Seroprevalence of of Human lmmunodeficiency Virus Type-1 Infection in Africa

The epidemiological characteristics of HIV-1 infection in Africa have gradually been elucidated through various studies. The HIV-1 infection is believed to have existed in the 1960s in Africa and is presently epidemic in Africa. The HIV-I seropositive rate for the general population is higher in urban regions than in rural areas. The peak age of males infected with the HIV-1 tends to be higher than that of females infected with the HIV-1 Sex difference is recognized in the HIV-1 serpopositive rates. Heterosexual contact, mother-to-child transmission and contaminated blood transfusion are confirmed as the modes of HIV-1transmission. Prostitutes and STD patients are recognized as being high-risk groups for the HIV-1 infection. Where HIV-1 infection is widely distributed in the general population, risk reduction strategies should place strong emphasis on safe-sex techniques in addition to the promotion of partner reduction. J Epidemiol, 1995; 5 : 1-9.


Seroprevalence of of Human lmmunodeficiency
Virus Type-1 Infection in Africa

Motonobu Miyazaki
The epidemiological characteristics of HIV-1 infection in Africa have gradually been elucidated through various studies.
The HIV-1 infection is believed to have existed in the 1960s in Africa and is presently epidemic in Africa. The HIV-I seropositive rate for the general population is higher in urban regions than in rural areas.
The peak age of males infected with the HIV-1 tends to be higher than that of females infected with the HIV-1 Sex difference is recognized in the HIV-1 serpopositive rates.
Heterosexual contact, mother-to-child transmission and contaminated blood transfusion are confirmed as the modes of HIV-1transmission. Prostitutes and STD patients are recognized as being high-risk groups for the HIV-1 infection.
Where HIV-1 infection is widely distributed in the general population, risk reduction strategies should place strong emphasis on safe-sex techniques in addition to the promotion of partner reduction. J Epidemiol, 1995; 5 : 1-9.
HIV-1 infection, Africa, epidemiology There are now a large number of reports of HIV-1 seropositive rates in African countries and we have conducted summarized comparable data on HIV-1 seropositive rates in Tables 1-4. (1) Urban and rural regions Table 1 shows the HIV-1 seropositive rates in urban and rural regions. The HIV-1seropositive rates were higher in urban regions than in rural regions. The HIV-1 seropositive rates are evidently greater in Central and East African countries than in other African countries. Of the Central and East African countries, Zaire, Uganda, Rwanda and Tanzania show the highest HIV-1 seropositive rates.
(2) Sex Table 2 shows the HIV-1 seropositive rates by sex. Sexual difference exists. The HIV-1 seropositive rates in females generally higher than in males regardless of target groups. Table 1. Seropositive rates of HIV-1 in general residents by urban and rural resions (%).
(3) Pregnant women and children Table 3 shows the HIV-1 seropositive rates of pregnant women and children. The HIV-11 seropositive rates of pregnant women tend to be higher in the countries where the HIV-1 is epidemic in general residents. The HIV-1 seropositive rates of children are the highest in Zaire, Uganda, Tanzania and Zambia. The HIV-1 seropositive rates in children are lower than in pregnant women. The HIV-1 seropositive rates in non-AIDS pediatric patients are higher in general children.
(4) High risk groups Table 4 shows the HIV-11 seropositive rates of patients with sexually transmitted disease (STD), blood transfusion or medical injection-experienced persons and prostitutes. The HIV-1 seropositive rates in these groups are evidently higher than in general residents. The prostitutes have the highest HIV-1 seropositive rates regardless of the countries and become an important key.category in the spread of the HIV-1 infection in Africa.

