Effectiveness of a community intervention on malaria in rural Tanzania - a randomised controlled trial

BACKGROUND

Malaria infections are a major public health problem in Africa and prompt treatment is one way of controlling the disease and saving lives.

METHODS

This cluster-randomised controlled community intervention conducted in 2003-2005 aimed at improving early malaria case management in under five children. Health workers were trained to train community-based women groups in recognizing malaria symptoms, providing first-line treatment for uncomplicated malaria and referring severe cases. Evaluation was through a pre- (2004) and a post-intervention survey (2005). Anaemia prevalence was the primary outcome.

RESULTS

1715 children aged 6-59 months were included in the pre-intervention survey and 2169 in the post-intervention survey. The prevalence of anaemia decreased significantly from 37% [95% CI 34.7-39.3] to 0.5% [95% CI 0.2-0.7] after the intervention (p<0.001); slightly more in the intervention (from 43.9% to 0.8%) than in the control (30.8% to 0.17%) group (p=0.038). Fever and reported fever decreased significantly and the mean body weight of the children increased significantly over the study period in both control and intervention groups.

CONCLUSION

The decrease in anaemia was significantly associated with the intervention, whereas the fever and body weight trends might be explained by other malaria control activities or seasonal/climate effects in the area. The community intervention was shown to be feasible in the study context.

Pre-referral rectal artesunate to prevent death and disability in severe malaria: a placebo-controlled trial

BACKGROUND

Most malaria deaths occur in rural areas. Rapid progression from illness to death can be interrupted by prompt, effective medication. Antimalarial treatment cannot rescue terminally ill patients but could be effective if given earlier. If patients who cannot be treated orally are several hours from facilities for injections, rectal artesunate can be given before referral and acts rapidly on parasites. We investigated whether this intervention reduced mortality and permanent disability.

METHODS

In Bangladesh, Ghana, and Tanzania, patients with suspected severe malaria who could not be treated orally were allocated randomly to a single artesunate (n=8954) or placebo (n=8872) suppository by taking the next numbered box, then referred to clinics at which injections could be given. Those with antimalarial injections or negative blood smears before randomisation were excluded, leaving 12 068 patients (6072 artesunate, 5996 placebo) for analysis. Primary endpoints were mortality, assessed 7-30 days later, and permanent disability, reassessed periodically. All investigators were masked to group assignment. Analysis was by intention to treat. This study is registered in all three countries, numbers ISRCTN83979018, 46343627, and 76987662.

RESULTS

Mortality was 154 of 6072 artesunate versus 177 of 5996 placebo (2.5%vs 3.0%, p=0.1). Two versus 13 (0.03%vs 0.22%, p=0.0020) were permanently disabled; total dead or disabled: 156 versus 190 (2.6%vs 3.2%, p=0.0484). There was no reduction in early mortality (56 vs 51 deaths within 6 h; median 2 h). In patients reaching clinic within 6 h (median 3 h), pre-referral artesunate had no significant effect on death after 6 h or permanent disability (71/4450 [1.6%] vs 82/4426 [1.9%], risk ratio 0.86 [95% CI 0.63-1.18], p=0.35). In patients still not in clinic after more than 6 h, however, half were still not there after more than 15 h, and pre-referral rectal artesunate significantly reduced death or permanent disability (29/1566 [1.9%] vs 57/1519 [3.8%], risk ratio 0.49 [95% CI 0.32-0.77], p=0.0013).

INTERPRETATION

If patients with severe malaria cannot be treated orally and access to injections will take several hours, a single inexpensive artesunate suppository at the time of referral substantially reduces the risk of death or permanent disability.

FUNDING

UNICEF/UNDP/World Bank Special Programme for Research and Training in Tropical Diseases (WHO/TDR); WHO Global Malaria Programme (WHO/GMP); Sall Family Foundation; the European Union (QLRT-2000-01430); the UK Medical Research Council; USAID; Irish Aid; the Karolinska Institute; and the University of Oxford Clinical Trial Service Unit (CTSU).

