Concurrent giardiasis and amoebiasis infections in Nigerian children diagnosed with Plasmodium falciparum malaria: prevalence and pathophysiological implications.
B Nwanguma, E Alumanah
amoebiasis, children, concurrent, giardiasis, malaria, plasmodium
B Nwanguma, E Alumanah. Concurrent giardiasis and amoebiasis infections in Nigerian children diagnosed with Plasmodium falciparum malaria: prevalence and pathophysiological implications.. The Internet Journal of Tropical Medicine. 2008 Volume 6 Number 1.
The prevalence of giardiasis and amoebiasis as concurrent infections in Nigerian children diagnosed with
Complicated childhood malaria, which remains a major cause of infant morbidity and mortality in the malaria endemic countries of the tropics(1), is associated with a number of metabolic and pathophysiological disorders including, anaemia, hypovolaemia, metabolic acidosis, hypoglycaemia, respiratory distress and a variety of neurological features, all of which contribute to the often undesirable outcome of malaria episodes in children(2, , 3, 4, 5, 6).
Contrary to the impression given by many studies on malaria (especially with laboratory-induced malaria), the prevailing climatic and socioeconomic conditions in the malaria - endemic countries of the tropics predispose affected populations to a number of other protozoan, bacterial and helminthic infections, which often confound episodes of malaria in these regions(7,8). When these diseases occur concurrently with malaria they have the ability to interfere with the immune responses to malaria(9, 10) and could also initiate (or aggravate) some of the life-threatening metabolic and pathophysiological disorders observed in childhood malaria. Thus, the severity, duration and eventual outcome of malaria episodes in children may depend on the absence or presence of these concurrent infections. However, these infections are usually ignored during diagnosis and treatment of malaria both during home management and in clinical settings.
Children are often more vulnerable to these infections because they have a comparatively poorly developed immune system, which may not be sufficiently exposed to these infections to acquire the additional capability that sometimes renders the immune systems of adults impervious to these infections. In addition, children have a uniquely delicate physiology that increases their susceptibility to the life-threatening metabolic and pathophysiological disturbances and disorders associated with these infections.
In our opinion, the likely presence of these concurrent infections is one of the major causes of the rapid debilitation, symptom aggravation and delayed recovery typical of malaria episodes in children. Thus, the concomitant presence of these often neglected infections could contribute significantly to why malaria remains a major threat to the survival of young children in many endemic countries of the tropics, where annual deaths due to malaria have remained unacceptably high despite the availability of a wide range of relatively effective preventive, prophylactic and therapeutic options (11, 12). There is need, therefore, to highlight the prevalence and possible pathophysiological implications of these concurrent infections in different populations of children as part of efforts to understand the complicated nature and unexpected outcomes of some episodes of childhood malaria.
In this study, stool samples from children presenting with signs of illness suspected to be due to malaria were examined for the presence of two protozoan parasites namely,
Materials and Methods
Subjects and Location
The study was conducted in Nsukka - a semi-urban town in Enugu State located in South Eastern Nigeria. A total of 425 children aged between 6 and 60 months (5 years), presenting with symptoms of illness presumed to be malaria, who were referred to our laboratory for confirmatory diagnosis, were included in the study. The commonest signs were fever (characterised by body temperature higher than 380C), vomiting and diarrhoea.
The test population was made up of 250 (58.82%) children who were diagnosed with
Following the explanation of the nature and purpose of the investigation, the consent of the accompanying parent/guardian was sought. Thereafter, consenting parents/guardian were requested to provide fresh stool samples of the children within 24 hours for examination. The test results were made available to the referring/consulting physician for the appropriate management. The experiment was conducted in consonance with the relevant guidelines for clinical research in the University of Nigeria, Nsukka.
Results of the study on the prevalence of
Out of 250 malaria-positive children in the test population, 13 (5.20%) were infected by GL alone, 69 (27.6%) were infected by EHD alone, while 38 (15.2%) had a mixed infection of both EHD and GL. Thus, 119 (47.60%) of the malaria-positive group were concurrently infected by one or both of the protozoan infections studied.
The prevalence of GL, EHD and mixed infections of GL and EHD in the malaria-free children were 3 (1.7%), 65 (37.14%) and 12 (6.86%), respectively.
Prevalence of giardiasis and amoebiasis in childhood malaria
Data on the prevalence of giardiasis and amoebiasis as concurrent infections in childhood malaria in Nigeria are lacking. The prevalence figures reported in this study for
EHD was the more common infection and had a higher prevalence than GL in both children with a positive blood smear and the malaria-free subjects. However, because the microscopic method used in the diagnosis of amoebiasis is unable to distinguish the 2 morphologically identical species of Entamoeba, namely,
The prevalence of GL in the malaria-infected children (5.20%) was significantly (p < 0.05) higher than the prevalence in the malaria-free controls (1.7%), but the prevalence of EHD in the malaria-infected children (27.6%) was lower than the prevalence in the malaria-free controls (37.14%). These observations are somewhat suggestive of an increased risk of giardiasis infection in children with malaria, but not amoebiasis. The suspicion of a predisposing effect by malaria on giardiasis alone or as mixed infection is strengthened by the observation that the prevalence of the mixed GL and EHD infections in the malaria-infected children (15.2%) was significantly (p < 0.05) higher than the prevalence in the malaria-free children (6.86%). Such an observation if proven could be attributed to the ability of
The prevalence of GL (1.7%) and EHD (37.14%) in the malaria – free children, all of whom presented with signs of illness initially presumed to be due to malaria, further highlights the significant contributions of these often neglected diseases to the debilitation of children in Nigeria.
Beyond mere prevalence, the concurrent occurrence of one or both GL and EHD infections with malaria is likely to predispose the patients to more severe forms of illness, with equally severe implications for recovery. Since the severity of giardiasis and amoebiasis in a symptomatic patient is determined largely by the immune status of the host (24, 25), the concomitant existence of malaria could predispose to severe illness. This can be likened to the scenario described by Hocqueloux
Pathophysiological implications of concurrent giardiasis and amoebiasis in childhood malaria.
In our experience, whereas the life-threatening disorders associated with childhood malaria appear quite mild in some children, they appear so severe in others. In the later group, the occurrence of severe symptoms often results in the rapid debilitation of the patients as-well-as their delayed recovery. One possible cause of such rapid debilitation in childhood malaria is the existence of one or more concomitant illnesses. The pathophysiological complications of childhood malaria which are most likely to be initiated or aggravated by concurrent giardiasis and/or amoebiasis, include metabolic acidosis, hypovolaemia, respiratory distress and hypoglycaemia.
Figure 2 is a representation of how some of the pathophysiological disorders often implicated in malaria-associated morbidity and mortality in children(27), could be initiated or potentiated by concurrent giardiasis and/or amoebiasis. As shown in figure 2, diarrhoea and vomiting - the commonest symptoms of giardiasis and amoebiasis – predispose to dehydration because they cause the excessive loss of body fluid and electrolytes, namely sodium, chloride, bicarbonate and potassium. In malaria patients, the risk of dehydration is increased by additional water losses through evaporation and vomiting due to fever and nausea, respectively. If the excessive loss of water and electrolytes is not promptly compensated for, the resulting dehydration could lead to a significant drop in blood volume (hypovolaemia), while the continued loss of bicarbonate could lead to metabolic or base-deficit
Giardiasis could also potentiate or aggravate the problem of energy metabolism, which often manifests partly as hypoglycaemia in childhood malaria (28). Because G.
In conclusion, a relatively high proportion of children infected with malaria in the rural areas of Nigeria are also concurrently infected by