MATERIALES COMPUESTOS REFORZADOS CON FIBRAS

Study area

The study was conducted at Federal Medical Centre Owerri. Owerri is the capital of Imo State in the South East geopolitical zone of Nigeria.

The state has a population of 3.93 million.¹¹⁵ It lies within latitude 4⁰45’North and 7⁰15’North, and longitude 6⁰50’East and 7⁰25’ East . It has an average annual rainfall of 60-80 inches per annum and average annual temperature of >20⁰C. Relative humidity is 75%, reaching 90% in rainy season.⁶⁹ Owerri, therefore, has the typical tropical climate necessary for transmission of malaria. It is hyper-endemic for malaria with fairly stable transmission all round the year.¹¹⁶

The study centre is the major health care facility in the state serving as a referral centre while at the same time undertaking primary health care services for those living in Owerri metropolis as well as the surrounding towns. The obstetric unit of the hospital has about three thousand six hundred deliveries per annum and an average of 9 deliveries per day. Close to the obstetrics ward are the postnatal ward and the Special Care Baby unit (SCBU).

There is also a modern laboratory facility equipped for appropriate diagnosis of most endemic illnesses and WHO certified malaria

Study design

This is a cross-sectional descriptive study.

Study duration

The study was carried out over two months, from July to August 2011.

Study population

Inclusion criteria included:

-Live neonate delivered at the study centre and the mother -Newborns less than 7 days

-Mothers who gave informed consent Exclusion criteria included:

-Babies with gross congenital abnormalities -Babies with perinatal asphyxia

-mothers who are clinically unstable

-Mothers currently on curative antimalarials.

Sample size determination

The sample size needed to achieve a precision of 5% at 95% confidence level was determined using the formula below.¹¹⁷

“n” = z²pq d²

Where “n” = the desired sample size

z = the standard normal deviation usually set at 1.96. This corresponds to 95% confidence level.

p = the proportion or the target population estimated to have a particular characteristic. Using the prevalence rate of 15.3%

documented by Mukhtar et al in congenital malaria in Lagos, Nigeria.³²

q = 1.0 – p, q = 0.847

d = Degree of accuracy desired or precision, set at 5% or 0.05, “n” = (1.96)² x (0.153) x (0.847)

(0.0025)²

“n” = 200

The sample size was increased to 230 pairs of mothers and babies to allow for exigencies using 15% attrition rate.

Sampling Technique

Mother/baby pairs were enrolled consecutively. Every delivery that fulfilled the inclusion criteria was enrolled until the sample size was reached.

Materials Used For The Study Glass slides with frosted end Graphite pencil

Slide rack Slide box

Methylated spirit swab Lancets

Syringes, thermometer Blades

EDTA bottles Gauze

Capillary tubes Plastacin

Microhaematocrit centrifuge

Micropippete, staining trough, draining rack Microscope

Masking tape Notebook and pen Geimsa powder

Geimsa stock/bench solutions, water

Training of Research Assistants

The method of sample collection was explained to the labour ward nurses who helped in the collection of samples from the placenta and the cord in the absence of the researcher. Smears were made from the samples later on, usually within one hour, by the researcher.

DATA COLLECTION PROCEDURE

The mother who fulfilled the inclusion criteria was recruited once labour was established. A questionnaire was administered by the researcher to the mother to get the bio-data, and obstetric history.

Peripheral blood was collected from the mother for malaria parasitaemia. The HIV status of the mothers was obtained from the folders as it’s the hospital policy to have all the pregnant women presenting in or before labour screened for HIV free of charge. At delivery, cord blood was collected into an EDTA bottle, while avoiding contamination as much as possible.⁴² This was used for baby’s hematocrit and to make a thick film for malaria parasite. Shortly after the placenta was delivered, an incision was made on the maternal surfacewith a blade, after wiping it.^11,48,89 Blood was allowed to ooze into the space and with a syringe, blood was drawn into an EDTA bottle for making a thick film. The newborn was weighed on a standardized Bassinet scale with an accuracy of 0.05kg and the gestational age assessed using the last menstrual period and the new Ballard score, when the gestational age is in doubt.¹¹⁸The baby was also examined, at the same time, for any abnormality. Warmth was provided with a radiant warmer and once mother was stable, she was handed over the baby for breastfeeding and bonding. After stabilization of both the mother and the baby, in the lying-in ward,

baby’s axillary temperature was measured using a mecury in- glass thermometer.