Patterns of resistance and DHFR/DHPS genotypes of Plasmodium falciparum in rural Tanzania prior to the adoption of sulfadoxine-pyrimethamine as first-line treatment

A study was carried out to assess the patterns of resistance and occurrence of DHFR/DHPS genotypes of Plasmodium falciparum prior to the adoption of sulfadoxine-pyrimethamine (SP) as first-line treatment for uncomplicated malaria in Tanzania. Children under five years (n = 117) with clinical, uncomplicated malaria were randomly allocated to standard treatments of either chloroquine (CQ) (25 mg/kg) or SP (25 mg sulfadoxine and 1.25 mg pyrimethamine/kg). Patients were monitored for 28 days. Clinical recovery was achieved in 98% (n = 58) and 90% (n = 59) of the patients in the SP and CQ groups, respectively. Parasitologically, 14% of the patients in the SP group and 51% in the CQ group exhibited RII/RIII resistance. When relating pre-treatment blood drug levels to treatment outcome and the degree of parasite resistance to the number of mutations, no relationships could be detected. There was an overall significant increase in haemoglobin levels from day 0 to day 28 in both patient groups. Sulfadoxine-pyrimethamine produced an acceptable clinical response but the high degree of parasitological resistance (RII/RIII) observed two years prior to the introduction of the drug as first-line treatment is of concern, especially considering the long half-lives of sulfadoxine and pyrimethamine.

Local understanding, perceptions and reported practices of mothers/guardians and health workers on childhood malaria in a Tanzanian district--implications for malaria control

Knowledge on local understanding, perceptions and practices of care providers regarding management of childhood malaria are needed for better malaria control in urban, peri-urban and rural communities. Mothers of under five children attending five purposively selected public health facilities in the Kibaha district, Tanzania, were invited to participate in 10 focus group discussions (FGDs). The health workers of these facilities were included in six other FGDs to elicit their professional views. Analysis was done using interpretative and qualitative approaches. Both health workers and all mothers were clear about the signs and symptoms of homa ya malaria, a description consistent with the biomedical definition of mild malaria. Although most of the mothers related this to mosquito bites, some did not. Mothers also described a severe childhood illness called degedege, consistent with convulsions. Most of the mothers failed to associate this condition with malaria, believing it is caused by evil spirits. Urinating on or fuming the child suffering from degedege with elephant dung were perceived to be effective remedies while injections were considered fatal for such condition. Traditional healers were seen as the primary source of treatment outside homes for this condition and grandmothers and mother in-laws are the key decision makers in the management. Our findings revealed major gaps in managing severe malaria in the study communities. Interventions addressing these gaps and targeting mothers/guardians, mother in-laws, grandmothers and traditional healers are needed.

Therapeutic efficacy of chloroquine and sulfadoxine/pyrimethamine against Plasmodium falciparum infection in Somalia

OBJECTIVE

To assess the efficacy of chloroquine and sulfadoxine/pyrimethamine in the treatment of uncomplicated Plasmodium falciparum infections in Somalia.

METHODS

Patients with clinical malaria in Merca, an area of high transmission of the disease, were treated with the standard regimens of chloroquine (25 mg/kg) or sulfadoxine/pyrimethamine (25 mg sulfadoxine and 1.25 mg pyrimethamine per kg). Similar patients in Gabiley, an area of low transmission, received the standard regimen of chloroquine. The clinical and parasitological responses were monitored for 14 days.

FINDINGS

Chloroquine treatment resulted in clinical failure in 33% (n = 60) and 51% (n = 49) of the patients in Merca and Gabiley respectively. There were corresponding parasitological failures of 77% RII/RIII and 35% RII/RIII. Patients who experienced clinical failure had significantly higher initial parasitaemia than those in whom there was an adequate clinical response, both in Merca (t = 2.2; P t = 2.8; P n = 50) of the patients achieved an adequate clinical response despite a parasitological failure rate of 76% RII/RIII.

CONCLUSION

Chloroquine should no longer be considered adequate for treating clinical falciparum malaria in vulnerable groups in the areas studied. Doubts about the therapeutic life of sulfadoxine/pyrimethamine in relation to malaria are raised by the high levels of resistance in the Merca area and underline the need to identify suitable alternatives.

