from strep except by throat culture), an ear infection, or croup. adenoviruses types 40 and 41 can also cause gastroenteritis. a combination of conjunctivitis and tonsillitis is particularly common with adenovirus infections. some children (especially the youngest) can develop adenovirus bronchiolitis or pneumonia, both of which can be severe. in babies, adenoviruses can also cause coughing fits that look almost exactly like whooping cough. adenoviruses can also cause viral meningitis or encephalitis. rarely, adenovirus can cause hemorrhagic cystitis (inflammation of the urinary bladder—a form of urinary tract infection—with blood in the urine). most people recover from adenovirus infections by themselves, but people with immunodeficiency sometimes die of adenovirus infections, and—rarely—even previously healthy people can die of these infections. this may be because sometimes adenoviral infection can lead to cardiac disorders. for example, in one study, some cardiac samples of patients with dilated cardiomyopathy were positive for presence of adenovirus type 8. adenoviruses are often transmitted by expectoration (e.g. aerosols), but they can also be transmitted by contact with an infected person, or by virus particles left on objects such as towels and faucet handles. some people with adenovirus gastroenteritis may shed the virus in their stools for months after getting over the symptoms. the virus can be passed through water in swimming pools that are not sufficiently chlorinated. as with many other illnesses, good handwashing practice is one way to inhibit the person-to-person transmission of adenoviruses. heat and bleach will kill adenoviruses on objects. treatment there are no proven antiviral drugs to treat adenoviral infections, so treatment is largely directed at the symptoms (such as acetaminophen for fever). the antiviral drug cidofovir has helped certain of those patients who had severe cases of illness; the number helped and to what degree, and the particular complications or symptoms it helped with, and when and where this happened, were not given in the source. a doctor may give antibiotic eyedrops for conjunctivitis, while awaiting results of bacterial cultures, and to help prevent secondary bacterial infections. currently, there is no adenovirus vaccine available to the general public, but a vaccine is available for the united states military for types 4 and 7. use in gene therapy and vaccination gene therapy adenoviruses have long been a popular viral vector for gene therapy due to their ability to affect both replicating and non-replicating cells, accommodate large transgenes, and code for proteins without integrating genetic material into the host cell genome. more specifically, they are used as a vehicle to administer targeted therapy, in the form of recombinant dna or protein. this therapy has been found especially useful in treating monogenic disease (e.g. cystic fibrosis, x-linked scid, alpha1-antitrypsin deficiency) and cancer. in china, oncolytic adenovirus is an approved cancer treatment. specific modifications on fiber proteins are used to target adenovirus to certain cell types; a major effort is made to limit hepatotoxicity and prevent multiple organ failure. adenovirus dodecahedron can qualify as a potent delivery platform for foreign antigens to human myeloid dendritic cells (mdc), and that it is efficiently presented by mdc to m1-specific cd8+ t lymphocytes. a safety issue with adenoviruses is that they can cause an immune response with a related inflammatory response as occurred in the death jesse gelsinger in 1999. to address this risk, the genome of the viral genes have been modified to remove some viral genes such. one such modification is the gutless vector that removes almost all the viral genome.: 58 adenovirus has been used for delivery of crispr/cas9 gene editing systems, but high immune reactivity to viral infection has posed challenges in use for patients. vaccines further information: viral vector vaccine modified (recombinant) adenovirus vectors, including replication incompetent types, can deliver dna coding for specific antigens. adenovirus have been used to produce viral vector covid-19 vaccines. "in four candidate covid-19 vaccines... ad5... serves as the 'vector' to transport the surface protein gene of sars-cov-2". the goal is to genetically express the spike glycoprotein of severe acute respiratory syndrome coronavirus 2 (sars-cov-2). a replication-deficient chimpanzee adenovirus vaccine vector (chadox1) is used by the oxford–astrazeneca covid-19 vaccine that has been approved for use. the janssen covid-19 vaccine uses modified recombinant adenovirus type-26 (ad26). recombinant adenovirus type-5 (ad5) are being used by ad5-ncov, immunitybio and uq-csl v451. the gam-covid-vac (aka sputnik-v) product is innovative because an ad26 based vaccine is used on the first day and an ad5 vaccine is used on day 21. another one is chad-sars-cov-2-s; the vaccine reportedly prevented mice that were genetically modified to have human ace2 (hace2) receptors, presumably receptors that allow virus-entry into the cells, from being infected with sars-cov-2. possible issues with using adenovirus as vaccine vectors include: the human body develops immunity to the vector itself, making subsequent booster shots difficult or impossible. in some cases, people have pre-existing immunity to adenoviruses, making vector delivery ineffective. hiv infection concerns the use of ad5 vaccines for covid-19 worried researchers who had experience with two failed trials of an ad5 vaccine, phambili and step, due to the increased risk for uncircumcised male patients of contracting hiv-1 via unprotected anal sex. at the time, it was concluded that heightened risk of hiv reception may be observed for any ad5-based vector vaccine. in october 2020, these researchers wrote in the lancet: "on the basis of these findings, we are concerned that use of an ad5 vector for immunisation against sars-cov-2 could similarly increase the risk of hiv-1 acquisition among men who receive the vaccine." vaccines using other technologies would not be affected, but sputnik v, convidecia and immunitybio's had5 would. two studies found that ad5-specific cd4 t cells are more susceptible to hiv infection than cd4 t cells specific to certain other vectors, such as cytomegalovirus and canarypox. by comparison, a science article reported that china had approved cansino's ebola vaccine based on an ad5 vector. it was tested in sierra leone, which had high hiv prevalence, making it more likely for such problems to be detected. cansino's ceo said "we haven't seen anything with the ebola vaccine" and speculated that hiv susceptibility might be limited to ad5 vaccines which produced hiv proteins. in research reported in the lancet in may, the company's researchers acknowledged the possibility, called it "controversial" and said they would watch for it in the company's covid-19 vaccine candidate's trials. it is not known to what extent lgbt discrimination in sierra leone could have contributed to masking a possible causal link in the ebola vaccine trial; while the step trial enrolled mainly homosexual and bisexual men, the phambili trial enrolled mainly heterosexual men and women and still found an apparent connection.