Prevalence and Intensity of Intestinal Parasitic Infections and Factors Associated with Transmission among School going Children

Objective: To determine the prevalence and intensity of intestinal parasitic infections and factors associated with transmission among primary school going children.Design: Cross-sectional descriptive study.Setting: Muthithi Location situated in Murang'a County; Kenya.Subjects: Multi-stage sampling was used to select 418 children. Stool specimens were examined using Kato-katz technique to determine the number of helminthes eggs per gram of stool and formol ether concentration technique to detect the different protozoan cysts. Data were analysed using Statistical Package format (SPSS version 20.0). Pearson's Chi-square test was used to establish the association between categorical variables. Multivariate analysis was used to determine the factors associated with the infections.Results: The study established that 53.8% (225 out of 418) were infected with one or more of intestinal parasite. Five species of helminthes were identifiedwith prevalence of 11.5%; the predominant helminth parasite identified was Ascaris lumbricoides 9.1% (38 cases). Intestinal protozoan identified in this population was Entamoeba histolytica with prevalence of 42.3% (177 cases). The factors established to be independently associated with presence of intestinal parasitic infection were: age 11-15 years P0.001; use of plain water for hand washing P0.05; eating food without spoon P0.05; consuming raw vegetables P0.001; untrimmed finger nails P0.001 and source of drinking water [river P0.001 and mixed sources (river; well and tap) P0.05]. Conclusion: This study revealed that intestinal parasites still pose a public health problem to school going children. Despite lack of school based deworming programme in this area; treatment combined with health education and other interventions in school age children is recommended as a way of controlling transmission

Hepatosplenomegaly associated with chronic malaria exposure: evidence for a pro-inflammatory mechanism exacerbated by schistosomiasis.

In sub-Saharan Africa, chronic hepatosplenomegaly, with palpable firm/hard organ consistency, is common, particularly among school-aged children. This morbidity can be caused by long-term exposure to malaria, or by Schistosoma mansoni, and it is exacerbated when these two occur together. Although immunological mechanisms probably underlie the pathogenic process, these mechanisms have not been identified, nor is it known whether the two parasites augment the same mechanisms or induce unrelated processes that nonetheless have additive or synergistic effects. Kenyan primary schoolchildren, living in a malaria/schistosomiasis co-transmission area, participated in cross-sectional parasitological and clinical studies in which circulating immune modulator levels were also measured. Plasma IL-12p70, sTNF-RII, IL-10 and IL-13 levels correlated with relative exposure to malaria, and with hepatosplenomegaly. Soluble-TNF-RII and IL-10 were higher in children infected with S. mansoni. Hepatosplenomegaly caused by chronic exposure to malaria was clearly associated with increased circulating levels of pro-inflammatory mediators, with higher levels of regulatory modulators, and with tissue repair cytokines, perhaps being required to control the inflammatory response. The higher levels of regulatory modulators amongst S. mansoni infected children, compared to those without detectable S. mansoni and malarial infections, but exposed to malaria, suggest that S. mansoni infection may augment the underlying inflammatory reaction.

Bancroftian filariasis: patterns of vector abundance and transmission in two East African communities with different levels of endemicity.

Intensive monitoring of Wuchereria bancrofti vector abundance and transmission intensity was carried out in two communities, one with high-level endemicity for bancroftian filariasis (Masaika, Tanzania) and the other with low-level (Kingwede, Kenya), on the East African coast. Mosquitoes were collected in light traps, from 50 randomly selected households in each community, once weekly for 1 year. They were identified, dissected and checked for parity and filarial larvae. Anopheles gambiae s. l., An. funestus and Culex quinquefasciatus transmitted W. bancrofti in the two communities but the importance of each of these taxa differed between the communities and by season. The overall vector densities and transmission intensities were significantly higher in Masaika than in Kingwede (the annual biting rate by 3.7 times and the annual transmission potential by 14.6 times), primarily because of differences in the available breeding sites for the vectors and in the vectorial capacity of the predominant vector species. A marked seasonal variation in vector abundance and transmission potential contributed to the complex transmission pattern in the communities. Generally, these indices were higher during and shortly after the rainy seasons than at other times of the year. Considerable differences in W. bancrofti transmission were thus observed between communities within a relatively small geographical area (mainly because of environmentally-determined differences in vector habitats), and these were reflected in the marked differences in infection level in the human populations. The variation in vector abundance, vector composition and transmission intensity in the two communities is discussed in respect to its cause, its effects, and its significance to those attempting to control bancroftian filariasis.