Antibodies to a non-repeat region of Plasmodium falciparum antigen Pf155/RESA in individuals from malaria-endemic areas

Human antibodies to the repeat regions of the Plasmodium falciparum asexual blood stage antigen Pf155/RESA interfere with parasite growth in vitro, but the significance in this respect of antibodies to non-repetitive epitopes is less clear. In this study the levels of antibodies to a non-repetitive part of Pf155/RESA (residue 199-221) in malaria-exposed individuals were analysed, as was the parasite-inhibitory capacity of such antibodies. Residue 199-221 is of particular interest since it includes a sequence homologous to a cytoadherence-related motif from band 3. Sera from donors in Liberia and Tanzania were analysed for reactivity in ELISA with synthetic peptides together overlapping this part of Pf155/RESA. High antibody reactivity was observed in most of the sera with two peptides including residues 199-211 and 202-214, respectively. Specific antibodies were affinity-purified from selected sera using these peptide sequences and were shown to react with Pf155/RESA by immunofluorescence and Western blotting. The purified antibodies were furthermore shown to inhibit parasite growth in vitro. The results suggest that both repeat and non-repeat epitopes in Pf155/RESA elicit antibodies with potential to protect against malaria infection.

A malariometric survey in a rural community in the Muheza district, Tanzania: age profiles in the development of humoral immune responses

A malariometric survey was carried out in a rural community situated in a malaria holoendemic endemic area of Tanzania. A random sample (n = 228) of different age groups was taken to elucidate the association between anti-Pf155/RESA and anti-Pf332 antibody responses and classical malaria indices. Parasitaemia, fever, splenomegaly, haematocrit and antimalarial consumption were assessed. Antibody responses against Pf155/RESA and Pf332 peptides were determined by ELISA. The age profiles of parasite density, splenomegaly, fever, haematocrit values and prevalence of antibody responses indicated intensive malaria exposure and the highest impact of malaria in small children. Forty-five percent of the study population had detectable chloroquine and desethyl-chloroquine blood levels, and the highest frequency and concentrations were recorded in the 12-23 months old. There was no significant association between the presence of drug and parasite density in the different age groups, although in the < 15 years old there was lower parasite prevalence among the children positive for drug in their blood (P < 0.05). High prevalence of antibody responses to all antigens was observed already at an early age, but the mean anti-Pf155/RESA and anti-Pf332 antibody levels increased significantly only in the adult group (P < 0.01). Significantly lower mean parasite densities were observed in high responders to Pf155/RESA and Pf332 peptides for the > or = 10 years old. For the 1-9 years, a similar difference was only observed in the high responders to Pf332. For the whole material, anti-Pf155/RESA and anti-Pf332 antibody levels correlated positively with age. When the effect of age was allowed for in analysing the relationship between parasite density and antibody level against the different antigens, a significant negative correlation was found only with regard to Pf332 in the > = 10 years age group. These results suggest that anti-Pf332 antibodies appear to be a better indicator for antiparasitic immunity, but both antigens are important for immune protection.

An epidemic of Plasmodium falciparum malaria in Balcad, Somalia, and its causation

The causative factors of an epidemic of falciparum malaria were investigated in Balcad, Somalia, a town with previously low malaria transmission, where malaria incidence rose more than twenty-fold between 1986 and 1988. The emergence of chloroquine resistance, accelerated by high drug pressure, low herd immunity and favourable meteorological conditions were identified as major causes of the epidemic. Chloroquine resistance of grades RII and RIII was first observed in Balcad in 1987 and rapidly increased to 72% of the Plasmodium falciparum infections in 1988. In the absence of alternative treatment, resistance resulted in the accumulation of a massive infective reservoir and therefore increased malaria transmission, associated with intensive clinical symptomatology. The advent of chloroquine resistance was less violent in the area of Malable, where malaria is stable and communal immunity higher than in Balcad.

