Materials: Ways of HIV transmission

WAYS OF PERSON IMMUNODEFFICIENCY VIRUS TRANSMISSION

Epidemiological researches, carried out in the world, detected three ways of HIV-infection transmission:

• Sexual;

• Through the blood (parenteral)

• From mother to a child (vertical).

At the present time there is a realization of all three ways of virus transmission in all countries. However, as a rule there is always one way of transmission, more important in the period of HIV- infection spread in the territory of concrete country or region, and also a group of population, more vulnerable during the realization of the main way of transmission. Usually they are people conducting a certain life style or practice dangerous forms of behavior. So, for USA a main way of epidemic transmission was a sexual and more vulnerable group – were MSM. In the countries of South-Eastern Asia (Thailand, Singapore, India and others) more vulnerable were the trafficked-women, among whom a level of infection reached in some cities 60-80 %. For the countries of Central Europe, CIS and also for Belarus, a main way of transmission was sexual. Beginning from June 1996 and up to now a parenteral way through drug injecting was leading. Along with parenteral way sexual and vertical ways are realized in the republic, which are excluding from world experience can be leading in the future.

In spite of that the blood transfusion is more dangerous: single transfusion of infected HIV blood brings to contamination almost in 100 % cases, this way of contamination have the least specific weight in the structure of reasons initialization. It happens because the quantity of donors and recipients (users) of blood in the world is very large. Besides, at the present time all donor blood in the majority of countries (also in Belarus) is testing on HIV, and also probability of the infected blood transfusion, so the epidemic significance of such way of virus transmission is small.

Joint drugs injection also pose hazard of HIV infection. However injected drug users- are a small part of all population, and though the infection among them is high, and such way of contamination does not pose hazard for the population who are not the drug users.

Women of genital age are the main significant part of any society, than syringe drug users or blood recipients, that is why in spite of small probability of birth of infected child from infected mother, children with HIV-infection are bigger in the world than HIV-infected drug users or HIV-infected blood recipients.

Sexual contact, heterosexual or MSM, is a principal way of HIV-infection transmission. Though the probability of virus transmission from infected sexual partner to the healthy man is not big (about 10 % during one sexual contact), about 70 % of all cases of contamination are included to this way, because the main part of population in the world is in sexually active age, and frequency of sexual relations is high.

Sexual way of transmission.

There is a risk of HIV-infection in all kinds of sexual relations. Every act of intercourse without protection (without condom) with HIV infected person, poses uninfected partner to hazard of contamination. Level of risk depends on the number of factors, such as:

• belonging of sexual partner to the vulnerable group, i.e. probability of that the partner is infected:

• kind of sexual contact;

• stage of infected partner disease;

• presence of other diseases, transmitting by a sexual way.

Belonging of sexual partner to the vulnerable group. Prevalence of HIV-infection is not the same in different groups of population and in different regions. A risk of infection by a sexual way increases if a sexual partner is a syringe drug user, have many other sexual partners, practices homo-or bisexual relations.

Sex and age of uninfected partner.

Virus transmission from man to a woman is about two folds probable than from woman to man. Usually women are more vulnerable for HIV-infection. HIV concentration in sperm is higher than in fluid separating vagina and neck of uterus.

Age is also a factor of women vulnerability, making them more sensitive to HIV-infection in the period to 20 and again after 45.

Kind of sexual contact:

Anal sexual contact between man and woman or between persons is fraught with higher risk of transmission, than vaginal intercourse because of big probability of rectum tissue damage accepting a (passive) partner, what is substantially facilitate the virus penetration form sperm into blood. Besides there are cells on the mucosal tunic of the rectum, which are carry on the same receptors, as the main virus targets of blood T-lymphocytes. These cells can adsorb on themselves a virus with subsequent transmission of it to the lymphocytes even in the lack of damages on the mucus tunic.

A risk of contamination in unprotected vaginal contact is slightly lowered than in anal. In this case as in anal sex, accepting partner (woman) incurs a risk, than man.

As a sperm so vagina contains HIV, theoretically there is a risk of transmission in anal sex. It is difficult to determine a stage of actual risk of transmission with a help of scientific methods: few persons are having the oral se, but having refused from other kinds of it, and if the contamination is occurred, then way of transmission remains unclear. However the oral sex causes substantially low risk of HIV transmission, then vaginal or anal intercourse. It explains rare cases of HIV transmission in the course of sexual relations from woman to woman.

In all kinds of sexual contacts a risk of transmission is higher, if there are scratches or abrasions on the skin or mucus tunic. In oral or vaginal sex a risk is higher, when a woman menstruates.

A stage of disease of the infected partner

HIGV-infected people more infectious for surroundings on the early stages –before appearance of antibodies in blood, i.e. during “seroconversional window”, and in later terms of disease, when there are clinical manifestations of AIDS. In these periods content of virus in blood and other biological spheres is higher, than in other time.

