The epidemiology of Plasmodium falciparum malaria in two Cameroonian villages: Simbok and Etoa.

In support of ongoing immunologic studies on immunity to Plasmodium falciparum, demographic, entomologic, parasitologic, and clinical studies were conducted in two Cameroonian villages located 3 km apart. Simbok (population = 907) has pools of water present year round that provide breeding sites for Anopheles gambiae, whereas Etoa (population = 485) has swampy areas that dry up annually in which A. funestus breed. Results showed that individuals in Simbok receive an estimated 1.9 and 1.2 infectious bites per night in the wet and dry season, respectively, whereas individuals in Etoa receive 2.4 and 0.4 infectious bites per night, respectively. Although transmission patterns differ, the rate of acquisition of immunity to malaria appears to be similar in both villages. A prevalence of 50-75% was found in children < 10 years old, variable levels in children 11-15 years old, and 31% in adults. Thus, as reported in other parts of Africa, individuals exposed to continuous transmission of P. falciparum slowly acquired significant, but not complete, immunity.

Malaria and pregnancy in Cameroonian women. Naturally acquired antibody responses to asexual blood-stage antigens and the circumsporozoite protein of Plasmodium falciparum.

Antibody responses to Plasmodium falciparum antigens in women during pregnancy were investigated in Mfou, a rural community in Cameroon. The study consisted of cross-sectional analyses involving 225 pregnant women and 75 non-pregnant controls. Blood samples were collected from each woman to determine serological reactivity to intraerythrocytic malarial antigens, ring-infected erythrocyte surface antigen (RESA) and circumsporozoite (CS) repeat peptide (NANP)5 by the indirect fluorescent antibody assay, modified immunofluorescent antibody assay, and enzyme-linked immunosorbent assay, respectively. Reactivity to intraerythrocytic asexual blood-stage antigens and to the CS repeat region was similar in both pregnant and non-pregnant women, and no correlation with parasitaemia was found. In contrast, anti-RESA antibody levels were significantly lower in pregnant than in non-pregnant women (P = 0.02) and in primigravidae than in multigravidae (P = 0.002), and were inversely correlated with parasitaemia (r = -0.36; P < 0.01). These data suggest that the increased susceptibility to malarial infection in pregnant women may be explained in part by their lower reactivity to RESA.

A short term projection of HIV infection and AIDS cases in Cameroon.

By September 1991 Cameroon had reported 650 cases of the acquired immune deficiency syndrome (AIDS). The results from the sentinnel surveillance system showed a seroprevalence of human immunodeficiency virus (HIV)1 of 1.3% among pregnant women, 2.5% in people attending sexually transmitted disease clinics and 3.5% in tuberculosis patients in 1990. The estimated number of persons infected with HIV varies between 10,000 and 30,000. The World Health Organization projection model was used to make a short-term projection of HIV infection and AIDS cases; it indicated that the number of persons infected with HIV will double by the year 1995, with an estimated 8500 AIDS cases. Even in a low prevalence country such as Cameroon, the impact of the HIV epidemic is important and will result in a burden for the health care system.

[Short term projections of infection by the human immunodeficiency (HIV) and the acquired immunodeficiency syndrome (AIDS) in Cameroon]. / Projections à court terme de l'infection par le virus de l'immunodéficience humaine (VIH) et du syndrome d'immunodéficience acquise (SIDA) au Cameroun.

As of December 1991, Cameroon has reported 827 cases of AIDS. The results from the Sentinel Surveillance System show a seroprevalence of 1.3% HIV1 among pregnant women, 2.5% in people attending STD clinic and 3.5% in tuberculosis patients. The World Health Organization projection model was used to make a short term projection of HIV infection and AIDS cases. Results show that the number estimated of HIV infected populations varies between 24 to 45,000 people by the year 1995. Results show also an estimated 8,500 cumulative AIDS cases. Even in a low prevalence country as Cameroon the impact of the HIV epidemic is important and will result in a burden for the health care system.

Malaria and pregnancy in Cameroonian women. Effect of pregnancy on Plasmodium falciparum parasitemia and the response to chloroquine.

The interaction between malaria and pregnancy was investigated in an epidemiologic study conducted in Mfou, a rural community in Cameroon. The study consisted of both cross-sectional and longitudinal analyses involving 225 pregnant women and 75 nonpregnant controls. Information was obtained by a standardized questionnaire to determine the pattern of antimalarial drug use. The parasitologic response to chloroquine was also determined. A dosage of chloroquine base (25 mg/kg of body weight) was given to women over a 3-day period, followed by 5 mg/kg doses administered weekly for 4 weeks. The results showed that Plasmodium falciparum infections occurred more frequently in pregnant (45%) than in nonpregnant (31%) women in terms of parasite rates (p = 0.03) and density (p less than 0.003), especially in primigravidae as compared with multigravidae matched for parity and age. Levels of parasitemia were also higher in the second trimester than in the first trimester of pregnancy (p less than 0.01). Failure to clear parasitemia after a chloroquine regimen was more frequent in pregnant than in nonpregnant women (p less than 0.01), particularly in primigravidae. Higher parasitemia and a lower parasitologic response to chloroquine in pregnant women, especially in primigravidae, suggest a relatively low level of clinical immunity and emphasize the need to target this group of women for malaria control strategies.