Epidemiology and morbidity of Schistosoma mansoni infection in a fishing community along Lake Albert in Uganda.

Schistosoma mansoni infection, associated morbidity and symptoms were studied in Piida fishing community at Butiaba, along Lake Albert, Uganda, from November 1996 to January 1997. The study revealed that S. mansoni is highly endemic with an overall prevalence of 72%, a mean intensity of 419.4 eggs per gram (epg) faeces (geometric mean for positives only), with 37.8% of males and 33.0% of females excreting over 1000 epg. Prevalence and intensity peaked in the 10-14 year old age group and decreased with increasing age. Females were less heavily infected than males. Differences were also shown between tribes. Diarrhoea and abdominal pain were commonly reported in Piida. However, no clear-cut correlation between intensity of S. mansoni infection and these conditions could be demonstrated, indicating that retrospective questionnaires concerning S. mansoni related-symptomatology are of limited value. Organomegaly, as assessed by ultrasonography, was frequent and hepatomegaly was associated with heavy S. mansoni infection. No correlation was demonstrated between splenomegaly and infection. This study emphasizes that schistosomiasis mansoni is a major public health problem in Piida fishing community and presumably also in many similar fishing communities. These observations call for immediate intervention and can help in planning long-term strategies for sustainable morbidity control.

Hepatosplenic morbidity in two neighbouring communities in Uganda with high levels of Schistosoma mansoni infection but very different durations of residence.

Peri-portal fibrosis can be a serious sequelae of Schistosoma mansoni infection. Age or duration of exposure have been identified as important risk factors, but their relative importance cannot be easily separated. Here, we have compared two cohorts, aged 6-50 years and resident for ten years or since birth, from two neighbouring villages (Booma and Bugoigo) on the eastern shore of Lake Albert, Uganda. Parasitological measurements were similar, whereas the prevalence of peri-portal fibrosis was 5-fold higher in Booma. Data from the cohorts were pooled to assess the relative contribution of age and duration of residency on the risk of disease. Amongst adults, duration of residency was the critical risk factor--individuals aged 17-31 years resident for more 22 years had an almost 12-fold increased risk of fibrosis than those resident for less than 15 years. Height-standardised Splenic Vein Diameter (SVD), Portal Vein Diameter (PVD), Para-sternal Liver Length (PLL) and Spleen Length (SL) values were all higher in Booma, and each organometric parameter except PLL increased with the severity of fibrosis. Our results clearly demonstrate that duration of exposure is a critical risk factor for the development of peri-portal fibrosis and its sequelae in adults. This parameter should therefore be a routine measurement during epidemiological surveys of S. mansoni.

Bancroftian filariasis in 12 villages in Kwale district, Coast province, Kenya - variation in clinical and parasitological patterns.

As part of a larger study on the effects of permethrin-impregnated bednets on the transmission of Wuchereria bancrofti, subjects from 12 villages in the Coastal province of Kenya, south of Mombasa, were investigated. The aims were to update the epidemiological data and elucidate the spatial distribution of W. bancrofti infection. Samples of night blood from all the villagers aged i 1 year were checked for the parasite, and all the adult villagers (aged >/= 15 years) were clinically examined for elephantiasis and, if male, for hydrocele. Overall, 16.0% of the 6531 villagers checked for microfilariae (mff) were found microfilaraemic, although the prevalence of microfilaraemia in each village varied from 8.1%-27.4%. The geometric mean intensity of infection among the microfilaraemic was 322 mff/ml blood. At village level, intensity of the microfilaraemia was positively correlated with prevalence, indicating that transmission has a major influence on the prevalence of microfilaraemia. Clinical examination of 2481 adults revealed that 2.9% had elephantiasis of the leg and that 19.9% of the adult men (10.8%-30.1% of the men investigated in each village) had hydrocele. Although the overall prevalence of microfilaraemia in the study villages had not changed much since earlier studies in the 1970s, both prevalence and intensity varied distinctly between the study villages. Such geographical variation over relatively short distances appears to be a common but seldom demonstrated feature in the epidemiology of bancroftian filariasis, and the focal nature of the geographical distribution should be carefully considered by those mapping the disease.

