Malaria anticircumsporozoite antibodies in Dutch soldiers returning from sub-Saharan Africa.

One hundred and twenty-five Dutch servicemen returning from central Africa after a short deployment were enrolled in a study aimed at assessing the effectiveness of malaria prevention measures. None of the persons developed an episode of clinically overt malaria during or after deployment, and no antibodies against blood stages of Plasmodium falciparum could be found. However, antibodies against the circumsporozoite protein (CS) of P. falciparum were demonstrable in 14 persons (11.2% of the study population) by an ELISA test using the recombinant CS-antigen R32tet32, while one person only was positive in an IFA test based on schizonts of P. fieldi as antigen. We concluded that the anti-CS-positive servicemen were probably bitten by mosquitoes carrying P. falciparum parasites while the IFA-positive person was possibly infected by P. vivax, P. ovale or P. malariae parasites. There was no significant association between the different antimalaria preventive measures and the development of anti-CS antibodies. Therefore mefloquine prophylaxis as the single most widely used preventive measure in this group of servicemen was possibly a major contributing factor in averting development of overt malaria.

[Malaria: under-notification and risk assessment for travelers to the tropics]. / Malaria: onderrapportage en risicoschatting voor tropenreizigers.

OBJECTIVE: To define the risk of contracting malaria for travellers to malaria-endemic areas and to calculate the under-notification under the current notification system. DESIGN: Retrospective epidemiological analysis. SETTING: Agricultural University Wageningen, The Netherlands. METHODS: Risks of contracting malaria were estimated by calculating the incidence per 100,000 travellers. This incidence was found using an estimated under-notification calculated on the basis of data from the "SIG Zorginformatie' (hospital cases) and the Medical Health Inspectorate (notified cases). RESULTS: The average under-notification in the Netherlands was at least 59% in the period January 1988 to June 1993 inclusive and increased by 10% each year. Judging by this estimation at least 3170 travellers returned to the Netherlands with malaria in this period. The risk in Africa appeared to be decreasing. In Asia the malaria incidence increased slightly in recent years while no trend was found for America. The imported malaria was mainly caused by Plasmodium falciparum. CONCLUSION: In order to improve the malaria notification system in the Netherlands a notification obligation for all microbiological laboratories should be introduced as almost all malaria is diagnosed there.

Detection of Plasmodium sporozoites in mosquitoes by polymerase chain reaction and oligonucleotide rDNA probe, without dissection of the salivary glands.

Dried Anopheles gambiae mosquito head+thorax portions, infected with Plasmodium falciparum sporozoites, were processed by the polymerase chain reaction. The PCR product was hybridized to an oligonucleotide probe (known as 114R or AW34) diagnostic for Plasmodium. The detection level by autoradiography was ten sporozoites per mosquito. Head+thorax of mosquitoes that contained mature P.falciparum oocysts, without sporozoites, gave no positive signal, indicating that the test detects only infective mosquitoes. This test can be applied to wild mosquito specimens collected, prepared and processed at different time intervals. The technique is convenient, highly sensitive, and could be used with a non-radioactive detection system and specific probes to differentiate Plasmodium spp.