it is about 10 km away from osogbo , the state capital of osun state nigeria . there is one public primary school , one secondary school and one primary health center in the community . the study was carried out from may to august 2009 , which spanned the rainy season . the study subjects were primary school pupils with age range of 3 to 16 years . the inclusion criteria for the study included : ( 1 ) children aged 8 - 16 years ; ( 2 ) parents or guardians gave written informed consent ; and ( 3 ) children lived in the study area . before samples were collected , demographic data such as sex , age , weight , and name of subject were recorded . ethical clearance for the work was obtained from the osun state ministry of health and ministry of education ethical committee ( ins / est/90 ) . blood samples were collected by finger prick for the determination of p. falciparum para - sitemia . thick blood films were prepared , airdried , giemsa - stained , and observed under the microscope for identification and quantification of malaria parasites . malaria parasites were counted against 200 leukocytes , and counts were expressed as the number of parasites per microliter of blood , assuming an average leukocyte count of 8,000 cells/l of blood.26 for packed cell volume ( pcv , % ) , microhematocrit tubes filled with blood were centrifuged in a microhematocrit rotor for 5 min at 10,000 g. pcv values 31% were considered as anemia , which was further classified as mild ( 2130% ) , moderate ( 15 - 20% ) , or severe ( 15%).13 clean plastic containers were distributed for stool collection , and instructions were given for proper collection . the formol - ether concentration technique was employed and kato - katz thick smear technique was used for quantitative determination of helminths ova.27 stool samples were processed within 12 hours of collection and examined microscopically within 1 hour of preparation to avoid missing hookworm ova . the intensity of infection was expressed as the number of eggs per gram of feces ( epg ) . statistical analysis was done using jmp version 5 for windows north carolina , usa . for uni - variate analysis , frequencies were compared using the fisher 's exact tests . it is about 10 km away from osogbo , the state capital of osun state nigeria . there is one public primary school , one secondary school and one primary health center in the community . the study was carried out from may to august 2009 , which spanned the rainy season . the study subjects were primary school pupils with age range of 3 to 16 years . the inclusion criteria for the study included : ( 1 ) children aged 8 - 16 years ; ( 2 ) parents or guardians gave written informed consent ; and ( 3 ) children lived in the study area . before samples were collected , demographic data such as sex , age , weight , and name of subject were recorded . ethical clearance for the work was obtained from the osun state ministry of health and ministry of education ethical committee ( ins / est/90 ) . blood samples were collected by finger prick for the determination of p. falciparum para - sitemia . thick blood films were prepared , airdried , giemsa - stained , and observed under the microscope for identification and quantification of malaria parasites . malaria parasites were counted against 200 leukocytes , and counts were expressed as the number of parasites per microliter of blood , assuming an average leukocyte count of 8,000 cells/l of blood.26 for packed cell volume ( pcv , % ) , microhematocrit tubes filled with blood were centrifuged in a microhematocrit rotor for 5 min at 10,000 g. pcv values 31% were considered as anemia , which was further classified as mild ( 2130% ) , moderate ( 15 - 20% ) , or severe ( 15%).13 clean plastic containers were distributed for stool collection , and instructions were given for proper collection . the formol - ether concentration technique was employed and kato - katz thick smear technique was used for quantitative determination of helminths ova.27 stool samples were processed within 12 hours of collection and examined microscopically within 1 hour of preparation to avoid missing hookworm ova . the intensity of infection was expressed as the number of eggs per gram of feces ( epg ) . statistical analysis was done using jmp version 5 for windows north carolina , usa . for uni - variate analysis , frequencies were compared using the fisher 's exact tests . it is about 10 km away from osogbo , the state capital of osun state nigeria . there is one public primary school , one secondary school and one primary health center in the community . the study was carried out from may to august 2009 , which spanned the rainy season . the study subjects were primary school pupils with age range of 3 to 16 years . the inclusion criteria for the study included : ( 1 ) children aged 8 - 16 years ; ( 2 ) parents or guardians gave written informed consent ; and ( 3 ) children lived in the study area . before samples were collected , demographic data such as sex , age , weight , and name of subject were recorded . ethical clearance for the work was obtained from the osun state ministry of health and ministry of education ethical committee ( ins / est/90 ) . blood samples were collected by finger prick for the determination of p. falciparum para - sitemia . thick blood films were prepared , airdried , giemsa - stained , and observed under the microscope for identification and quantification of malaria parasites . malaria parasites were counted against 200 leukocytes , and counts were expressed as the number of parasites per microliter of blood , assuming an average leukocyte