Co-trimoxazole for childhood febrile illness in malaria-endemic regions

Cotrimoxazole versus sulfadoxine-pyrimethamine for intermittent preventive treatment of malaria in HIV-infected pregnant women in Bangui, Central African Republic: A pragmatic randomised controlled trial

OBJECTIVE

The main objective of the MACOMBA (Maternity and Control of Malaria-HIV co-infection in Bangui) trial was to show that cotrimoxazole (CTX) is more effective than sulphadoxine-pyremethamine-IPTp (IPTp-SP) to prevent placental malaria infection (primary end point) among HIV-positive pregnant women with a CD4+ count ≥350 cells/mm³ in Bangui, CAR.

METHODS

MACOMBA is a multicentre, open-label randomised trial conducted in four maternity hospitals in Bangui. Between 2013 and 2017, 193 women were randomised and 112 (59 and 53 in CTX and IPTp-SP arms, respectively) were assessed for placental infection defined by microscopic parasitaemia or PCR.

RESULTS

Thirteen women had a placental infection: five in the CTX arm (one by microscopic placental parasitaemia and four by PCR) and eight by PCR in the SP-IPTp (8.5% vs. 15.1%, p = 0.28). The percentage of newborns with low birthweight (<2500 g) did not differ statistically between the two arms. Self-reported compliance to CTX prophylaxis was good. There was a low overall rate of adverse events in both arms.

CONCLUSION

Although our results do not allow us to conclude that CTX is more effective, drug safety and good compliance among women with this treatment favour its widespread use among HIV-infected pregnant women, as currently recommended by WHO.

Cotrimoxazole Prophylaxis Discontinuation among Antiretroviral-Treated HIV-1-Infected Adults in Kenya: A Randomized Non-inferiority Trial

BACKGROUND

Cotrimoxazole (CTX) prophylaxis is recommended by the World Health Organization (WHO) for HIV-1-infected individuals in settings with high infectious disease prevalence. The WHO 2006 guidelines were developed prior to the scale-up of antiretroviral therapy (ART). The threshold for CTX discontinuation following ART is undefined in resource-limited settings.

METHODS AND FINDINGS

Between 1 February 2012 and 30 September 2013, we conducted an unblinded non-inferiority randomized controlled trial of CTX prophylaxis cessation versus continuation among HIV-1-infected adults on ART for ≥ 18 mo with CD4 count > 350 cells/mm3 in a malaria-endemic region in Kenya. Participants were randomized and followed up at 3-mo intervals for 12 mo. The primary endpoint was a composite of morbidity (malaria, pneumonia, and diarrhea) and mortality. Incidence rate ratios (IRRs) were estimated using Poisson regression. Among 538 ART-treated adults screened, 500 were enrolled and randomized, 250 per arm. Median age was 40 y, 361 (72%) were women, and 442 (88%) reported insecticide-treated bednet use. Combined morbidity/mortality was significantly higher in the CTX discontinuation arm (IRR = 2.27, 95% CI 1.52-3.38; p < 0.001), driven by malaria morbidity. There were 34 cases of malaria, with 33 in the CTX discontinuation arm (IRR = 33.02, 95% CI 4.52-241.02; p = 0.001). Diarrhea and pneumonia rates did not differ significantly between arms (IRR = 1.36, 95% CI 0.82-2.27, and IRR = 1.43, 95% CI 0.54-3.75, respectively). Study limitations include a lack of placebo and a lower incidence of morbidity events than expected.

CONCLUSIONS

CTX discontinuation among ART-treated, immune-reconstituted adults in a malaria-endemic region resulted in increased incidence of malaria but not pneumonia or diarrhea. Malaria endemicity may be the most relevant factor to consider in the decision to stop CTX after ART-induced immune reconstitution in regions with high infectious disease prevalence. These data support the 2014 WHO CTX guidelines.

TRIAL REGISTRATION

ClinicalTrials.gov NCT01425073.