Thick blood smear was made from baby’s blood by pricking the heel with a sterile lancet, after wiping it with a spirit swab. Generally, blood smears were made from the respective EDTA bottles by drawing up 6ul of the blood with a micropippete. They were then air dried in a horizontal position and packaged in a slide pack to keep them away from dust and flies. The slides were then sent to the laboratory in batches where the researcher stained the smears with 10% freshly prepared Giemsa stain maintained at a p^H of 7.2 for 10 minutes. The stains were then rinsed off by dipping them in buffered water and latter kept vertically on a drying rack to dry. The Geimsa stain for each day was freshly prepared from the stock solution. The stained blood smear was viewed under a light microscope using x100 objective lens of the microscope in oil immersion and the diagnosis of malaria was based on the identification of asexual forms of Plasmodium on the thick blood smears.

Blood film was declared negative if no parasite was seen after viewing 200 microscopic fields.

A baby was regarded as having congenital malaria once the asexual form of P.falciparum was identified in it’s peripheral and/or cord blood irrespective of the presence of clinical symptoms.^55-57,119

The staining procedure, including the daily preparation of fresh Giemsa and the staining technique was often crosschecked by the malaria microscopist.

Parasite density was calculated for the positive films as follows:

 Two tally counters were used to count parasites and leucocytes separately.

 Counting of the parasites continued until 200 leucocytes were counted.

 The formula below was then used to calculate the parasite density: No of parasites x 8000

No of leucocytes = parasites/ul

An average of 8000 was used as the total White Blood Cell (WBC) count since the patients’ total WBC counts were not available.¹⁰⁸

The blood sample collected from each baby’s cord for hematocrit was spun in a Hawksley micro-hematocrit centrifuge using two capillary tubes at 12,000 rpm for 5 minutes and read off with a Hawksley haematocrit reader. This was done in the departmental side laboratory. An average of the two readings is taken and documented.

A child was regarded as being anaemic if hematocrit was less than 36.5%.¹²⁰

All the babies were examined on the day of delivery but only the babies with malaria parasitemia were further examined until they were

discharged from the hospital, for any feature of congenital malaria and other abnormalities. Temperature of greater than 37.5 [axillary] was regarded as fever.^121-122

Symptomatic babies were referred to Special Care Baby Unit (SCBU) for further investigations and appropriate management.

The mothers of parasitaemic babies who were asymptomatic were counselled to bring them back to the hospital if any symptom develops subsequently.^2,14 The researcher explained to the mothers what the symptoms may look like and also gave out her phone number to such mothers should they need to make any inquiry.

DATA COLLATION AND ANALYSIS

The data collected was sorted, coded and entered into SPSS version 16.0 software. Frequency tables were used to present relevant variables. Tables and charts were used to illustrate important observed patterns. Descriptive statistics such as mode was used to summarize number of parasitaemia in blood samples while qualitative variables (socio-demographic characteristics etc.) were summarized by proportions. Prevalence of congenital malaria was determined by calculating the proportion of babies with parasitaemia to overall sample of babies. The relationship between placental parasitaemia, peripheral blood parasitaemia in mothers and occurrence of congenital

parasitaemia was tested using chi-square. Chi-square test was used to investigate association between categorical variable (use of preventive measures) and occurrence of congenital malaria while Odd ratio was used to calculate the relative risk. Student t-test was used where applicable to compare means. All analyses were done at the 5% level of significance with P<0.05 considered statistically significant.

Ethical Considerations

1) The approval for the study was obtained from the ethical committee of Federal Medical Centre, Owerri.

2) Permission was obtained from the management of the labour ward, paediatrics unit,and the microbiology department.

3) Written consent was obtained from the mothers.

4) The participants were tested for malaria parasites and the

symptomatic ones appropriately referred for further investigations and management.