count of 8,000 cells/l of blood.26 for packed cell volume ( pcv , % ) , microhematocrit tubes filled with blood were centrifuged in a microhematocrit rotor for 5 min at 10,000 g. pcv values 31% were considered as anemia , which was further classified as mild ( 2130% ) , moderate ( 15 - 20% ) , or severe ( 15%).13 clean plastic containers were distributed for stool collection , and instructions were given for proper collection . the formol - ether concentration technique was employed and kato - katz thick smear technique was used for quantitative determination of helminths ova.27 stool samples were processed within 12 hours of collection and examined microscopically within 1 hour of preparation to avoid missing hookworm ova . the intensity of infection was expressed as the number of eggs per gram of feces ( epg ) . statistical analysis was done using jmp version 5 for windows north carolina , usa . for uni - variate analysis , frequencies were compared using the fisher 's exact tests . one hundred and seventeen stool and blood specimens collected from primary school children aged 4 up to 15 years were microscopically investigated in order to determine the prevalence of intestinal helminths and malaria infection among the children . the mean age of the study population was 9.9  3.1 years while the mean height was 127  14.0 cm and the mean weight was 25.5  6.7 kg . the mean pcv of the study population was 33.6  3.4 g / dl and none of the subjects had severe or moderate anaemia while 15 ( 12.8% ) children had mild anemia . table 1 shows the prevalence of intestinal helminth and falciparum malaria parasite in the study subjects according to age group . the prevalence of malaria parasite in the study was 25.6% while that of intestinal helminth was 40.2% . five species of helminths were recovered from the stool samples and these were ascaris lumbricoides ( 34.2% ) , hookworm ( 5.1% ) , trichuris trichiura ( 2.6% ) , diphyllobothrium latum ( 0.9% ) and tri - chostrongylus species ( 0.9% ) . the mean malaria parasite density in the study was 173  335 p/l while the mean egg count of a. lumbricoides ( 1345  3137 ages 4 - 7 years had the highest prevalence ( 31% ) and mean parasite density ( 109.3 p/l ) of malaria . the distribution of mean parasite density of malaria shows a gradual decrease as the age increases . for intestinal helminth , the older age group ( 12 - 15 years ) was generally more infected with a. lumbricoides recording the highest prevalence of 46.5% . the highest intensity ( egg output ) of 2040 egg / gm of stool was also recorded in a. lumbricoides among age group 8 - 11 years . age group 12 - 15 years had the highest prevalence of malaria and intestinal helminth co - infection ( 9.3% ) . prevalence of malaria parasite and intensity of intestinal helminth by age the prevalence of malaria parasite and intestinal helminths by sex is shown in table 2 . females had a higher prevalence ( 26.5% ) of malaria compared to their male counterparts ( 24.5% ) but the difference was not statistically significant . males tend to have a higher prevalence with intestinal helminths ( 55.1% ) compared to their female counterparts ( 35.3% ) and the difference was statistically significant ( p = 0.0390 ) . for a. lumbricoides , males ( 44.9% ) were more infected compared to females ( 26.5% ) and the difference was statistically significant ( p = 0.0487 ) . for the co - infection of both malaria and any of the intestinal helminths , females ( 5.9% ) were more infected than males ( 2.0% ) showing no statistically significant difference . prevalence of malaria parasite and intestinal helminth by sex the association between malaria parasite and intestinal helminths among the study subjects is shown in table 3 . out of the 30 ( 25.6% ) children that were positive for malaria , 23 ( 77% ) were co - infected with intestinal helminths and the difference was statistically significant ( p = 0.0053 ) . children who were infected with intestinal helminth were almost approximately one time ( rr = 0.7295 ) as likely to be infected with p. falciparum as children with no worm infection . the results of the present study showed the occurrence of asymptomatic falciparum malaria and intestinal helminths parasites of public health importance among schoolchildren in primary schools in kajola , osun state , nigeria . the high prevalence of asymptomatic malaria ( 25.6% ) recorded in the study confirms previous reports that malaria is hyperendemic in osun state nigeria.22 it was previously observed that the majority of malaria infections in individuals living in endemic regions are asymptomatic with the young children bearing the highest burden of disease and carrying asymptomatic infections for most of the time.2829 the decline of p. falciparum parasite density with age , observed in this study is characteristic of both symptomatic and asymptomatic infection in endemic regions.3032 the mean values observed are lower compared to asymp - tomatic values found in a longitudinal survey of malaria infection in individuals living in this area22 and other highly malarious endemic region of papua new.3033 like malaria , soil transmitted helminths are highly prevalent in rural communities as a result of poor sanitary conditions prevailing in most of these areas . this study recorded a prevalence of 43.6% for helminth infections , with a. lumbricoides having the highest prevalence , followed in decreasing order by hookworm and t. trichiura infections . in earlier studies among school children in osun state nigeria , the prevalence of these 3 species were in similar order but these works recorded higher prevalence.3435 