The detection of antibodies against Schistosoma mansoni soluble egg antigens (SEA) and CEF6 in ELISA, before and after chemotherapy.

Circulating IgG antibody reactivity and excreted egg counts were investigated in 489 Kenyans given chemotherapy for schistosomiasis mansoni. Antibody reactivity was measured in ELISA, using either unfractionated aqueous soluble constituents of Schistosoma mansoni eggs (SEA) or CEF6 (a soluble fraction of S. mansoni eggs containing two cationic antigens) as the antigen source. Antibody reactivity for each antigen source was strongly associated with egg counts, both pre- and post-treatment. Approximately 6 months after chemotherapy, egg counts were zero in 84% of the subjects. The mean optical densities (OD) measured in the post-treatment ELISA were 60% (CEF6) or 45% (SEA) lower than the pre-treatment values, the reduction in the OD with CEF6 as antigen source being significantly greater than that observed with SEA (P <0.001). The usefulness of an assay for antibody reactivity in monitoring the effects of the treatment of schistosomiasis is discussed.

Frequencies of sickle cell trait and glucose-6-phosphate dehydrogenase deficiency differ in highland and nearby lowland malaria-endemic areas of Kenya.

Sickle cell genotype prevalence was 26% in a malaria-holoendemic lowland area compared with 3% in a highland area of Kenya. The prevalence of glucose-6-phosphate dehydrogenase deficiency was 7% and 1% in holoendemic lowland and highland areas, respectively. Lack of protective polymorphisms may contribute to morbidity and mortality during outbreaks of malaria in the highlands.

Efficacy and side effects of praziquantel treatment in a highly endemic Schistosoma mansoni focus at Lake Albert, Uganda.

The aim of the study was to assess the efficacy and side effects following single and repeated (6 weeks apart) praziquantel treatment (40 mg/kg) in a Schistosoma mansoni-endemic focus with long-standing transmission at Lake Albert in Uganda between December 1996 and January 1997. The results were based on 482 individuals, randomly representing all age and both gender groups. The cure rate following the first and second treatments was 41.9% and 69.1%, respectively. The cure rate was higher in adults than in children, irrespective of intensity of infection. In addition, the cure rate declined markedly with increasing intensity of infection. The reduction in intensity of infection was marked, being 97.7% and 99.6% after the first and second treatments, respectively. A pre- and post-treatment symptom questionnaire revealed a broad range of side effects, including abdominal pain and diarrhoea. However, no serious or long-lasting complications affecting compliance were observed. The marked reductions in faecal egg excretion and the acceptable level of side effects point to a single praziquantel treatment (40mg/kg) as the strategy of choice in such a highly endemic S. mansoni focus.

Efficacy of oxamniquine and praziquantel in school children from two Schistosoma mansoni endemic areas.

OBJECTIVE: To determine the relative susceptibility of Schistosoma mansoni infections to treatment with the oxamniquine (OXA) and praziquantel (PZQ). DESIGN AND SETTING: Three separate cross sectional studies were performed in six primary schools located in two Schistosoma mansoni endemic areas in Eastern Kenya: Kangundo (low morbidity) and Kibwezi (high morbidity). SUBJECTS: One thousand two hundred and fourteen infected children aged 6-20 years were involved. INTERVENTION: Each child received either 15-mg OXA/kg body weight twice within an interval of six hours or a single dose of 40 or 60 mg PZQ/kg body weight. Three duplicate Kato stool examinations were done before and four or five weeks after treatment to assess treatment efficacy. RESULTS: The cure rates in different schools with OXA were 71.7-79.7% in Kangundo and 56.7-61.9% in Kibwezi. In children treated with PZQ, the 40-mg/kg-dose regimen achieved cure rates of 77.6-87.2% in Kangundo and 67.1-81.1% in Kibwezi, whereas the 60-mg/kg dose regimen attained cure rates of 93.2% in Kangundo and 76.3% in Kibwezi. Both OXA and PZQ efficacy declined significantly with age in Kangundo, whereas the age effect was not seen in Kibwezi. CONCLUSION: The poorer cure rates in Kibwezi than in the Kangundo children were not due to known previous drug exposure to either OXA or PZQ. The varying efficacy may be attributed to innate low drug susceptibility, possibly related to schistosome strain differences between the two areas.