Presence of other diseases, transmitting by sexual way (STD). Researches show that the presence of diseases, transmitting by sexual way (ulcerous or non ulcerous kind), repeatedly increases a risk of infection. In inflammatory process which emerge in the organism in STD causative agent appearance, to the place of inflammation focuses which are as rule set on the genital organ, are fixing for the curb of T-lymphocytes and cells- macrophage infection. Some of these cells in the HIV-infected person will carry a virus in it, what increase a risk of its transmission to the uninfected partner. Besides many STDs (syphilis, herpes and others) cause to the emerging of in the area of genital organs, what substantially facilitate a virus penetration into blood.

Transmission of the HIV through the blood.

Blood of the infected person contains a large quantity of virus and is an extremely infectious during its directly getting into the bloodstream of other person. A higher risk may be during donor blood transfusion. A virus can also be transmitted through the blood products, i.e. separate elements of blood, which are not exposed to the processing (for example, VIII factor of blood, injected by hemophilia patient).

HIV transmission through the blood depends on virus quantity, contained in a certain “dose” (portion) of blood. That is why a risk to be contaminated through the pollutant-loaded needle, syringe or any other piercing instrument is far lower than in blood transfusion. Nevertheless this way takes a significant place, among the injected drug users as they are posed to a danger very often-several times a day. As a result, usage of common needle and syringes by the drug users became a main reason of HIV-infection spread in all countries (also in our republic).

Undamaged skin is a good barrier for virus. However there is a small risk of virus penetration through unnoticeable micro traumas and fractures during a long exposure of blood on a skin. There is always a danger of virus penetration through mucus tunics, for example, in penetration of blood into eyes or mouth cavity.

Contamination is possible through a shaving blade pollutant-loaded with blood or manicure articles. However at the present time there are no documental acknowledgements of such contamination.

Transmission from mother to a child (vertical way).

There are three periods, during which the infected mother can transmit a virus to a child. These periods are:

• prenatal (in uterus or before the birth);

• birth (in the process of birth);

• postnatal (after birth).

Infection of fetus happens in the case if mother is infected – virus transmission in prenatal period occurs from mother. HIV can not “penetrate along with sperm of infected father and penetrate into embryo, without infecting a mother”.

Epidemic of fear and prejudices

HIV-infection and AIDS epidemic as much of its development and spread on the globe caused to one more epidemic –fear and prejudices. At the present time it is connected with fatality of disease because of effective medicines and vaccines lack, with its connection first of all with marginal layers of society (trafficked women, drug users, MSM), with a weak knowledge of population about ways of virus transmission, methods and means of protection from it.

Actually a virus was detected in the laboratorial conditions from all biological fluids and organism medium. However HIV contains in the concentrations which are high enough to be infectious only in blood, sperm, vaginal fluid, cerebrospinal fluid and human milk.

HEREBY, CONDITIONS ASSISTING TO HIV TRANSMISSION:

• HIV should be in the organism or in fluids of person organism

• In order a contamination is occurred, HIV should get into the necessary place (into the blood stream or on mucosal tunic) and in necessary quantity

Organism fluids, containing a virus in concentration, sufficient for contamination

(listed with taking into concede ration a virus concentration –from high to low) and

• blood;

• sperm;

• vaginal secretion(these fluids contain high virus concentration, they are infectiously dangerous!)

HIV is also transmitting in breast-feeding (through blood or milk)

Except the listed below fluids HIV is also noted in:

• in urine;

• in saliva;

• in tears

these fluids contain low concentration of virus, they are infectiously dangerous only in large scales)

HIV was not noted:

• in sweat;

• in stools;

• earwax.

Additional factors of HIV transmission

They can not optionally lead to the HIV transmission, but can increase a risk of infection:

• Repeated effect (possible contact with HIV infected fluids) can be the additional factor, increasing a risk of contamination.

• Presence of other STDs in the person is a factor substantially increasing a risk of HIV contamination, as a skin and mucus covers are damaged, and the immunity is lowered.

That is why it is SAFE:

• To go in transport;

• Use the common toilet, bathroom, door-handle, dishes, linen:

• Share a food with AIDS patient, to take care of him, embrace him.

Sting of mosquito and other bloodsucking insects (mosquitoes, fleas, cimexes) are not posing a hazard. First of all, because a virus is quickly demolishing in the stomach of insects; secondly, digestive apparatus of insects is set in that way that it is practically impossible blood hemorrhage from stomach and back.

One more proof of it is the mosquitoes and other bloodsucking insects which are not the carriers of HIV, is the fact that epidemiological view of this HIV-infection is not quite so, as it should be if virus transmitted by the insects, as for example, in malaria, yellow fever and other infection diseases. In these diseases an equal distribution of patients are observed among all age groups of population. HIV-infection is rarely observed in the children to 15 years old (those who were contaminated from their mothers) and in old people, i.e. those who are not sexually active. Therewith a level of distribution of HIV-infection in rural area usually lower than in cities, though the mosquitoes are far higher namely in countryside.