Dr. Rakesh Pandit

Signs and Symptoms

• After being bitten by a mosquito carrying the virus, the incubation period ranges from three to 15 (usually five to eight) days before the signs and symptoms of dengue appear.
• This infectious disease is manifested by a sudden onset of fever, with severe headache, muscle and joint pains and rashes. The dengue rash is characteristically bright red petechia and usually appears first on the lower limbs and the chest – in some patients, it spreads to cover most of the body. There may also be gastritis with some combination of associated abdominal pain, nausea, vomiting or diarrhea. The glands (lymph nodes) in the neck and groin are often swollen.
• Some cases develop much milder symptoms which can, when no rash is present, be misdiagnosed as influenza or other viral infection. Patients with dengue can only pass on the infection through mosquitoes or blood products while they are still febrile.
• The classic dengue fever lasts about six to seven days, with a smaller peak of fever at the trailing end of the disease (the so-called “biphasic pattern”). Clinically, the platelet count will drop until the patient’s temperature is normal.
• Cases of DHF also show higher fever, haemorrhagic phenomena, thrombocytopenia & haemoconcentration. A small proportion of cases lead to dengue shock syndrome (DSS) which has a high mortality rate.

Diagnosis

• The diagnosis of dengue is usually made clinically. The classic picture is high fever with no localising source of infection, a petechial rash with thrombocytopenia and relative leukopenia.
• For dengue haemorrhagic fever, all four criteria must be fulfilled:
  • Fever
  • Haemorrhagic tendency (spontaneous bruising, bleeding from mucosa, gingiva, injection sites, etc.; vomiting blood, or bloody diarrhea)
  • Thrombocytopaenia (< 100,000 platelets per mm³ or estimated as less than 3 platelets per high power field)
  • Evidence of plasma leakage (hematocrit more than 20% higher than expected, or drop in haematocrit of 20% or more from baseline following IV fluid, pleural effusion, ascites, hypoproteinaemia)
• Dengue shock syndrome is defined as dengue haemorrhagic fever plus:
  • Weak rapid pulse,
  • Narrow pulse pressure (less than 20 mm Hg)
  • Cold, clammy skin and restlessness.

Serology and PCR (polymerase chain reaction) studies are available to confirm the diagnosis of dengue if clinically indicated.

How is dengue contracted?

The virus is contracted from the bite of a striped Aedes aegypti mosquito (which feeds during the day) that has previously bitten an infected person. One mosquito bite can inflict the disease. The virus is not contagious and cannot be spread directly from person to person. There must be a person-tomosquito- toanother- person pathway.

Prevention

• The transmission of the virus to mosquitoes must be interrupted to prevent the illness. Patients are kept under mosquito netting until the second bout of fever is over and they are no longer contagious.
• The prevention of dengue requires control or eradication of the mosquitoes carrying the virus that causes dengue.
• Wear long pants and long sleeves. For personal protection, use mosquito repellant sprays that contain DEET when visiting places where dengue is endemic.
• Limiting exposure to mosquitoes by avoiding standing water and staying indoors two hours before sunrise and sunset will help.
• There is currently no vaccine available for dengue fever. There is a vaccine undergoing clinical trials, but it is too early to tell if it will be safe or effective.

Treatment

• The mainstay of treatment is supportive therapy. Increased oral fluid intake is recommended to prevent dehydration. Supplementation with intravenous fluids may be necessary to prevent dehydration and significant concentration of the blood if the patient is unable to maintain oral intake.
• A platelet transfusion is indicated in rare cases if the platelet level drops significantly (below 20,000) or if there is significant bleeding. The presence of melena may indicate internal gastrointestinal bleeding requiring platelet and/or red blood cell transfusion.
• It is very important to avoid aspirin and non-steroidal antiinflammatory medications. These drugs are often used to treat pain and fever though in this case they may actually aggravate the bleeding tendency associated with some of these infections. Patients should receive, instead acetaminophen preparations to deal with these symptoms if dengue is suspected.

What Is Diabetes Mellitus?What Is Malarial Fever?What Is Pneumonia?What Is Tuberculosis (TB)?What Is Typhoid (Enteric) Fever?

Cause

The disease is caused by protozoan parasites of the genus Plasmodium. The most serious forms of the disease are caused by Plasmodium falciparum and Plasmodium vivax, but other related species (Plasmodium ovale, Plasmodium malariae, and sometimes Plasmodium knowlesi) can also infect humans. This group of humanpathogenic Plasmodium species is usually referred to as malaria parasites.

Transmission

• Malaria parasites are transmitted by female Anopheles mosquitoes.
• The parasites multiply within red blood cells, causing symptoms that include symptoms of anemia (light headedness, shortness of breath, tachycardia etc.), as well as other general symptoms such as fever, chills, nausea, flu-like illness, and in severe cases, coma and death. Infection begins with a bite from an infected mosquito.
• he parasite travels from the mosquito to your liver, where the parasite begins to reproduce. If another mosquito bites an infected person, that mosquito can then carry the infection to someone else.