Effectiveness of two antifolate prophylactic strategies against malaria in HIV-positive pregnant women in Bangui, Central African Republic: study protocol for a randomized controlled trial (MACOMBA)

BACKGROUND

Co-infection with malaria parasite and HIV is an emerging public health problem in tropical areas, particularly in pregnant women, and management of the concurrent effects of these two infections is challenging. Co-trimoxazole is a sulfamide preparation used to prevent opportunistic infections in HIV-infected patients, and many studies have reported that it has significant activity against malaria. As the efficacy of intermittent preventive treatment (IPT) with sulfadoxine-pyrimethamine (SP) against malaria is decreasing, co-trimoxazole might be an alternative for preventing malaria among HIV-infected populations. The aim of this study is to compare the effectiveness of SP-IPT, which is recommended for the prevention of malaria during pregnancy in the Central African Republic, with that of a daily dose of co-trimoxazole against P. falciparum infections among HIV-infected pregnant women in Bangui, the capital of the Central African Republic.

METHODS/DESIGN

The MACOMBA study (MAternity and COntrol of Malaria-HIV co-infection in BAngui) is a multicentre open-label randomized clinical trial conducted at four maternity hospitals in Bangui. All HIV-infected pregnant women presenting for an antenatal clinic visit between the weeks 16 and 28 of amenorrhoea, with a CD4 count of more than 350 cells/mm3, will be eligible. All the women will provide written consent before being enrolled in the study and will then be randomly allocated to either SP-IPT (25 mg of sulfadoxine and 1.25 mg of pyrimethamine) or daily co-trimoxazole doses (960 mg per dose). The primary end-point is the placental malaria parasitaemia rate at delivery. Other main outcome measures include the number of malaria episodes during pregnancy, safety, and treatment compliance. Furthermore, the frequency of molecular resistance markers dhfr and dhps will be measured.

DISCUSSION

In this trial, we seek to confirm whether co-trimoxazole is operationally suitable to replace SP-IPT in order to prevent malaria among pregnant women infected with HIV in the Central African Republic.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT01746199.

Cotrimoxazole in the treatment of acute uncomplicated falciparum malaria in nigerian children : a controlled clinical trial

OBJECTIVES

To evaluate the efficacy of cotrimoxazole in the treatment of Plasmodium falciparum malaria and to compare the efficacy of cotrimoxazole with that of pyrimethamine-sulfadoxine, a second-line antimalarial drug, in an area of high malaria transmission.

PATIENTS AND METHODS

Children aged between 10 months and 10 years with clinical and parasitological evidence of P. falciparum malaria were randomised to receive either cotrimoxazole or pyrimethamine-sulfadoxine. 145 children (73 and 72, respectively, in the cotrimoxazole and pyrimethamine-sulfadoxine groups) completed the study per protocol and were evaluated.

RESULTS

Pretreatment clinical and parasitological parameters were similar in the two treatment groups. The time to clear fever and other symptoms was similar in the two groups: 1.94 +/- 1.10 days versus 2.20 +/- 0.96 days, p > 0.05. Parasite clearance times were also similar: 2.62 +/- 0.91 days versus 2.94 +/- 1.17 days, respectively, for cotrimoxazole and pyrimethamine-sulfadoxine; p > 0.05. The cure rates on days 14, 21 and 28 were, respectively, 84.9, 75.3 and 74.0% for the cotrimoxazole group and 84.7, 80.5 and 75.0% for the pyrimethamine-sulfadoxine group. Both drugs were well tolerated.

CONCLUSIONS

These results indicate that cotrimoxazole has similar efficacy to pyrimethamine-sulfadoxine in the treatment of acute uncomplicated P. falciparum malaria in children resident in an endemic area of Southwest Nigeria.

Drug repositioning in the treatment of malaria and TB

The emergence and spread of drug resistance in the malaria parasite Plasmodium falciparum as well as multi- and extremely drug-resistant forms of Mycobacterium tuberculosis, the causative agent of TB, could hamper the control of these diseases. For instance, there are indications that the malaria parasite is becoming resistant to artemisinin derivatives, drugs that form the backbone of antimalarial combination therapy. Likewise, Mycobacterium tuberculosis strains that are multidrug-resistant or extremely drug-resistant to first- and second-line drugs have been associated with increased mortality. Thus, more than ever, new antimalarials and anti-TB drugs are needed. One of the strategies to discover new drugs is to reposition or repurpose existing drugs, thus reducing the cost and time of drug development. In this review, we discuss how this concept has been used in the past to discover antimalarial and anti-TB drugs, and summarize strategies that can lead to the discovery and development of new drugs.

