Direct Contact Diseases Due to Viruses

Presenting By:

Abdul QaharAbdul Wali Khan University Mardan

(Buner Campus)

Direct contact Diseases An easy way to catch most infectious

diseases is by coming in contact with a person or animal who has the infection.

Three ways infectious diseases can be spread through direct contact are:

1. Person to person. The most common way for infectious

diseases to spread is through the direct transfer of bacteria, viruses or other germs from one person to another.

2. Animal to person

Pets can carry many germs , Being bitten or scratched by an infected animal can make you sick and, in extreme circumstances, can be fatal.

3. Mother to unborn child

A pregnant woman may pass germs that cause infectious diseases to her unborn baby. Some germs can pass through the placenta.

Direct Contact Disease due to Viruses

AIDS (Acquired immune deficiency syndrome)

Caused by human immunodeficiency virus (HIV), a lentivirus within the family Retroviridae

It was believed that it have evolved in Africa from viruses that infect other primates

This Disease occurs worldwide, but certain groups are more at risk Homosexual/bisexual men Intravenous drug users Transfusion patients Newborn children of infected mothers

This Virus is acquired by direct exposure of the person’s bloodstream to body fluids

Containing the virus; can also be transmitted via breast milk

Virus targets CD4+ cells such as T-helper cells, macrophages, dendritic cells, and monocytes

Four types of pathological changes

AIDS-related complex (ARC) mild fever, weight loss, lymph node enlargement, and

presence of antibodies to HIV; can develop to full-blown AIDS

Cold sores – (fever blisters, herpes labialis)

Caused by herpes simplex type 1 (HSV-1), a dsDNA virus

Transmission is by direct contact

Blister at site of infection is due to viral- and host-mediated tissue destruction Lifetime latency is established when virus migrates to trigeminal nerve ganglion

70-90% of U.S. adults have been infected

Virus is periodically reactivated in times of physical or emotional stress

Herpetic keratitis - recurring infections of the cornea that can result in blindness

Drugs are available that are effective against cold sores, but treatment is mostly supportive

Diagnosed by cell culture and immunological tests

Common cold (coryza) Caused by many different rhinoviruses as well as

other viruses

Many do not confer durable immunity

Understanding rhinovirus structure has suggested approaches to developing vaccines and drugs.

At one time, common cold was thought to be spread by explosive sneezing, but now it is believed to be primarily spread by hand-to-hand contact

Treatment is supportive

Leukemia Certain leukemias (adult T-cell

leukemia and hairy-cell leukemia) are caused by retroviruses (HTLV-1 and HTLV-2, respectively) and are spread similarly to AIDS

Often fatal and there is no effective treatment, although interferon has shown some promise to cure the disease.

Thank you Very much

NEXT SLIDES for

Next Class

Rabies Caused by a number of different strains

of neurotropic viruses of the family Rhabdoviridae (negative-strand RNA viruses)

Transmitted by bites of infected animals, aerosols in caves where bats roost, or by scratches, abrasions, open wounds, or mucous membranes contaminated with saliva of infected animals

Virus multiplies in skeletal muscle and connective tissue, then migrates to central nervous system, causing a rapidly progressing encephalitis

Diagnosis

Past - presence of Negri bodies (masses of virus particles or unassembled viral subunits)

Today - immunological tests, virus isolation, as well as the detection of Negri bodies

Rabies cases in the U.S

Humans - about 10 per year

Animals - about 8,000 per year

Viral hepatitis

Hepatitis is any inflammation of the liver Currently eleven viruses are recognized as

causing hepatitis Herpesviruses CMV and EBV - do not cause

permanent liver damage Nine hepatotropic viruses Some have not been well characterized

Hepatitis B (serum hepatitis)

Caused by hepatitis B virus (HBV), a dsDNA virus with a circular genome

Virus is transmitted by Blood transfusions Contaminated equipment Unsterile needles Any body secretion Also transplacental transmission to fetus

occurs

Hepatitis C Caused by hepatitis C virus (HCV), an

ssRNA virus within the family Flaviviridae

Virus is spread by Intimate contact with virus-

contaminated blood In utero from mother to fetus Fecal-oral route Organ transplants Diagnosis is by serological tests

Hepatitis D Is caused by hepatitis D virus (HDV)

(formally called the delta agent), which only causes disease if the individual is co-infected with hepatitis B virus

Co infection may lead to a more serious acute or chronic infection than that normally seen with HBV alone

Diagnosis is by serological tests

Treatment is difficult and often involves administration of alpha interferon

Prevention and control is by the use of the hepatitis B vaccine

Recently, hepatitis F and hepatitis G have been identified and are currently being investigated

Cytomegalovirus (CMV) inclusion disease

More than 80% of U.S. adults older than 35 years have been exposed to CMV and carry a lifelong infection

Most infections are asymptomatic but infection can be serious in immunologically compromised individuals

Virus persists in the body and is shed for several years in saliva, urine, semen, and cervical secretions

Infected cells have intranuclear inclusion bodies

Diagnosis is by viral isolation and serological tests

Some antiviral agents are available for treatment, but only used in high-risk patients

Prevention

Avoiding close personal contact with infected individual

Use blood/organs from seronegative donors

Genital herpes

Caused by herpes simplex type 2 (HSV-2),

a dsDNA virus that is a member of Herpesviridae

Virus is most frequently transmitted by sexual contact

Disease has active and latent phases 1. Active Phase 2. Latent Phase

1. Active Phase

Virus rapidly reproduces Patient can be symptom free or painful

blisters in the infected area may occur, as well as other symptoms

Fever Burning Sensation Genital Soreness

2. Latent Phase after resolution of active phase virus

retreats to nerve cells where the viral genome resides in the nuclei of host cells and can be periodically reactivated

There is no cure, but acyclovir decreases healing time, duration of viral shedding, and duration of pain