Bladder cancer in Nigeria: Why snails matter (1)
Globally, there were about 430,000 new cases of bladder cancer and about 165,000 deaths from bladder cancer in 2012. In Nigeria, there are about 1000 new cases of bladder cancer and over 600 deaths annually. This implies that bladder cancer kills two Nigerians every day.
This number excludes so many victims who die of the ailment undiagnosed, due to poor diagnostic facilities especially in rural areas where it is prevalent. A recent well-known casualty was Rt. Hon. Samuel Ajayi Adesina, Speaker, Ondo State House of Assembly who died in February 2014, at the age of 56.
Unlike the western world where tobacco smoking is the main contributor to bladder cancer, the major risk factor in Nigeria is infection with a parasitic flatworm called Schistosoma hematobium. This infection is known as schistosomiasis (bilharziasis) or “snail fever”.
The infection usually occurs in childhood. Prevalence and intensity of infection increase with age, peaking in the 5 to 14 year age group.
If untreated, it could result in bladder cancer in adulthood with a peak age incidence in the late 40s and 50s. The majority of bladder cancer cases occur in farmers and fishermen living in regions along the river.
This relationship between schistosomiasis and bladder cancer explains why schistosomiasis is one of the targeted diseases of the Big War Against Cancer in Nigeria, the flagship focal cause of the Committee Encouraging Corporate Philanthropy (CECP-Nigeria). The first phase of the Big War is aimed at “Taking holistic health care to the grassroots” by raising funds to acquire and deploy 37 Mobile Cancer Centres (MCCs), one for each state and Abuja.
Schistosomiasis ranks second only to malaria as the most common parasitic disease. However, it is the most deadly Neglected Tropical Disease (NTD) – the so-called forgotten diseases of forgotten people – killing an estimated 280,000 people globally, each year.
About 700 million people are at risk of schistosomiasis in 78 countries, with almost 240 million people infected worldwide. The infection is prevalent in tropical and sub-tropical areas, in poor communities without potable water and adequate sanitation, with 90% of the burden occurring in Africa.
Sadly, Nigeria is thought to have the greatest number of people infected with schistosomiasis in the world, with approximately 20 million sufferers — mostly children. Delta, Edo, Plateau and Nasarawa states have the highest incidence.
For communities already burdened by poverty and ravaged by scourges such as malaria and tuberculosis, schistosomiasis is especially devastating, weakening the body’s resistance to other infections and preventing children from reaching their full potential.
Schistosomiasis is transmitted by contact with contaminated fresh water (lakes and ponds, rivers, dams) inhabited by snails carrying the Schistosoma parasite. Swimming, bathing, fishing and domestic chores such as laundry can put people at risk of contracting the disease.
Hygiene and play habits make children especially vulnerable to infection. Larvae emerge from the snails and swim in the water until they come into contact with and penetrate human skin.
Once inside the body, the larvae develop into worms, which live together in the blood vessels for years. Female worms release thousands of eggs which are passed out of the body in the urine and feces.
If people urinate or defecate in bodies of freshwater, the eggs migrate to snails where they eventually hatch and begin the cycle again. Some Schistosoma eggs, however, remain trapped in the body and migrate to specific organs where they can inflict major damage. Urinary schistosomiasis causes scarring of the bladder and kidneys, and can lead to bladder cancer.
For the avoidance of doubt, it is important to stress that neither snail farming nor snail consumption puts a person or community at the risk of schistosomiasis or bladder cancer.
Symptoms of urinary schistosomiasis include initial itching and rash at infection site (“swimmer’s itch”), frequent, painful or bloody urine and lymph node enlargement. Ironically, the incidence of schistosomiasis is so high in some communities in Nigeria that youths regard the bloody urine passed at some stage of the disease as a sign of attainment of maturity, a rite of passage from adolescence to adulthood. Therefore, they do not seek medical advice or treatment. Symptoms of bladder cancer are similar to that of schistosomiasis. The most common symptom of bladder cancer is blood in the urine which can happen suddenly and may come and go.
The mainstay of schistosomiasis control is treatment with a single dose of a tablet known as Praziquantel. Other control measures include improved sanitation, health education and control of freshwater snails.
Early and regular administration of Praziquantel reduces the occurrence, extent, severity, and long-term consequences of the disease. The goal should be to achieve a minimum target of regular administration of Praziquantel to at least 75% of all school-age children and at risk special groups.
Schistosomiasis outbreaks can be identified by mapping the rates of blood in the urine of school-age children. If the rates are high, the drug is distributed to the entire community at risk. Annual dosing of Praziquantel is recommended for areas at high risk for re-infection, and to help reduce the severity of symptoms in chronic sufferers.
Merck (the manufacturer of Praziquantel) has committed to donate 250 million tablets of praziquantel annually, at a cost of US$ 23 million per year. So far, over 100 million tablets have been donated, and over 28 million children have been treated.
The major control effort in Nigeria has been through the Carter Centre, an America-based organization, which has been working in Delta, Nasarawa, Edo, and Plateau states since 1999. The current coverage of the schistosomiasis control programme in Nigeria is less than six per cent in spite of the fact that the drug has been donated free of charge by Merck. According to data released by WHO, Nigeria has one of the worst coverage in the world and compares unfavourably with better coverage in countries like Burkina Faso (96.4%), Togo (94.80%), among others.
Little wonder then, a study in Nigeria, showed nearly five fold increase in the number of bladder cancer cases between 1999 and 2004. On the other hand, the use of this drug, as well as lower infection rates due to urbanization, is thought to have led to a substantial decrease in incidence of schistosoma-associated bladder cancer in Egypt over the past few decades.
•To be continued tomorrow.
•Dr. Nzelu (Executive Secretary, CECP-Nigeria) can be reached via email@example.com or firstname.lastname@example.org
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