Self-treatment by Kenyan and Ugandan schoolchildren and the need for school-based education.

Studies on Kenyan and Ugandan primary schoolchildren's knowledge of medicines and self-treatment practices show that children aged between 10 and 18 years have a broad knowledge of herbal and biomedical remedies and that they use them frequently, often without adults' involvement. They use pharmaceuticals, including prescription-only drugs, but lack knowledge about indications and dosages. There is a gap between the children's life worlds and the school health education as it is presently designed and taught in Kenya and Uganda. It limits itself to disease prevention and health promotion, and does not teach treatment or medicine-use. Self-treatment based on insufficient knowledge poses a threat to children's health and to the health of the wider community. Therefore, education on the critical and appropriate use of medicines needs to be developed and tested for possible use in Kenya, Uganda and other countries in which home-treatment is common. The proposed education on medicines should go beyond providing information on accurate dosage and indication: it should create critical awareness with regard to medicine-use, enabling children to use them appropriately and cautiously. Kenyan and Ugandan primary schoolchildren are active agents within pluralistic medical fields. By taking the children seriously as competent health care agents, the dangers of self-treatment could be reduced, and the potential of children could be guided to fruitful use. Educational interventions cannot solve the problems of self-treatment, which are related to the wider social and economic context, but they could contribute to increased awareness as a necessary condition for change.

The health workers for change impact study in Kenya.

This paper reports the detailed results of a study of the impact of the Health Workers for Change (HWFC) workshop series on clients' perceptions of health services, relationships within the health centre and relations between the health facility and the district health system. The study was carried out in three stages: baseline, intervention and evaluation over a period of 20 months. Data, both qualitative and quantitative, were collected at three levels: client, facility and system. Results indicate that relations between health workers and clients improved a great deal after the intervention while those between the facility and the system remained to a large extent unchanged. The paper concludes that, with external support and help, especially from the health system level, health workers can work towards improving health services and their job satisfaction, which can lead to better health worker-client relations.

Schistosoma haematobium-induced urinary tract morbidity correlates with increased tumor necrosis factor-alpha and diminished interleukin-10 production.

This study examined the hypothesis that the nature of the host cellular immune response to schistosome ova is a risk factor for urinary tract morbidity in areas in which Schistosoma haematobium is endemic. S. haematobium-infected children and adolescents with bladder pathology assessed by ultrasonography had 54-fold greater tumor necrosis factor (TNF)-alpha production and a 120-fold greater ratio of TNF-alpha to interleukin (IL)-10 release by peripheral blood mononuclear cells in response to egg antigens, in comparison with control children and adolescents matched by age, sex, and infection severity. Mycobacterial antigens also stimulated 7-fold more TNF-alpha among subjects with bladder morbidity than in control subjects, which suggests an innate predisposition to enhanced TNF-alpha production. Levels of egg antigen-induced IL-4 and -5 and interferon-gamma were equivalent in subjects with and without bladder pathology. Thus, children and adolescents predisposed to increased TNF-alpha production to S. haematobium infection are more likely to develop an exaggerated granulomatous response to ova trapped in the bladder wall, with associated urinary tract pathology.

A comparative study of different albendazole and mebendazole regimens for the treatment of intestinal infections in school children of Usigu Division, western Kenya.