Symptoms

High fever, body aches, headache, nausea, shaking chills (rigors), sweating, weakness, splenomegaly (enlarged spleen), cerebral ischemia, hepatomegaly (enlarged liver), hypoglycemia, and hemoglobinuria with renal failure may occur. Renal failure may cause blackwater fever, where hemoglobin from lysed red blood cells leaks into the urine.

Genetic effects of malaria

• Sickle-cell disease
• Thalassaemias

Prevention

• • Avoid exposure to mosquito’s during the early morning and early evening hours (the hours of greatest mosquito activity).
  • Wear appropriate clothing (long-sleeved shirts and long pants, for examples) especially when you are outdoors.
  • Apply insect repellent to the exposed skin.

Spray mosquito repellents on clothing to prevent mosquitoes from biting through thin clothing.

• Use a mosquito net over your bed.
• Have screens over windows and doors.
• Spray insecticide in the bedroom before going to bed.

Treatment

• Although some are under development, no vaccine is currently available for malaria; preventative drugs must be taken continuously to reduce the risk of infection.
• Malaria infections are treated through the use of antimalarial drugs, such as quinine or artemisinin derivatives, although drug resistance is increasingly common.
• Drink lots of fluids and do not become dehydrated.

What Is Pneumonia?What Is Tuberculosis (TB)?

What Is Typhoid (Enteric) Fever?

Symptoms

Most people who develop pneumonia initially have symptoms of a cold which are then followed by a high fever (sometimes as high as 104 degrees Fahrenheit), shaking chills, and a cough with sputum production. The sputum is usually discolored and sometimes bloody. Patients may become short of breath. Chest pain may develop if the outer aspects of the lung are involved. This pain is usually sharp and worsens when taking a deep breath. At times, the individual’s skin color may change and become dusky or purplish (a condition known as “cyanosis”) due to their blood being poorly oxygenated. Children and babies who develop pneumonia often do not have any specific signs of a chest infection, but develop a fever, appear quite ill, and can become lethargic. Elderly people may also have few symptoms with pneumonia.

Diagnosis

• A chest x-ray is usually ordered to confirm the diagnosis of pneumonia.
• Sputum samples can be collected and examined under the microscope.
• A blood test that measures white blood cell count (WBC) may be performed. An individual’s white blood cell count can often give a hint as to the severity of the pneumonia and whether it is caused by bacteria or a virus.
• Bronchoscopy is a procedure in which a thin, flexible, lighted viewing tube is inserted into the nose or mouth after a local anesthetic is administered. The breathing passages can then be directly examined by the doctor, and specimens from the infected part of the lung can be obtained.
• Sometimes, fluid collects in the pleural space around the lung as a result of the inflammation from pneumonia. This fluid is called a pleural effusion. If the amount of this fluid that develops is large enough, it can be removed by inserting a needle into the chest cavity and withdrawing the fluid with a syringe in a procedure called a thoracentesis.

Causes

The most common is a bacterial pneumonia where there is usually an abrupt onset of the illness with shaking chills, fever, and production of a rust-colored sputum. A vaccine (Pneumovax) is available and is recommended for the elderly, infants, people who have diabetes, chronic heart, lung, or kidney disease, those with alcoholism, cigarette smokers, and in those persons who have had their spleen removed.

Treatment

• Antibiotics often used in the treatment of bacterial pneumonia include Penicillin,Amoxycillin, Augmentin, erythromycin, azithromycin and clarithromycin.
• Legionnaire’s disease is caused by the bacterium and is most often found in contaminated water supplies and air conditioners. It is a potentially fatal infection if not accurately diagnosed. Pneumonia is part of the overall infection, and symptoms include high fever, a relatively slow heart rate, diarrhea, nausea, vomiting, and chest pain. Older men, smokers, and people whose immune systems are suppressed are at higher risk of de v e loping Legionna i r e ‘ s di s e a s e . Fluoroquinolones are the treatment of choice in this infection.
• Viral pneumonias do not typically respond to antibiotic treatment. These pneumonias usually resolve over time with the body’s immune system fighting off the infection. It is important to make sure that a bacterial pneumonia does not secondarily develop. If it does, then the bacterial pneumonia is treated with appropriate antibiotics.
• Fungal infections can lead to pneumonia .Each fungus has specific antibiotic treatments, among which are amphotericin B, fluconazole (Diflucan), penicillin, and sulfonamides.

Conclusion

Pneumonia can be a serious and life-threatening infection. This is true especially in the elderly, children, and those that have other serious medical problems, such as COPD, heart disease, diabetes, and certain cancers. Fortunately, with the discovery of many potent antibiotics, most cases of pneumonia can be successfully treated. In fact, pneumonia can usually be treated with oral antibiotics without the need for hospitalization.

Tuberculosis (TB)

Tuberculosis (TB) is an infectious disease caused by bacteria Mycobacterium tuberculosis. TB most commonly affects the lungs but also can involve almost any organ of the body. Today, tuberculosis usually can be treated successfully. There is also a group of organisms referred to as atypical tuberculosis which do not cause disease and are referred to as “colonizers,” because they simply live alongside other bacteria in our bodies without causing damage. At times, these bacteria can cause an infection that sometimes appears as typical tuberculosis.

