Page 406 - Review of Medical Microbiology and Immunology ( PDFDrive )

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mebooksfree.com mebooksfree.com mebooksfree.com Infection in pregnant women can cause serious fetal 395 mebooksfree.com
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CHAPTER 46 Minor Viral Pathogens
SAPPORO VIRUS
abnormalities, including microcephaly. Infection also
Sapporo virus is a calicivirus that causes acute gastroenteri-
predisposes to Guillain-Barre syndrome. Approximately
tis, primarily in adults. The main symptoms are vomiting
80% of infections are asymptomatic. The typical illness
and diarrhea. It is transmitted by ingestion of food or water
lasts a few days to a week. Most symptomatic adults
contaminated with human feces. There is no antiviral drug
recover without sequelae.
or vaccine. It is named after Sapporo, Japan, the city where
The vector is the Aedes mosquito and the vertebrate
it was first isolated.
hosts are non-human primates and humans. Almost all
infections are transmitted by mosquitoes but semen can
contain the virus and sexual transmission occurs.
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SPUMAVIRUSES
There is no confirmed report of transmission by blood
Spumaviruses are a subfamily of retroviruses that cause a
transfusion or breast milk.
foamy appearance in cultured cells. They can present a
Disease caused by ZIKV was very rare until 2007
problem in the production of viral vaccines if they con-
taminate the cell cultures used to make the vaccine. There
Micronesia. In 2015, ZIKV caused outbreaks in the
Caribbean and South America. By March 2016, ZIKV
are no known human pathogens.
had spread to 33 countries in the Americas, causing
disease in thousands of people.
TACARIBE COMPLEX OF VIRUSES
The diagnosis is established either by finding viral RNA
The Tacaribe complex contains several human pathogens,
in the serum using an ELISA test. Interpretation of the
all of which cause hemorrhagic fever.
antibody test is complicated by cross-reacting antibody in
The best known are Sabia virus in Brazil, Junin virus in in the serum using a PCR assay or by finding IgM antibody
people infected with other flaviviruses, such as dengue
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Argentina, and Machupo virus in Bolivia. Hemorrhagic fevers,
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virus, or who have received the yellow fever vaccine. Treat-
as the name implies, are characterized by fever and bleeding
ment is symptomatic. There is no effective antiviral drug
into the gastrointestinal tract, skin, and other organs. The
bleeding is due to thrombocytopenia. Death occurs in up to
The main goal of prevention is to eliminate infection
20% of cases, and outbreaks can involve thousands of people.
in pregnant women. Prevention involves protective
Agricultural workers are particularly at risk.
clothing, mosquito repellent, bed nets, and screened
Similar to other arenaviruses such as Lassa fever virus
windows. Pregnant women should not travel to areas
and lymphocytic choriomeningitis virus, these viruses are
where outbreaks are occurring. Men who may have
endemic in the rodent population and are transmitted to
become infected should use condoms or refrain from
humans by accidental contamination of food and water by
rodent excreta. The diagnosis can be made either by isolat-
ing the virus or by detecting a rise in antibody titer. In a
laboratory-acquired Sabia virus infection, ribavirin was an sexual intercourse.
SELF-ASSESSMENT QUESTIONS
effective treatment. No vaccine is available.
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mebooksfree.com mebooksfree.com mebooksfree.com (A) Its main clinical manifestation is encephalitis. mebooksfree.com
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1. Regarding Sin Nombre virus (a hantavirus), which one of the fol-
lowing is most accurate?
WHITEWATER ARROYO VIRUS
(B) The main reservoir is domestic animals such as pigs.
This virus is the cause of a hemorrhagic fever/acute
(C) Infection is acquired by inhalation of dried mouse feces and
respiratory distress syndrome in the western part of the
urine.
United States. It is a member of the arenavirus family, as is
(D) Oseltamivir is an effective prophylactic drug if given within
Lassa fever virus, a cause of hemorrhagic fever in Africa
48 hours of exposure.
(see page 393). Wood rats are the reservoir of this virus,
(E) Immunization of children at the age of 15 months with the
and it is transmitted by inhalation of dried rat excrement.
killed vaccine has greatly reduced the incidence of disease.
This mode of transmission is the same as that of the hanta-
virus, Sin Nombre virus (see page 392). There is no estab-
lowing is most accurate?
lished antiviral therapy, and there is no vaccine. 2. Regarding Japanese encephalitis virus (JEV), which one of the fol-
(A) The principal reservoir of JEV is bats.
(B) It is transmitted by the bite of the dog tick, Dermacentor.
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(C) Acyclovir is the drug of choice for encephalitis caused by
ZIKA VIRUS
JEV.
Zika virus (ZIKV) is a flavivirus that causes an illness
endemic area.
similar to dengue characterized by fever, arthralgia,
(E) JEV is a nonenveloped virus with a circular double-stranded
maculopapular rash, and non-purulent conjunctivitis.
RNA genome.
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