MEASLES

Measles, also known as morbilli, rubeola, or red measles, is a highly contagious infection caused by the measles virus.Initial signs and symptoms typically include fever, often greater than 40 °C , cough, runny nose, and red eyes.Two or three days after the start of symptoms small white spots may form inside the mouth, known as Koplik's spots. A red, flat rash which usually starts on the face and then spreads to the rest of the body typically begins three to five days after the start of symptoms.

SIGNS AND SYMPTOMS

The classic signs and symptoms of measles include four-day fevers and the three C's cough, coryza head cold)(fever), and conjunctivitis red eyes along with fever and rashes.Fever is common and typically lasts for about one week; the fever seen with measles is often as high as 40 °C.Koplik's spots seen inside the mouth are pathognomonic diagnostic for measles, but are temporary and therefore rarely seen.[10] Recognizing these spots before a person reaches their maximum infectiousness can help physicians reduce the spread of the disease.

CAUSE

Measles is caused by the measles virus, a single-stranded, negative-sense, enveloped RNA virus of the genus Morbillivirus within the family Paramyxoviridae.The virus was first isolated in 1954 by Nobel Laureate John F. Enders and Thomas Peebles, who were careful to point out that the isolations were made from patients who had Koplik's spots.

TREATMENT

There is no specific treatment for measles. Most people with uncomplicated measles will recover with rest and supportive treatment. It is, however, important to seek medical advice if the patient becomes sicker, as they may be developing complications.

Some people will develop pneumonia as a consequence of infection with the measles virus. Other complications include ear infections, bronchitis either viral bronchitis or secondary bacterial bronchitis, and brain inflammation.Brain inflammation from measles has a mortality rate of 15%. While there is no specific treatment for brain inflammation from measles, antibiotics are required for bacterial pneumonia, sinusitis, and bronchitis that can follow measles.

TUBERCULOSIS

Tuberculosis is a widespread and in many cases fatal, infectious disease caused by various strains of mycobacteria, usually Mycobacterium tuberculosis.Tuberculosis typically attacks the lungs, but can also affect other parts of the body. It is spread through the air when people who have an active TB infection cough, sneeze, or otherwise transmit respiratory fluids through the air.Most infections do not have symptoms, known as latent tuberculosis. About one in ten latent infections eventually progresses to active disease which, if left untreated, kills more than 50% of those so infected.

Signs and Symptoms

Extrapulmonary TB occurs when tuberculosis develops outside of the lungs, although extrapulmonary TB may coexist with pulmonary TB, as well.

General signs and symptoms include fever, chills, night sweats, loss of appetite, weight loss, and fatigue.Significant nail clubbing may also occur.

CAUSES

The main cause of TB is Mycobacterium tuberculosis, a small, aerobic, nonmotile bacillus.The high lipid content of this pathogen accounts for many of its unique clinical characteristics.It divides every 16 to 20 hours, which is an extremely slow rate compared with other bacteria, which usually divide in less than an hour. Mycobacteria have an outer membrane lipid bilayer.If a Gram stain is performed, MTB either stains very weakly Gram positive or does not retain dye as a result of the high lipid and mycolic acid content of its cell wall.MTB can withstand weak disinfectants and survive in a dry state for weeks. In nature, the bacterium can grow only within the cells of a host organism, but M. tuberculosis can be cultured in the laboratory.

TRANSMISSION

When people with active pulmonary TB cough, sneeze, speak, sing, or spit, they expel infectious aerosol droplets 0.5 to 5.0 µm in diameter. A single sneeze can release up to 40,000 droplets.Each one of these droplets may transmit the disease, since the infectious dose of tuberculosis is very small (the inhalation of fewer than 10 bacteria may cause an infection.

PREVENTION

Tuberculosis prevention and control efforts primarily rely on the vaccination of infants and the detection and appropriate treatment of active cases.The World Health Organization has achieved some success with improved treatment regimens, and a small decrease in case numbers.

VACCINES

The only available vaccine as of 2011 is bacillus Calmette-Guérin.In children it decreases the risk of getting the infection by 20% and the risk of infection turning into disease by nearly 60%.

SALMONELLA

 There are only two species of Salmonella, Salmonella bongori and Salmonella enterica, of which there are around six subspecies and innumerable serovars. The genus Escherichia, which includes the species E.coli belongs to the same family.