How does a person get tb?

A person can become infected with tuberculosis bacteria when he or she inhales minute particles of infected sputum from the air. The bacteria get into the air when someone who has a tuberculosis lung infection coughs, sneezes, shouts, or spits (which is common in some cultures). People who are nearby can then possibly breathe the bacteria into their lungs. You don’t get TB by just touching the clothes or shaking the hands of someone who is infected. Tuberculosis is spread (transmitted) primarily from person to person by breathing infected air during close contact. There is a form of tuberculosis, however, that is transmitted by drinking unpasteurized milk caused by Mycobacterium bovis. Previously, this bacterium was a major cause of TB in children, but it rarely causes TB now since most milk is pasteurized (a heating process that kills the bacteria).

What happens to the body when a person gets tb?

When the inhaled tuberculosis bacteria enter the lungs, they can multiply and cause a local lung infection (pneumonia). The local lymph nodes associated with the lungs may also become involved with the infection and usually become enlarged. In addition, TB can spread to other parts of the body. The body’s immune (defense) system, however, can fight off the infection and stop the bacteria from spreading. The immune system does so ultimately by forming scar tissue (fibrosis) around the TB bacteria and isolating it from the rest of the body and the infection is contained in an inactive state. Such an individual typically has no symptoms and cannot spread TB to other people. The scar tissue and lymph nodes may eventually harden, like stone, due to the process of calcification of the scars (deposition of calcium from the bloodstream in the scar tissue). Sometimes, however, the body’s immune system becomes weakened and the TB bacteria break through the scar tissue. For example, the immune system can be weakened by old age, the development of another infection or a cancer, or certain medications such as cortisone, anti-cancer drugs, or certain medications used to treat arthritis or inflammatory bowel disease. The breakthrough of bacteria can result in a recurrence of the pneumonia and a spread of TB to other locations in the body. The kidneys, bone, and lining of the brain and spinal cord (meninges) are the most common sites affected by the spread of TB beyond the lungs.

Who gets Tb?

Anyone can get TB, but certain people are at higher risk, including:

• People who live with individuals who have an active TB infection,
• Poor or homeless people,
• Foreign-born persons from countries that have a high prevalence of TB
• Nursing home residents and prison inmates,
• Alcoholics and intravenous drug abusers,
• People with diabetes, certain cancers, and HIV infection (the AIDS virus)
• Healthcare workers.
• There is no strong evidence for a genetically determined (inherited) susceptibility for TB.

How does a doctor diagnose tuberculosis?

How does a doctor diagnose tuberculosis?

TB can be diagnosed in several different ways, including chest X-rays, analysis of sputum, and skin tests. The chest x-rays can reveal evidence of active tuberculosis pneumonia or may show scarring (fibrosis) or hardening (calcification) in the lungs. Examination of the sputum on a slide (smear) under the microscope can show the presence of the tuberculosis bacteria. A sample of the sputum can also be grown (cultured) in special incubators so that the tuberculosis bacteria can subsequently be identified. The organism can take up to six weeks to grow in culture in the microbiology lab. Several types of skin tests are used to screen for TB. These socalled tuberculin skin tests include the Mantoux test and the PPD (purified protein derivative) test. In each of these tests, a small amount of purified extract from dead tuberculosis bacteria is injected under the skin. If a person is not infected with TB, then no reaction will occur at the site of the injection (a negative skin test). If a person is infected with tuberculosis, however, a raised and reddened area will occur around the site of the test injection. This reaction, a positive skin test, occurs about 48 to 72 hours after the injection. If the infection with tuberculosis has occurred recently, however, the skin test can be falsely negative. The reason for a false negative test with a recent infection is that it usually takes 2 to 10 weeks after the time of infection with tuberculosis before the skin test becomes positive. The skin test can also be falsely negative if a person’s immune system is weakened or deficient due to another illness such as AIDS or cancer, or while taking medications that can suppress the immune response, such as cortisone or anti-cancer drugs. The special test detects the genetic material of the bacteria, called the PCR (polymerase chain reaction). This test is extremely sensitive (it detects minute amounts of the bacteria) and specific (it detects only the TB bacteria). One can usually get results from the PCR test within a few days.

How is tuberculosis treated?

• A person with a positive skin test, a normal chest x-ray, and no symptoms most likely has only a few TB germs in an inactive state and is not contagious. Nevertheless, treatment may be recommended for this person to prevent the TB from turning into an active infection.

Is HIV/aids associated with tuberculosis?

Because of HIV, a tremendous increase in the frequency (incidence) of TB occurred in the ’80s and throughout the ’90s. This increase in TB happened because suppression of the body’s immune (defense) system by HIV allowed TB to occur as a so-called opportunistic infection. Hopefully, control of HIV in the future will check this resurgence of tuberculosis.

Can tuberculosis be prevented?

Yes. The most important step is to find, isolate and treat all disease carriers until they are no longer an infective risk to others. Make sure that you eat well and enjoy plenty of sunlight and exercise It is always advisable not to get too close to people who are coughing; equally, people with a cough should be aware of those around them and try not to cough near them. Seek medical attention if you develop a cough that persists for more than three weeks.