Population Based Reference Intervals for Common Blood Haematological and Biochemical Parameters in the Akuapen North District

Objectives : To estimate the reference intervals for commonly used blood haematology and biochemical parameters in an adult (18-55yrs) population of residents of Mampong Akuapem. Design: This was a population based cross sectional study of a randomly selected sample of the adult population of Mampong. The sample was selected from an updated census list of the Mampong area. Results: Median values (95 range) for measured parameters were established as follows: Haemoglobin; (males) 14.2 g/dl (females) 12.0 g/dl Alanine aminotransferase (ALT); (female) 19.6 U/L (males) 26.1 U/L and Creatinine; (males) 108 mmol/L (females) 93 mmol/L. Conclusion: In comparison to reference values that are commonly used in Ghana; the haemoglobulin levels from this study were lower; and liver function parameters higher. This could be a result of genetic or environmental differences and calls for the need to establish site specific reference values applicable to our population

Predicting the timing of second praziquantel treatment and its effect on reduction of egg counts in southern Ghana.

Schistosoma haematobium infection could be associated with morbidity. Generally, the cost of schistosomiasis control is high and it becomes a burden for governments or non-governmental organisations to repeat control programs so as to reduce morbidity. There is therefore, the need to optimise the available meagre resources for its control. From 1993 to 1997 the Noguchi Memorial Institute for Medical Research of the University of Ghana carried out a schistosomiasis control program in southern Ghana. Using the generated data, an attempt is made to determine the timing of the second praziquantel treatment and the period needed after the second chemotherapy to have egg counts reduced to low levels in southern Ghana. It was revealed that the second praziquantel treatment in areas 1, 2, and 3 should be administered latest at 13.8, 11.8 and 13.2 months, respectively after the first one. Most importantly, it takes 24.4 months to bring egg counts to zero in area 3 while in area 1, it takes about 29 months after the second praziquantel treatment. Egg counts were not reduced to zero in area 2 after the second chemotherapy. At least passive health education and continuous safe water supply should support the chemotherapy in addition to weed removal at the water contact sites.

Highly symptom-aware children were heavily infected with urinary schistosomiasis in southern Ghana.

OBJECTIVES: To assess the relationship between the infection status of children and their knowledge, attitudes, beliefs, and practices (KABP) related to urinary schistosomiasis. DESIGN: Questionnaire survey. SETTING: Nine schools in eight rural communities (total population: 4,636) in Ga and South Akuapem Districts, Ghana. SUBJECTS: Four hundred and six children attending primary and secondary schools. MAIN OUTCOME MEASURE: Schistosoma haematobium infection status of children and their KABP. RESULTS: Of 354 children who responded and also submitted their urine samples, 297 (83.9%) tested positive for S. haematobium and the intensity of infection was 90 (95% CI: 74 to 110) eggs per 10 ml urine. General knowledge variables such as the knowledge of symptoms (p < 0.001), and knowledge of swimming or bathing in the river as a transmission route (p < 0.001) showed significant association for higher prevalence and intensity of infection. Treatment-seeking behaviour was not associated with the lower prevalence or intensity of infection. Practice variables such as washing clothes in the stream (p < 0.001) and fishing in the stream (p < 0.01) were significantly associated with both higher prevalence and higher intensity of infection. Children who knew of contact with river water as a transmission route reported more water contact activities (p < 0.001). CONCLUSION: This study showed that highly symptom-aware people were heavily infected, and people frequently exposed to infested water were heavily infected. Moreover, highly symptom-aware people never constituted a group whose exposure was slight. Why was awareness of disease symptoms and general knowledge of the disease not linked to low infectivity? Why didn't awareness result in avoidance of infested water sources? This report highlights the urgent need to address these important questions in future research.

Antibody response to 17D yellow fever vaccine in Ghanaian infants.

OBJECTIVES: To assess the seroresponses to yellow fever vaccination at 6 and 9 months of age; assess any possible adverse effects of immunization with the 17D yellow fever vaccine in infants, particularly at 6 months of age. METHODS: Four hundred and twenty infants who had completed BCG, OPV and DPT immunizations were randomized to receive yellow fever immunization at either 6 or 9 months. A single dose of 0.5 ml of the reconstituted vaccine was administered to each infant by subcutaneous injection. To determine the yellow fever antibody levels of the infants, each donated 1 ml whole blood prior to immunization and 3 months post-immunization. Each serum sample was titred on Vero cells against the vaccine virus. FINDINGS: The most common adverse reactions reported were fever, cough, diarrhoea and mild reactions at the inoculation site. The incidences of adverse reactions were not statistically different in both groups. None of the pre-immunization sera in both age groups had detectable yellow fever antibodies. Infants immunized at 6 months recorded seroconversion of 98.6% and those immunized at 9 months recorded 98% seroconversion. The GMT of their antibodies were 158.5 and 129.8, respectively. CONCLUSIONS: The results indicate that seroresponses to yellow fever immunization at 6 and 9 months as determined by seroconversion and GMTs of antibodies are similar. The findings of good seroresponses at 6 months without significant adverse effects would suggest that the 17D yellow fever vaccine could be recommended for use in children at 6 months in outbreak situations or in high risk endemic areas.