Daily co-trimoxazole prophylaxis in severely immunosuppressed HIV-infected adults in Africa started on combination antiretroviral therapy: an observational analysis of the DART cohort

BACKGROUND

Co-trimoxazole prophylaxis can reduce mortality from untreated HIV infection in Africa; whether benefits occur alongside combination antiretroviral therapy (ART) is unclear. We estimated the effect of prophylaxis after ART initiation in adults.

METHODS

Participants in our observational analysis were from the DART randomised trial of management strategies in HIV-infected, symptomatic, previously untreated African adults starting triple-drug ART with CD4 counts lower than 200 cells per muL. Co-trimoxazole prophylaxis was not routinely used or randomly allocated, but was variably prescribed by clinicians. We estimated effects on clinical outcomes, CD4 cell count, and body-mass index (BMI) using marginal structural models to adjust for time-dependent confounding by indication. DART was registered, number ISRCTN13968779.

FINDINGS

3179 participants contributed 14 214 years of follow-up (8128 [57%] person-years on co-trimoxazole). Time-dependent predictors of co-trimoxazole use were current CD4 cell count, haemoglobin concentration, BMI, and previous WHO stage 3 or 4 events on ART. Present prophylaxis significantly reduced mortality (odds ratio 0.65, 95% CI 0.50-0.85; p=0.001). Mortality risk reduction on ART was substantial to 12 weeks (0.41, 0.27-0.65), sustained from 12-72 weeks (0.56, 0.37-0.86), but not evident subsequently (0.96, 0.63-1.45; heterogeneity p=0.02). Variation in mortality reduction was not accounted for by time on co-trimoxazole or current CD4 cell count. Prophylaxis reduced frequency of malaria (0.74, 0.63-0.88; p=0.0005), an effect that was maintained with time, but we observed no effect on new WHO stage 4 events (0.86, 0.69-1.07; p=0.17), CD4 cell count (difference vs non-users, -3 cells per muL [-12 to 6]; p=0.50), or BMI (difference vs non-users, -0.04 kg/m(2) [-0.20 to 0.13); p=0.68].

INTERPRETATION

Our results reinforce WHO guidelines and provide strong motivation for provision of co-trimoxazole prophylaxis for at least 72 weeks for all adults starting combination ART in Africa.

FUNDING

UK Medical Research Council, the UK Department for International Development, the Rockefeller Foundation, GlaxoSmithKline, Gilead Sciences, Boehringer-Ingelheim, and Abbott Laboratories.

In vitro activity of antifolate and polymorphism in dihydrofolate reductase of Plasmodium falciparum isolates from the Kenyan coast: emergence of parasites with Ile-164-Leu mutation

We have analyzed the activities of the antifolates pyrimethamine (PM), chlorcycloguanil (CCG), WR99210, trimethoprim (TMP), methotrexate (MTX), and trimetrexate (TMX) against Kenyan Plasmodium falciparum isolates adapted in vitro for long-term culture. We have also assessed the relationship between these drug activities and mutations in dihydrofolate reductase (dhfr), a domain of the gene associated with antifolate resistance. As expected, WR99210 was the most potent drug, with a median 50% inhibitory concentration (IC50) of <0.075 nM, followed by TMX, with a median IC50 of 30 nM. The median IC50 of CCG was 37.80 nM, and that of MTX was 83.60 nM. PM and TMP were the least active drugs, with median IC50s of 733.26 nM and 29,656.04 nM, respectively. We analyzed parasite dhfr genotypes by the PCR-enzyme restriction technique. No wild-type dhfr parasite was found. Twenty-four of 33 parasites were triple mutants (mutations at codons 108, 51, and 59), and only 8/33 were double mutants (mutations at codons 108 and 51 or at codons 108 and 59). IC50s were 2.1-fold (PM) and 3.6-fold (TMP) higher in triple than in double mutants, though these differences were not statistically significant. Interestingly, we have identified a parasite harboring a mutation at codon 164 (Ile-164-Leu) in addition to mutations at codons 108, 51, and 59. This quadruple mutant parasite had the highest TMP IC50 and was in the upper 10th percentile against PM and CCG. We confirmed the presence of this mutation by sequencing. Thus, TMX and MTX are potent against P. falciparum, and quadruple mutants are now emerging in Africa.

