200 cells/μL of blood in Limbe, Cameroon. Regardless of the mechanism, recognition of anaemia at initiation of ART could be useful to alert clinicians with regard to children requiring closer monitoring for possible treatment failure. It is also possible that anaemic children who did not respond adequately to ART might have been harbouring some drug resistant strains of HIV. Anaemia has been highlighted as an important independent prognostic factor in HIV-infected individuals. It is also thought to increase the risk of progression to AIDS and consequently death in HIV infected patients [36]. The adverse long term outcomes more likely reflect anaemia as a proxy of more advanced disease.

The oldest children (11–15 years) had the highest prevalence of anaemia while the youngest (<5 years) had the lowest. This contrasts with other studies carried out in southwest Cameroon [11, 22, 39] and Uganda [33]. Additionally, all children with severe anaemia were also malaria parasite negative. This difference could be attributed to the presence of the HIV infection and other possible opportunistic infections. It is worth noting that anaemia could have been caused by several factors including haemoglobinopathies, poor nutritional status, bacterial, viral and other parasitic infections like hookworm and Entamoeba histolytica. However, these were not investigated in this study.

Our findings also revealed a high prevalence of anaemia in children who presented with fever. This may be attributed to the high malaria prevalence and density observed in patients who presented with fever. The main mechanism of malaria anaemia pathogenesis involves the destruction of both infected and uninfected red blood cells [40] thus leading to a reduction in haemoglobin values.

The study is the first of its kind in Mutengene, Cameroon. Some limitations of this study include firstly the lack of data on a comparable group of HIV negative children in the same setting and this limits our ability to interpret the prevalence results precisely. A convenience sampling technique was used. This sampling was biased and the sample may not be a representative of the entire population. Self-reported information on mosquito preventive methods by participants was not verified and some of the information might have been biased. We were not able to get any information on viral loads as bouts of malaria are known to lead to higher viral loads. We did not have information on the nutritional status of the participants and this might have had an influence on anaemia in the patients. Our sample size was very large in the dry season as compared to the rainy season and this made seasonal comparison difficult.