Incidence of symptomatic and asymptomatic Plasmodium falciparum infection following curative therapy in adult residents of northern Ghana.

Adult residents of holoendemic malaria regions in Africa have a naturally acquired immunity (NAI) to malaria that renders them more resistant to new infections, limits parasitemia, and reduces the frequency and severity of illness. Given such attributes, it is not clear how one might evaluate drug or vaccine efficacy in adults without serious confounding. To determine symptomatic and asymptomatic malaria attack rates in adults of northern Ghana, 197 men and women underwent curative therapy for any pre-existing malaria infections at the start of the high transmission (wet) season. They were monitored for first parasitemia and first clinical episode of infection by Plasmodium falciparum over a 20-week period (May-October 1996). The cumulative incidence of primary infection by P. falciparum was 0.98 and incidence density of infection was calculated to be 7.0 cases/person-year. Symptoms were reported by 19.5% of the individuals at the time of first recurrent parasitemia. Incidence of infection, parasite density, and the frequency of symptoms were comparable in males and females. The results suggest that NAI did not provide these adults with significant defense against rapid re-infection and suggest that this population-infection design could serve to demonstrate the efficacy of a drug or vaccine in preventing parasitemia.

Novel Plasmodium falciparum clones and rising clone multiplicities are associated with the increase in malaria morbidity in Ghanaian children during the transition into the high transmission season.

A survey of Plasmodium falciparum infection and clone multiplicity in Ghanaian children was carried out to study the effect of the onset of the malaria transmission season on disease incidence. Fortnightly blood samples were collected from 40 children living in the rural town of Dodowa, between February and August 1998. P. falciparum parasite densities were calculated and PCR genotyping was carried out using the polymorphic MSP-1 and MSP-2 genes as target loci for the estimation of the number of parasite clones in each sample. The average clone number was estimated using maximum likelihood techniques and the minimum number of clones per patient was analysed for the effects of age, sex, season, minimum number of clones per child, level of parasitaemia and parasite genotype. The statistical analysis indicated that the more clones a child carried, the more likely they were to have a clinical malaria episode. This was true after adjusting for age and season effects and for the measured circulating parasitaemia. The probability of clinical disease also increased if the MSP-1 MAD 20 and the MSP-2 FC 27 alleles were present. This longitudinal analysis thus indicates that the probability of a Ghanaian child having a symptomatic malaria episode is positively associated with both increasing numbers and novel types of P. falciparum clones.

Antibodies to variant antigens on the surfaces of infected erythrocytes are associated with protection from malaria in Ghanaian children.

Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1) is a variant antigen expressed on the surface of infected erythrocytes. Each parasite genome contains about 40 PfEMP1 genes, but only 1 PfEMP1 gene is expressed at a given time. PfEMP1 serves as a parasite-sequestering ligand to endothelial cells and enables the parasites to avoid splenic passage. PfEMP1 antibodies may protect from disease by inhibiting sequestration, thus facilitating the destruction of infected erythrocytes in the spleen. In this study, we have measured antibodies in Ghanaian children to a conserved region of PfEMP1 by enzyme-linked immunosorbent assay and antibodies to variant molecules on erythrocytes infected with field isolates of P. falciparum by flow cytometry. Based on close clinical monitoring, the children were grouped into those who did (susceptible) and those who did not (protected) have malaria during the season. The prevalences of antibodies to both the conserved PfEMP1 peptide and the variant epitopes were greater than 50%, and the levels of immunoglobulin G (IgG) correlated with age. The levels of antibodies to both the conserved peptide and the variant epitopes were higher in protected than in susceptible children. After correcting for the effect of age, the levels of IgG to variant antigens on a Sudanese and a Ghanaian parasite isolate remained significantly higher in protected than in susceptible children. Thus, the levels of IgG to variant antigens expressed on the surface of infected erythrocytes correlated with protection from clinical malaria. In contrast, the levels of IgG to a peptide derived from a conserved part of PfEMP1 did not correlate with protection from malaria.