DISCUSSION
Basic virological, serological and clinical studies are important for understanding of HIV-1 pathogenicity. However, basic studies can not clarify virus distribution, infectious risk factors and/or transmission modes.
Epidemiological research and analysis is required for this purpose. The monitoring of the HIV-1 epidemic has been carried out gradually in the general residents, patients and high-risk group in Africa. As a result, although the HIV-1 infection in the general residents, children, patients and prostitutes in African regions are reported, it is known that HIV-1 infections are concentrated generally in Central and East Africa (Table 1- 4). The higher seropositive rates were seen in general among prostitutes and the STD patients.
The HIV-1infection is mainly transmitted by sexual contact in Africa. This is known because STD patients and prostitutes have the highest HIV-1 seropositive rates (Tables 4). Low-class prostitutes have higher HIV-1 ser-opositive rates than high-class prostitutes"'- ' 17). Infections are present in heterosexual-contact partners of the HIV-1 seropos 113,118-120) and in the persons with multipul sex partners2s,54,105,117,121> The frequent sexual contacts with different partners is an important factor more than the types of sexual intercourse 122). In addition, seropositive rates among groups with using condom are lower than with non-using condom 123). As for the peak age with the HIV-1 infection, the female seropositive are aged from 20 to 29 years, while the male seropositive are aged between 30 and 39 years29,45,66) Males tend to be older than females. These facts suggest that sexual contact plays a key role as one of the modes of HIV-1 transmission. This is likely to be due to the movement and migration of the high sexual activities spreading the HIV-1 by sexual contact. In Africa, Blood transfusion is frequent for the therapy of malaria and sicle cell anemia 124,125). the more blood transfusion the children have received, the higher the HIV-1 seropositive rates have been reported 1920,23,74,76> Blood transfusion-experienced adults also have higher HIV-1 seropositive rates in the general re sidents21,44,124,126 The history of blood transfusion is a behavioral factor of HIV-1 infection in Africa.
Injections are also frequently carried out in Africa, and this fact is related to the peculiar African custom of patients preferring to receiving parenteral therapy rather than oral medicine127). The number of medical injections are related to the HIV-1 seropositive rates in Africa regard-less of age or sex19,21, 64,74,103,104,106,128) These facts suggest that blood transfusion and medical injections through insufficient treatment are the important mode of HIV-1 transmission. Because blood transfusion and medical injections are so frequent in Africa, guidelines should be developed for improved laboratory service and reduction of unnecessary blood transfusion.
It is also a serious problem for pregnant women that the V can be contracted through heterosexual contact. The HIV-1 seropositive rates of pregnant women are increasing25,80,84)The peak age of HIV-1 seropositive rates in pregnant women is between 20 and 29 years86), and it is reported that HIV-1seroprevalence is associated with syphilis seropositity in pregnant women 17). It is feared that HIV-1 infections will spread to children, because it is estimated that the transmission rate of HIV-1 from mother Table 3. Seropositive rates of HIV-1 on maternal and child (%) Table 4. Seropositive rates of HIV-1 in risk groups (%).
to child is 25% to 40%53,129-133) The mother to child transmission is an important mode of HIV-1 epidemic in Africa.
With regard to clinical factors on HIV-1 infection, an evident relationship between the HIV-1 infection and history of STD (Table 4), and HIV-1 seropositive rates in STD seropositive group tend to increase 68,81). However, the whole relationship between HIV-1 infection and history of TB is now still unclear in Africa because reports are not many, although sporadic reports show the HIV-1 seropositive rates among TB patients47,84,94,134,135) Further studies of the epidemiology of HIV-1 infection will be necessary in the future on how frequently TB appear in Africa60,130,136-143).
The traditional cultural practices, such as labial and gingival totooing, clitoridectomy, scarification, and circumcision are preformed in Africa as African custom50) Several reports suggest that the lack of circumcision is a cofactor facilitating HIV-1 transmission 106,138,144-146) However, the relationship between the traditional practices and HIV-1 transmission is not clarified so far50>. The potential for HIV-1 transmission by these traditional practices should be re-assessed.
In Africa in general, when AIDS affects the general heterosexual population147), a very high proportion of adult transmission of HIV-1 is likely to be through heterosexual contact. STD is probably cofactors that increase the HIV-1 transmission in Africa. Where HIV-1 infection is widely distributed in the general population, risk reduction strategies should, in addition to the promotion of partner reduction, place strong emphasis on safe-sex techniques. Interventions designed to change male sexual behavior are also urgently needed.