A clinical trial to compare the effectiveness of 4- and 6-mo repeated treatment with albendazole 600 mg (Zentel, SmithKline Beecham) or mebendazole 600 mg (Vermox, Janssen) on geohelminth infections was carried out on children in 6 primary schools; the study included 1,186 children, ages 4 to 19 yr. Kato-Katz examination was performed on stool samples before and after treatment. Overall, albendazole produced better cure rates and egg reduction rates for geohelminths. The cure rates for albendazole were 92.4% for hookworm infection, 83.5% for Ascaris lumbricoides, and 67.8% for Trichuris trichiura. Mebendazole given either 2 or 3 times in a year had cure rates of 50 and 55.0% (respectively) for hookworm, 79.6 and 97.5% for A. lumbricoides, and 60.6 and 68.3% for T. trichiura infection. The geometric mean intensity of hookworm eggs per gram (epg) of stool decreased by 96.7% after albendazole treatment compared with 66.3 and 85.1%, respectively, for 2 or 3 doses of mebendazole (P < 0.05) over the same period. Reductions in epg for A. lumbricoides and T. trichiura were comparable for both drugs. Our results indicate that treatment with albendazole at a 6-mo interval was more effective than mebendazole regimens and may be the best choice for use in the control of the 3 geohelminths.

Prevalence and familial aggregation of schistosomal liver morbidity in Kenya: evaluation by new ultrasound criteria.

Severe periportal fibrosis is not an inevitable consequence of infection with Schistosoma mansoni. Genetic predisposition may be a deciding factor in the development of disease. To assess the contribution of genetic factors in the severity of hepatic fibrosis, the degree of familial aggregation was determined in a Kenyan population. Schistosomal fibrosis was identified with hepatic ultrasound and newly proposed World Health Organization criteria, which include both qualitative and quantitative observations. These 2 aspects of the criteria correlated well with one another. The peak prevalence of ultrasound proven fibrosis trailed 5-10 years behind peak prevalence of infection and declined sharply after age 50 years. This pattern was consistent with either resolution of severe fibrosis over 10-20 years or early death of those severely affected. Genetic predisposition appears to be a weak factor in the development of severe disease in this population, since no household or familial aggregation could be identified.

Intestinal helminths and schistosomiasis among school children in a rural district in Kenya.

OBJECTIVE: To determine the extent of intestinal schistosomiasis, ascariasis, trichuriasis and hookworm infections among school children of Usigu and Bondo divisions of Bondo District. DESIGN: A cross sectional study. SETTING: Fifty out of 130 primary schools in Usigu and Bondo divisions, Bondo District. SUBJECTS: Randomly selected school children (n= 3158) aged five to 20 years, were examined for intestinal helminths and schistosomiasis using Kato thick smear technique. RESULTS: The overall prevalence and geometric mean egg counts per gram/faeces for Schistosoma mansoni were 31.6% and 3.1; hookworm 36.8% and 4.1; Trichuris trichiura 21.8% and 1.5, and Ascaris lumbricoides 16.5% and 2.5. More girls (34.9%) than boys (28.6%) were infected with S. mansoni whereas more boys (39.0%) than girls (34.5%) were infected with hookworm. The prevalence of S. mansoni and hookworm infections increased with age but Ascaris and Trichuris infections decreased with age without any sex differences. Children under ten years of age tended to be more heavily infected with ascariasis, trichuriasis and hookworm than the older ones, while the intensity of S. mansoni increased gradually with age. There were positive relationships between different infections except for a significant negative correlation between Schistosoma mansoni and hookworm infections. Only four cases out of 789 had S. haematobium infection. CONCLUSION. Schistosoma mansoni and geohelminths were endemic in Bondo District, where two thirds of the school children suffered from these parasites. Polyparasitism was also common. There was a little overlap in the distribution of Schistosoma mansoni and hookworm, whereas ascariasis and trichuriasis were fairly distributed in the district.

Evidence against rapid emergence of praziquantel resistance in Schistosoma haematobium, Kenya.

We examined the long-term efficacy of praziquantel against Schistosoma haematobium, the causative agent of urinary schistosomiasis, during a school-based treatment program in the Msambweni area of Coast Province, Kenya, where the disease is highly endemic. Our results, derived from treating 4,031 of 7,641 children from 1984 to 1993, indicate substantial year-to- year variation in drug efficacy. However, the pattern of this variation was not consistent with primary or progressive emergence of praziquantel resistance. Mathematical modeling indicated that, at current treatment rates, praziquantel resistance will likely take 10 or more years to emerge.