Frequent and persistent, asymptomatic Plasmodium falciparum infections in African infants, characterized by multilocus genotyping.

To determine the duration and complexity of naturally acquired Plasmodium falciparum infections in small children, a longitudinal cohort study of 143 newborns was conducted in coastal Ghana. On average, children experienced 2 episodes of infection in their first 2 years of life, the median duration of an asymptomatic infection was <4 weeks, and estimates of the mean number of parasite genotypes per infection were 1.15-2.28. Nevertheless, 40% of the children experienced infections lasting 5 months old. The ability of very young children to clear or control malaria infections indicates the presence of effective innate or immune antiparasite mechanisms.

Single-dose treatment of Wuchereria bancrofti infections with ivermectin and albendazole alone or in combination: evaluation of the potential for control at 12 months after treatment.

The effect of single-dose ivermectin (150-200 micrograms/kg) and albendazole (400 mg) treatment alone and in combination on Wuchereria bancrofti microfilaraemia, antigenaemia and clinical manifestations was compared 12 months after treatment in a double-blind placebo-controlled field trial carried out in Ghana in 1996-98, to evaluate the potential of these treatments for control. Both ivermectin and combination treatments resulted in pronounced reductions in microfilaraemia among individuals who were microfilaria positive before treatment. Among individuals who were positive for circulating filarial antigen before treatment, antigen levels increased considerably over the 1-year period after treatment in the placebo group, whereas they decreased in the ivermectin and combination groups. However, the post-treatment difference reached statistical significance in neither microfilaraemia nor antigenaemia between the ivermectin and the combination groups. Albendazole treatment alone showed only a minor effect on microfilaraemia and antigenaemia. No effect of the treatments on the incidence of new cases of microfilaraemia or antigenaemia, or on clinical manifestations, was observed. Both ivermectin and combination treatment thus appeared effective for control of W. bancrofti infections, but the difference in efficacy between the 2 treatments after 12 months appeared to be minimal.

Lack of association between maternal antibody and protection of African infants from malaria infection.

Maternally derived antibodies are believed to protect infants against infection, but there is little direct evidence for a protective role of passively acquired antibodies against malaria. A longitudinal study of malaria infection in 143 infants was conducted in a region of southern Ghana where Plasmodium falciparum is endemic. Infants born in the high-transmission season were less likely to become infected in the first 20 weeks of life than children born in the low-transmission season. Plasma, obtained at birth, was tested for immunoglobulin G (IgG) and IgG subclasses to P. falciparum schizonts and recombinant circumsporozoite antigen, MSP-1(19), MSP-2, AMA-1, and Pf155 (also called ring-infected erythrocyte surface antigen). Antibody levels at birth were not associated with resistance to malaria infection. On the contrary, antibodies at birth were positively associated with infection, indicating that high levels of maternally derived antibodies represent a marker for intensity of exposure to malaria infection in infants. However, all five children who experienced high-density infections (>100 parasites/microl of blood) were seronegative for MSP-1(19) at the time of infection.

Health centre versus home presumptive diagnosis of malaria in southern Ghana: implications for home-based care policy.

A study was conducted in 1997 to compare the accuracy of presumptive diagnosis of malaria in children aged 1-9 years performed by caretakers of the children to that of health centre staff in 2 ecological zones in southern Ghana. Similar symptoms were reported in the children at home and at the health centre. In the home setting, symptoms were reported the same day that they occurred, 77.6% of the children with a report of fever were febrile (axillary temperature > or = 37.5 degrees C) and 64.7% of the reports of malaria were parasitologically confirmed. In the health centre, the median duration of symptoms before a child was seen was 3 days (range 1-14 days), 58.5% of the children with a report of fever were febrile and 62.6% of the clinically diagnosed cases were parasitologically confirmed. In the 2 settings almost all the infections were due to Plasmodium falciparum. Parasite density was 3 times higher in the health centre cases compared to the home-diagnosed cases. Early and appropriate treatment of malaria detected in children by caretakers may prevent complications that arise as a result of persistence of symptoms and attainment of high parasitaemic levels.

A randomized double-blind placebo-controlled field trial of ivermectin and albendazole alone and in combination for the treatment of lymphatic filariasis in Ghana.

