Tanzania Journal of Health Research Health User's Trust Fund (HRUTF) ISSN: 1821-6404 Vol. 12, Num. 4, 2010, pp. 283-285

Tanzania Journal of Health Research, Vol. 12, No. 4, Oct, 2010, pp. 283-285

Short Communication

Association of intestinal helminths and P. falciparum infections in co-infected school children in northwest Tanzania

Humphrey D. Mazigo^1*, Benson R. Kidenya¹, Emmanuela E. Ambrose¹, Maria Zinga¹ and Rebecca Waihenya ²

¹Weill-Bugando University College of Health Sciences, P.O. Box 1464, Mwanza, Tanzania
²Department of Zoology, Jomo Kenyatta University of Agriculture and Technology, Nairobi, Kenya
*Correspondence: Dr. Humphrey D. Mazigo; E-mail: humphreymazigo@bugando.ac.tz

Received 5 July 2010
Revised 23 August 2010
Accepted 10 September 2010

Code Number: th10040

Abstract

Plasmodium falciparum malaria and intestinal helminth infections are among the most common infections in the tropics and they share the same spatial distribution.The objective of this study was to explore the association between infections with intestinal helminths and P. falciparum infection as single helminth infections or co-infections among school children. A cross-sectional study was conducted among 400 school children in Nyamtongo, Sengerema District in Tanzania. The study involved examination of single stool and finger prick blood samples for intestinal helminths and malaria parasites. A Kato-Katz technique was employed to screen for intestinal helminths and Giemsa stained thin and thick blood smears were used to screen for malaria parasites. The results of logistic regression model adjusted for age and sex indicated no association between P. falciparum and S. mansoni (OR= 0.749, 95%CI 0.418-1.344), P. falciparum and hookworm (OR= 0.885, 95%CI 0.489-1.605) and P. falciparum and co-infection of S. mansoni and hookworm (OR=0.859, 95%CI 0.422-1.745). Using multinomial regression model adjusted for age and sex, no association was observed between P. falciparum with Schistosoma mansoni[Ratio of Relative Risk (RRR) = 0.651, 95% Confidence Interval (CI) 0.331-1.363] and hookworm (RRR=0712, CI 0.280-1.765). Similarly, no association was observed between co-infections of S. mansoni + hookworm (RRR=0.635, CI 0.268-1.504) with P. falciparum infection. Co-infections of S. mansoni, hookworm and P. falciparum among school children is common in the Nyamatongo ward, Sengerema District. We recommend prospective longitudinal studies to elucidate the interactions of malaria and helminths and its health impact in risk groups.

Keywords: malaria, schistosomiasis, hookworms, school children, Tanzania 

In sub-Saharan Africa, the overlapping distribution of P. falciparum and helminths infections is common and resulting into high rates of co-infections (Mazigo et al., 2010). Co-infections of helminth and P. falciparum malaria may results into synergistic or antagonistic association in causing various morbidities in infected individuals (Adrienne et al., 2005). Co-infections of soil-transmitted helminths and Schistosoma mansoni are reported to increase the incidence of clinical malaria in children (Spigel et al., 2003). In Tanzania, concomitant occurrence of asymptomatic malaria and helminth infections have been reported in school children (Mazigo et al., 2010), however, reports on their association in co-infected individuals living in various epidemiological settings in Tanzania are very limited. Thus, the present study was conducted to explore the associations of P. falciparum malaria and helminths infections in co-infected school children living in endemic area of northwest Tanzania.

This cross-sectional study used data collected at baseline (before treatment) from 400 school children living and studying in selected schools in Nyamatongo village in Sengerema District in Tanzania. The village is located close to Lake Victoria. The study area, design, inclusion criteria and recruitment procedures have been describe elsewhere (Mazigo et al., 2010). At recruitment, demographic characteristics (age and sex) of the children and a finger prick blood sample were obtained and in this sample, thin and thick blood smears were prepared, stained with Giemsa and examined under the microscopy (Mazigo et al., 2010). Intensity of P. falciparum was estimated as the number of P. falciparum per 200 WBC (Mazigo et al., 2010). A single stool sample collected from primary school by HDM in a labeled container was processed within an hour at a field laboratory set at school environment using Kato-Katz method (Mazigo et al., 2010). Two Kato-Katz slides were prepared for each sample; the slides were examined within 30 minutes for hookworm and examined the following day for other intestinal helminth (A. lumbricoides, T. trichuris and S. mansoni) by experienced parasitologists. Intensity of hookworm, A. lumbricoides, T. trichiura and S. mansoni was categorized according to WHO criteria.