Salmonellae are found worldwide in both cold-blooded and warm-blooded animals, and in the environment. They cause illnesses such as typhoid fever, paratyphoid fever, and food poisoning.

Detection, culture and growth conditions

Most subspecies of Salmonella produce hydrogen sulfide,which can readily be detected by growing them on media containing ferrous sulfate, such as is used in the triple sugar iron test TSI.Most isolates exist in two phases: a motile phase I and a nonmotile phase II. Cultures that are nonmotile upon primary culture may be switched to the motile phase using a Cragie tube.

Salmonella can also be detected and subtyped using PCR rom extracted salmonella DNA, various methods are available to extract salmonella DNA from target samples.

Mathematical models of salmonella growth kinetics have been developed for chicken, pork, tomatoes, and melons.Salmonella reproduce asexually with a cell division rate of 20 to 40 minutes under optimal conditions.

LEPROSY

Leprosy is a chronic infection caused by the bacteria Mycobacterium leprae and Mycobacterium lepromatosis.Initially, infections are without symptoms and typically remain this way for 5 to as long as 20 years

SIGNS AND SYMPTOMS

Skin lesions light or dark patches are the primary external sign.If untreated, leprosy can progress and cause permanent damage to the skin, nerves, limbs, and eyes. Contrary to folklore, leprosy does not cause body parts to fall off, although they can become numb or diseased as a result of secondary infections; these occur as a result of the body's defenses being compromised by the primary disease.Secondary infections, in turn, can result in tissue loss causing fingers and toes to become shortened and deformed, as cartilage is absorbed into the body.

CAUSE

An intracellular, acid-fast bacterium, M. leprae is aerobic and rod-shaped, and is surrounded by the waxy cell membrane coating characteristic of the Mycobacterium genus.

Due to extensive loss of genes necessary for independent growth, M. leprae and M. lepromatosis are obligate intracellular pathogens, and unculturable in the laboratory, a factor that leads to difficulty in definitively identifying the organism under a strict interpretation of Koch's postulates.The use of nonculture-based techniques such as molecular genetics has allowed for alternative establishment of causation.

Leprosy be transmitted to humans by armadillos and may be present in three species of non-human primates.

Two exit routes of M. leprae from the human body often described are the skin and the nasal mucosa, although their relative importance is not clear. Lepromatous cases show large numbers of organisms deep in the dermis, but whether they reach the skin surface in sufficient numbers is doubtful.

PREVENTION/ TREATMENT

Medications can decrease the risk of those living with people with leprosy from acquiring the disease and likely those with whom people with leprosy come into contact outside the home.However, concerns are known of resistance, cost, and disclosure of a person's infection status when doing follow-up of contacts. Therefore, the WHO recommends that people who live in the same household be examined for leprosy and only be treated if symptoms are present.

Multidrug therapy remains highly effective, and people are no longer infectious after the first monthly dose.It is safe and easy to use under field conditions due to its presentation in calendar blister packs.Relapse rates remain low, and no resistance to the combined drugs is seen.

LEPTOSPIROSIS

Leptospirosis is an infection caused by corkscrew-shaped bacteria called Leptospira. Symptoms can range from none to mild such as headaches, muscle pains, and fevers; to severe with bleeding from the lungs or meningitis.If the infection causes the person to turn yellow, have kidney failure and bleeding it is then known as Weil's disease.If it causes lots of bleeding from the lungs it is known as severe pulmonary haemorrhage syndrome.

SIGNS AND SYMPTOMS

 Leptospirosis is a biphasic disease that begins suddenly with fever accompanied by chills, intense headache, severe myalgia muscle ache, abdominal pain, conjunctival suffusion red eye, and occasionally a skin rash.The symptoms appear after an incubation period of 7–12 days. The first phase acute or septicemic phase ends after 3–7 days of illness.The disappearance of symptoms coincides with the appearance of antibodies against Leptospira and the disappearance of the bacteria from the bloodstream. The patient is asymptomatic for 3–4 days until the second phase begins with another episode of fever.The hallmark of the second phase is meningitis inflammation of the membranes covering the brain.

CAUSE

Leptospirosis is caused by spirochaete bacteria belonging to the genus Leptospira. 21 species of Leptospira have been identified.13 species cause disease or have been detected in human cases.

