Cockroaches are tropical pests but also found in temperate climates but in warm corners of the house. They are nocturnal in behaviour but hide in cracks in walls, kitchen cabinets, door frames, furniture, cupboards, television, radio and bathrooms during the day. They are also found in septic tanks and sewers, drains and refuse dumps.
Cockroaches feed on human food, feaces, sputum, nails of babies and very sick adults, books, ceiling boards and even inner lining of shoes.
Cockroaches travel from house to house, from dumps, drains and septic and sewers to houses inhabited by man and feed on food if unprotected both cooked and uncooked. Because they feed on faeces and filth cockroaches can easily contaminate food with germs and/or eggs of worms.
Cockroaches have health effects on man for two main reasons: a substance called allergen contained in their excreta, saliva and body skin and also because of the germs carried by cockroaches on their hairy legs.
The germs (bacteria and viruses) cockroaches carry can contaminate food which can lead to typhoid fever, food poisoning, pneumonia, and worm infestations.
1. Diarrhoea and Dysentery
Diarrhoea is the passage of watery stools more than three times a day. In the case of dysentery, stooling is also loose and more than three times but mixed with blood and mucus.
Diarrhoea is caused by over twenty five different types of bacteria, viruses and parasites while dysentery is caused by a bacterium called shigella in most cases.
The germs causing diarrhea and dysentery are passed in stool and can contaminate food through flies and /or cockroaches.
2. Cholera
Cholera is a disease of the intestines characterised by very frequent and very watery stools and vomiting. It has been responsible for several epidemics (affecting many people simultaneously in an area) and pandemics (affecting a whole country/ whole continent/the world).
The period between infection and symptoms varies from 2 to 5 days.
Up to date, Cholera has caused seven pandemics with six occurring before 1923. Most of the six pandemics originated in India and Bangladesh. The seventh epidemic which is apparently still on started in 1961 in Indonesia spreading to South-East Asia in 1962 and the rest of Asia in the following years. In 1970, it reached Europe and some parts of Africa involving about 28 countries in the 1970s before regressing to India and Bangladesh. In 1991, the pandemic spread to South and Central America. In 1993, 80 countries reported cholera epidemics, 2003, – 45 countries with 894 deaths. The disease has drastically declined in developed countries, now mainly in developing/underdeveloped countries of Africa, South – east Asia, South and Central America. Only imported cases are reported in developed countries.
Cholera has been reported in the following African countries in the last five years Rwanda, Zimbabwe, Zambia, Guinea, Democratic Republic of Congo, Chad, Mali, DR Congo, Mozambique, Angola, Nigeria, Tanzania, Burundi, Uganda, Rwanda, Sierra Leone among others.
In 2013, 18 countries in Africa including Nigeria were affected. The World Health Organisation (WHO) estimates about 3-5million cholera cases are recorded in a year with about 100,000 to 120,000 deaths.
It is caused by a bacterium-Vibrio Cholerae which has about four strains.
Man is the reservoir of the infection. It is transmitted through water or food contaminated by the stool of an infected person directly (either sick or not, about 3 days before the onset of symptoms and up to 3-4 weeks after recovery) or indirectly by flies/cockroaches.
3. Typhoid fever
Typhoid fever is caused by a bacterium called Salmonella Typhi; there are three types of the bacterium: O, H and Vi. The bacterium can thrive in extreme temperatures-freezing temperatures and very hot and dry conditions, thus it survives in ice, frozen foods and dust.
Man is the reservoir of the agent and can continue to spread the disease even long after he has recovered from the illness and in a few unfortunate cases he can continue to spread it for life.
Typhoid fever spreads through contaminated food and water. The agent is passed out in the stool of an infected person; it may also be present in his urine, spite or vomit.
Food/ Water can be contaminated by cockroaches which can carry the agent from the stool of an infected person
4. Poliomyelitis
Polio (A.K.A. Poliomyelitis) is an extremely contagious and debilitating disease caused by the polio virus. It occasionally causes death but the infection leads to paralysis, death results if the respiratory muscles are paralyzed.  Polio is only found in human and spreads from person to person through food, water and hands contaminated by faeces (stool) containing the virus.  Uncovered food can also be contaminated by flies and/or cockroaches carrying faces containing the virus.  The virus attacks the brain and the spinal cord.
5. Worm infestations
Cockroaches are found in corners of gardens where their hairy bodies can pick up eggs of worms such as round worms (ascaris) and whipworm and then contaminate human food.
6. Allergy
A substance called allergen is contained in excreta, saliva and body skin of cockroaches, owing to the allergens mentioned above, cockroaches trigger allergies in man, this is shown by increased asthmatic attacks in asthmatics, skin rash, running nostrils and breathing problems.

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