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Karnal bunt: a deadly menace
A FEW months ago the Federal Ministry of Agriculture & Livestock and the National Agriculture Research Council (NARC) rejected a consignment of much-needed 1.5 million tones of wheat worth $33 million from Australia, explaining that it was contaminated with certain viruses. Consequently, a severe shortage of wheat was experienced in Pakistan.
The crisis allowed profiteers to earn a huge sum of Rs three billion while the cost of wheat flour jumped from Rs12 to Rs20 per kg in a few days. It has been reported that Punjab banned inter-province transportation of wheat but huge quantities are being smuggled to Afghanistan from NWFP and Punjab with the help of the food department and police. A bag of wheat worth Rs800 is sold in Afghanistan at Rs2500-3200.
Interestingly enough, the rejected wheat was delivered to at least three other countries for human consumption. Recently, Pakistan imported one million ton of wheat from Russia, Australia and America through the Trade Corporation of Pakistan to meet the shortage in Sindh and NWFP but there has been relaxation regarding import conditions. Concerns have been raised about possible infection of wheat by fungus Karnal Bunt, named after the Indian town Karnal, where it was first detected and is now found in Middle East, Afghanistan and even Pakistan. The Ministry of Food and Agriculture and the Pakistan Agriculture Research Council have failed to point out this contamination and the fact that this wheat is not fit for human consumption.
Some years ago complete testing of most grains, spices and dry fruits, etc was carried out by the Pakistan Council for Scientific & Industrial Research, (PCSIR) along with the Commonwealth Bureau of Agriculture. They found that most edible grains, spices and dry fruits were infected with different kinds of fungus. Presently, the Karnal Bunt fungus has been found in Mexico and USA. The latter banned export of its wheat to at least 21 countries but, some countries including Japan agreed to accept this wheat. Pakistan has recently imported one million ton of wheat from Russia (150,000) USA (376,000) and Australia (400,000). The Prime Minister has considered importing another one million ton to build up stock in case of another shortage.
Furthermore, proper storage facilities for wheat and other grains are non-existent. In fact, most bagged grains are stored in bricks or thatched buildings where the quality often deteriorates due to lack of an aeration system, which either aggravates or initiates fungal infections. Scientific research has found that though the fungus Karnal Bunt is seed-borne, it is not harmful to humans and animals, so it is considered a minor grain infection with little risk, if quarantined in time.
However, the ability of Karnal Bunt to spread through air-borne spores is dangerous, for it can easily spread throughout the world (because of increased international trade). Karnal Bunt attacks only bread wheat and to a lesser extent, durum wheat and tactical but it infects only a few kernels in a head, that is, partial bunt. Unlike other bunts, it infects only the embryo and not the whole kernel. The spores of the said fungus attacks individual flowers in the head via air but, they can survive in the soil up to five years under warm conditions while some reports suggest that they can even survive freezing temperatures.
Most commonly, spores germinate in the soil during summer and spread through air currents or moisture. The fungus does not infect developing grains so partially bunted kernels germinate and produce a normal crop. The infected grain heads turn into smelly, black and powdery spots.
The climatic conditions in Pakistan ideally favour grain fungal infections. However, much of the blame lies with post-harvest handling, storage and transportation from one place to another in hot and humid conditions. Mycotoxins are their metabolite and there is a long list of these hazardous toxins. Aflatoxins are considered hepatocarcogenic. Aspergillus flavus and aspergillus parasiticus are two commonly known fungi or molds producing aflatoxin but fusarium has 24 different species producing mycotoxins like zearalenone, T-2, trococethiene and fusarsin, causing human health problems.
In fact, maize infected with fusarium moniliforme is responsible for rising cases of esophageal cancer in Africa and China. Cereal crops in many Asian, African and South American countries get infected with fusarium even when fed to livestock and poultry and negatively affect their growth but, some toxins when metabolized in their body, continue to remain in their meat, milk and eggs. Presently, a high incidence of human hepatitis has been related to the consumption of mycotoxins in the food chain. Blind hepatitis vaccinations under such circumstances are not expected to bear any results.
The severity of infection depends on the toxicity level, extent of exposure, age, synergetic effects of other chemical and toxins. Most aflatoxins are immunosuppressive, mutagenic, teratogenic and carcinogenic compounds. Outbreaks have been recorded in tropical countries where corn is their staple food with a mortality rate of 10-60 per cent. Aflatoxins have been detected in the blood of pregnant women, and in the breast milk of mothers consuming contaminated food in several African countries. Six different samples of corn from the local wholesale market showed the following mycotoxin contents by Elisa Test technique as shown in the table.
Action levels for human food are 20 ppb for total aflatoxins except 0.5 ppb for aflatoxin M1 in milk, according to US-FDA standards.
Mycotoxicosis often remains undetected in unless a large population is infected. Consequently, the demographic data of Pakistan has not indicated incidence of this disease. However, jaundice in children is common and so is hepatitis, caused by ingestion of aflatoxins. They are considered to be in the etiology of encephalopathy and fatty degeneration of viscera as commonly seen in countries with hot and humid climate. In China, mouldy sugarcane poisoning was reported in children and young people during 1972-88, with clinical symptoms of vomiting, dystonia, staring to one side, convulsions, spasms and coma.
Ochratoxins are metabolites of fusarium and penicillinium, often infecting cereals and bread and cause fatal renal diseases. Cases have been reported from Tunisia, Croatia, Bosnia-Herzegovina, Yugoslavia, Bulgaria and Romania. Trochocethene toxicity causes depression of immune response to vaccination, nausea and vomiting resulting from ingestion of bread containing toxic flour or rice.
Fumonisins are mycotoxins produced by fusarium monoloforme infesting corn. In India, an outbreak was reported involving 27 villages where people consumed harvested maize and sorghum left in fields during the monsoon season. It caused abdominal pain and diarrhea and was associated with esophageal cancer. Mycotoxins have also been associated with perinatal deaths, abortion, multiple fetuses and induced labour in early stage of pregnancy in Norway. They can be inhaled during harvesting crops and cause burning eyes, throat and chest irritation, cough and fever.
Sadly, most food grains in Pakistan are infected with various fungi and moulds but precautions have not been taken in this regard. Thus, efforts should be made to curb this menace before it rises to endemic proportions, causing massive death and destruction throughout the country.
The writer
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