Leptospira are also classified based on their serovar. About 250 pathogenic serovars of Leptospira are recognized. The diverse sugar composition of the lipopolysaccharide on the surface of the spirochete is responsible for the antigenic difference between serovars. Antigenically related serovars are grouped into 24 serogroups, which are identified using the microscopic agglutination test MAT. A given serogroup is often found in more than one species, suggesting that the LPS genes that determine the serovar are exchanged between species

Leptospirosis is transmitted by the urine of an infected animal and is contagious as long as the urine is still moist. Although Leptospira has been detected in reptiles and birds, only mammals are able to transmit the bacteria to humans and other animals.Rats, mice, and moles are important primary hosts but a wide range of other mammals including dogs, deer, rabbits, hedgehogs, cows, sheep, raccoons, opossums, skunks, and certain marine mammals carry and transmit the disease as secondary hosts.

PREVENTION/ TREATMENT

Effective rat control and avoidance of urine contaminated water sources are essential preventive measures. Human vaccines are available in a few countries, including Cuba and China.Currently, no human vaccine is available in the US. Animal vaccines only cover a few strains of the bacteria. Dog vaccines are effective for at least one year.

Effective antibiotics include penicillin G, ampicillin, amoxicillin and Doxycycline. In more severe cases cefotaxime or ceftriaxone should be preferred.

Glucose and salt solution infusions may be administered; dialysis is used in serious cases. Elevations of serum potassium are common and if the potassium level gets too high special measures must be taken. Serum phosphorus levels may likewise increase to unacceptable levels due to renal failure.

JAPANESE ENCEPHALITIS

Encephaliti is a disease caused by the mosquito-borne Japanese encephalitis virus.The Japanese encephalitis virus is a virus from the family Flaviviridae.

SIGNS AND SYMPTOMS

Severe rigors may mark the onset of this disease in humans. Fever, headache and malaise are other non-specific symptoms of this disease which may last for a period of between 1 and 6 days. Signs which develop during the acute encephalitic stage include neck rigidity, cachexia, hemiparesis, convulsions and a raised body temperature between 38–41 °C 100.4–105.8 °F. Mental retardation developed from this disease usually leads to coma.

PREVENTION

A formalin-inactivated mouse-brain derived vaccine was first produced in Japan in the 1930s and was validated for use in Taiwan in the 1960s and in Thailand in the 1980s. The widespread use of vaccine and urbanization has led to control of the disease in Japan, Korea, Taiwan and Singapore. The high cost of this vaccine, which is grown in live mice, means that poorer countries have not been able to afford to give it as part of a routine immunization program.

TYPHOID FEVER

Typhoid fever, also known simply as typhoid, is a symptomatic bacterial infection due to Salmonella Typhi.Symptoms may vary from mild to severe and usually begin six to thirty days after exposure.Often there is a gradual onset of a high fever over several days.

SIGN & SYMPTOMS

In the first week, the body temperature rises slowly, and fever fluctuations are seen with relative bradycardia Faget sign, malaise, headache, and cough. A bloody nose epistaxis is seen in a quarter of cases, and abdominal pain is also possible. A decrease in the number of circulating white blood cells leukopenia occurs with eosinopenia and relative lymphocytosis; blood cultures are positive for Salmonella typhi or S. paratyphi. The Widal test is negative in the first week.

In the second week of the infection, the patient lies prostrate with high fever in plateau around 40 °C (104 °F) and bradycardia sphygmothermic dissociation or Faget sign, classically with a dicrotic pulse wave. Delirium is frequent, often calm, but sometimes agitated. This delirium gives to typhoid the nickname of "nervous fever". Rose spots appear on the lower chest and abdomen in around a third of patients. Rhonchi are heard in lung bases.

The abdomen is distended and painful in the right lower quadrant, where borborygmi can be heard. Diarrhea can occur in this stage: six to eight stools in a day, green, comparable to pea soup, with a characteristic smell. However, constipation is also frequent. The spleen and liver are enlarged (hepatosplenomegaly) and tender, and liver transaminases are elevated. The Widal test is strongly positive, with antiO and antiH antibodies. Blood cultures are sometimes still positive at this stage.

CAUSES

The bacterium that causes typhoid fever may be spread through poor hygiene habits and public sanitation conditions, and sometimes also by flying insects feeding on feces.

