The first documented case of AIDS was in an African man in 1959. The initial infections were presumably sporadic and isolated until mutations produced a more virulent strain that was readily transmit ted from human to human. Today, transmission of HIV generally occurs by one of four routes listed below (Figure 1). There has been no firm evidence for transmission by saliva, urine, nonsexual contact in which blood is not exchanged, or by an insect bite.

Fig1. Common modes of transmission of human immunodeficiency virus (HIV).

1. Sexual contact: HIV, present in both semen and vaginal secretions, is transmitted primarily as cell-associated virus in the course of either homosexual or heterosexual contact. Disruption of mucosal surfaces by sexually transmitted diseases, particularly those such as syphilis and chancroid that result in genital ulcerations, may greatly facilitate HIV-1 infection. The nonulcerative sexually transmitted pathogens have also been documented to enhance HIV transmission, at least in part due to replicative synergy between the viral and bacterial pathogens.

 2. Transfusions: HIV has been transmitted by transfusion with whole blood, plasma, clotting factors, and cellular fractions of blood.

 3. Contaminated needles: Transmission can occur by inoculation with HIV-contaminated needles or syringes among drug users or accidentally if a contaminated needle punctures the skin of a health care worker.

4. Perinatal transmission: An HIV-infected woman has a 15 to 40 percent chance of transmitting the infection to her newborn, either transplacentally, during passage of the baby through the birth canal, or via breastfeeding. Because of the high rates of HIV-1 infection in women of childbearing age in developing countries, perinatally acquired HIV-1 infection is responsible for approximately 20 percent of all AIDS cases in these areas. Figure 2 compares the modes of transmission worldwide with those occur ring in the United States.

Fig2. Modes of HIV transmission in the United States compared with those worldwide. (A) In the United States, the primary mode of HIV trans mission is homosexual sex. Transmission in western Europe is similar to that in the United States. (B) In most of the world, transmission is primarily by heterosexual sex. [Note: Segment labeled "Other" includes perinatal transmission.]

اخر الاخبار

اخبار العتبة العباسية المقدسة

قسم شؤون المعارف ينظم دورة متقدمة في تحقيق المخطوطات لملاكاته

قسم الشؤون الفكرية يصدر العدد العشرين من مجلة دراسات إفريقية

المجمَع العلمي يكرم الأساتذة المشاركين في مشروع الدورات القرآنية الصيفية في كربلاء

العتبة العباسية المقدسة تختتم فعاليات البرنامج المركزي الأسبوعي لمنتسبيها

المزيد

الآخبار الصحية

تحذير من "عدوى بكتيرية" تسبب نوبات قلبية

ماذا يحصل لجسمك عند التوقف عن استخدام الزيت في الطهي؟

الأمل في كبسولة.. "فيتامين شهير" يبطئ التقدم في العمر

اشتهاء أطعمة بشكل مفاجئ.. ناقوس خطر للسرطان ؟!

المزيد

الآخبار التكنلوجية

زلزال أفغانستان يحصد أكثر من ألف قتيل.. ويدمر آلاف المنازل !

ناجٍٍ وحيد من انزلاق أرضي.. دمّر قرية سودانية بأكملها !

نهر الفرات.. مورد مائي بين الندرة والتقاسم

ما السر وراء مشية إيلون ماسك الغريبة والسريعة ؟

المزيد

مواضيع ذات صلة

Pathogenesis and clinical significance of HIV

HIV replication

Hepatitis D

Prevention and Treatment of hepatitis B

Differentiating Acute and Chronic Hepatitis and the Chronic Carrier State

Flaviviridae

Togaviridae

Caliciviridae

Picornaviridae

Laboratory Assays of Hepatitis B

Epidemiology of Hepatitis B

Hepatitis A