Malaria in South Africa: 110 years of learning to control the disease.

In Africa today, the drive towards controlling malaria is comparable with efforts made in the 1950s and 1960s during the World Health Organization's Global Malaria Eradication Campaign. Unlike the Eradication Campaign that 'covered' the globe but excluded Africa, the current endeavours focus on Africa, but not to the exclusion of the rest of the tropical and sub-tropical world. Major donor agencies are partnering with African governments in an attempt to curb transmission of malaria parasites, and in some countries on the edges of the distribution of malaria, there is talk of eliminating the disease. South Africa is at the very southernmost fringe of malaria distribution on the African continent and has a long history of intense malaria control activities. This article looks at what South Africa has achieved in the past and where it needs to go in the future, not only to maintain the status quo, but hopefully to eliminate transmission of the disease within its borders. 

Persistence of antibodies to the Salmonella typhi Vi capsular polysaccharide vaccine in South African school children ten years after immunization.

Between 10 and 11 years after children were vaccinated with Vi capsular polysaccharide of Salmonella typhi or meningococcal A + C control vaccine in a double blind randomized trial, we traced 83 subjects, aged 16-20 years. A blood sample was taken for determination of Vi antibody titres in both groups by radioimmunoassay. TO and TH titres were also done to assess if the participants had had recent exposure to typhoid fever. Fifty-eight percent of subjects in both groups had protective levels of Vi antibody against Salmonella typhi (a titre greater than 1 microgram ml-1). There was no significant difference in the levels of Vi antibodies in the cases versus the controls (p = 0.5). Two of the children who had received meningococcal A + C vaccine had recently had typhoid fever. Our data show that adolescents in typhoid endemic areas have high levels of Vi antibodies regardless of previous vaccination status, suggesting that Vi antibodies are acquired in adolescence by a large percentage of the population in this area. Moreover, Vi vaccination has led to ongoing antibody production in greater than 50% of Vi vaccinated children in an endemic area for a period of 10 years. Ongoing antigenic exposure may have contributed to these antibody levels.

Chloroquine resistance in Plasmodium falciparum in KwaZulu, 1983-1988.

Patients with Plasmodium falciparum infections in northern KwaZulu adjacent to the Mozambique border were treated with chloroquine 25 mg/kg. Persistent parasitaemias increased from nil in 1983 to 21.2% and 16.1% for hospital and field treatments respectively in 1987. After a change to sulfadoxine-pyrimethamine (Fansidar; Roche) treatment (adults 1,500 mg and 75 mg respectively) these rates fell in March 1988 to 6.9% and 0.4%.

An evaluation of co-trimoxazole in the treatment of Plasmodium falciparum malaria.

Two dosage schedules of co-trimoxazole, the standard antibacterial and a 2-day high-dose schedule, were compared with a standard course of chloroquine in the treatment of uncomplicated Plasmodium falciparum malaria. Parasites were cleared from the blood at similar rates, but pyrexia responded more slowly following the standard cotrimoxazole dose. No recrudescences were detected in those observed for up to 60 days after treatment.

Malaria along the southernmost fringe of its distribution in Africa: epidemiology and control.

After more than thirty years of malaria control in northern Transvaal with residual insecticides, malaria prevalence has been reduced to a low level. However, low-grade transmission of Plasmodium falciparum continues, with periodic focal outbreaks after abnormally high rainfall. From October 1973 to September 1976, the operational and epidemiological factors involved in this residual transmission were studied in over 17 000 people of an area of northern Transvaal. Incidence surveys based on the screening of fever cases revealed 42 autochthonous cases of malaria in 1974-75 and 10 cases in 1975-76. Parasite prevalence surveys were not sensitive enough to assess the malaria situation, and serological testing indicated different levels of infection according to the method used. One of the two principal vectors of malaria in Africa-Anopheles funestus Giles-was not detected in the project area, and the A. gambiae group (species A and B) was found in extremely low numbers, so that it could not have accounted for the low-grade transmission in the area. A recently discovered member of the A. funestus group somewhat resembling A. aruni Sobti, and a species hitherto undiscovered in the Transvaal, which is abundant in the area and is indistinguishable from A. flavicosta Edwards, may be involved. Both were found biting man-mostly outdoors during the four hours following dusk, when people frequently gather outside their houses and are thus vulnerable to mosquito bites.