Lack of effect of desipramine on the response to chloroquine of patients with chloroquine-resistant falciparum malaria

The potential of desipramine to improve the efficacy of chloroquine against chloroquine-resistant Plasmodium falciparum in vivo in man was investigated. Fifty-three malaria patients were selected according to the criteria for the standard World Health Organization (WHO) in vivo test and were randomly divided in 2 groups. One group (n = 27) was given standard therapeutic doses of chloroquine (25 mg/kg body weight of base) and the other (n = 26) was given standard doses of chloroquine, as above, in combination with desipramine (1.3-2.8 mg/kg body weight) daily for 3 consecutive days. Standard WHO in vitro micro-tests were performed in parallel with the tests in vivo to provide chloroquine sensitivity patterns of the P. falciparum parasites. The results in vitro from both groups did not differ with regard to chloroquine sensitivity and the means of the pre-treatment parasite densities were similar. There was no apparent difference in parasite clearance in vivo between the 2 groups. This study provided no evidence for enhanced chloroquine efficacy in vivo through the use of desipramine in doses corresponding to the usual therapeutic range.

Susceptibility of Plasmodium falciparum in vitro to chloroquine, mefloquine, quinine and sulfadoxine/pyrimethamine in Somalia: relationships between the responses to the different drugs

The susceptibilities of Plasmodium falciparum to chloroquine, mefloquine, quinine and sulfadoxine/pyrimethamine were investigated in Mogadishu in 1988, after chloroquine resistance had spread widely in Somalia. Possible correlations of the responses to these drugs were also investigated. Standard World Health Organization in vitro micro-tests were performed. Of 76 isolates tested for chloroquine susceptibility, 58 (76%) were resistant to the drug with mean EC50 and EC99 values of 1.06 x 10(-6) mol/litre and 10.44 x 10(-6) mol/litre of blood, respectively, indicating a high prevalence and degree of resistance. In contrast, all isolates tested were inhibited by mefloquine 3.2 x 10(-6) mol/litre of blood, quinine at 2.56 x (-6) mol/litre of blood-medium mixture, and sulfadoxine/pyrimethamine at 6.0/0.075 x 10(-6) mol/litre of blood-medium mixture, indicating full sensitivity to these 3 drugs. However, a significant positive correlation was found between responses to quinine and chloroquine and between those to quinine and mefloquine; the responses to chloroquine and mefloquine were not correlated. The results may suggest that sites responsible for the correlation are shared between quinine and chloroquine but not essentially between chloroquine and mefloquine. Thus the evolution of chloroquine resistance together with increased use of quinine treatment of P. falciparum may increase the risks of development of quinine resistance, whereas the development of mefloquine resistance would not be triggered by chloroquine resistance.

The changing pattern of Plasmodium falciparum susceptibility to chloroquine but not to mefloquine in a mesoendemic area of Somalia

The response of Plasmodium falciparum to chloroquine and mefloquine was investigated in a mesoendemic area of Somalia from 1986 to 1989. Serial in vivo field tests for chloroquine sensitivity were performed and the sensitivity in vitro to chloroquine and mefloquine was evaluated using the standard WHO in vitro microtest. Chloroquine treatment in vivo (25 mg base/kg body weight) resulted in parasite clearance in all patients within 7 d (S/RI) in 1986, while 17%, 19% and 30% RII/RIII responses were found in 1987, 1988 and 1989 respectively. There was consistent increase of parasite clearance time of the S/RI cases in all years. The sensitivity study in vitro in 1986 showed a low degree of chloroquine resistance in 3 of 29 isolates tested and a mean 50% effective dose (EC50) and EC99 of 0.34 x 10(-6) M and 1.99 x 10(-6) M, respectively. In contrast, in 1989, 12 of the 19 isolates tested were resistant to chloroquine. The mean EC50 and EC99 values had increased to 0.78 x 10(-6) M and 7.50 x 10(-6) M respectively. The data in vivo and in vitro indicate a rapid increase of chloroquine resistance both in frequency and degree. All isolates tested in 1986 and 1989 were fully inhibited by mefloquine at 3.2 x 10(-6) M, suggesting full sensitivity. Thus, increased resistance of P. falciparum to chloroquine did not significantly influence the sensitivity pattern of mefloquine.