Recommendations for treatment of childhood non-severe pneumonia

WHO recommendations for early antimicrobial treatment of childhood pneumonia have been effective in reducing childhood mortality, but the last major revision was over 10 years ago. The emergence of antimicrobial resistance, new pneumonia pathogens, and new drugs have prompted WHO to assemble an international panel to review the literature on childhood pneumonia and to develop evidence-based recommendations for the empirical treatment of non-severe pneumonia among children managed by first-level health providers. Treatment should target the bacterial causes most likely to lead to severe disease, including Streptoccocus pneumoniae and Haemophilus influenzae. The best first-line agent is amoxicillin, given twice daily for 3–5 days, although co-trimoxazole may be an alternative in some settings. Treatment failure should be defined in a child who develops signs warranting immediate referral or who does not have a decrease in respiratory rate after 48–72 h of therapy. If failure occurs, and no indication for immediate referral exists, possible explanations for failure should be systematically determined, including non-adherence to therapy and alternative diagnoses. If failure of the first-line agent remains a possible explanation, suitable second-line agents include high-dose amoxicillin–clavulanic acid with or without an affordable macrolide for children over 3 years of age.

Rifampicin/Cotrimoxazole/Isoniazid versus mefloquine or quinine + sulfadoxine- pyrimethamine for malaria: a randomized trial

OBJECTIVES

Previous studies of a fixed combination including cotrimoxazole, rifampicin, and isoniazid (Cotrifazid) showed efficacy against resistant strains of Plasmodium falciparum in animal models and in small-scale human studies. We conducted a multicentric noninferiority trial to assess the safety and efficacy of Cotrifazid against drug-resistant malaria in Papua New Guinea.

DESIGN

The trial design was open-label, block-randomised, comparative, and multicentric.

SETTING

The trial was conducted in four primary care health facilities, two in urban and two in rural areas of Madang and East Sepik Province, Papua New Guinea.

PARTICIPANTS

Patients of all ages with recurrent uncomplicated malaria were included.

INTERVENTIONS

Patients were randomly assigned to receive Cotrifazid, mefloquine, or the standard treatment of quinine with sulfadoxine-pyrimethamine (SP).

OUTCOME MEASURES

Incidence of clinical and laboratory adverse events and rate of clinical and/or parasitological failure at day 14 were recorded.

RESULTS

The safety analysis population included 123 patients assigned to Cotrifazid, 123 to mefloquine, and 123 to quinine + SP. The Cotrifazid group experienced lower overall incidence of adverse events than the other groups. Among the efficacy analysis population (72 Cotrifazid, 71 mefloquine, and 75 quinine + SP), clinical failure rate (symptoms and parasite load) on day 14 was equivalent for the three groups (0% for Cotrifazid and mefloquine; 1% for quinine + SP), but parasitological failure rate (P. falciparum asexual blood-stage) was higher for Cotrifazid than for mefloquine or quinine + SP (9% [PCR corrected 8%] versus 0% and 3%, respectively [p = 0.02]).

CONCLUSION

Despite what appears to be short-term clinical equivalence, the notable parasitological failure at day 14 in both P. falciparum and P. vivax makes Cotrifazid in its current formulation and regimen a poor alternative combination therapy for malaria.