Cytokine responses to Plasmodium falciparum liver-stage antigen 1 vary in rainy and dry seasons in highland Kenya.

Seasonal epidemics of malaria occur in highland areas of western Kenya where transmission intensity varies according to rainfall. This study describes the seasonal changes in cytokine responses to Plasmodium falciparum liver-stage antigen 1 (LSA-1) by children (< or =17 years old) and adults (> or =18 years old) living in such a highland area. Fourteen- to 24-mer peptides corresponding to the N- and C-terminal nonrepeat regions of LSA-1 stimulated production of interleukin-5 (IL-5), interleukin-10 (IL-10), gamma interferon (IFN-gamma), and tumor necrosis factor alpha (TNF-alpha) by peripheral blood mononuclear cells (PBMC) from 17 to 73% of individuals in both age groups in both seasons. IL-10 and TNF-alpha responses were more frequent during the high-transmission, rainy season than during the low-transmission, dry season (73 and 67% versus 17 and 25% response rates, respectively). In contrast, there was no seasonal change in the proportion of LSA-1-driven IFN-gamma and IL-5 responses. Children produced less IFN-gamma than adults, but IL-5, IL-10, and TNF-alpha levels were similar for both age groups. Depletion of CD8(+) cells from PBMC decreased IFN-gamma but increased IL-10 production. Individuals with LSA-1-stimulated IL-10 responses in the dry season were less likely to become reinfected in the subsequent rainy season than those without IL-10 responses (25% versus 49%; P = 0.083). These data support the notion that maintenance of LSA-1-driven IL-10 and TNF-alpha responses requires repeated and sustained exposure to liver-stage P. falciparum. In contrast, IFN-gamma responses increase slowly with age but persist once acquired. CD8(+) T cells are the major source of IFN-gamma but may suppress production or secretion of IL-10.

Children and medicines: self-treatment of common illnesses among Luo schoolchildren in western Kenya.

In a rural area of western Kenya, primary schoolchildren's health seeking behaviour in response to common illnesses was investigated. 57 primary schoolchildren (age 11-17 years, median 13 years) were interviewed weekly about their health status and health seeking activities for 30 weeks. The children each experienced on average 25 illness episodes during this period. Most episodes could be categorised into 4 groups: 'cold', 'headache', 'abdominal complaints' and 'injuries'. One fifth (21%) of the illness episodes were serious enough to keep the children from school. In 28% of them, an adult was consulted, while 72% were not reported to an adult caretaker. Of the episodes without adult involvement, 81% remained untreated, while 19% were treated by the children themselves with either herbal or Western medicines. Of all the medicines taken by the children, two thirds were provided or facilitated by adults (assisted treatment) and one third taken by the children themselves without adult involvement (self-treatment). Among boys, the proportion of illnesses, which were self-treated increased with age from 12% in the youngest age group (< 13 years) to 34% in the oldest (> 14 years). In girls, the proportion of illnesses which were self-treated was consistently lower than among boys and remained constant around 9% for all age groups. The proportion of Western pharmaceuticals used for self-treatment increased with age from 44% in the youngest age group to 63% in the oldest (average 52% Western pharmaceuticals). Again, there were differences between boys and girls: among the youngest age group, boys were twice as likely to use pharmaceuticals than girls (62 versus 32% of the self-treatments, respectively) and in the oldest age group they were nearly three times more likely (75 versus 25%, respectively). These differences in self-treatment practices and choice of medicines between girls and boys may reflect the higher income potential of boys, who can earn money by fishing. Pharmaceuticals were generally preferred for the treatment of headache and fevers, or colds, while herbal remedies were the preferred choice for the treatment of abdominal complaints and wounds. The most commonly used pharmaceuticals were antimalarials (mainly chloroquine), painkillers and antipyretics (mainly aspirin and paracetamol), which were stocked in most small shops in the village at low prices and readily sold to children. Throughout primary school age Kenyan children are growing into a pluralistic medical practice, integrating Western pharmaceuticals into the local herbal medical system, and gradually become autonomous agents in their health care.