PREVENTION

Two typhoid vaccines are licensed for use for the prevention of typhoid the liveR, oral Ty21a vaccine sold as Vivotif by Crucell Switzerland AG) and the injectable typhoid polysaccharide vaccine (sold as Typhim Vi by Sanofi Pasteur and 'Typherix by GlaxoSmithKline. Both are 50 to 80% protective and are recommended for travellers to areas where typhoid is endemic. Boosters are recommended every five years for the oral vaccine and every two years for the injectable form. An older, killed-whole-cell vaccine is still used in countries where the newer preparations are not available, but this vaccine is no longer recommended for use because it has a higher rate of side effects (mainly pain and inflammation at the site of the injection.

TREATMENT

Antibiotics, such as ampicillin, chloramphenicol, trimethoprim-sulfamethoxazole, amoxicillin, and ciprofloxacin, have been commonly used to treat typhoid fever in microbiology.Treatment of the disease with antibiotics reduces the case-fatality rate to about 1%.

FOOD POISONING

People infected with food-borne organisms may be symptom-free or may have symptoms ranging from mild intestinal discomfort to severe dehydration and bloody diarrhea. Depending on the type of infection, people can even die as a result of food poisoning

CAUSES

Food poisoning can affect one person or a group of people who all ate the same food. It is more common after eating at picnics, school cafeterias, large social functions, or restaurants.

When germs get into the food, it is called contamination. This can happen in different ways:

• Meat or poultry can come into contact with bacteria from the intestines of an animal that is being processed.
• Water that is used during growing or shipping can contain animal or human waste.
• Food may be handled in an unsafe way during preparation in grocery stores, restaurants, or homes.

SIGNS AND SYMPTOMS

Symptoms from the most common types of food poisoning will often start within 2 - 6 hours of eating the food. That time may be longer or shorter, depending on the cause of the food poisoning.

TREATMENT

Most of the time, you will get better in a couple of days. The goal is to ease symptoms and make sure your body has the proper amount of fluids.

Getting enough fluids and learning what to eat will help keep you comfortable. You may need to:

• Manage the diarrhea
• Control nausea and vomiting
• Get plenty of rest

CHOLERA

Cholera is an acute intestinal infection caused by ingestion of food or water contaminated with the bacterium Vibrio cholerae. It has a short incubation period, from less than one day to five days, and produces an enterotoxin that causes a copious, painless, watery diarrhoea that can quickly lead to severe dehydration and death if treatment is not promptly given. Vomiting also occurs in most patients.

SIGNS AND SYMPTOMS

The primary symptoms of cholera are profuse diarrhea and vomiting of clear fluid.These symptoms usually start suddenly, half a day to five days after ingestion of the bacteria.The diarrhea is frequently described as rice water in nature and may have a fishy odor.An untreated person with cholera may produce 10 to 20 litres 3 to 5 US gal of diarrhea a day.Severe cholera, without treatment, kills about half of affected individuals.If the severe diarrhea is not treated, it can result in life-threatening dehydration and electrolyte imbalances.Estimates of the ratio of asymptomatic to symptomatic infections have ranged from 3 to 100.Cholera has been nicknamed the "blue death" because a person's skin may turn bluish-gray from extreme loss of fluids.

CAUSE

Cholera is typically transmitted to humans by either contaminated food or water. Most cholera cases in developed countries are a result of transmission by food, while in the developing world it is more often water.Food transmission occurs when people harvest seafood such as oysters in waters infected with sewage, as Vibrio cholerae accumulates in zooplankton and the oysters eat the zooplankton.

PREVENTION

Sterilization: Proper disposal and treatment of infected fecal waste water produced by cholera victims and all contaminated materials clothin, bedding are essential. All materials that come in contact with cholera patients should be sanitized by washing in hot water, using chlorine bleach if possible. Hands that touch cholera patients or their clothing, bedding, etc., should be thoroughly cleaned and disinfected with chlorinated water or other effective antimicrobial agents.

Sewage: antibacterial treatment of general sewage by chlorine, ozone, ultraviolet light or other effective treatment before it enters the waterways or underground water supplies helps prevent undiagnosed patients from inadvertently spreading the disease.

Sources: Warnings about possible cholera contamination should be posted around contaminated water sources with directions on how to decontaminate the water (boiling, chlorination etc.) for possible use.