Knowledge, attitudes and practices towards malaria among primary school pupils in Ndirande, Blantyre, Malawi

A qualitative cross-sectional study was conducted at Ndirande Primary School in the peri-urban area of Blantyre, Malawi in 2002. The aim was to describe the knowledge, attitudes and practices towards malaria among pupils. Forty pupils (20 boys and 20 girls) were recruited into four focus group discussions. There was very good knowledge about the role of the female Anopheles mosquito as an agent for transmission of malaria. Respondents were also aware of the clinical features of malaria and what measures could be taken to prevent the disease. However, the survey showed that many of the environmental modification measures were difficult to implement in the overcrowded peri-urban areas. Respondents did not believe that they could influence parents or other authorities in instituting environmental modification interventions. We conclude that children are unlikely to be effective change agents if the social environment does not offer them the opportunity to influence key community figures.

Resistance to antifolates in Plasmodium falciparum, the causative agent of tropical malaria

Every year there are 270 million clinical attacks of malaria and 2 million deaths, caused by the protozoan Plasmodium falciparum. Most of these cases occur in Africa. Chloroquine-resistance has led to reliance on anti-malarial antifolates, in particular the synergistic combination sulfadoxine/pyrimethamine (S/P) which targets enzymatic synthesis of folate co-factors through dihydropteroate synthase (DHPS) and dihydrofolate reductase (DHFR). Resistance to S/P is now increasing and replacement antimalarials are needed. Crystal structures are not yet available for these key enzymes in the folate pathway. This review focuses on the activity of drugs on DHFR in malaria parasites, attempts to interpret differences in activity of pyrimethamine and its related drugs, and to clarify how residue changes due to point mutations determine the development of resistance. In homology-modelled P. falciparum DHFR (PfDHFR), the typical structure of four alpha-helices, 8-stranded beta-sheet, four Loops and eight Turns is clearly seen. Long polar sequences specific for Plasmodium are inserted in Turns 1 and 2. Structures immediately concerned in drug binding are beta-A, L1, alpha-B, alpha-C, T-3, beta-E, alpha-F, and beta-F. The roles of several mutations associated with resistance are discussed. In view of sequence differences in turn 3 in PfDHFR and in the human enzyme, and the marked interaction with residues of T3 of the experimental flexible antifolate WR99210 effective in pyrimethamine and cycloguanil resistance, further drug development in this area is indicated.

Co-trimoxazole compared with sulfadoxine-pyrimethamine in the treatment of uncomplicated malaria in Kenyan children

Sulfadoxine-pyrimethamine (SP) and co-trimoxazole were both effective in reducing fever, clearing parasitaemia and improving anaemia in children aged < 5 years with uncomplicated malaria in 2 Kenyan endemic sites, Oyugis in the west and Tiwi on the coast. We compared the efficacy of these 2 regimens (in May-July 1998) by evaluating clinical and parasitological responses over 14 days. The combined incidence of parasitological failure for the combined sites for co-trimoxazole was 14/123 (11%) and for SP 23/145 (16%) (RR 0.72, 95% confidence interval [CI] 0.31-1.46, P = 0.289). The 14-day clinical failure rate for the combined sites for co-trimoxazole was 4/123 (3.3%), and for SP 8/145 (5.5%), (RR 1.69, 95% CI 0.91-3.15, P = 0.129). The results indicate that the risk of treatment failure for the 2 regimens was similar. The antimalarial use of co-trimoxazole in uncomplicated malaria needs further investigation, since the 10-12-h elimination half-life of both components should reduce selective pressure for resistance. In addition, use of a 2-day high-dose course, tested previously, requires further study to demonstrate its efficacy.

A reversed-phase high-performance liquid chromatography method for the determination of cotrimoxazole (trimethoprim/ sulphamethoxazole) in children treated for malaria