The efficacy and safety of single-dose ivermectin (150-200 micrograms/kg) and albendazole (400 mg) treatment administered separately or in combination for Wuchereria bancrofti infections were assessed in 1996-98 in a randomized double-blind placebo-controlled field trial in Ghana: 1425 individuals from 4 lymphatic filariasis-endemic villages, 340 of whom were microfilaria (mf)-positive before treatment, were randomized into 4 groups to receive albendazole alone, ivermectin alone, combination of albendazole and ivermectin, or placebo, respectively. Individuals were followed for 5 days after treatment to record any adverse reactions, and the effect of treatment on microfilaraemia was monitored in night-blood samples after 3, 6 and 12 months. Treatment efficacy was analysed for 236 mf-positive individuals who had > or = 100 mf/mL of blood and who were also present for examination at 12 months after treatment. Compared to the placebo group, the ivermectin and combination groups both showed statistically significant reductions in geometric mean mf intensities at the follow-up examinations (to 6.7% and 0.9%, 9.9% and 6.9%, and 21.7% and 11.4% of pre-treatment levels, respectively, at 3, 6 and 12 months after treatment). Compared to the ivermectin group, however, the reduction in the combination group was significantly greater only at 3 months after treatment, but not after 6 or 12 months. The albendazole group showed a slow but non-significant reduction over the same period. Adverse reactions were few and mostly mild (no severe reactions were recorded), and no significant differences were observed between the treatment groups. Both ivermectin and combination treatment thus appeared effective and safe for treatment of lymphatic filariasis, but the difference in efficacy was minor and the study did not provide clear evidence for the combination drug therapy, as compared to ivermectin therapy alone, to be superior for control of lymphatic filariasis.

Urinary schistosomiasis in southern Ghana: 1. Prevalence and morbidity assessment in three (defined) rural areas drained by the Densu river.

Epidemiological studies on urinary schistosomiasis were carried out in eight villages in the Ga and Akuapem South districts in Ghana. Single urine samples were collected from individuals aged 5 years and above between 10.00 and 14.00 h. The samples were examined for the presence of Schistosoma haematobium eggs using a filtration technique. Indirect morbidity was determined as the presence of microhaematuria and proteinuria using reagent strips, and macrohaematuria was recorded with the naked eye. Out of the study population of 3912 subjects, 2562 (65.5%) submitted urine samples. The prevalence of a Schistosoma haematobium infection ranged between 54.8 and 60.0%. Infection rates increased by age with a peak in the 10-19 years category, and decreased with increasing age. Disease prevalence was higher in males aged 15 years and above in Areas 2 (Ntoaso and Sansami Amanfro) and 3 (Dom Faase, Papase, Chento and Gidi Kope), whereas it was higher among males aged 10 years and above in Area 1 (Ayikai Doblo and Akramaman). The intensity of infection was highest among children aged 10-14 years in most of the villages. More than half of egg-positive children in this age group had a heavy infection (100 eggs and above in 10 ml of urine). Although both egg-positive and egg-negative individuals manifested variable degrees of macro- or micro-haematuria, microhaematuria was more prevalent among egg-positives (chi(2)=918.5, d.f.=1, P<0.01). The degree of microhaematuria and proteinuria were significantly associated with the intensity of the infection. These results indicate a high transmission of disease in the study area.

High frequency of circulating gamma delta T cells with dominance of the v(delta)1 subset in a healthy population.

TCR gamma delta(+) cells constitute <5% of all circulating T cells in healthy, adult Caucasians, and V(delta)1(+) cells constitute a minority of these cells. In contrast to TCR alpha beta(+) cells, their repertoire is selected extrathymically by environmental antigens. Although increased frequencies of V(delta)1(+) cells are found in several diseases, their function remains obscure. Here we show that the frequency of peripheral blood gamma delta T cells in healthy West Africans is about twice that of Caucasians, mainly due to a 5-fold increase in V(delta)1(+) cells, which is consequently the dominant subset. No age dependency of V(delta)1 frequencies was identified and the V(delta)1(+) cells in the African donors did not show preferential V(gamma) chain usage. Analysis of the CDR3 region size did not reveal any particular skewing of the V(delta)1 repertoire, although oligoclonality was more pronounced in adults compared to children. The proportions of CD8(+), CD38(+) and CD45RA(hi)CD45RO(-) cells within the V(delta)1(+) subset were higher in the African than in the European donors, without obvious differences in expression of activation markers. No significant correlations between levels of V(delta)1(+) cells and environmental antigens or immunological parameters were identified. Taken together, the evidence argues against a CDR3-restricted, antigen-driven expansion of V(delta)1(+) cells in the African study population. Our study shows that high frequencies of TCR gamma delta(+) cells with dominance of the V(delta)1(+) subset can occur at the population level in healthy people, raising questions about the physiological role of V(delta)1(+) T cells in the function and regulation of the immune system.

Distinct patterns of cytokine regulation in discrete clinical forms of Plasmodium falciparum malaria.

