Page 44 - parasitology for medical and clinical laboratoryprofessionals

24 CHAPTER 2

Source: Centers for Disease Control and Prevention (CDC)

FIGURE 2-10 Standing, stagnant water is a perfect breeding place for mosquito larvae

Antimalarial drugs such as chloroquine are often waste products (toxic waste) that are products of their
begun prophylactically before traveling to endemic areas. metabolism and that may poison the body. Sometimes
The drug is not always perfectly protective, and insect these toxins are reabsorbed in the intestines and patients
repellent along with mosquito barriers of fine mesh are have difficulty ridding their bodies of the toxins that
used in addition to prophylactic therapy. Malaria cases are recycled over and over. The immune system may be
have also been reduced dramatically by preventing stand- overwhelmed as parasites are capable of producing pro-
ing water in which mosquitoes breed (Figure 2-10). Many digious numbers of offspring on a daily basis. These or-
birds, including those in North America, may be infected ganisms have hijacked the bodies of humans or animals
with various species. This disease is spread to man by a infected by the parasitic organisms to the detriment of the
certain species of the Anopheles mosquito, which is in- one infected. The immune system may appear depressed
fected while taking a blood meal from an infected victim. in the presence of infection and this may lead to further
In rare cases, the organism has been transmitted through damage from bacteria and viruses concomitant with the
blood transfusions. Complex stages of the malaria life parasitic infection.
cycle that differ according to species occur in both the
human host and the mosquito.
Mosquitoes consume both microgametocytes and ROUTES OF PARASITIC
macrogametocytes. Further development takes place in INFECTION
the mosquito that produces infectious sporozoites that
are injected into humans from organisms mixed with Parasitic infections occur via three main routes of
the mosquito’s saliva. Mosquitoes apparently suffer no infection. The organisms listed previously, along with
ill effects from being infected. Many parasites rob their many other species less commonly encountered, are
hosts of vital vitamin and mineral nutrients, the amino contracted predominantly by drinking contaminated wa-
acids needed for muscle building, and digestion en- ter (Figure 2-11). In the United States, Giardia lamblia
zymes. Some sufferers become anemic and are drowsy is extremely prevalent in our water supply, particularly
and fatigued after eating. Many of the parasites release water coming from private wells that are still common