A high-performance liquid chromatography (HPLC) method was developed for the simultaneous analysis of trimethoprim (TMP), sulphamethoxazole (SMX), and acetylsulphamethoxazole (AcSMX) in small amounts of blood. The method involved precipitation with 50 microL trichloracetic acid (1M) to 125 microL plasma or serum sample. 60 microL supernatant was added to 60 microL mobile phase, modified with 50microL 1 M sodium hydroxide/mL. The mobile phase consisted of 20% acetonitrile and 80% phosphate buffer adjusted to pH 6.15. Using 125 microL of the sample, limits of quantitation were 0.1 microg/mL for TMP, 1.0 microg/mL for SMX, and 1.0 microg/mL for AcSMX. The precision of the method was 2% to 11% over the range of concentrations tested, 0.5-30 microg/mL for TMP, 5-300 microg/mL for SMX, and 2.5-150 microg/mL for AcSMX, respectively. No interference with other commonly used drugs was observed. The method is rapid, simple, specific, and sensitive enough for pharmacokinetic studies. The small amount of blood required makes it suitable for pediatric patients. The method was used to analyze samples from Tanzanian children aged 6-59 months participating in a cotrimoxazole (TMP/SMX)/chloroquine randomized trial for the treatment of uncomplicated malaria. Venous blood samples from 68 children were collected 2 hours after the first dose of TMP/SMX (4 mg/kg TMP/20 mg/kg SMX at two divided doses for 5 days) and again at treatment day 4. Individual variations in plasma concentrations of TMP, SMX, and AcSMX were considerable. The mean and SEM plasma concentrations (g/mL) of TMP, SMX, and AcSMX 2 hours after the first treatment dose were 2.0 +/- 1.0 (range 0.5-6), 53 +/- 22 (range 24-146), and 13.5 +/- 12 (range 0-65), respectively. On the fourth day the attained plasma concentrations were not significantly different from samples collected after the first dose.

Early chemoprophylaxis with trimethoprim-sulphamethoxazole for HIV-1-infected adults in Abidjan, Côte d'Ivoire: a randomised trial. Cotrimo-CI Study Group

BACKGROUND

In sub-Saharan Africa, various bacterial diseases occur before pneumocystosis or toxoplasmosis in the course of HIV-1 infection, and are major causes of morbidity and mortality. We did a randomised, double blind, placebo-controlled clinical trial at community-health centres in Abidjan, Côte d'Ivoire, to assess the efficacy of trimethoprim-sulphamethoxazole (co-trimoxazole) chemoprophylaxis at early stages of HIV-1 infection.

METHOD

843 HIV-infected patients were screened and 545 enrolled in the study. Eligible adults (with HIV-1 or HIV-1 and HIV-2 dual seropositivity at stages 2 or 3 of the WHO staging system) received co-trimoxazole chemoprophylaxis (trimethoprim 160 mg, sulphamethoxazole 800 mg) daily or a matching placebo. The primary outcome was the occurrence of severe clinical events, defined as death or hospital admission irrespective of the cause. Analyses were by intention to treat.

FINDINGS

Four of the randomised patients were excluded (positive for HIV-2 only). 120 severe events occurred among 271 patients in the co-trimoxazole group and 198 among 270 in the placebo group. Significantly fewer patients in the co-trimoxazole group than in the placebo group had at least one severe event (84 vs 124); the probability of remaining free of severe events was 63.7% versus 45.8% (hazard ratio 0.57 [95% CI 0.43-0.75], p=0.0001) and the benefit was apparent in all subgroups of initial CD4-cell count. Survival did not differ between the groups (41 vs 46 deaths, p=0.51). Co-trimoxazole was generally well tolerated though moderate neutropenia occurred in 62 patients (vs 26 in the placebo group).

INTERPRETATION

Patients who might benefit from co-trimoxazole could be recruited on clinical criteria in community clinics without knowing the patients CD4-cell count. This affordable measure will enable quick public-health intervention, while monitoring bacterial susceptibility and haematological tolerance.

Resistance in vivo of Plasmodium falciparum to co-trimoxazole in western Uganda

In the context of the 'integrated management of childhood illnesses' (IMCI) programme the World Health Organization recommends treating children in malarious areas presenting with fever and respiratory symptoms with co-trimoxazole. In order to verify its effectiveness in uncomplicated Plasmodium falciparum malaria we carried out a study in vivo in western Uganda: 180 children under 5 years old were enrolled and treated with 40/8 mg/kg/d co-trimoxazole over 5 d, and 159 could be followed on days 3, 7 and 14. Effectiveness of treatment was found to be significantly different in various parts of the study area. In Bundibugyo District, bordering République Democratique du Congo (Zaire), 59.1% (39/66) of children were clinically cured after 14 d and 56.1% were parasitologically cured. In the east of Kabarole District (43 children), the figures were 76.7% and 65.1%, respectively. In western Kabarole (50 children) the rates were 96.0% and 90.0%, respectively. We conclude that, in view of the high level of clinical failures in parts of the study area, co-trimoxazole should not be used in the IMCI programme for combined treatment of malaria and pneumonia in the region. Assessment of therapeutic effectiveness of antimalarial drugs needs to consider the microepidemiology of resistance.

