Malaria is a life-threatening blood disease caused by parasites transmitted to humans through the bite of the Anopheles mosquito. Once an infected mosquito bites a human and transmits the parasites, those parasites multiply in the host's liver before infecting and destroying red blood cells.
The disease can be controlled and treated if diagnosed early on. Unfortunately, this is not possible in some areas of the world lacking in medical facilities, where malaria outbreaks can occur.
Researchers are working hard on improving the prevention of malarial infection, early diagnosis and treatment, with just one malaria vaccine close to being licensed so far
Diabetes, often referred to by doctors as diabetes mellitus, describes a group of metabolic diseases in which the person has high blood glucose (blood sugar), either because insulin production is inadequate, or because the body's cells do not respond properly to insulin, or both. Patients with high blood sugar will typically experience polyuria (frequent urination), they will become increasingly thirsty (polydipsia) and hungry (polyphagia).
Typhoid is an infection caused by the bacteria Salmonella typhimurium. The bacterium lives in the intestines and bloodstream of humans. It is spread between individuals by direct contact with the feces of an infected person.
No animals carry this disease, so transmission is always human to human.
If untreated, around 1 in 4 cases of typhoid end in death. If treatment is given, less than 4 in 100 cases are fatal.
S. typhi enters through the mouth and spends 1-3 weeks in the intestine. After this time, it makes its way through the intestinal wall and into the bloodstream.
From the bloodstream, it spreads into other tissues and organs. The immune system of the host can do little to fight back because S. typhi can live within the host's cells, safe from the immune system.
Typhoid is diagnosed by detecting the presence of S. typhi via blood, stool, urine, or bone marrow sample.
Symptoms of typhoid
Symptoms normally begin 6-30 days after exposure to the bacteria. The two major symptoms of typhoid are fever and rash. Typhoid fever is particularly high, gradually increasing over several days up to 104 degrees Fahrenheit.
The rash, which does not affect every patient, consists of rose-colored spots, particularly on the neck and abdomen.
Other symptoms can include weakness, abdominal pain, constipation, and headaches; rarely, symptoms might include confusion, diarrhea, and vomiting (but not normally severe).
In serious, untreated cases, the bowel can become perforated; this can lead to peritonitis (an infection of the tissue that lines the inside of the abdomen), which can be very serious indeed.5
Note: paratyphoid has similar symptoms to typhoid but is caused by Salmonella enterica. Both conditions are of similar severity.
How to avoid typhoid
Countries with less access to clean water and washing facilities typically have a higher number of typhoid cases.
People traveling in Africa, South America, and Asia (India in particular) should be vigilant.
Typhoid is spread by contact and ingestion of infected human feces. This can happen through an infected water source or when handling food.
The following are some general rules to follow when traveling to help minimize the chance of typhoid infection:
Drink bottled water (preferably carbonated)
If bottled water cannot be sourced, ensure water is heated on a rolling boil for at least one minute before consuming
Be wary of eating anything that has been handled by someone else
Avoid eating at street food stands, and only eat food that is still piping hot
Do not have ice in drinks
Avoid raw fruit and vegetables and peel fruit yourself (do not eat the peel)
Typhoid vaccination[Typhoid vaccine]
If traveling to an area where typhoid is prevalent, vaccination is recommended.
Before traveling to a high-risk area, getting vaccinated against typhoid fever is recommended. This can be achieved by oral medication or a one-off injection:
Oral - live, attenuated vaccine. Consists of 4 tablets - one taken every other day, the last of which is taken 1 week before travel.
Shot - inactivated vaccine, administered 2 weeks before travel.
Note: vaccines are not 100 percent effective and caution should still be exercised when eating and drinking.
Vaccination should not be started if the individual is currently ill or if they are under 6-years of age. Anyone with HIV should not take the live, oral dose.
There may be side effects to the vaccine:
Shot: fever (1 in 100 cases)
Shot: headache (1 in 30 cases)
Shot: redness or swelling at the site of injection (1 in 15 cases)
Oral: fever or headache (1 in 20 cases)
Oral: stomach pain, nausea, vomiting, rash (rare)
Even when the symptoms of typhoid have passed, it is still possible to be carrying the bacteria. As a result, it is difficult to entirely stamp out the disease because carriers whose symptoms have finished may stop showing caution when washing food or interacting with others.
Although there are two types of typhoid vaccine available, a more powerful vaccine is still needed. The live, oral version of the vaccine is the strongest of the two; after 3 years, it still protects individuals from infection 73 percent of the time. However, this vaccine has more side effects.
The current vaccines are not always effective, and because typhoid is so prevalent in poorer countries, more research needs to be done to find better ways of preventing its spread.
Regardless of efficacy, treating children in risky areas with current vaccines would be of benefit. Unfortunately, because of their relatively high cost, governments are reluctant to adopt them.
Treatment of typhoid
The only effective treatment for typhoid is antibiotics. The most commonly used are ciprofloxacin (for non-pregnant adults) and ceftriaxone. Other than antibiotics, it is sensible to rehydrate by drinking adequate water.
In more severe cases, where the bowel has become perforated, surgery may be required.
Typhoid antibiotic resistance
As with a number of other bacterial diseases, the problem of antibiotic resistance is impacting the choice of drugs available to typhoid sufferers. In recent years, typhoid has become resistant to trimethoprim-sulfamethoxazole and ampicillin.
Ciprofloxacin, one of the key medications for typhoid, is also suffering a similar fate. Some studies have found Salmonella typhimurium resistance rates to be around 35 percent.
Some individuals are asymptomatic carriers of typhoid, meaning that they harbor the bacteria but suffer no ill effects. As many as 1 in 6 people have the capacity to be a silent carrier.
These individuals are particularly dangerous within high-risk populations.
Mary Mallon, better known as "Typhoid Mary" (1869-1938), was the first known asymptomatic typhoid carrier in the U.S. During her career as a cook, Mary is thought to have infected at least 51 people, three of whom died.
Mary, an Irish immigrant, worked as a cook for a string of families, infecting numerous members of each household before moving on to work elsewhere.
Mallon was eventually tracked down and quarantined. In all, she spent the best part of three decades in forced isolation. She died, aged 69, of pneumonia.
Macrophages and S. typhi
Research has revealed that S. typhi can live within macrophages, a part of the immune system. Macrophages are normally responsible for killing pathogens, but S. typhi can avoid their attack by replicating inside them.
Scientists are slowly untangling how the bacteria are capable of this feat.