Isolated malaria outbreak in Somalia: role of chloroquine-resistant Plasmodium falciparum demonstrated in Balcad epidemic

A study was conducted in Balcad in December 1988 during a reported outbreak of malaria in order to investigate possible factors contributing to the outbreak. The slide positivity rate of 71% among fever patients, which was significantly higher than the usual rate, suggests the existence of a fresh malaria outbreak in the area. High parasite densities together with the pronounced malaria symptoms among both resident children and adult immigrants indicated little, if any, malaria experience in these patients. This outbreak could not be explained by gross climatic changes, e.g. unusual rainfalls. The in-vivo response of P. falciparum to the standard therapeutic regimen of chloroquine showed a high degree of resistance, with 31 of 36 patients showing resistance, including five RI responses and 26 RII-RIII responses. Micro in-vitro tests for chloroquine susceptibility showed resistance in 33 out of 37 isolates with a mean EC50 and EC99 of 1.50 and 10.97 X 10(-6) mol l-1 blood, respectively, indicative of a high degree of chloroquine resistance. All isolates tested against sulphadoxine/pyrimethamine showed a sensitive response. The frequent presence (78%) of detectable chloroquine levels prior to treatment did not apparently alter the in-vitro parasite growth. This is a sign of widespread use of this drug resulting in a high 'drug pressure' in the area. The proportion of sensitive parasites was inversely related to the pretreatment chloroquine concentration providing evidence of the selection of resistant parasites by the previous drug intake.(ABSTRACT TRUNCATED AT 250 WORDS)

Consecutive determinations of seroreactivities to Pf 155/RESA antigen and to its different repetitive sequences in adult men from a holoendemic area of Liberia

Sera from 32 adult men residing in a malaria holoendemic area of Liberia were investigated for seroreactivities to different asexual blood-stage malaria antigens on five consecutive occasions from 1984 to 1986. The seroreactivities to crude parasitic antigens and to Pf 155/RESA (EMIF) were determined by immunofluorescence and to repetitive sequences of Pf 155/RESA by enzyme-linked immunosorbent assay (ELISA). All sera were highly reactive against the crude parasitic antigens with reciprocal titres varying from 5000 to 100,000. The EMIF titres showed a wider variation from negative (less than 10) to 25,000, and when the same individuals were re-examined on subsequent surveys similar EMIF titres were found. The ELISA seroreactivities to three different repetitive sequences of Pf 155/RESA also showed different individual profiles which were rather consistent on consecutive surveys. High EMIF titres appeared to be correlated mainly to one of the peptide sequences, namely (EENV)2. The consistent individual profiles of the seroreactivities to Pf 155 and its repetitive sequences suggest genetic restriction of the humoral immune response. Although no significant correlation was found between EMIF titres and parasitic densities in the adult hyperimmune men the specific peptides, however, offer new possibilities of further investigating protective capacities of different immune responses to specific epitopes of the malaria parasite.

The seroreactivity against Pf155 (RESA) antigen in villagers from a mesoendemic area in Somalia

Pf155 (RESA), a malaria antigen in the membrane of infected red cells, was recently identified as a possible future malaria vaccine candidate. In this study the seroreactivities against this antigen were compared with those against crude parasitic antigens in 195 subjects from a Somali village with mesoendemic malaria. The seroreactivities were determined with immunofluorescence. With age, there was an increased seroreactivity to both Pf155 and the crude parasitic antigens. However, the acquisition of seroreactivity was much slower against Pf155. Hence in the age group 15-24 years, only half of the subjects had detectable antibodies against Pf155.

Susceptibility of Plasmodium falciparum to chloroquine and mefloquine in Somalia

A field study was conducted in the Malable area, in Somalia, to assess the susceptibility of Plasmodium falciparum to chloroquine and mefloquine. The in vivo response of P. falciparum to standard therapeutic regimen of chloroquine was studied in 16 children (1-12 years) using the standard WHO in vivo field test. All subjects were parasite free by day 3 and no recrudescence occurred during a 7-d follow-up. In the 24 h micro in vitro tests for chloroquine, 29 of 39 tests performed were successful. Of the 29 isolates, 3 showed distinct resistance and 2 were borderline. The drug concentration yielding 99% (EC99) inhibition was 1.64 x 10(-6) M, indicating low grade resistance. For mefloquine, 11 of 20 tests gave interpretable results and were sensitive, although with some heterogeneity. The EC50 and EC99 of 0.24 x 10(-6) M and 1.31 x 10(-6) M respectively indicate sensitivity.