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Since 1993 sulphadoxine/pyrimethamine (SP) has been used as the first-line drug for uncomplicated Plasmodium falciparum malaria in Malawi. To investigate the current efficacy of SP and other antimalarial drug resistance, we studied in vivo and in vitro responses to SP, chloroquine (CQ), mefloquine (MF), quinine (QN), and halofantrine (HF) in Salima, central Malawi. In a follow-up of 14 days, nine (13.8%) of 65 children under five showed RII/RIII parasitological resistance, and in in vitro microtests 18 (62.1%) of 29 isolates showed < 90% inhibition of schizont maturation at pyrimethamine 75 nmol/l blood medium mixture, indicating resistance. The discrepancy between in vivo and in vitro results might be partially explained by acquired immunity in this holoendemic area. In vitro one (3.4%) of 29 isolates failed schizont inhibition at 1.6 micromol/l blood of CQ, indicating resistance. Compared with an in vitro study conducted in 1988 in another region of Malawi using the same cut-off point, the proportion of resistant isolates had decreased significantly (P < 0.01). Although 31% of isolates were borderline, showing schizont maturation at 0.8 micromol/l blood but no schizonts at 1.6 micromol/l in our study, the results suggest possible recovery of CQ sensitivity after long-term absence of drug pressure. Resistance remains a major problem in malaria control. Monitoring resistance patterns in vitro provides early warning signs of impending loss of therapeutic efficacy of the standard treatment, and may detect changing patterns in alternative drug resistance. [ABSTRACT FROM AUTHOR]

Objective: To determine age-specific measles antibody prevalence and serological response to vaccination during the first mass campaign against measles in Malawi., Design: Cross-sectional study using a questionnaire and a serological particle agglutination (PA) test., Setting: Two health centres in Salima district, central Malawi during the national measles immunisation week, 1998., Participants: Two hundred forty six under-five year old children., Results: Seventy four per cent of enrolled children (95% confidence interval, 69-80%) were measles PA antibody positive at the vaccination. The antibody positive rate was 17.4% in children aged 8-12 months and gradually increased up to 90% by four years-old, while the age-specific geometric mean titers (GMTs) in 48-59 months-old group were significantly lower than those in 24-35 months-old group, suggesting antibody waning after previous vaccination (p = 0.0047). Two hundred and thirty follow up specimens were obtained eight weeks after the vaccination. The sero-conversion rate was 100% in 58 children sero-negative at the vaccination and the GMTs in 172 children seropositive at the vaccination were significantly increased (p < 0.001)., Conclusion: These results indicated that the first national measles immunisation campaign successfully immunised the enrolled children or gave a booster response of antibody levels. It was also confirmed that the PA test was easy to perform and most suitable for the field condition in developing countries.

In a prospective study, 132 hospital out-patients presenting with bloody diarrhoea ('cases') were evaluated in Malawi, Central Africa; 73 out-patient tuberculosis suspects acted as controls. Most (100/132, 76%) subjects reported an illness lasting < or = 5 d with > 5 bowel actions in the preceding 12 h; 39/132 (30%) reported use of systemic antimicrobial drugs in the preceding week; 57% (74/130) had a body mass index < 20; 4% (5/131) were febrile; and 18/130 (13%) had one or more sign(s) of dehydration. The 73 controls reported no diarrhoea and more systemic antimicrobial drug use (P = 0.0003), but were otherwise comparable to the subjects. All stool samples from controls and 38/124 (31%) from cases were macroscopically normal. Only 32% (40/124) of the cases had blood visible in the stool. Parasitic gut infections were found in 42/124 (34%) cases compared with 1/60 (2%) controls (P < 0.0001). The commonest parasite was Schistosoma mansoni. Bacterial cultures were positive in 32/124 (26%) of the subjects. Shigella dysenteriae (Sd) 1 accounted for 53% (17/32) of these. All bacterial isolates were sensitive in vitro to nalidixic acid and ciprofloxacin, while only 18% were sensitive to cotrimoxazole. Sd 1 with significant antimicrobial resistance continues to cause seasonal epidemics of dysentery in Malawi. During these, approximately two-thirds of patients presenting with bloody diarrhoea have no blood visible in the stool. Nalidixic acid remains the drug of choice but its use should be restricted to patients at greatest risk of complicated shigellosis.