SALMONELLA AND HIV CO-INFECTION
The human immunodeficiency virus (HIV) was unknown until the early 1980's but since then has infected millions of persons in a worldwide pandemic. The result of HIV infection is relentless destruction of the immune system leading to onset of the acquired immunodeficiency syndrome (AIDS).
The AIDS pandemic has already resulted in the deaths of over half its victims. All HIV-infected persons are at risk for illness and death from opportunistic infections and neoplastic complications because of the inevitable manifestations of AIDS. Once HIV infection became established in humans, the spread of HIV has been driven by multiple factors.
The advent of quick air travel in the 20th century provided a means for spread not present in past human pandemics. Urbanization has led to increased numbers of persons at risk in close proximity. Human sexual practices with promiscuity have included a larger number of persons in populations around the world. A practical and easily available means for delivery of drugs of abuse through injection became more widespread in the 20th century.
The AIDS pandemic has evolved over time, with four main phases of evolution. In the initial phase, HIV emerged from endemic rural areas to spread among urban populations at an accelerating rate. In the second phase, dissemination occurred and involved definable risk groups.
Behaviors in these risk groups, including sexual promiscuity and injection drug use, led to the third phase of escalation, which occurred through the 1980’s. A fourth phase of stabilization has occurred in some regions such as Western Europe, North America, and Australia, where control measures appear to be having a positive effect. However, some regions such as central Africa and Asia continued to experience escalation of the pandemic through the 1990's and into the 21st century.
Although the HIV infection rate in the United States increased rapidly in the 1980's, peaked in the 1990’s, and has declined since, the reservoir of HIV-infected persons developing AIDS and requiring therapy continued to increase through the 1990's and into the 21st century.
At the end of 2008, estimates of nearly 1.2 million persons living with HIV, including almost 0.25 million whose infection was undiagnosed, were present in the U.S. Globally, the incidence of new HIV infections probably peaked in 1997. At the end of the 20th century, over 21 million persons worldwide had died from AIDS; over 34 million were living with HIV infection, and over 95% of HIV infected persons resided in developing nations.
Nine countries in southern Africa, with 2% of the world’s population, accounted for a third of all HIV-infected persons (). At the start of the 21st century, the prevalence of HIV infection stabilized at about 0.8%. The age group most affected was young persons from 15 to 24 years of age, accounted for 45% of new HIV infections.
Worldwide, over half the victims of AIDS are women and a consequence of this is perinatal infection resulting in a significant number of children born with HIV infection. The scope of the AIDS pandemic has already led to serious consequences, not only for health care systems of countries unable to cope with many AIDS victims, but also for the national economies of those countries because of the loss of young to middle aged who are economically most productive.
Costs for detection, diagnosis, and treatment are considerable when effective therapies for persons with complications of HIV infection are instituted to prolong survival. In the 1990’s in the U.S., the average cost for medical care of an HIV-infected patient was double the average income for half of all such patients.
Though the pharmacologic therapies exist for prolonging the lives of persons infected with HIV, such therapies are expensive and out-of-reach for many persons worldwide. The years of useful life lost by the predominantly younger population infected by HIV has a serious economic impact. In the era of antiretroviral therapy in the U.S. the average life expectancy for persons diagnosed with HIV infection increased from 10.5 years in 1996 to 22.5 years in 2005 (Garcia and Miller,1991). According to the United Nations Development Program, when the prevalence of AIDS reaches 1% of the adult population, the pandemic will become difficult to constrain or reverse unless drastic and effective measures are taken (Schwartz et al., 1996).
In Eastern Europe, Asia, and Africa governmental responses to the spread of HIV have often been delayed and haphazard. One notable exception has been Thailand, which mounted a countrywide campaign to educate and screen its population. When less than 5% of adult men visit commercial sex workers, or barrier precaution use is high, and rates of injection drug use remain low, then the spread of HIV remains low.
Targeting high risk groups with educational campaigns, increasing condom use, male circumcision, reducing sexually transmitted diseases, increasing the availability of antiretroviral drugs, and needle-exchange programs for injection drug users have shown success in reducing or stabilizing rates of HIV infection. Treatment programs for those with AIDS are expensive and difficult to administer.
Brazil has had success in reducing health care costs of HIV infection with use of more widely available antiretroviral drugs. Some pharmaceutical manufacturers have agreed to subsidize the costs, or allowed generic production of antiretroviral agents, lessening therapy to about 1$ U.S. per day, but the numbers of infected persons make treatment an expensive option for many countries. Lack of resources for health care has limited budgets to deal with HIV when other health problems loomed large.
On the other hand, Salmonellosis is an infection caused by the bacterium Salmonella enterica which has over 2,000 serotypes (for example Salmonella Typhimurium). Salmonella bacteria are found in the gastrointestinal tracts of many species of animals, birds, reptiles, and humans, and also in the environment which may be contaminated by the feces of animals and people.
Salmonellosis is illness caused by Salmonella bacteria, which belong to the family Enterobacteriaceae. The bacteria are transmitted in food and water or sometimes from certain animals such as chicken, fowl, livestock, domestic pets, and turtles. The bacterium enters the body orally and then grows in the small intestine. In people with HIV, the bacterium often goes into the bloodstream and is transported to other parts of the body, thus causing recurring problems. HIV-positive people who repeatedly have salmonella bacteria in their blood (i.e. they are bacteraemic) are diagnosed as having AIDS. High bacteraemia is associated with declining CD4 cell counts in HIV-infected individuals (Deng et al., 1996).
People with HIV who have had salmonellosis may continue to excrete (infectious) salmonella in their urine and faeces, even after treatment with antibiotics. To avoid transmitting infection to others, it is wise to take extra care with food preparations and with sexual contact. Hygienic food preparation helps prevent infection with salmonella in the first place. The most common symptoms of salmonellosis are non-specific problems such as fever, chills, sweats, weight loss, diarrhoea (which can be severe and bloody), and anorexia. Although bowel problems are common in AIDS, they are usually not caused by salmonella.
Salmonellosis is diagnosed by growing the bacteria from a sample of stool or blood. In people with HIV, salmonella infections are usually treated with a three-week course of antibiotics. The most commonly used is ampicillin. If the bacterium is resistant, other treatments may include chloramphenicol (Chloromycetin), cephalosporins, ciprofloxacin, ofloxacin, and cotrimoxazole.
Diarrhoea can usually be alleviated by standard anti-diarrhoea medicines. Salmonellosis often recurs after an episode has been successfully treated, so long-term maintenance therapy may be necessary. Some research suggests that anti-HIV drugs and/or cotrimoxazole may help to prevent recurrences. HIV-infected individuals with salmonella are more likely than others to have antibiotic resistance and salmonella bacteraemia, making treatment of this condition difficult (Feng et