Reservoirs of infection

Several pools of nonreplicating virus serve as reservoirs of infection and hmit the effectiveness of antiretroviral therapy. HIV can hve and multiply in monocytes and macrophages these cells are present in all tissues and can live for many months. Infective virus can also reside in long-lived resting CD4+ lymphocytes. 

Clearly, serology based on the PGL-I-related NGCs has a place in the control of leprosy, although it does not meet pressing needs in terms of measuring incidence and reservoirs of infection, chains of disease transmission, and early diagnosis. 

Figure 7-3 a The function of interferon. When a virus infects a host cell, the cell expresses interferon. Interferon activates natural killer cells, causing killing of the infected host cells and elimination of the reservoir of infection. At the same time, interferon induces an antiviral state in neighboring cells, effectively breaking the cycle of infection. 

Acellular pertussis vaccines contain selective components of the B. pertussis organism. All acellular vaccines contain pertussis toxin (PT), and some contain one or more additional bacterial components (e.g., filamentous hemagglutinin [FHA], pertactin [a 69-kDa outer membrane protein], and fimbriae types 2 and 3). Acellular pertussis vaccine is recommended for all doses of the pertussis schedule at 2, 4, 6, and 15 to 18 months of age. A fifth dose of permssis vaccine is given to children 4 to 6 years of age. Pertussis vaccine is administered in combination with diphtheria and tetanus (DTaP). Although the permssis vaccine is not recommended for individuals 7 years of age and older, booster doses for adolescents and adults may be incorporated into future recommendations because members of these groups are important reservoirs of infection. 

Monocytes and macrophages are infected but not necessarily destroyed, so they serve as a reservoir of infection. 

Between outbreaks, the plague bacterium is believed to circulate within populations of certain species of rodents without causing excessive monality. Such groups of infected animals serve as silent, long-term reservoirs of infection. 

Reservoir of infection Site where microorganisms can persist and maintain their abihty to infect. 

Tularaemia results from systemic infection with the gram-negative bacteria Francisella tularensis. Wild rodents (in particular, hares) and other small-animal populations are the main reservoir of infection. In humans, most cases are sporadic, related to tick bites (Dermacentor) or direct contact with infected animals. Hunters are at greatest risk, but the disease also affects butchers, farmers, foresters, laboratory workers and veterinarians (Evans et al. 1985). The incubation period varies from 1 day to 10 days. The clinical manifestation is usually an ulcerated nodule at the point of inoculation, associated with enlargement and, later, breakdown of lymph nodes. Systemic symptoms and toxaemia may be severe. Minocycline is considered to be efficacious in most cases (100 mg twice per day for 4 weeks). 

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