Water purification: All water used for drinking, washing, or cooking should be sterilized by either boiling, chlorination, ozone water treatment, ultraviolet light sterilization e.g. by solar water disinfection,or antimicrobial filtration in any area where cholera may be present. Chlorination and boiling are often the least expensive and most effective means of halting transmission. Cloth filters or sari filtration, though very basic, have significantly reduced the occurrence of cholera when used in poor villages in Bangladesh that rely on untreated surface water. Better antimicrobial filters, like those present in advanced individual water treatment hiking kits, are most effective. Public health education and adherence to appropriate sanitation practices are of primary importance to help prevent and control transmission of cholera and other diseases.

HEPATITIS A

Hepatitis A is an acute infectious disease of the liver caused by the hepatitis A virus HAV.Many cases have little or no symptoms especially in the young.The time between infection and symptoms, in those who develop them, is between two and six weeks. When there are symptoms they typically last eight weeks and may include: nausea, vomiting, diarrhea, yellow skin, fever, and abdominal pain.Around 10–15% of people experience a recurrence of symptoms during the six months after the initial infection.Acute liver failure may rarely occur with this being more common in the elderly.

                                         A case of jaundice caused by hepatitis A

SIGN & SYMPTOMS

Fatigue
Fever
Nausea
Appetite loss
Jaundice, a yellowing of the skin or whites of the eyes due to hyperbilirubinemia
Bile is removed from blood stream and excreted in urine, giving it a dark amber colour
Diarrhea
Light, or clay-coloured faeces

PREVENTION

There are two types of vaccines: one containing inactivated hepatitis A virus, and another containing a live but attenuated virus.Both provide active immunity against a future infection. The vaccine protects against HAV in more than 95% of cases for longer than 25 years.^[31] In the US the vaccine was first phased in 1996 for children in high-risk areas, and in 1999 it was spread to areas with elevating levels of infection.

TREATMENT

There is no specific treatment for hepatitis A. Sufferers are advised to rest, avoid fatty foods and alcohol these may be poorly tolerated for some additional months during the recovery phase and cause minor relapses eat a well-balanced diet, and stay hydrated.

Meningitis

Meningitis is a relatively rare infection that affects the delicate membranes called meninges (men-in'-jeez that cover the brain and spinal cord. Bacterial meningitis can be contagious among people in close contact.

Viral meningitis tends to be less severe, and most people recover completely.

Causes

Meningitis is almost always caused by a bacterial or viral infection that began elsewhere in the body, such as in the ears, sinuses, or upper respiratory tract. Less common causes of meningitis include fungal infection, autoimmune disorders, and medications.

 Bacterial meningitis is caused by any one of several bacteria. Neisseria meningitidis or "meningococcus" is common in children and young adults, and Streptococcuspneumoniae or "pneumococcus" is another common cause in children and adults. Haemophilus influenzae type b Hib was a common cause of meningitis in infants and young children until the Hib vaccine was introduced for infants. Neisseria meningitidis and Streptococcus pneumoniae account for most of the bacterial meningitis cases in the U.S. Vaccines are available for both Neisseria meningitidis and 

Streptococcus pneumoniae. They're recommended for all children and adults at special risk.

Tests

Complete blood count, to check for signs of infection.

Blood culture, to check for infections.

Urine test, to check for infection in the urinary tract.

Chest X-ray, to check for lung infections.

Biopsy of a skin rash.CT scan or MRI, to look for swelling of brain tissue or for complications such as brain damage.

HIV/AIDS disease

The human immunodeficiency virus HIV is a lentivirus a subgroup of retrovirus that causes the acquired immunodeficiency syndrome AIDS a condition in humans in which progressive failure of the immune system allows life-threateningopportunistic infections and cancers to thrive. Without treatment, average survival time after infection with HIV is estimated to be 9 to 11 years, depending on the HIV subtype.

 Many HIV-positive people are unaware that they are infected with the virus.For example, in 2001 less than 1% of the sexually active urban population in Africa had been tested, and this proportion is even lower in rural populations.Furthermore, in 2001 only 0.5% of pregnant women attending urban health facilities were counselled, tested or receive their test results.Again, this proportion is even lower in rural health facilities.Since donors may therefore be unaware of their infection, donor blood and blood products used in medicine and medical research are routinely screened for HIV.