the lower prevalence recorded in this study might reflect the increase awareness and improved sanitary conditions brought about by urbanization . while the previous studies were conducted in typical rural communities , the present study was conducted in semi - urban community that shares proximity with osogbo the state capital of osun state nigeria . a significant difference has previously been reported in infection rate between urban and rural school children in this area.36 in the present study , the co - infection of malaria and intestinal helminths is 4.3% and of the children who had malaria , the geo - helminth - positive children tended to be parasitaemic and there was statistically significant association between helminth status and parasitaemia . a similar observation was made in thailand , where , a positive and statistically significant association between geohelminth and malarial infection was also reported.25 in this study , it was observed that children with a. lumbricoides infections were almost two times as likely to have p. falciparum infection as children without a. lumbricoides infection . the mechanism behind this association is not clearly understood , but could be that th2 profile - associated immunoglobulin e production seen in ascaris infection may down - modulate th1 antimalarial immune responses , resulting in increased risk of malaria infection.37 there are , however , conflicting reports on how helminth infection affects malarial infection and vice versa . a similar association was previously observed among cohort of pregnant women in ghana . in uganda , geohelminth positive children tended to be parasitaemic but were not statistically significant.38 in developing countries , although mild anaemia occurs commonly among the general population , moderately severe anaemia is most frequently seen in areas where infections can cause or exacerbate anaemia.39 in this study , the presence of both malaria and helminths parasites among children was not associated with anaemia . this observation could be attributed to the fact that none of the children in this study had a high density of both p. falciparum and helminths infection thus , these parasites are unlikely to have contributed significantly to the presence of anemia in this study population . in individuals with precarious iron balance , however , relatively small hookworm loads may result in anemia . also , high helminths burden in co - infections involving p. falciparum may in the long run exacerbate anemia caused by the malaria parasites . in conclusion , this study observed co - infection of both p. falciparum and intestinal helminths among school children in osun state nigeria . given the plausible hypothesis of a biological interaction between helminths and p. falciparum and increasing advocacy for deworming , there is a need for prospective studies of the effects of helminths and the treatment of helminth infection on p. falciparum in this area . this work is undoubtedly the first study to document the prevalence of asymptomatic malaria among children in this area . the success of malaria control will depend on a systematic understanding of the micro - geographic risk of malaria transmission that would enable identification of high risk spots . the identification , quantification , and spatiotemporal mapping of the asymptomatic subpopulation will provide an opportunity to estimate the epidemiological importance of this group to malaria transmission . oo carried out the design and coordinated the study and also prepared the manuscript , participated in most of the experiments and prepared the manuscript .
background : malaria and intestinal helminths are parasitic diseases causing high morbidity and mortality in most tropical parts of the world , where climatic conditions and sanitation practices favor their prevalence . 
 the aim of this study was to determine the prevalence and possible impact of falciparum malaria and intestinal helminths co - infection among school children in kajola , osun state , nigeria.methods:fresh stool and blood samples were collected from 117 primary school children age range 4 - 15 years . 
 the stool samples were processed using both kato - katz and formol - ether concentration techniques and microscopically examined for intestinal parasitic infections . 
 blood was collected by finger prick to determine malaria parasitemia using thick film method ; and packed cell volume ( pcv ) was determined by hematocrit . 
 univariate analysis and chi - square statistical tests were used to analyze the data.results:the prevalence of plasmodium falciparum , intestinal helminth infections , and co - infection of malaria and helminth in the study were 25.6% , 40.2% and 4.3% , respectively . 
 five species of intestinal helminths were recovered from the stool samples and these were ascaris lumbricoides ( 34.2% ) , hookworm ( 5.1% ) , trichuris trichiura ( 2.6% ) , diphyllobothrium latum ( 0.9% ) and trichostrongylus species ( 0.9% ) . for the co - infection of both malaria and intestinal helminths , females ( 5.9% ) were more infected than males ( 2.0% ) but the difference was not statistically significant ( p = 0.3978 ) . 
 children who were infected with helminths were equally likely to be infected with malaria as children without intestinal helminths [ risk ratio ( rr ) = 0.7295 ] . children with a. lumbricoides ( rr = 1.359 ) were also likely to be infected with p. falciparum as compared with uninfected children.conclusions:asymptomatic falciparum malaria and intestinal helminth infections do co - exist without clinical symp - toms in school children in nigeria .