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Forgotten Disease: Kala Azar | part 6/13

This is the fifth disease I present in the forgotten disease series, in which I in layman’s terms present Kala Azar.

Kala Azar: visceral leishmaniasis

Now, do not shy away just because leishmaniasis is difficult to remember. Kala Azar is the more colloquial name for this parasitic disease, which is caused by 20+ species of a parasitic protozoa known under the genus Leishmania. It is a big burden in the majority world, often spreading through virtually unstoppable epidemics, such as a ten-year long epidemic in Sudan’s Western Upper Nile province, killing more than 100 000 people between 1984 and 1994.

Sickness

Kala Azar is, as stated, the name for visceral leishmaniasis (VL), but there are more leishmaniasises diseases, viz. cutaneous leishmaniasis, diffuse cutaneous leishmaniasis, and mucocutaneous leishmaniasis. While cutaneous leishmaniasis is the most common type, it is the visceral type that is the most serious with a death rate of 100%.  The cutaneous type mainly causes an open sore at the site of the parasite’s bite. VL is the second worst parasitic killer in the world, with 500 000-2 000 000 (numbers ambiguous!)  infections per year, only the malaria plasmodium kills more people.

The parasite is transported via a vector, the female sandfly, that enters the body through bites. The sandfly pick the parasite up from biting an infected person and then carries it to the person it bites the next. VL affects the entire body, with symptoms occuring 2-8 months after the bite and lead to deadly complications as the parasites compromises the immune system by killing off immune system cells. Symptoms include difficulty breathing, slow-healing skin sores, stuffy or runny nose with nosebleeds, difficulty swallowing, and ulcers in mouth, tongue, gums, lips, and nose. In children, further symptoms are coughing, diarrhoea, fever, and vomiting. Adults have less acute symptoms, e.g. fatigue, lethargy, and loss of appetite. All symptoms may increase as disease progresses. Death often occur because of opportunistic disease, within 2 years time.

Poor areas run higher risks of being hit by epidemics, and previously unexposed populations run even higher risks. In 88 countries the disease is endemic, killing around 60 000 people per year. Over 90% of all VL cases occur in Bangladesh, India, Nepal, Brazil, and Sudan.

Detection

Physical exams show enlarged spleen, liver, and lymph nodes. Checking for skin sores may also indicate Kala Azar. There are numerous manners to diagnose the condition, e.g. spleen/bone marrow/lymph node/skin biopsies. Testing antibody presence and blood values can also indicate the disease. Disfigurement of the face is a more serious effect.

Prevention

Today there is no vaccine for the disease, although in February of 2012 the world’s first clinical trial of a potential vaccine was launched by the Seattle-based Infectious Disease Research Institute. The vaccine is a recombinant form of two fused Leishmania proteins. Two phase 1 trials are conducted, one in Washington state and one in India. Otherwise, there is unfortunately little international cooperation to fight this disease.

Easy preventative measures are using mesh netting around the bed, screening of windows, and wearing protective clothing and insect repellent. Public measures can be initiated to control the sandfly populations and hence restrict the spread of the disease.

Treatment

According to Médecins Sans Frontières, the most common treatment for VL was developed already in the 1930s. Drugs called antimony-containing compounds are the main bulk of medicines used. They are sodium stibogluconate (SSG) which is taken via intramuscular injection over at least a month. This substance exists under several brand names. Fortunately, generics of exist, forcing price drops that make the drug affordable for relief organisations. The drug is allegedly not that bad, but growing resistance is a problem – in India up to 65% of patients are resistant. In addition, the month-long period is painful and in some patients toxic reactions occur.

Cure rates are high, and treatment should begin before the immune defence is damaged.

Why dangerous?

  • Is a reliable killer, attacking the infected person’s immune defence to leave him or her open to opportunistic infection that kills within 2 years.
  • The most deadly type has a mortality rate, if untreated, at about 100% and no prevention exists.
  • Endemic in 88 countries, affecting up to 2 million people, it is a potential world-wide killer, and is today already the second largest parasite killer after malaria.
  • No vaccine exists, and since VL has been registered in all continents apart from Australia and Antarctica, all of us risk getting infected.

***

Sources

http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0002362/

http://www.doctorswithoutborders.org/news/issue.cfm?id=2394

http://en.wikipedia.org/wiki/Visceral_leishmaniasis

http://en.wikipedia.org/wiki/Visceral_leishmaniasis#Prevention

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