BLACK DEATH

The Black Death was one of the most devastating pandemics in human history, resulting in the deaths of an estimated 75 to 200 million people and peaking in Europe in the years 1346–1353.Although there were several competing theories as to the etiology of the black death, analysis of DNA from victims in northern and southern Europe published in 2010 and 2011 indicates that the pathogen responsible was the Yersinia pestis bacterium, probably causing several forms of plague.

Origins of the disease

The Black Death is thought to have originated in the arid plains of Central Asia, where it then travelled along the Silk Road, reaching the Crimea by 1343.From there, it was most likely carried by Oriental rat fleas living on the black rats that were regular passengers on merchant ships. Spreading throughout the Mediterranean and Europe, the Black Death is estimated to have killed 30 to 60% of Europe's total population.In total, the plague reduced the world population from an estimated 450 million down to 350–375 million in the 14th century.

Symptoms

Contemporary accounts of the plague are often varied or imprecise. The most commonly noted symptom was the appearance of buboes or gavocciolos in the groin, the neck and armpits,which oozed pus and bled when opened.


A hand showing how acral gangrene of the fingers due to bubonic plague causes the skin and flesh to die and turn black.

Chikungunya (Malaysia)

Chikungunya fever is a viral disease transmitted to humans by the bite of infected mosquitoes. Chikungunya virus is a member of the alphavirus genus, in the family Togaviridae. Chikungunya fever is diagnosed based on symptoms, physical findings, laboratory testing, and the possibility of exposure to infected mosquitoes.

Symptoms

Chikungunya virus infection can cause a debilitating illness, most often characterized by fever, headache, fatigue, nausea, vomiting, muscle pain, rash, and joint pain. The term ‘chikungunya’ means ‘that which bends up’ in the Kimakonde language of Mozambique.

Can Chikungunya cause death?

In Malaysia, Chikungunya has never been reported as causing haemorrhage bleeding or death. However, some patients experience prolonged symptoms. Aged patients could suffer from recurrent joint aches ranging from several months to a year.

Vaccine

Currently, no approved vaccines are available. A phase-II vaccine trial used a live, attenuated virus, to develop viral resistance in 98% of those tested after 28 days and 85% still showed resistance after one year.However, 8% of people reported transient joint pain,and attenuation was found to be due to only two mutations in the E2 glycoprotein.Alternative vaccine strategies have been developed, and show efficacy in mouse models, but have so far not reached clinical trials.

BLIGHT DISEASE 

Blight refers to a specific symptom affecting the plant in response to infection by a pathogenic organism.It is simply a rapid and complete chlorosis, browning, then death of plant tissues such as leaves, branches, twigs or floral organs.
Many diseases that primarily exhibit this symptom are called blights

Notable examples are:

Late blight of potato, caused by the water mold.Phytophthora infestans Mont de Bary, the disease which led to the Great Irish Famine

DIFFERENT TYPE PF PLAGUE

Bubonic Plague

When a flea bites a human and contaminates the wound with regurgitated blood, the plague carrying bacteria are passed into the tissue.Y. pestis can reproduce inside cells, so even if phagocytosed, they can still survive. Once in the body,the bacteria can enter the lymphatic system, which drains interstitial fluid. Plague bacteria secrete several toxins, one of which is known to cause dangerous beta-adrenergic blockade.

Septicemic Plague

Lymphatics ultimately drain into the bloodstream, so the plague bacteria may enter the blood and travel to almost any part of the body. In septicemic plague, bacterial endotoxins cause disseminated intravascular coagulation DIC, causing tiny clots throughout the body and possibly ischaemic necrosis tissue death due to lack of circulation/perfusion to that tissue from the clots.DIC results in depletion of the body's clotting resources,so that it can no longer control bleeding. 

Pneumonic Plague

The pneumonic form of plague arises from infection of the lungs. It causes coughing and sneezing and thereby produces airborne droplets that contain bacterial cells and are likely to infect anyone inhaling them. The incubation period for pneumonic plague is short, usually two to four days, but sometimes just a few hours. 

Pharyngeal plague

This is an uncommon form of plague that resembles tonsillitis found in cases of close contact of patients with other forms of plague.

Meningeal Plague

This form of plague occurs when bacteria cross the blood-brain barrier, leading to infectious meningitis.