Safety, immunogenicity and limited efficacy study of a recombinant Plasmodium falciparum circumsporozoite vaccine in Thai soldiers.

Thai soldiers were vaccinated with a recombinant protein derived from the central repeat region of the circumsporozoite (CS) protein of Plasmodium falciparum conjugated to Toxin A (detoxified) of Pseudomonas aeruginosa (R32Tox-A) to evaluate its safety, immunogenicity and efficacy. In a randomized, double-blind manner, 199 volunteers received either R32Tox-A or a control vaccine at 0, 8 and 16 weeks. Immunization was performed in a malaria non-transmission area, after completion of which volunteers were deployed to an endemic border area and monitored closely to allow early detection and treatment of infection.

Demonstration by the polymerase chain reaction of mixed Plasmodium falciparum and P. vivax infections undetected by conventional microscopy.

Mixed malaria infections (Plasmodium falciparum and P. vivax) are suspected to occur at a greater frequency than is detected by conventional light microscopy. To determine this frequency we carried out a prospective 'blinded' comparison of diagnosis by conventional light microscopy and enzymatic amplification of the circumsporozoite gene extracted from dried spotted blood samples.

Occupational malaria in Thai Rangers: epidemiological, clinical and immunological features.

Malaria continues to be a serious disease threat to soldiers deployed in tropical environments. Distinct features of the disease and the host immune response require that malaria occurring in occupational groups be investigated separately from the infection as found in endemic populations. For the first time since the Vietnam War, malaria has been systematically studied in soldiers under combat conditions.