In vitro activities of novel antifolate drug combinations against Plasmodium falciparum and human granulocyte CFUs

The potency of antimalarial dihydrofolate reductase inhibitors, alone and in synergistic combination with dihydropteroate synthetase inhibitors, against the Kenyan K39 strain of Plasmodium falciparum (pyrimethamine resistant) and against normal replicating human bone marrow cells in in vitro culture has been studied. Therapeutic indices and rank order of synergistic potency were derived. Trimethoprim, pyrimethamine, and the quinazolines WR159412 and WR158122 had the smallest therapeutic indices (1.39, 4.38, 2.56, and 90.0, respectively), while the three triazines clociguanil, WR99210, and chlorcycloguanil had the largest (3,562, 3,000, and 2,000, respectively). In rank order of decreasing activity against P. falciparum, the six most potent drug combinations were WR99210-dapsone, chlorcycloguanil-dapsone, WR158122-dapsone, WR159412-dapsone, WR159412-sulfamethoxazole, and chlorcycloguanil-sulfamethoxazole; pyrimethamine-sulfadoxine was the least potent combination. These experiments form a basis for the selection of rapidly eliminated antifolate combinations for further clinical testing.

Overlap in the clinical features of pneumonia and malaria in African children

Pneumonia and malaria are common causes of childhood morbidity and mortality in many developing countries and simple guidelines have been proposed to facilitate their diagnosis by relatively unskilled health workers. We have studied children in The Gambia attending out-patient and under-five clinics with clinically suspected pneumonia (cough or difficulty in breathing and a raised respiratory rate) during periods of high or low malaria transmission. During a period of high malaria transmission, 33% of these children had radiological evidence of pneumonia (with or without malaria parasitaemia) compared to 38% who had malaria parasitaemia, no radiological evidence of pneumonia and no other obvious cause of fever. Corresponding figures during a period of low malaria transmission were 48% and 6% respectively. The clinical overlap between pneumonia and malaria has important implications for case management strategies and evaluation of disease-specific interventions in regions in which both pneumonia and malaria are prevalent.

Usefulness of clinical case-definitions in guiding therapy for African children with malaria or pneumonia

The World Health Organisation has developed disease-specific clinical case-definitions to guide management of children with fever or cough, the cardinal signs of malaria and pneumonia. To assess the usefulness of the case-definitions and to investigate their interaction, we studied children with fever or cough brought to a hospital in Lilongwe, Malawi. For all children, a thick blood smear was examined for Plasmodium falciparum parasites. Chest radiography was done only for children with parasitaemia and those who satisfied the clinical case-definition for pneumonia; others were assumed to have normal chest radiographs. Of 1599 enrolled children, 566 (35%) had parasitaemia and 116 had radiographic evidence of pneumonia; 43 had both pneumonia and parasitaemia. Of the 471 children who met the clinical definition for pneumonia, 449 (95%) also met the malaria clinical definition. Among children with radiographic evidence of pneumonia, the clinical definition for malaria was not predictive of parasitaemia (sensitivity 93%, specificity 5%). Whether malaria parasitaemia was present or absent, the pneumonia clinical definition distinguished children with and without radiographic evidence of pneumonia (sensitivity and specificity > 60%). Children who satisfied the pneumonia clinical definition were more likely to have radiographic evidence of pneumonia (odds ratio 10.4, 95% confidence interval 5.2-20.7), parasitaemia (1.6, 1.2-2.2), or both at the same time (4.2, 2.1-8.4) than were children who did not meet the definition. Children who satisfy the malaria and pneumonia clinical definitions need treatment for both disorders. Scarce diagnostic methods, especially microscopy, are needed for more specific treatment of children with fever and cough.