ABSTRACT
Zika virus (ZIKV) has two lineages: African and Asian. Mosquito-borne flaviviruses are thought to replicate initially in dendritic cells and then spread to lymph nodes and the blood stream. Risk for infection through blood transfusion, sexual practices and perinatal transmission exists. The possible routes of perinatal transmission are during delivery, breastfeeding and by close contact between the mother and her newborn. Also, mucocutaneous exposures to the virus by infected blood or monkey bite, organ transplantation or hemodialysis are the other routes of ZIKV transmission. There are two types of ZIKV infection; Zika fever and congenital infection. Clinical presentation of Zika fever varies from asymptomatic infections to a self-limiting febrile disease with low grade fever, conjunctivitis, maculopapular rash, headache, retro-orbital pain and arthritis/arthralgia with periarticular edema, myalgia, vertigo, vomiting and asthenia. This clinical feature could be mistaken for dengue or chikungunya fevers. Microcephaly is the most important and frequently reported clinical picture of suspected congenital Zika syndrome. Laboratory tests are needed for diagnosis of ZIKV infection, because there is no known pathognomonic clinical, biochemical or radiological features. RT-PCR is the most well-liked assay. Serum samples are tested by immunoglobulin G ELISA with ZIKV antigen. Samples are also tested by immunoglobulin M ELISA. There is no certified vaccine or therapeutic medication. In asymptomatic or uncomplicated patients, treatment is not necessary.
ABSTRACT
Ebola virus is transmitted to people as a result of direct contact with body fluids containing virus of an infected patient. The incubation period usually lasts 5 to 7 d and approximately 95% of the patients appear signs within 21 d after exposure. Typical features include fever, profound weakness, diarrhea, abdominal pain, cramping, nausea and vomiting for 3-5 days and maybe persisting for up to a week. Laboratory complications including elevated aminotransferase levels, marked lymphocytopenia, and thrombocytopenia may have occurred. Hemorrhagic fever occurs in less than half of patients and it takes place most commonly in the gastrointestinal tract. The symptoms progress over the time and patients suffer from dehydration, stupor, confusion, hypotension, multi-organ failure, leading to fulminant shock and eventually death. The most general assays used for antibody detection are direct IgG and IgM ELISAs and IgM capture ELISA. An IgM or rising IgG titer (four-fold) contributes to strong presumptive diagnosis. Currently neither a licensed vaccine nor an approved treatment is available for human use. Passive transfer of serum collected from survivors of Junin virus or Lassa virus, equine IgG product from horses hypervaccinated with Ebola virus, a "cocktail" of humanized-mouse antibodies (ZMapp), recombinant inhibitor of factor VIIa/tissue factor, activated protein C, RNA-polymerase inhibitors and small interfering RNA nano particles are among the therapies in development. Preclinical evaluation is also underway for various vaccine candidates. One is a chimpanzee adenovirus vector vaccine; other vaccines involve replication-defective adenovirus serotype 5 and recombinant vesicular stomatitis virus.