Typhus, also known as typhus fever, is a group of infectious diseases that include epidemic typhus, scrub typhus, and murine typhus. Common symptoms include fever, headache, and a rash. Typically these begin one to two weeks after exposure.The diseases are caused by specific types of bacterial infection. Epidemic typhus is due to Rickettsia prowazekii spread by body lice, scrub typhus is due to Orientia tsutsugamushi spread by chiggers, and murine typhus is due to Rickettsia typhi spread by fleas.Vaccines have been developed, but none are commercially available. Prevention is achieved by reducing exposure to the organisms that spread the disease. Treatment is with the antibiotic doxycycline. Epidemic typhus generally occurs in outbreaks when poor sanitary conditions and crowding are present. While once common, it is now rare. Scrub typhus occurs in Southeast Asia, Japan, and northern Australia. Murine typhus occurs in tropical and subtropical areas of the world.Typhus has been described since at least 1528. The name comes from the Greek tûphos (τῦφος) meaning fever or delusion, describing the state of mind of those infected. While "typhoid" means "typhus-like", typhus and typhoid fever are distinct diseases caused by different types of bacteria. Note, however, that in some languages such as German, typhus does mean "typhoid fever". Signs and symptoms
These signs and symptoms refer to epidemic typhus, as it is the most important of the typhus group of diseases.Signs and symptoms begin with sudden onset of fever and other flu-like symptoms about one to two weeks after being infected.
However, large cysts can cause hydrocephalus. Genetic causes
There is a possible association between ultrasound-detected fetal CPCs and Trisomy 18. It is not correlated to the presence of Trisomy 21 (Down syndrome). Therefore, genetic counseling is often recommended to provide more information about fetal CPCs, to answer questions and concerns, and to outline available options such as amniocentesis or a blood test from the mother.Generally the risks are very low if there are no other risk factors. If no additional abnormalities are detected by a thorough "level II" ultrasound, the likelihood the fetus has trisomy 18 is very low.A meta-analysis of 8 studies between 1990 and 2000 with choroid plexus cysts that were identified in second-trimester (an incidence of 1.2%). The incidence of the cysts in women younger than 35 was 1% (n=1017). The study found no cases of trisomy 18 in fetuses with cysts whose mother was younger than 35. The study concluded that "there is no evidence that detection of isolated choroid plexus cyst in women who are <35 years of age increases the risk of trisomy 18".Other factors which may have a bearing on the babys chances of developing chromosome problems include:
mothers age at the expected date of delivery
the results of serum screening; XAFP triple testing or quad screening
evidence of other "fetal findings" seen at the time of the ultrasound that may suggest a chromosome problem

References
Further reading
Lun, Melody P.; Monuki, Edwin S.; Lehtinen, Maria K. (2015). "Development and functions of the choroid plexus–cerebrospinal fluid system". Nature Reviews Neuroscience. 16 (8): 445–457. doi:10.1038/nrn3921. PMC 4629451.