Data were analysed using Stata version 11 (Stata Corp, College station, Texas, USA). The relationships between S. mansoni, hookworm and S. mansoni + hookworm with P. falciparum were investigated by fitting logistic regression model taking P. falciparum as response variable. Furthermore, co-infections analysis was investigated by fitting multinomial logistic regression model where all combination of diseases status was considered in the model (No infection, S. mansoni only, hookworm only and S. mansoni + hookworm). The models were adjusted for age and sex. The significance of associations of P. falciparum with S. mansoni, hookworm and co-infection of hookworm and S. mansoni were estimated by Odds Ratios (OR) in logistic regression model and by Ratio of Relative Risk (RRR) in multinomial logistic regression model with “no infection” used as a base. Statistical significance for all analyses was determined at P-value <0.05 at 95% confidence interval.

The study was approved by the Institutional Review Board (Research and Publication Committee, certificate No. BREC/001/03/2009) of the Weill-Bugando University College Health Sciences Mwanza, Tanzania. Informed written consents were obtained from children's parents or guardians and in addition assent was subsequently obtained from children.

A total of 400 schoolchildren aged 8-16 years (mean age 12.23 years) were recruited in the study between April and May 2009. The prevalence of single parasitic infection were asymptomatic Plasmodium falciparum 14% (n=56/400), Schistosoma mansoni 42.3%, (169/400) and hookworm 16%, (64/400). The prevalence of double parasitic infection was P. falciparum + S. mansoni (5.5%, 22/400), P. falciparum + hookworm (2.3%, 9/400) and S. mansoni + hookworm (22%, 88/400). For triple infection, P. falciparum + S. mansoni + hookworm was 2.8%, (88/400). Ascaris lumbricoides and T. trichiura were not recovered. No significant associations were observed between P. falciparum+ S. mansoni, P. falciparum + hookworm and P. falciparum + co-infection S. mansoni + hookworm (Table 1, 2).

Lack of association between hookworm infection and P. falciparum observed in this study have also been observed in Uganda (Shapiro et al., 2005). This was different from the study of Midzi et al., (2009) in Zimbabwe who observed strong association between hookworm and P. falciparum. A significant number of the children infected with P. falciparum were also infected with S. mansoni. However, no association was observed between S. mansoni and asymptomatic P. falciparum, in conflict with the results of the previous study (Midzi et al., 2009) but in agreement with another study from Uganda that reported no association (Shapiro et al., 2005). The lack of association observed in the present study can be attributed to low infection intensity of hookworm and S. mansoni. Only few children were observed to have high infection intensity of the two helminths. In addition, the use of single stool sample for screening of intestinal helminth, a small sample size of 400 school children, low prevalence of P. falciparum (13.5%), the use of single diagnostic method for intestinal parasites and malaria and the season during which the study was conducted, (April-May) at the end of long rain season may have contributed to the recovering of only few individuals with heavy infections.

In summary, this analysis has explored the association of helminth-P. falciparum co-infection in primary school children. The present findings suggest no association between infection with helminth species and P. falciparum malaria in Nyamatongo ward, Sengerema district in contrast to observations from other studies. Taken together these findings illustrate the importance of conducting prospective longitudinal studies to elucidate the interactions of P. falciparum malaria and helminths and its health impact in sufficient large samples size of risk groups such as school children. 

Acknowledgements 

We acknowledge the valuable cooperation of parents, guardians, teachers and school children during data collection. This report is part of the master thesis for HDM in Medical Parasitology and Entomology at Institute of Tropical Medicine and Infectious Diseases, KEMRI + JKUAT, Kenya. The study received funds from Weill-Bugando University College of Health Sciences, Mwanza, Tanzania.

Conflicts of interest statement

The authors have no conflicts of interest concerning the work reported in this paper. The authors also declare that they have no financial competing interests

References

• Adrienne, E., Edridah, M., Jennifer, K., Clarkea, K., Pascal, M., Annette, O., Narcis, B., Kabatereine. & Simon, B. (2005). Epidemiology of helminth infection and their relationship to clinical malaria in Southwest Uganda. Transactions of the Royal Society of Tropical Medicine and Hygiene 99, 18-24.
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