The pathogenesis of two of the most severe complications of Plasmodium falciparum malaria, cerebral malaria (CM) and severe malarial anaemia (SA) both appear to involve dysregulation of the immune system. We have measured plasma levels of TNF and its two receptors in Ghanaian children with strictly defined cerebral malaria (CM), severe malarial anaemia (SA), or uncomplicated malaria (UM) in two independent studies in an area of seasonal, hyperendemic transmission of P. falciparum. Levels of TNF, soluble TNF receptor 1 (sTNF-R1) and 2 (sTNF-R2) were found to be significantly higher in CM than in the other clinical categories of P. falciparum malaria patients. Levels of both receptors depended on clinical category, whereas only sTNF-R1 levels were significantly dependent on parasitemia. Detailed analysis of the interrelationship between these variables resolved this pattern further, and identified marked differences between the patient categories. While levels of TNF, sTNF-R1 and sTNF-R2 correlated with parasitemia in UM, this was not the case in CM and SA. Rather, there was a tendency towards high levels of TNF and its receptors in CM and low levels in SA without significant correlation to parasitemia in either category. This, and the fact that malaria-induced increases in plasma levels of IL-10 are much lower in SA compared to CM, suggest that distinct forms of dysregulation of the immune response to infection contribute to the pathogenesis of CM and SA.

Naturally acquired antibodies to the glutamate-rich protein are associated with protection against Plasmodium falciparum malaria.

The development of effective malaria vaccines depends on the identification of targets of well-defined protective immune responses. Data and samples from a longitudinal study of a cohort of children from coastal Ghana were used to investigate the role of antibody responses to 3 regions of the Plasmodium falciparum glutamate-rich protein (GLURP). The data show that levels of the GLURP-specific IgG that occurs in the nonrepeat region of the antigen are significantly correlated with clinical protection from P. falciparum malaria, after correction for the confounding effect of age. Furthermore, levels of cytophilic antibodies were found to be of particular importance for protection, lending support to the hypothesis that antibody-dependent cellular inhibition is the important element in GLURP-specific protective immunity.

Severe anemia in young children after high and low malaria transmission seasons in the Kassena-Nankana district of northern Ghana.

Malaria and anemia accounted for 41% and 18% respectively of hospital deaths in the Kassena-Nankana district of northern Ghana during 1996. We measured hemoglobin (Hb), malaria prevalence, and anthropometric indices of 6--24-month-old infants and young children randomly selected from this community at the end of the high (May-October, n = 347) and low (November-April, n = 286) malaria transmission seasons. High transmission season is characterized by rainfall (the equivalent of 800-900 mm/yr.), while the remaining months receive less than 50 mm/yr. Severe anemia, defined as Hb < 6.0 g/dL, was 22.1% at the end of the high transmission season compared to 1.4% at the end of the low transmission season (Odds Ratio [OR] = 20.1; 95% CI: 7.1-55.3). Parasitemia was 71% and 54.3% at these time points (OR = 2.1; 95% CI: 1.5-2.9). Nutritional anemia appeared to have little impact upon this seasonal difference since anthropometric indices were comparable. Although the relative contributions of other causes of severe anemia were not assessed, repeated malaria infections may be a primary determinant of severe anemia among infants and young children during the high transmission season.

Lymphatic filariasis related perceptions and practices on the coast of Ghana: implications for prevention and control.

A qualitative study to investigate lymphatic filariasis related perceptions and practices that may be relevant for the design of appropriate health education and control programmes was conducted in four endemic villages in coastal Ghana. The villagers were aware of the common manifestations of filariasis, such as adenolymphangitis (ADL), lymphoedema, elephantiasis and hydrocele, which were specifically described with local terminology. ADL attacks were identified as the most dreaded health problem in the communities, and elephantiasis and hydrocele also ranked high in importance among reported diseases. Generally the respondents did not accept the mosquito theory of transmission, but they believed in other physical, and in spiritual and hereditary causes. Hydrocele was considered to have no link to the other disease manifestations. The manifestations were most often treated with herbal preparations which were used orally, smeared on affected parts or given as enema. In some cases the affected parts were scarified before herbal preparations were applied. The manifestations affected the work output of its victims and subjected them to hardships such as teasing, unsuitability for marriage, sexual dysfunction and divorce. Although the etiology was seen as different, the local perception of the developmental process of elephantiasis closely paralleled that of the biomedical understanding. It is suggested that this coincidence is used as an entry point for health education, to advance a broader biomedical knowledge on etiology, transmission and treatment options, and thereby to ensure co-operation of the target populations in the control of this complex disease.